In-situ gel-forming enema with rifamycin for treatment of pouchitis and distal ulcerative colitis

Abstract

FIELD: pharmaceutical industry.SUBSTANCE: use of a pharmaceutical composition in the treatment of pouchitis, proctitis and / or ulcerative colitis of distal areas, including proctosigmoiditis, wherein the pharmaceutical composition comprises: a therapeutically effective amount of rifamycin SV or a pharmaceutically acceptable salt thereof; and a polymer mixture; wherein the pharmaceutical composition is formulated in such a way that it is suitable for rectal administration, is a liquid at room temperature and forms a gel in situ at the body temperature of said patient; wherein the polymer mixture comprises: at least one thermosensitive polymer; at least one ion-sensitive polymer; and at least one bioadhesive polymer.EFFECT: formation of a gel-forming in situ retention enema containing rifamycin SV, an extension of the contact time with the mucous membrane and a delayed release of the active substance locally over time.23 cl, 24 dwg, 10 tbl, 19 ex

Description

State of the art

[0001] The present invention relates to an in situ gelling enema containing rifamycin SV (also referred to herein as rifamycin) and its use in the treatment of pouchitis, proctitis, and distal ulcerative colitis (including proctosigmoiditis). More specifically, the present invention describes a long-acting in situ gelling retention enema containing rifamycin SV for the treatment, amelioration, reduction in severity, or slowing down the progression of pouchitis.

[0002] Publications and other materials used in this document to highlight the state of the art or to provide additional data concerning practical application are incorporated by reference and are grouped for convenience accordingly in the bibliography.

[0003] A potential surgical treatment option for both ulcerative colitis (UC) and familial adenomatous polyposis (FAP) is anal sphincter-preserving reconstructive proctocolectomy (RPC) followed by ileal pouch-anal reconstruction (IPAA), which recreates a fecal reservoir [Li and Shen, 2014]. Although this surgical procedure improved patients' quality of life and significantly reduced the risk of dysplasia or neoplasia in patients with ulcerative colitis, complications are common.

[0004] Pouchitis is an inflammatory disease of the ileal pouch, an artificial rectum surgically created from ileal tissue. It is the most common long-term complication of ileal pouch surgery and has a significant adverse impact on patients’ quality of life [Li and Shen, 2014]. Approximately 50% of patients with IPAA in ulcerative colitis develop at least one episode of subsequent ileal pouchitis (pouchitis), which may develop into a long-term complication [Li and Shen, 2014]. On the other hand, only 0-11% of patients with FAP develop pouchitis. These data suggest that pouchitis is less related to the structure of the pouch but is a function of the underlying immune dysregulation of the patient interacting with the pouch.

[0005] Pouchitis, similar to inflammatory bowel disease (IBD), is a complex condition that is not caused by a single factor. Rather, it likely arises from a combination of both dysregulated host inflammatory mechanisms and interactions with the intestinal microbiota. Bacterial overgrowth and fecal impaction in the small intestine can contribute to the development of pouchitis. Therefore, most patients with pouchitis are treated with antibiotics.

[0006] The most common indicative symptoms of pouchitis include dysfunction associated with increased bowel frequency, changes in stool consistency, rectorrhagia, pain, abdominal cramping, urgency, tenesmus, fecal incontinence, fever, and extraintestinal manifestations. Clinical diagnosis should preferably be confirmed by endoscopy and biopsy of the pouch mucosa. Endoscopic examination reveals inflammatory changes, which may include mucosal edema, granular texture, contact bleeding, loss of vascular markings, hemorrhage, and ulceration. Histological examination reveals acute inflammation, including neutrophilic infiltration and mucosal ulceration, superimposed on a background of chronic inflammation, including intestinal villous atrophy, crypt hyperplasia, and chronic inflammatory cell infiltration.

[0007] Pouchitis is classified as acute or chronic pouchitis. Acute pouchitis is characterized by symptoms present for up to 4 weeks and responding to 2-week courses of antibiotics. Chronic pouchitis is characterized by symptoms present for more than 4 weeks (>4 weeks) despite standard courses of antibiotics and requiring continued antibiotic or anti-inflammatory therapy [Isaacs et al., 2007]. Approximately 10-15% of patients with acute pouchitis develop chronic pouchitis, which has subgroups such as antibiotic-dependent pouchitis and antibiotic-resistant pouchitis.

[0008] The diagnosis of pouchitis is based on a combined assessment of symptoms, endoscopic findings, and histological examinations. Sandborn et al. (1994) proposed the pouchitis activity index (PDAI), which is a 19-point index of pouchitis activity based on both clinical symptoms and endoscopic and histological findings. Active pouchitis is defined as a PDAI>7, and remission is defined as a PDAI <7 [Nguyen, 2019]. A later study showed that excluding histological findings from the PDAI (modified PDAI) can provide similar diagnostic accuracy compared to the PDAI for patients with acute pouchitis [Akiyama et al., 2021].

[0009] The pathogenesis of pouchitis is not fully understood, but various hypotheses have been proposed, including: (1) recurrent UC, (2) dysbiosis of the ileal microbiota, (3) short-chain fatty acid deficiency, (4) mucosal ischemia and free oxygen radical damage, (5) host genetic susceptibility, and (6) immune dysregulation. However, none of these hypotheses alone can fully explain the pathogenesis of pouchitis. It has been suggested that pouchitis may represent a new third form of inflammatory bowel disease (IBD). Similar to IBD, pouchitis is a complex disease not caused by a single factor. It is more likely that pouchitis occurs through a combination of both dysregulated host inflammatory mechanisms and interactions with the luminal microbiota.Bacteria have been implicated in the disease mechanism, as bacterial overgrowth and fecal impaction in the small intestine can contribute to the development of pouchitis.

[0010] Although pouchitis has not been well studied, most patients with pouchitis are treated with antibiotics. While antibiotics provide some clinical benefit in Crohn's disease (CD), this effect is significantly less than in the treatment of pouchitis, in which antibiotics are more effective than any other treatment. While many different treatments for pouchitis have been reported with varying results, antibiotic treatment remains the most studied and is the mainstay of treatment. {0011} Pouchitis is classified into three categories based on its response to standard antibiotic-based drug therapy: (1) antibiotic-responsive, (2) antibiotic-dependent, and (3) antibiotic-resistant. Patients who respond positively to a 10- to 14-day course of antibiotics are considered antibiotic-responsive.Approximately 7-19% of patients with pouchitis require long-term, continuous antibiotic treatment to maintain remission, and these patients are considered antibiotic-dependent. A small percentage of patients (<5%) can be classified as antibiotic-resistant. These patients do not respond to antibiotic therapy and often require aminosalicylates (e.g., mesalamine), immunosuppressants (e.g., 6-mercaptopurine), or biologics to induce or maintain remission [Schieffer et al., 2016].

[0012] Treatment for pouchitis is primarily oral, but several topical treatments, such as enemas and gels, including in-situ gels, are in development. For example, CN 102151242 describes a delayed-release in-situ gel containing microspheres of the active ingredient and a temperature-sensitive in-situ gel. The identified active ingredients include rifampin in the list of active ingredients.

[0013] Al-Joufi, F., et al. (2021) describe rectal mucoadhesive gels and in situ rectal gels containing, for example, rifampicin.

[0014] WO 2019 / 122253 describes a liquid composition, which may be a structured viscous composition or a soft gel, containing two or three specific polymers for the in situ delivery or release of an active substance. The active substance may be antimicrobial agents or antibiotics selected from, among others, rifamycin SV, rifaximin, and rifampicin. The liquid composition can be used in the diagnosis, prevention, alleviation, treatment, and / or reduction of pathologies or disorders affecting the human body, including pathologies or disorders that affect the gastrointestinal tract, such as disorders that are inflammatory and / or degenerative pathologies. Example 11 describes a liquid composition containing three specific polymers and rifamycin SV for the treatment of fistula.

[0015] Rifamycin SV is a semi-synthetic antibacterial drug belonging to the ansamycin class; it exhibits its antibacterial activity by irreversibly binding to the β-subunit of bacterial DNA-dependent RNA polymerase, thereby inhibiting bacterial RNA synthesis. Rifamycin SV exhibits antibacterial activity against most bacterial enteropathogens commonly associated with infectious diarrhea and other intestinal infections, including Enterobacteriaceae and non-Enterobacteriaceae [Clin Drug Investig 2019 Jul., 39(7):691-697]. Rifamycin SV corresponds to the sodium salt of rifamycin or rifamycin sodium. In colonic diseases such as diverticulitis, inflammatory bowel syndrome (IBS), or IBD, bacterial proliferation or microbial dysbiosis are associated with a strong inflammatory component. This inflammation has a significant impact on the liver via the gut-liver axis.Rifamycin SV exhibits anti-inflammatory activity based on its effects on two key regulators of inflammation: pregnane X receptor (PXR) and nuclear factor-κB (NFκB). Rifamycin SV was found to activate PXR and its two downstream targets, cytochrome P450 3A4 (CYP3A4) and P-glycoprotein (PgP), in liver and intestinal cell lines. Rifamycin also directly inhibited NFκB in a cell line lacking PXR expression [Rosette et al., 2019]. This dual activity likely explains the inhibition of proinflammatory cytokine secretion by human colon cell lines and activated CD4+ T cells [Rosette et al., 2013]. Rifamycin exhibits its clinical effect by local action on the intestinal tract (J-reservoir, or S-reservoir, or W-reservoir in the case of pouchitis) and is characterized by insignificant absorption into the bloodstream.Rifamycin is a safe drug and has a favorable safety profile compared to, for example, ciprofloxacin and metronidazole, which are currently used in the treatment of gastrointestinal diseases with an inflammatory component, such as pouchitis, proctitis, or ulcerative colitis.

[0016] Proctitis and / or distal ulcerative colitis are inflammatory diseases often associated with IBD in terms of symptoms and causes. Proctitis is an inflammation of the rectal mucosa. Depending on the cause, proctitis may occur suddenly and last a short time or be long-lasting with frequent relapses. In relation to IBD in general, bacterial overgrowth and / or dysregulation may be an aggravating factor. Distal ulcerative colitis defines diseases affecting the area distal to the splenic flexure, which includes proctitis (affecting only the rectum), proctosigmoiditis (affecting the rectum and sigmoid colon), and left-sided colitis (affecting the descending colon or splenic flexure).

[0017] UC, along with Crohn's disease, is one of the main forms of IBD. UC is a chronic disease characterized by inflammation and ulceration of the colon and rectum, resulting in the main clinical symptoms: rectal bleeding, diarrhea, urgency, abdominal pain, tenesmus, and fever. Although the exact pathogenesis of UC is not fully understood, it is widely recognized in the scientific community that altered interactions between the host intestinal immune system and commensal bacteria that normally colonize the human colon play a primary role in the pathogenesis of the disease. This altered interaction is exacerbated by impaired barrier function of the epithelium lining the colonic mucosa, which leads to innate immune cells (e.g., dendritic cells and macrophages) interacting with commensal microbiota and their antigens. This leads to an aberrant immune response and subsequent inflammation.Initially, UC most often affects the rectum (ulcerative proctitis); thereafter, the inflammation may extend proximally, involving the sigmoid colon (proctosigmoiditis) and the descending colon up to the splenic flexure (distal UC, also known as left-sided UC). Inflammation extending beyond the splenic flexure is known as total UC (or pancolitis). A recent systematic review of the literature found that at diagnosis, approximately 40.1% of patients have distal UC, 30.5% have total colitis, and 29.4% have proctitis [Fumiery wet al., 2018].

[0018] Current clinical guidelines for the treatment of UC, including American and European guidelines, recommend the use of topical (rectal) treatment in patients with proctitis, proctosigmoiditis, or distal UC. First-line therapy consists of rectal preparations containing 5-aminosalicylic acid (also known as mesalamine or mesalazine), and second-line therapy consists of rectal preparations containing corticosteroids (eg, budesonide or hydrocortisone). These rectal treatments are available in the form of suppositories (used to treat proctitis), as well as enemas or rectal foams (used to treat proctosigmoiditis and distal UC). However, all approved products have the disadvantage of remaining liquid upon insertion (enemas and foams) or becoming liquid upon insertion (suppositories).Therefore, these products can be easily eliminated by the patient after administration, resulting in reduced contact time at the site of action and loss of activity over time. Furthermore, these approved products only exert anti-inflammatory activity and do not target the bacterial component of the disease, which plays a primary role in its pathogenesis. Finally, most clinical trials of UC, including studies of biologic agents (e.g., anti-TNFα or anti-integrin monoclonal antibodies), have specific exclusion criteria to exclude patients diagnosed with proctitis. Therefore, most recently approved drugs for the treatment of UC are not approved for the treatment of proctitis.

[0019] Therefore, there is a specific medical need for a new effective drug intended for the treatment of proctitis, proctosigmoiditis and / or distal UC.Brief disclosure of the present invention

[0020] The present invention relates to an in-situ gelling enema containing rifamycin SV (also referred to herein as rifamycin) or its pharmaceutically acceptable salts, and its use in the treatment of pouchitis and / or proctitis and / or distal ulcerative colitis (including proctosigmoiditis). The present invention also relates to a method of treating pouchitis by administering an (in-situ gelling) enema containing rifamycin SV or its pharmaceutically acceptable salts to a subject in need of such treatment. The present invention further relates to a method of treating proctitis and / or distal ulcerative colitis (including proctosigmoiditis) by administering an in-situ gelling enema containing rifamycin SV or its pharmaceutically acceptable salts to a subject in need of such treatment.The present invention further relates to the use of the pharmaceutical compositions disclosed herein containing rifamycin SV in the manufacture of a medicament for the treatment of pouchitis. The present invention further relates to the use of the pharmaceutical compositions disclosed herein containing rifamycin SV or pharmaceutically acceptable salts thereof in the manufacture of a medicament for the treatment of proctitis and / or distal ulcerative colitis (including proctosigmoiditis). More specifically, the present invention describes a long-acting in situ gelling enema containing rifamycin SV for the treatment, amelioration, reduction in severity, induction, maintenance of remission, and / or slowing the progression of pouchitis.Furthermore, the present invention describes a long-acting, in-situ gelling enema containing rifamycin SV or its pharmaceutically acceptable salts for the treatment, amelioration, reduction in severity, induction, maintenance of remission, and / or slowing of the progression of proctitis and / or distal ulcerative colitis (including proctosigmoiditis). Accordingly, the composition of the invention can be a ready-to-use enema solution. Furthermore, the present invention provides an enema kit containing the composition of the present invention. The enema kit can comprise a container and a cannula. The cannula is suitable for administering the enema solution through the rectum. Accordingly, the composition comprises water or a physiologically acceptable solvent and, optionally, an alcohol, such as ethanol.For example, the liquid carrier may be water or a physiologically acceptable solvent, or a mixture of water and one or more physiologically acceptable solvents. Typical such solvents include, for example, glycerol, ethylene glycol, propylene glycol, polyethylene glycol, and polypropylene glycol. Water is a particularly preferred liquid carrier.

[0021] According to one aspect, the invention relates to a pharmaceutical composition comprising an active substance and a polymer mixture as described herein. The pharmaceutical composition can form a gel in situ upon contact with the target site of action (the distal part of the gastrointestinal tract and / or an artificial cavity created surgically, such as an ileal reservoir), ileal reservoir), providing an extension of the contact time with the mucosa, providing a sustained release of the active substance locally over time. This means that the pharmaceutical composition can provide a composition that, when applied to the intestinal mucosa, turns into a long-acting gel that acts for some time on the target site.According to one embodiment, the polymer mixture comprises at least one thermosensitive polymer (first polymer), at least one ion-sensitive polymer (second polymer), and at least one bioadhesive polymer (third polymer).

[0022] According to one embodiment, the first polymer is selected from the group including, but not limited to: block copolymers of polyoxyethylene and polyoxypropylene such as poloxamer 124, poloxamer 188, poloxamer 237, poloxamer 338, poloxamer 407, etc., block copolymers of poly(ethylene glycol) / poly(lactide-co-glycolide) (PEG-PLGA), poly(ethylene glycol)-poly(lactic acid)-poly(ethylene glycol) (PEG-PLA-PEG), poly(N-isopropylacrylamide) and cellulose derivatives such as methylcellulose (MC) and hydroxypropyl methylcellulose (HPMC), etc., and mixtures thereof.

[0023] According to another embodiment, the second polymer is selected from the group including, but not limited to, carrageenan, gellan gum, pectin, alginate, alginate salts, and the like, and mixtures thereof.

[0024] According to a further embodiment, the third polymer is selected from the group including, but not limited to: chitosan, hyaluronic acid and its salts, cellulose derivatives such as methylcellulose, hydroxypropyl methylcellulose, hydroxypropyl cellulose, sodium carboxymethylcellulose, etc., polyvinyl alcohol, polyvinylpyrrolidone, polyacrylic acid, polyethylene oxides, cyclodextrins, tragacanth, sodium alginate, xanthan gum, gelatin, pectin, etc. and mixtures thereof.

[0025] The pharmaceutical composition may further comprise at least one other excipient, such as, for example, antioxidants, chelating agents, preservatives, antimicrobial agents, surfactants, co-surfactants, lipophilic compounds, purified water, organic salts, inorganic salts, buffering agents, or mixtures thereof. According to a preferred embodiment, the pharmaceutical composition further comprises at least one antioxidant and at least one preservative.

[0026] According to a second aspect, the invention relates to the use of a pharmaceutical composition as a long-acting in situ gelling enema for the treatment, alleviation of intensity, reduction of severity, slowing of progression, induction of remission or maintenance of remission of pouchitis and / or proctitis and / or distal ulcerative colitis (including proctosigmoiditis). According to a preferred embodiment, the active substance is rifamycin SV.

[0027] According to one embodiment, the long-acting in situ gel-forming enema is a retention enema capable of providing a delayed release of an active ingredient, ensuring that the drug remains embedded in a thin gel layer in close contact with the site of action, prolonging the duration of its pharmacological activity in situ.

[0028] According to a third aspect, the invention relates to a method for treating, ameliorating, reducing the severity, slowing the progression, inducing remission, or maintaining remission of pouchitis, said method comprising administering a pharmaceutical composition in the form of a long-acting in situ gelling enema to a patient in need of such treatment. According to a preferred embodiment, the active substance is rifamycin SV or its pharmaceutically acceptable salts.

[0029] According to another aspect, the invention relates to a method for treating, ameliorating, reducing the severity, slowing the progression, inducing remission or maintaining remission of proctitis and / or distal ulcerative colitis (including proctosigmoiditis), said method comprising administering a pharmaceutical composition in the form of a long-acting in situ gel-forming enema to a patient in need of such treatment. According to a preferred embodiment, the active substance is rifamycin SV or its pharmaceutically acceptable salts.

[0030] According to one embodiment, the pharmaceutical composition is administered rectally to a human patient.

[0031] According to a fourth aspect, the invention relates to the use of a pharmaceutical composition comprising rifamycin SV or pharmaceutically acceptable salts thereof, as described herein, in the manufacture of a medicament for the treatment of pouchitis.

[0032] According to another aspect, the invention relates to the use of a pharmaceutical composition comprising rifamycin SV or pharmaceutically acceptable salts thereof, as described herein, in the manufacture of a medicament for the treatment of proctitis and / or distal ulcerative colitis (including proctosigmoiditis. Brief description of the figures

[0033] The drawings directly relate to the examples given in this document and are explained in detail later in this document.

[0034] Fig. 1 shows the measurement region of the DoE (DoE design of experiment) method, "simplex centroid design", used to determine the optimal quantitative composition of the polymer mixture.

[0035] Fig. 2 shows the viscosity curves of experiments 1-6 and experiments 8-9 with rifamycin SV both at a temperature of 25°C and at a temperature of 37°C.

[0036] Fig. 3 shows the temperature range for experiment 2 at a frequency of 10 Hz.

[0037] Fig. 4 shows the Fmax values ​​for experiments 1-10 in the presence and absence (control sample) of mucin at a concentration of 8% w / w.

[0038] Fig. 5 shows the adhesion work for experiments 1-10 in the presence and absence (control sample) of mucin at a concentration of 8% w / w.

[0039] Fig. 6 shows the contour graph of the normalized adhesion work.

[0040] Fig. 7 shows the measurement region of the DoE method, "factorial full design of experiment", used to determine the optimal quantitative composition of the polymer blend.

[0041] Fig. 8 shows the logarithmic viscosity curve of experiments 1-14 of the "factorial full design" with rifamycin SV.

[0042] Fig. 9 shows the temperature range of the carrier 9.

[0043] Fig. 10 shows the temperature range of the carrier 14.[004 4] Fig. 11 shows the contour graph of the normalized adhesion work.

[0045] Fig. 12 shows the loss tangent (tan 5) as a function of frequency at 25°C and 40°C.[004 6] Fig. 13 shows the time-dependent profiles for the placebo and rifamycin SV formulations.

[0047] Fig. 14 shows the viscosity curve at 37°C comparing the polymer blend without rifamycin SV (carrier) with pharmaceutical compositions containing 0.5% and 1% rifamycin SV.

[0048] Fig. 15 shows the MIC values ​​of rifamycin SV tested on bacteria involved in pouchitis.[004 9] Fig. 16 shows the zones of bacterial growth inhibition (mm) for rifamycin SV enema formulations in-situ and the MIC (μg / mL) for rifamycin SV.

[0050] Fig. 17 shows the stimulation of PXR transcriptional activity in a reporter cell line by rifamycin in situ enema formulations 7670 and 7574 and rifamycin SV.

[0051] Fig. 18 shows the inhibition of mTOR and S6R phosphorylation in primary human colonocytes.

[0052] Fig. 19 shows the stimulation of PXR transcriptional activity in a reporter cell line by in situ gel-forming rifamycin enema and rifamycin SV.

[0053] Fig. 20 shows images of the colon obtained at 0.5, 1, 2, 4, and 6 hours after a single administration of composition 7639 via enema to evaluate the stability of the gel in the colon. The area inside the rectangle indicates the area where the gel is clearly visible.

[0054] Fig. 21 shows the concentration of rifamycin (ng / g) in colon homogenates of rats treated with enema with composition 7 639 at different time points after administration.

[0055] Fig. 22A-D show the in vivo effects of the compounds tested in the DSS-induced colitis mouse model: in vivo colitis parameters. A. Body weight AUC; B. Colon weight / length (CW / CL); C. Clinical AUC score; D. Stool total score.

[0056] Fig. 23 shows the effects of the compounds tested in vivo in the mouse model of DSS-induced colitis: histological examination index.

[0057] Fig. 24 shows the concentration of rifamycin measured by HPLC-MS / MS in the colon of mice treated with the in situ gel-forming enema composition (designated as CB0125 in the figure) and rifamycin in water at the indicated time point after administration. Detailed disclosure of the present invention

[0058] The present invention relates to a composition comprising rifamycin SV having therapeutic use and preferably to an in-situ gelling enema comprising rifamycin SV (also referred to as rifamycin or rifamycin sodium) or its pharmaceutically acceptable salts, and its use in the treatment of diseases affecting the distal gastrointestinal tract. According to some embodiments, such diseases of the distal gastrointestinal tract may be selected from the group consisting of pouchitis and / or proctitis and / or ulcerative colitis of the distal portions (including proctosigmoiditis). As provided herein, the term "ulcerative colitis of the distal portions" (also known as left-sided ulcerative colitis) also includes ulcerative proctosigmoiditis (or simply proctosigmoiditis).The present invention also relates to a method for treating pouchitis, proctitis and / or distal ulcerative colitis (including proctosigmoiditis), comprising administering a pharmaceutical composition of the invention to a patient in need of such treatment, wherein said pharmaceutical composition is preferably provided in the form of an in-situ gel-forming enema containing rifamycin or its pharmaceutically acceptable salts as an active substance. The present invention also relates to the use of a pharmaceutical composition of the invention in the treatment of pouchitis and / or proctitis and / or distal ulcerative colitis (including proctosigmoiditis), characterized in that said pharmaceutical composition is administered to a subject in need of such treatment, preferably in the form of an in-situ gel-forming enema and containing rifamycin or its pharmaceutically acceptable salts as an active substance.Furthermore, the present invention relates to the use of the pharmaceutical composition described herein, containing rifamycin or pharmaceutically acceptable salts thereof, in the manufacture of a medicament for the treatment of pouchitis and / or proctitis and / or ulcerative colitis of the distal areas (including proctosigmoiditis).

[0059] The present invention also relates to a method for treating pouchitis and / or proctitis and / or ulcerative colitis of the distal areas (including proctosigmoiditis), comprising administering a pharmaceutical composition to a patient in need of such treatment, and using the pharmaceutical composition described herein containing rifamycin or its pharmaceutically acceptable salts in the manufacture of a medicament for treating proctitis and / or ulcerative colitis of the distal areas (including proctosigmoiditis).

[0060] More specifically, the present invention describes a long-acting in situ gelling enema containing rifamycin SV or its pharmaceutically acceptable salts, and its use for treating, ameliorating, reducing the severity, or slowing the progression of, inducing and / or maintaining remission of gastrointestinal diseases of the distal gastrointestinal tract. According to some embodiments, the long-acting in situ gelling enema is a retention enema. According to some embodiments, the long-acting in situ gelling enema provides sustained and / or prolonged action of the active ingredient at the site of action.

[0061] According to some embodiments, such a distal part of the gastrointestinal tract includes the distal colon (descending colon and sigmoid colon) and the rectum, more particularly the sigmoid colon and rectum. According to such embodiments, such diseases affecting the distal part of the gastrointestinal tract, more particularly the descending colon, sigmoid colon and rectum, can be selected from the group consisting of proctitis and / or ulcerative colitis of the distal portions (including proctosigmoiditis). According to an embodiment, such a disease affecting the distal part of the gastrointestinal tract is ulcerative colitis of the distal portions, including proctosigmoiditis. According to another embodiment, such a disease affecting the distal part of the gastrointestinal tract is proctitis.According to another embodiment, such a distal portion of the gastrointestinal tract comprises an artificial lumen created surgically due to disease or injury. In one embodiment, the lumen is an ileal reservoir (J-reservoir or S-reservoir or W-reservoir) created by surgical intervention with an ileoanal anastomosis (J-reservoir or S-reservoir or W-reservoir) or an ileostomy (K-reservoir). In this embodiment, the disease affecting the distal portion of the gastrointestinal tract, more specifically the ileal reservoir, is pouchitis.

[0062] According to one embodiment, the present disclosure describes a long-acting in situ gel-forming enema containing rifamycin SV or pharmaceutically acceptable salts thereof for treating, ameliorating, reducing the severity of, or slowing the progression of pouchitis.

[0063] According to one embodiment, the present invention describes a long-acting in situ gelling enema containing rifamycin SV or pharmaceutically acceptable salts thereof for the treatment, amelioration, reduction in severity, induction and / or maintenance of remission, or slowing the progression of proctitis. According to another embodiment, the present invention describes a long-acting in situ gelling retention enema containing rifamycin SV or pharmaceutically acceptable salts thereof for the treatment, amelioration, reduction in severity, induction and / or maintenance of remission, or slowing the progression of distal ulcerative colitis.According to a preferred embodiment, the present invention describes a long-acting, gelling, in situ retention enema containing rifamycin SV or pharmaceutically acceptable salts thereof for the treatment, amelioration, reduction in severity, induction and / or maintenance of remission, or slowing the progression of pouchitis. According to a further preferred embodiment, the present invention describes a long-acting, gelling, in situ retention enema containing rifamycin SV or pharmaceutically acceptable salts thereof for the treatment, amelioration, reduction in severity, induction and / or maintenance of remission, or slowing the progression of distal ulcerative colitis (including proctosigmoiditis).

[0064] According to one aspect, the invention relates to a pharmaceutical composition comprising rifamycin SV or its pharmaceutically acceptable salts, and a polymer mixture as described herein. The pharmaceutical composition is capable of forming a gel in situ upon contact with a site, providing sustained and / or prolonged release of the active substance locally over time at the target site. According to one embodiment, the polymer mixture comprises at least one thermosensitive polymer (first polymer), at least one ion-sensitive polymer (second polymer), and at least one bioadhesive polymer (third polymer).

[0065] The mechanisms of action of these polymers vary. The temperature-sensitive polymer (first polymer) forms a gel or is capable of creating a structure in the body or body cavity when the temperature reaches an appropriate range. The ion-sensitive polymer (second polymer) forms a gel or is capable of creating a structure with a biorelevant environment in the presence of specific ions in appropriate concentrations. The bioadhesive polymer (third polymer) provides improved adhesion of the pharmaceutical composition and improved retention time at the loading site. The bioadhesive polymer (third polymer) provides improved adhesion as a result of interaction with the mucosa of the distal gastrointestinal tract and / or a surgically created artificial cavity (ileopoietic reservoir).Together, the bioadhesive polymer improves the contact of the pharmaceutical composition with the body tissue, while the first and second polymers improve the structure of the gel-forming thin layer obtained by distributing the pharmaceutical composition on the target surface of the body, acting as a reservoir or a three-dimensional matrix system that provides durability and prolonged pharmacological activity.

[0066] According to one embodiment, the first polymer forms a gel or creates a structured state upon contact with a biorelevant environment or at normal body temperature (i.e., at approximately 37°C); the effect of the first polymer is further enhanced by the interaction of the second polymer with the target site, where the presence of specific trigger ions enhances the interaction with the environment of the other, which leads to an increase in the ability of the polymer mixture to form a gel or a structured state. Upon contact with a site in the body or a body cavity (e.g., the distal gastrointestinal tract and / or a surgically created artificial cavity, such as an ileal reservoir), characterized by normal body temperature (i.e., ≥34°C), the third polymer further provides and enhances the bioadhesive contact of the pharmaceutical composition with the body tissues.The polymer blend is effective due to the optimal blend of the first, second, and third polymers, which ensures synergy between the polymers themselves and the polymers and microenvironment, leading to enhanced gelation / structuring of the pharmaceutical composition at the target site. This enhanced gelation is demonstrated by a significant increase in the viscoelastic modulus G', as described in WO 2019 / 122253, incorporated herein by reference in its entirety.

[0067] Rifamycin SV was found to interact strongly with the polymer blend, and this interaction was investigated using the "mixture design plan" model, as described in the examples. Evaluation of the rheological properties of an in situ gelling composition is one of the most important parameters for predicting in vivo properties. Rheological properties particularly affect ease of administration and retention time in the target area. Rheological properties are determined at room temperature (25°C) and normal body temperature (37°C) to observe changes in the gel structure. Structural and dynamic properties are studied by determining G', the storage modulus (an indicator of elasticity), and G'', the loss modulus of elastic deformation (representing the viscous component).

[0068] Viscoelastic properties, characterized by the tendency of switching between G' (storage modulus) and G'' (viscous modulus), implying the thermogelation of the sample, and determined by the modulus of G' (storage modulus) at a temperature of 37°C, are compared with G'' (viscous modulus) at the same temperature. G' exceeds G'' at a temperature of 37°C, and the discrepancy between the two moduli is greater at a temperature of 37°C, indicating the formation of a strong gel or structured state and an increase in elasticity, and also confirms the transition from a liquid form to a gel state upon application or to a structured state after application. The transformation of sol into gel allows the composition to be distributed and applied to the site as a gel layer, followed by enhanced adhesion properties over a suitable long period of time.The transformation of the sol into gel is mainly initiated by an increase in body temperature upon administration, preferably into the reservoir cavity in the case of pouchitis, and interaction with the intestinal environment (mainly colonic fluid and / or colonic and / or reservoir mucosa), allowing rifamycin SV to remain embedded in a thin gel layer, in close contact with the site of action, and increasing the duration of its pharmacological activity in situ.

[0069] As described herein, a pharmaceutical composition comprises a polymer mixture comprising at least one thermosensitive polymer (first polymer), at least one ion-sensitive polymer (second polymer) and at least one bioadhesive polymer (third polymer) such that the composition can be easily administered to a patient in need of such treatment while providing a prolonged presence at the site of action for a desired period of time.

[0070] In preparing the pharmaceutical composition described herein, suitable thermosensitive polymers (first polymers) and their concentrations are selected to obtain a final composition that is in a liquid state at a temperature below body temperature (i.e., below about 37°C), preferably at a temperature of from about 20°C to about 25°C), and that becomes a gel or acquires a structured state when exposed to body temperature or above (i.e., at a temperature of about 37°C or above). It is known that rifamycin SV, which is an ionic macromolecule, potentially interacts with biopolymers, changing the corresponding properties (e.g., thermogelation and / or bioadhesive and / or ionotropic properties).The compositions of the present invention, containing a combination of the three above-mentioned polymers, unexpectedly make it possible to solve this problem and modulate the residence time of said compositions at the target site.

[0071] In obtaining the pharmaceutical composition described herein, the selection of a suitable ion-sensitive polymer (second polymer) and their concentration is carried out to obtain an appropriate sol-to-gel conversion or conversion into a structured composition in the presence of specific ions.

[0072] As described herein, the ion-sensitive polymer may be selected from those that are capable of binding mono- and / or divalent inorganic ions, such as Na + , K + , Mg 2+ , Sa 2+ and Zn 2+, and high-affinity organic ions. Sensitivity to ionic strength is a typical property of polymers containing ionizable groups. Changes in ionic strength can cause changes in the size of polymer micelles and polymer solubility.

[0073] Upon administration, the pharmaceutical composition of the invention, comprising the active substance, preferably rifamycin SV, and the polymer mixture as described herein, is automatically heated to body temperature (i.e., approximately 37°C). Such an increase in temperature triggers the transition of the pharmaceutical composition from a liquid state to a gel-like state (sol-to-gel transformation) or to a structured state due to the thermosensitive first polymer; then, due to the interaction of the ion-sensitive second polymer with ions present in the biorelevant medium and / or the surrounding environment, said gel or structured state is further strengthened, as evidenced by an increase in the viscoelastic modulus G'.[007 4] The transition from a liquid form to a gel or structured state increases the bioadhesiveness of the pharmaceutical composition, which is due to the presence of said at least one bioadhesive polymer (third polymer) in the polymer mixture, with a subsequent increase in adhesion to tissues, such as the intestinal or rectal mucosa, over a suitable period of time, as evidenced by the results of adhesion to the mucosa at a temperature of 37°C.

[0075] In addition, an increase in the viscoelastic modulus of the pharmaceutical composition slows down the diffusion of at least one active substance, delaying its delivery to the affected area, with a prolongation of the therapeutic effect.

[0076] When administered, the pharmaceutical compositions described herein are capable of forming a thin gel layer or structured layer (state) over the affected area, which has a reduced tendency to spread along the organ walls. This property maximizes the contact time of the pharmaceutical compositions described herein with the affected area: as a result, the active substance contained therein can remain in contact with the cell membrane of the epithelial cells of the mucosa for a longer period of time compared to other known compositions.

[0077] According to some embodiments, the pharmaceutical composition of the present invention can be used to treat diseases of the distal gastrointestinal tract, preferably in cases where the target site is covered by mucosal tissue, ensuring the process of bringing into contact. According to some embodiments, such a distal part of the gastrointestinal tract includes the distal part of the colon (i.e., the descending colon and sigmoid colon) and the rectum, more particularly the sigmoid colon and rectum. According to such embodiments, such diseases affecting the distal part of the gastrointestinal tract, more particularly the descending colon, sigmoid colon and rectum, can be selected from the group consisting of: proctitis and / or ulcerative colitis of the distal portions.According to an embodiment, such a disease affecting the distal gastrointestinal tract is distal colitis, including proctosigmoiditis. According to another embodiment, such a disease affecting the distal gastrointestinal tract is proctitis. According to another embodiment, such a distal gastrointestinal tract comprises an artificial cavity created surgically as a result of disease or injury. According to one embodiment, the cavity is an ileopoietic reservoir (J-pouch or S-pouch or W-pouch) created by surgical intervention with an ileoanal anastomosis (J-pouch or S-pouch or W-pouch) or an ileostomy (K-pouch). According to such an embodiment, the disease affecting the distal gastrointestinal tract, more particularly the ileopoietic reservoir, is pouchitis.

[0078] According to an embodiment, the administration of the pharmaceutical composition of the present invention to a subject in need of such treatment causes a remission of proctitis. According to another embodiment, the administration of the pharmaceutical compositions of the present invention to a subject in need of such treatment maintains a remission of proctitis. According to another embodiment, the administration of the pharmaceutical compositions of the present invention to a subject in need of such treatment causes a remission of distal ulcerative colitis (including proctosigmoiditis). According to another embodiment, the administration of the pharmaceutical compositions of the present invention to a subject in need of such treatment maintains a remission of distal ulcerative colitis (including proctosigmoiditis). According to a preferred embodiment, the administration of the pharmaceutical compositions of the present invention to a subject in need of such treatment causes a remission of pouchitis.According to another preferred embodiment, administration of the pharmaceutical compositions of the present invention to a subject in need of such treatment maintains remission of pouchitis.

[0079] According to some embodiments, the present invention discloses a method for inducing remission of a disease affecting the distal gastrointestinal tract, wherein such method comprises administering a pharmaceutical composition in the form of an in-situ gel-forming enema containing a rifamycin or pharmaceutically acceptable salts thereof to a subject in need of such treatment. According to some embodiments, the present invention discloses the use of a pharmaceutical composition in the form of an in-situ gel-forming enema containing a rifamycin or pharmaceutically acceptable salts thereof for inducing remission of a disease of the distal gastrointestinal tract in a subject in need of such treatment.According to some embodiments, the present invention discloses a method for maintaining remission of a disease affecting the distal gastrointestinal tract, wherein such method comprises administering a pharmaceutical composition in the form of an in situ gelling enema containing rifamycin or pharmaceutically acceptable salts to a subject in need of such treatment. According to some additional embodiments, the present invention discloses the use of a pharmaceutical composition in the form of an in situ gelling enema containing rifamycin or pharmaceutically acceptable salts thereof for maintaining remission of a distal gastrointestinal tract disease in a subject in need of such treatment. According to some embodiments, said distal gastrointestinal tract disease may be selected from the group consisting of pouchitis, ulcerative colitis of the distal portions (including proctosigmoiditis) and / or proctitis.According to a preferred embodiment, said distal gastrointestinal tract disease is distal ulcerative colitis (including proctosigmoiditis). In another preferred embodiment, said distal gastrointestinal tract disease is pouchitis.

[0080] For the purposes of the present invention, induction of remission and maintenance of remission shall be considered to include, but not be limited to, alleviation, amelioration, or reduction of clinical symptoms, endoscopic signs, or histological signs, or a combination thereof. According to one embodiment, administration of the pharmaceutical composition alleviates and / or alleviates and / or reduces the intensity of one or more clinical symptoms selected from the group including, but not limited to: an increase in the frequency of bowel movements (also referred to as a change in bowel rhythm); a change in stool consistency, rectorrhagia, hematochezia, pain, abdominal cramps, urge, tenesmus, fecal incontinence, fever, and / or extraintestinal manifestations, or a combination thereof.

[0081] The goal of pouchitis therapy is to alleviate symptoms and achieve and / or maintain clinical and endoscopic remission with demonstrated mucosal healing. Histological improvement (i.e., elimination of the acute inflammatory cell infiltrate) becomes an additional component of disease remission. Endoscopic healing is an important goal of therapy, since symptoms alone may not reflect the inflammatory status of the pouch. In one embodiment, administration of the pharmaceutical compositions of the present invention to a subject in need of such treatment induces remission of pouchitis. According to a second embodiment, administration of the pharmaceutical compositions of the present invention to a subject in need of such treatment maintains remission of pouchitis.For the purposes of the present invention, induction of remission and maintenance of remission should be understood as including, but not limited to, alleviation or reduction in the intensity or amelioration of clinical symptoms, endoscopic signs or histological signs, or a combination thereof. According to one embodiment, administration of the pharmaceutical composition alleviates and / or alleviates and / or reduces the intensity of one or more clinical symptoms selected from the group including, but not limited to: an increase in the frequency of bowel movements (also referred to as a change in bowel rhythm), a change in stool consistency, rectogenesis, hematochezia, pain, abdominal cramps, urge, tenesmus, fecal incontinence, fever, and / or extraintestinal manifestations, or a combination thereof.According to one embodiment, the administration of the pharmaceutical composition alleviates and / or attenuates and / or reduces the incidence of one or more endoscopic signs selected from the group including, but not limited to: blood and ulceration. According to an embodiment, the administration of the pharmaceutical composition alleviates and / or attenuates and / or reduces the incidence of one or more histological symptoms selected from the group including, but not limited to: polymorphic infiltration, ulceration, erosions, mononuclear leukocyte infiltration, and intestinal villous atrophy.

[0082] The treatment regimen and administration regimen of the composition of the present invention to subjects in need of such treatment can be adapted depending on the nature of the disease (e.g., acute or chronic), its severity, and the general condition of the patient. According to one embodiment, the treatment period with the composition of the present invention can last from about 2 weeks to about 4 weeks for each treatment cycle. According to some embodiments, the treatment period with the composition of the present invention can last about 1 week, 2 weeks, 3 weeks, or 4 weeks. According to a preferred embodiment, the treatment period with the composition of the present invention can last 2 weeks. According to another preferred embodiment, the treatment period with the composition of the present invention can last 4 weeks.

[0083] According to some embodiments, the treatment period with the composition of the present invention may last from about 2 weeks to about 8 weeks for each treatment cycle. According to some embodiments, the treatment period with the composition of the present invention may last about 2 weeks, 3 weeks, 4 weeks, 5 weeks, 6 weeks, 7 weeks, or 8 weeks. According to a preferred embodiment, the treatment period with the composition of the present invention may last 4 weeks. According to another preferred embodiment, the treatment period with the composition of the present invention may last 6 weeks. According to another preferred embodiment, the treatment period with the composition of the present invention may last 8 weeks.

[0084] According to some embodiments, the pharmaceutical composition of the present invention can be administered once a day, or twice a day, or three times a day, or four times a day. According to a preferred embodiment, the pharmaceutical composition of the present invention is administered once a day. According to another preferred embodiment, the pharmaceutical composition of the present invention is administered twice a day.

[0085] According to one embodiment, the pharmaceutical composition of the present invention containing 0.5% by weight of rifamycin SV can be administered once a day as a single dose via a 60 ml enema.

[0086] According to one embodiment, the pharmaceutical composition of the present invention containing 1.0% by weight of rifamycin SV can be administered once a day as a single dose via a 60 ml enema.

[0087] According to one embodiment, the pharmaceutical composition of the present invention containing 0.5% by weight of rifamycin SV can be administered twice a day as a single dose via a 60 ml enema.

[0088] According to one embodiment, the pharmaceutical composition of the present invention containing 1.0% by weight of rifamycin SV can be administered twice a day as a single dose via a 60 ml enema.

[0089] According to one embodiment, the pharmaceutical composition of the present invention containing 0.5% by weight of rifamycin SV can be administered once a day as a single dose via an 80 ml enema.

[0090] According to one embodiment, the pharmaceutical composition of the present invention containing 1.0% by weight of rifamycin SV can be administered once a day as a single dose via an 80 ml enema.

[0091] According to one embodiment, the pharmaceutical composition of the present invention containing 0.5% by weight of rifamycin SV can be administered twice a day as a single dose via an 80 ml enema.

[0092] According to one embodiment, the pharmaceutical composition of the present invention containing 1.0% by weight of rifamycin SV can be administered twice a day as a single dose via an 80 ml enema.

[0093] According to one embodiment, the pharmaceutical composition of the present invention containing 0.5% by weight of rifamycin SV can be administered once a day as a single dose via a 100 ml enema.

[0094] According to one embodiment, the pharmaceutical composition of the present invention containing 1.0% by weight of rifamycin SV can be administered once a day as a single dose via a 100 ml enema.

[0095] According to one embodiment, the pharmaceutical composition of the present invention containing 0.5% by weight of rifamycin SV can be administered twice a day as a single dose via a 100 ml enema.

[0096] According to one embodiment, the pharmaceutical composition of the present invention containing 1.0% by weight of rifamycin SV can be administered twice a day as a single dose via a 100 ml enema.

[0097] According to some embodiments, treatment with the pharmaceutical composition of the present invention can be administered once to achieve induction of remission or maintenance of remission of the disease in a subject in need of such treatment. According to other embodiments, treatment with the pharmaceutical compositions of the present invention can be repeated cyclically to maintain remission of the disease and / or prevent relapse of the disease in a subject in need of such treatment. According to further embodiments, such cyclic treatments with the pharmaceutical composition of the present invention can be repeated once a month, or every two months, or every three months, or every four months, or every five months, or every six months. According to a preferred embodiment, such cyclic treatment with the pharmaceutical composition of the present invention is repeated once a month.According to a preferred embodiment, such cyclic treatments with the pharmaceutical composition of the present invention are repeated once every two months. According to a further preferred embodiment, such cyclic treatment with the pharmaceutical composition of the present invention is repeated once every three months. The frequency of treatment cycles with the pharmaceutical composition of the present invention depends on the frequency of disease relapses. The frequency of treatment cycles with the pharmaceutical composition of the present invention depends on the maintenance of remission. According to some embodiments, the frequency of treatment courses in the case of maintaining remission is every month for two to four weeks. The administration regimen will depend on whether the pouchitis is acute or chronic, and whether the patient is responsive to antibiotic treatment or antibiotic-dependent.

[0098] According to one embodiment, at least one heat-sensitive polymer (the first polymer) is selected from the group including, but not limited to, block copolymers of polyoxyethylene and polyoxypropylene such as poloxamer 124, poloxamer 188, poloxamer 237, poloxamer 338, poloxamer 407, etc., block copolymers of poly(ethylene glycol) / poly(lactide-co-glycolide) (PEG-PLGA), poly(ethylene glycol)-poly(lactic acid)-poly(ethylene glycol) (PEG-PLA-PEG), poly(N-isopropylacrylamide), and cellulose derivatives such as methylcellulose (MC) and hydroxypropyl methylcellulose (HPMC), etc., and mixtures thereof.

[0099] According to a preferred embodiment, at least one temperature-sensitive polymer of the polymer mixture is poloxamer 188. According to another preferred embodiment, the temperature-sensitive polymer of the polymer mixture is poloxamer 407. According to a further preferred embodiment, the temperature-sensitive polymer of the polymer mixture includes some mixtures of poloxamer 188 and poloxamer 407. According to another preferred embodiment, the temperature-sensitive polymer of the polymer mixture is a cellulose derivative, preferably methylcellulose.

[00100] The amount of at least one thermosensitive polymer is in the range of from about 0.5% to about 30% by weight relative to the weight of the (liquid) pharmaceutical composition, preferably from about 1% to about 25% by weight relative to the weight of the liquid pharmaceutical composition, more preferably between about 12% and about 18% by weight relative to the weight of the liquid pharmaceutical composition. Optimal in-situ gelation occurs when at least one thermosensitive polymer is present in an amount of from about 12% by weight to about 18% by weight relative to the weight of the (liquid) pharmaceutical composition.

[00101] According to a preferred embodiment, said at least one temperature-sensitive polymer is present in an amount of about 0.5%, or about 1.0%, or about 5.0%, or about 10.0%, or about 14%, or about 15%, or about 16%, or about 16.5% by weight relative to the weight of the liquid pharmaceutical composition.

[00102] According to one embodiment, the at least one ion-sensitive polymer (second polymer) can be selected from a group of polysaccharides including, but not limited to, carrageenan, gellan gum, pectin, alginic acid and / or their salts. Any mixtures of said ion-sensitive polymers can be used to form the corresponding polymer mixture. According to a preferred embodiment, said at least one ion-sensitive acid is alginic acid and / or its salts.According to another embodiment, the at least one ion-sensitive polymer is sodium alginate.

[00103] According to one embodiment, the at least one ion-sensitive polymer is present in an amount that is in the range of from about 0.005% to about 5% by weight relative to the weight of the liquid pharmaceutical composition, more preferably from about 0.01% to about 5%, about 3% by weight relative to the weight of the liquid pharmaceutical composition, even more preferably from about 0.1% to about 2.0% by weight relative to the weight of the liquid pharmaceutical composition. Optimal in-situ gelling occurs when the at least one ion-sensitive polymer is present in an amount of from about 0.1% by weight to about 2.0% by weight relative to the weight of the (liquid) pharmaceutical composition.

[00104] According to a preferred embodiment, at least one ion-sensitive polymer is contained in an amount of about 0.1%, or about 0.2%, or about 0.3%, or about 0.4%, or about 0.5%, or about 1%, or about 2% by weight relative to the weight of the liquid pharmaceutical composition.

[00105] According to one embodiment, at least one bioadhesive polymer (the third polymer) is selected from the group including, but not limited to: chitosan, hyaluronic acid and its salts, cellulose derivatives such as methylcellulose, hydroxypropyl methylcellulose, hydroxypropyl cellulose, sodium carboxymethylcellulose, etc., polyvinyl alcohol, polyvinylpyrrolidone, polyacrylic acid, polyethylene oxides, tragacanth, sodium alginate, xanthan gum, gelatin, pectin, etc. and mixtures thereof.Any mixture of said bioadhesive polymers can be used to obtain suitable pharmaceutical compositions as defined herein.

[00106] According to a preferred embodiment, at least one bioadhesive polymer is sodium carboxymethylcellulose. According to another preferred embodiment, said at least one bioadhesive polymer is hyaluronic acid and / or a salt thereof. At least one bioadhesive polymer (the third polymer) provides an additional synergistic effect with the first and second polymers, which provides an improved level of adhesion of the pharmaceutical composition and a longer retention time at the desired site.

[00107] According to one embodiment, at least one bioadhesive polymer is contained in an amount that is in the range of about 0.005% to about 5% by weight relative to the weight of the pharmaceutical composition, more preferably from about 0.01% to about 2.0% by weight relative to the weight of the pharmaceutical composition, and even more preferably from about 0.05% to about 0.1% by weight relative to the weight of the pharmaceutical composition. Too much bioadhesive polymer can lead to gelation before administration. Optimal in-situ gelation occurs when the bioadhesive polymer is present in an amount of from about 0.05% by weight to about 0.1% by weight relative to the weight of the (liquid) pharmaceutical composition.

[00108] According to a preferred embodiment, at least one bioadhesive polymer is present in an amount of about 0.005% or about 0.01%, and preferably about 0.05%, by weight relative to the weight of the pharmaceutical composition.

[00109] According to one embodiment, the active substance present in the pharmaceutical composition is rifamycin SV or its pharmaceutically acceptable salts.Rifamycin SV or its pharmaceutically acceptable salts are contained in an amount that is in the range of from about 0.01% to about 10% by weight relative to the weight of the pharmaceutical composition, preferably from about 0.1% to about 5% by weight relative to the weight of the pharmaceutical composition, more preferably from about 0.25% to about 3% by weight relative to the weight of the pharmaceutical composition, for example, from about 0.25% to about 2.5% by weight relative to the weight of the pharmaceutical composition. In some embodiments, rifamycin SV or pharmaceutically acceptable salts thereof are present in an amount of about 0.1%, or 0.2%, or 0.3%, or 0.4%, or 0.5%, or 0.6%, or 0.7%, or 0.8%, or 0.9%, or 1.0%, or 1.1%, or 1.2%, or 1.3%, or 1.4%, or 1.5%, or 1.6%, or 1.7%, or 1.8%, or 1.9%, or 2.0%.According to a preferred embodiment, rifamycin SV or its pharmaceutically acceptable salts are contained in an amount of about 0.1% or about 0.2% or about 0.25% or about 0.3% or about 0.4% or about 0.5% or about 1% or 2.5%, and more preferably about 0.5% or 1.0% by weight relative to the weight of the pharmaceutical composition. According to one preferred embodiment, rifamycin SV or its pharmaceutically acceptable salts are contained in an amount of about 0.5% by weight relative to the weight of the pharmaceutical composition. According to another preferred embodiment, rifamycin SV or its pharmaceutically acceptable salts are contained in an amount of about 1.0% by weight relative to the weight of the pharmaceutical composition.According to one embodiment, the dosage of rifamycin SV or its pharmaceutically acceptable salts in the pharmaceutical composition of the present invention is determined to achieve a local concentration of rifamycin SV at the site of action that exceeds its minimum inhibitory concentration (MIC) for a specific bacterial population typically localized at that site. MIC is defined as the lowest concentration, expressed in mg / L (equivalent to μg / mL), of an antimicrobial or antibacterial active substance that is bacteriostatic, i.e., prevents visible bacterial growth. MICs are used to evaluate the antimicrobial efficacy of various compounds by measuring the effect of reducing antibiotic concentrations over a specified period in terms of inhibiting the growth of a microbial population. MIC is generally considered the most basic laboratory indicator of the activity of an antimicrobial substance against an organism.Since a lower MIC value indicates that less drug is required to inhibit the growth of an organism, drugs with lower MIC values ​​are more effective antimicrobial or antibacterial active substances.

[00110] According to one embodiment, the dosage of rifamycin SV can be determined based on the MIC value of rifamycin SV against bacteria typically present in and around the reservoir (J-reservoir or S-reservoir or W-reservoir), or surgical intervention - ileostomy (K-reservoir). According to one embodiment, the dosage of rifamycin SV can be selected based on the MIC values ​​against the typically present bacteria. The dosage of rifamycin SV can be a dosage that kills all bacteria that cause pouchitis.According to one embodiment, the pharmaceutical composition may be prepared to contain a given dose of rifamycin SV and stored for later use. According to another embodiment, the pharmaceutical composition may be prepared without the active substance and may be stored prior to use. A suitable dosage of rifamycin SV, as described herein above, may be added to said pharmaceutical composition prior to administration.

[00111] According to one embodiment, rifamycin SV or its pharmaceutically acceptable salts are completely dissolved in the pharmaceutical composition of the present invention. According to another embodiment, rifamycin SV or its pharmaceutically acceptable salts are partially dissolved and partially in a solid suspension in the pharmaceutical composition of the present invention.According to one embodiment, the pharmaceutical composition may contain one or more pharmaceutically acceptable excipients. According to the present invention, said pharmaceutically acceptable excipients may be selected from the group consisting of: diluents, stabilizers, preservatives, antioxidants, buffers, and other ingredients that correspond to the nature, composition, and route of administration of the pharmaceutical composition described herein. The types and amounts of pharmaceutically acceptable excipients that can be used in the pharmaceutical composition can be easily determined by one of skill in the art. According to one embodiment, the pharmaceutical composition contains at least one antioxidant as a pharmaceutically acceptable excipient.According to another embodiment, a pharmaceutical composition comprising at least one antioxidant further comprises at least one preservative as an additional pharmaceutically acceptable excipient. Pharmaceutically acceptable antioxidants and preservatives are well known to those skilled in the art.

[00112] According to one embodiment, the pharmaceutical composition described herein can be used to deliver rifamycin SV directly to the target rectosigmoid colon by direct local administration. According to one embodiment, the pharmaceutical composition is suitable for rectal administration. According to one embodiment, the pharmaceutical composition is in the form of an enema.According to one embodiment, the pharmaceutical composition is a liquid in the form of a solution, suspension, foam, emulsion or microemulsion; preferably, the pharmaceutical composition is in the form of a solution and more preferably in the form of an aqueous solution.

[00113] According to one embodiment, the pharmaceutical composition of the present invention is in the form of an enema and its individual content per unit is in the range of 50 ml to 150 ml. According to some embodiments, the individual content per unit of the pharmaceutical compositions of the invention in the form of an enema is 50 ml, or 60 ml, or 70 ml, or 80 ml, or 90 ml, or 100 ml, or 110 ml, or 120 ml, or 130 ml, or 140 ml, or 150 ml. According to a preferred embodiment, the individual content per unit of the pharmaceutical composition of the present invention in the form of an enema is 50 ml.According to another preferred embodiment, the individual content per unit of the pharmaceutical composition of the present invention in the form of an enema is 60 ml. According to another preferred embodiment, the individual content per unit of the pharmaceutical composition of the present invention in the form of an enema is 80 ml. According to yet another preferred embodiment, the individual content per unit of the pharmaceutical composition of the present invention in the form of an enema is 100 ml.

[00114] Accordingly, the pharmaceutical compositions of the present invention are intended for the treatment of diseases affecting the distal colon, more particularly the sigmoid colon and the rectum. According to some embodiments, such diseases affecting the distal colon are proctitis and / or ulcerative colitis of the distal portions (including proctosigmoiditis).According to another embodiment, the pharmaceutical composition can be administered directly rectally, for example by enema, into cavities created surgically as a result of disease or as a result of injury. According to one embodiment, the cavity is an ileoreservoir (J-reservoir or S-reservoir or W-reservoir) created by surgical intervention with an ileoanal anastomosis (J-reservoir or S-reservoir or W-reservoir) or an ileostomy (K-reservoir). Thus, the pharmaceutical composition described herein is particularly suitable for the treatment of pouchitis.

[00115] The pharmaceutical composition is prepared by serially adding the components of the pharmaceutical composition to water with stirring until completely dissolved or a homogeneous mixture is obtained, finally containing partially suspended rifamycin SV, as described in more detail in the examples below.

[00116] According to a preferred embodiment, the pharmaceutical composition comprises rifamycin SV as an active substance and a polymer mixture comprising at least one thermosensitive polymer, at least one ion-sensitive polymer and at least one bioadhesive polymer. According to one embodiment, the at least one thermosensitive polymer may comprise poloxamer 407, the at least one ion-sensitive polymer may comprise alginic acid or its salts, and the at least one bioadhesive polymer may comprise sodium carboxymethylcellulose. According to one preferred embodiment, the polymer mixture comprises poloxamer 407, sodium alginate and sodium carboxymethylcellulose.

[00117] According to one embodiment, poloxamer 407 may be present in an amount of from about 5% to about 30% by weight relative to the weight of the pharmaceutical composition, optionally in the range of from about 10% to about 25% by weight of the pharmaceutical composition, or in the range of from about 12% to about 18% by weight of the pharmaceutical composition, preferably about 16% or 15% or 14% by weight relative to the weight of the pharmaceutical composition. According to a preferred embodiment, poloxamer 407 may be present in an amount of about 16.5% by weight relative to the weight of the pharmaceutical composition.

[00118] According to one embodiment, sodium alginate may be present in an amount of from about 0.005% to about 5% by weight relative to the weight of the pharmaceutical composition, optionally in the range of from about 0.001% to about 3.0% by weight relative to the weight of the pharmaceutical composition, or in the range of from about 0.05% to about 2.0% by weight relative to the weight of the pharmaceutical composition, preferably 0.2% or 0.1% (w / w) relative to the weight of the pharmaceutical composition.

[00119] According to one embodiment, sodium carboxymethylcellulose may be present in an amount of from about 0.005% to about 5% by weight relative to the weight of the pharmaceutical composition, optionally in the range of from about 0.001% to about 2% by weight relative to the weight of the pharmaceutical composition, or in the range of from about 0.05% to about 0.1% by weight relative to the weight of the pharmaceutical composition, preferably about 0.05% (w / w) relative to the weight of the composition.

[00120] According to one embodiment, the pharmaceutical composition may further comprise at least one antioxidant. According to one embodiment, the antioxidant may be potassium metabisulfite, ascorbic acid, or sodium ascorbate, or mixtures thereof. According to one embodiment, the antioxidant comprises the three antioxidants.According to one embodiment, the pharmaceutical composition may further comprise at least one preservative. According to one embodiment, the preservative may be potassium sorbate, sodium benzoate, or ethanol, or mixtures thereof. According to one embodiment, the preservative comprises ethanol or a mixture of potassium sorbate and sodium benzoate.

[00121] According to one embodiment, the mixture of polymers and rifamycin SV is a unique system in which the amount of rifamycin SV in soluble form, as well as in partially suspended form, affects the rheological properties of the polymer mixture. The rheological properties unexpectedly decrease with increasing amount of rifamycin SV added to the pharmaceutical composition.According to one embodiment, a pharmaceutical composition containing from 0.25 to 3.0% by weight of rifamycin SV has a qualitative / quantitative composition of selected polymers that ensures the onset of sol-to-gel conversion at a temperature of from 27°C to 37°C. For example, a pharmaceutical composition containing 0.5% by weight or 1.0% by weight of rifamycin SV has a qualitative / quantitative composition of selected polymers that leads to the onset of sol-to-gel conversion at a temperature of from 27°C to 37°C. For example, a pharmaceutical composition containing 0.5% by weight or 1.0% by weight of rifamycin SV forms a gel at body temperature (about 37°C), which in turn ensures the use of the product at room temperature in liquid form (patient compliance), and after rectal administration provides a gel product at body temperature (about 37°C).The addition of Rifamycin SV to a polymer blend unexpectedly results in a two-degree (2°C) shift in the temperature transition between the G' and G'' moduli compared to the vehicle (polymer blend without Rifamycin SV or placebo) and reduces the intensity of the G' modulus compared to the vehicle. According to one embodiment, the amount of Rifamycin SV added to the composition unexpectedly exhibits an increase in the G' modulus over time at 37°C (time dependence), which is not observed in the polymer blend in the absence of Rifamycin SV (vehicle). Unexpectedly, a time dependence of the pharmaceutical composition with Rifamycin SV relative to the vehicle composition was found, as evidenced by the G' curve. This unexpectedly demonstrated that the addition of Rifamycin SV to polymer blends provides an improved long-term gel effect at the target site compared to the use of the polymer blend alone.Unexpectedly, rifamycin SV interacts with the polymer mixture, increasing the G' modulus over time, allowing rifamycin SV to remain embedded in a thin gel layer in close contact with the site of action and prolonging the duration of its pharmacological activity in situ by strengthening the gel structure at the target site (see Example 7). In one embodiment, a pharmaceutical composition comprising rifamycin SV fully maintains the MIC value of rifamycin SV tested alone, as described in the examples below. In addition to improved in situ retention due to the enema vehicle, this MIC maintenance provides longer-lasting efficacy of the topical formulation in terms of antibiotic effect. In one embodiment, a pharmaceutical composition comprising rifamycin SV exhibits an enhanced anti-inflammatory effect compared to the same amount of rifamycin SV tested alone.Those skilled in the art will appreciate that the enhanced anti-inflammatory activity of pharmaceutical compositions containing rifamycin SV according to the present invention, compared to similar amounts of the active substance rifamycin SV tested alone, is unexpected and unpredictable. The inactive components of the pharmaceutical composition according to the present invention, as described above, consist of known pharmaceutical excipients that do not exhibit any anti-inflammatory activity. The lack of anti-inflammatory activity is confirmed by the results of an anti-inflammatory test conducted on the pharmaceutical composition according to the present invention without the active substance (also referred to as the "carrier").As expected, this test confirmed the absence of any anti-inflammatory activity of the carrier alone, without the inclusion of rifamycin SV, given the known lack of pharmacological activity of the pharmaceutical excipients of the invention disclosed herein. One skilled in the art will appreciate that a synergistic effect or beneficial and effective interaction may exist between the carrier of the present invention and the active substance rifamycin SV, enhancing the intrinsic anti-inflammatory activity of the active substance rifamycin SV.Accordingly, the pharmaceutical compositions of the present invention, formulated as an in situ gel-forming enema containing rifamycin SV, exhibit anti-inflammatory activity that is higher than that of rifamycin SV alone and, in particular, are effective in treating, ameliorating, reducing the severity of, inducing, maintaining remission and / or slowing the progression of gastrointestinal diseases with an inflammatory component, such as pouchitis or proctitis or ulcerative colitis (including proctosigmoiditis).

[00122] The pharmaceutical composition of the present invention, containing rifamycin SV and the three polymers described above, is thus capable of providing a long-lasting effect and enhanced adhesion of rifamycin SV or its pharmaceutically active salts at the site of action (the distal part of the gastrointestinal tract and / or an artificial cavity, a surgically created ileoreservoir), preventing rapid evacuation of the composition with a significant loss of activity.In addition, rifamycin SV demonstrated a dual therapeutic effect, combining an antibiotic effect with an anti-inflammatory effect, providing a comprehensive therapeutic system with a broad spectrum of action. Currently, there is no treatment capable of combining a dual therapeutic effect with a longer residence time at the site with improved long-term adhesion.

[00123] The anti-inflammatory efficacy together with the antibiotic action of rifamycin SV included in the pharmaceutical composition of the present invention, comprising three polymer mixtures, provides the effect of treating, reducing the intensity, reducing the severity, inducing, maintaining remission, and / or slowing the progression of gastrointestinal diseases with an inflammatory and / or infectious component.The short-term but immediate clinical action of rifamycin in reducing inflammation, its clinical action in eliminating bacterial infection and minimal absorption at the intestinal level make the composition of the present invention effective in the treatment of all three categories of pouchitis: antibiotic-susceptible and antibiotic-dependent and antibiotic-resistant or any other gastrointestinal diseases with an inflammatory and / or infectious component.

[00124] Rifamycin SV included in the in situ gelling composition of the invention is unique.

[00125] Minimal systemic absorption of rifamycin SV in the gastrointestinal tract is a distinctive key element compared to other antibiotics currently used for the treatment of pouchitis (e.g. ciprofloxacin and metronidazole).These treatments are administered orally, and their systemic absorption can often lead to an increase in antibiotic-resistant bacterial strains over time, as well as long-term side effects due to systemic exposure and biodistribution. Because patients with pouchitis often experience more than two to three acute episodes per year, the use of a non-absorbable antibiotic such as rifamycin may provide a decisive advantage for these patients with frequent relapses. Furthermore, serious adverse reactions reported in patients treated with various antibiotics, such as seizures and peripheral neuropathy, can be prevented. Therefore, a non-absorbable antibiotic with a favorable safety profile, such as rifamycin SV, can be used in these patients, offering a safer alternative to current standard treatments (such as ciprofloxacin and metronidazole).

[00126] In the treatment of distal ulcerative colitis (including proctosigmoiditis) and / or proctitis, the compositions of the present invention offer significant advantages over currently available treatment methods. In fact, it has been demonstrated that the pharmaceutical compositions of the present invention undergo a sol-to-gel transformation under physiological conditions, which ensures long-term retention of the compositions themselves at the site of action after administration, whereas currently available treatments remain liquid (enemas or rectal foam) or liquefy at body temperature (suppositories) and are therefore eliminated from the body in a short time due to their physical structure.Moreover, the compositions of the present invention have a significant advantage because they act on two components known to be involved in the pathogenesis of such diseases, i.e., intestinal bacteria that are responsible for the activation of the innate immune system and subsequent inflammation. Currently available treatments target inflammation only.

[00127] Another advantage of the pharmaceutical compositions of the present invention is the improved stability of solutions of rifamycin and its salts. As described in detail in the examples, the pharmaceutical compositions of the present invention were subjected to stability studies under various storage conditions together with a commercially available liquid formulation of rifamycin (Rifocin®). The results of the analyses indicate that the active substance rifamycin exhibits a lower degree of degradation compared to a standard liquid formulation of rifamycin.Improved stability simplifies handling of the product, allowing it to be stored at room temperature for at least several months. Definitions

[00128] References in the description to "one embodiment," "an embodiment," "one aspect," "aspect," and the like indicate that the described embodiment or aspect may include a particular aspect, feature, structure, or characteristic. Moreover, such phrases may, but do not necessarily, refer to the same embodiment or aspect as is indicated in other parts of the description. Furthermore, when a particular aspect, feature, structure, or characteristic is described in connection with an embodiment or aspect, one skilled in the art, within the scope of his or her competence, may influence the specified aspect, feature, structure, or characteristic or associate it with another embodiment or aspect, regardless of whether it is explicitly described or not.Singular forms of a noun include plural forms unless the context clearly requires otherwise. Thus, for example, a reference to a "compound" includes a plurality of such compounds. It is also noted that claims may be drafted to exclude any optional element. Accordingly, this statement serves as a precursor to the use of exclusionary terminology such as "exclusively," "only," and the like in connection with the recitation of claim elements or the use of a "negative" limitation.

[00129] The term "and / or" means any of the elements, any combination of elements, or all of the elements to which the term is associated.

[00130] The terms "comprising," "having," "including," and "containing" are to be construed as open-ended terms (i.e.,meaning "including, but not limited to"), and also be considered as providing support for terms such as "consists essentially of", "consisting essentially of", "consists of" or "consisting of".

[00131] The terms "consists essentially of", "consisting essentially of" are to be considered as semi-closed terms meaning that no other ingredients that have a significant impact on the basic and novel characteristics (and optionally physiologically acceptable excipients and / or adjuvants) of the present invention are included.

[00132] The terms "consists of", "consisting of" are to be considered as closed terms.

[00133] The term "polymer mixture" means a pharmaceutical composition without an active substance.Thus, in its simplest usage, a "polymer mixture" includes water or another suitable enema vehicle, at least one heat-sensitive polymer, at least one ion-sensitive polymer, and at least one bioadhesive polymer, as well as any excipients described herein.

[00134] Unless otherwise specified herein, the term "about" includes values, such as weight percentages, close to the stated range that are equivalent in terms of the functionality of an individual ingredient, composition, or embodiment.

[00135] One of skill in the art will appreciate that, for all purposes, particularly in terms of providing a written description, all ranges recited herein also encompass any possible subranges and combinations of subranges thereof, as well as individual values ​​that make up the range, particularly integer values.The stated range includes each specific value, integer, decimal number, or unit element within the range.

[00136] One skilled in the art will understand that when members are grouped together on a single basis, such as in a Markush group, the invention encompasses not only the entire group stated as a whole, but also each individual member of the group and all possible subgroups of the main group. Furthermore, the invention encompasses, in all respects, not only the main group, but also a main group from which one or more members of the group are absent. Thus, the invention contemplates the express exclusion of any or more members of the stated group.Accordingly, exceptions may apply to any of the disclosed categories or embodiments, whereby any or more of the listed elements, types, or embodiments may be excluded from such categories or embodiments, such as those used in an explicit negative limitation.

[00137] The term "alleviating" refers to alleviating the symptoms and / or manifestations of inflammatory and / or degenerative diseases of the gastrointestinal tract.

[00138] The term "reducing" refers to reducing the degree of damage caused by inflammatory and / or degenerative diseases of the gastrointestinal tract, or to reducing the clinical signs or symptoms associated with such damage.

[00139] "Viscosity" characterizes the resistance of a liquid or semi-solid to flow. The flow of liquids or semi-solids is described by viscosity, or more precisely, by shear viscosity η.The shear viscosity of a fluid expresses its resistance to shear flows when adjacent layers move parallel to each other at different velocities. Common units of viscosity are pascal second (Pas), poise (P), and cP (centipoise).

[00140] "G' modulus" refers to the modulus of elasticity or storage modulus obtained in dynamic mode. The modulus of elasticity (also known as the elastic modulus) is a quantity that determines the ability of an object or substance to resist elastic (i.e., non-permanent) deformation when a force is applied to it. The modulus of elasticity of an object is defined as the slope of its stress-strain curve in the elastic region.

[00141] "Body temperature" refers to the level of heat generated and maintained by body processes. Heat is generated within the body through the metabolism of nutrients and is lost from the body surface through radiation, convection, and evaporation of sweat.Heat production and loss are regulated and controlled in the hypothalamus and brainstem. The normal adult body temperature, measured orally, is 37°C, although slight variations are usually recorded throughout the day.

[00142] "Room temperature" (RT) is generally defined as the ambient air temperature of any environment used for a given procedure. More specifically, it is defined as 20-25°C, since some ambient temperatures are inherently outside this range. Typically, protocols requiring a procedure to be performed at room temperature require that the temperature be no lower than 18°C ​​and no higher than 27°C.

[00143] "MIC" refers to the minimum inhibitory concentration and is defined as the lowest concentration, expressed in mg / L (equivalent to μg / mL), of an antimicrobial ingredient or substance that is bacteriostatic (prevents visible bacterial growth).

[00144] "DoE" refers to a design of experiments and is defined as a statistical and mathematical tool for systematically conducting experiments and analyzing data efficiently.

[00145] "Rifamycin SV" refers to rifamycin, the sodium salt of rifamycin, defined by CAS No. 14897-39-3.

[00146] The term "therapeutically effective amount" refers to the amount of a compound that, when administered to a subject in need of such treatment, is sufficient to treat the disease. In this case, a therapeutically effective amount of rifamycin SV is the amount of rifamycin SV required to treat, alleviate, reduce the severity, slow the progression of, induce or maintain remission of pouchitis and / or proctitis and / or ulcerative colitis of the distal sites (including proctosigmoiditis) when administered to a patient in need of such treatment.

[00147] The term "sustained acting" means that the composition remains at the site of action for the time necessary to exert a therapeutic effect. Embodiments

[00148] The following are some preferred embodiments: 1. A pharmaceutical composition comprising: a therapeutically effective amount of rifamycin SV or a pharmaceutically acceptable salt thereof; and a polymer mixture; wherein the pharmaceutical composition is a liquid at room temperature and is capable of forming a gel in situ at body temperature. 2. The pharmaceutical composition according to embodiment 1, wherein the polymer mixture comprises: at least one thermosensitive polymer; at least one ion-sensitive polymer; and at least one bioadhesive polymer; 3. The pharmaceutical composition according to embodiment 1 or 2, wherein the pharmaceutical composition is an enema. 4.The pharmaceutical composition according to embodiment 2 or 3, wherein the thermosensitive polymer is selected from the group consisting of: polyoxyethylene-polyoxypropylene block copolymers, poly(ethylene glycol) / poly(lactide-co-glycolide) (PEG-PLGA) block copolymers, poly(ethylene glycol)-poly(lactic acid)-poly(ethylene glycol) (PEG-PLA-PEG), poly(N-isopropylacrylamide) and cellulose derivatives. 5. The pharmaceutical composition according to embodiment 2, 3 or 4, wherein the thermosensitive polymer is a polyoxyethylene-polyoxypropylene block copolymer selected from the group consisting of: poloxamer 124, poloxamer 188, poloxamer 237, poloxamer 338 and poloxamer 407. 6. The pharmaceutical composition according to any one of embodiments 2-4, wherein the heat-sensitive polymer is a cellulose derivative selected from the group consisting of methylcellulose (MC), hydroxypropylmethylcellulose (HPMC), and mixtures thereof.7.The pharmaceutical composition according to any one of embodiments 2-5, wherein the thermosensitive polymer is poloxamer 188, poloxamer 407 or mixtures thereof. 8. The pharmaceutical composition according to any one of embodiments 2-7, wherein the at least one thermosensitive polymer is present in an amount of from about 1% to about 25% by weight based on the weight of the pharmaceutical composition; preferably from about 12% to about 18% by weight based on the weight of the pharmaceutical composition. 9. The pharmaceutical composition according to any one of embodiments 2-8, wherein the ion-sensitive polymer is a polysaccharide. 10. The pharmaceutical composition according to any one of embodiments 2-9, wherein the ion-sensitive polymer is selected from the group consisting of: carrageenan, gellan gum, pectin, alginic acid, salts thereof and mixtures thereof.The pharmaceutical composition according to any one of embodiments 2-10, wherein the ion-sensitive polymer is sodium alginate. 12. The pharmaceutical composition according to any one of embodiments 2-11, wherein the at least one ion-sensitive polymer is present in an amount of from about 0.01% to about 3% by weight relative to the weight of the pharmaceutical composition; preferably from about 0.1% to about 2.0% by weight relative to the weight of the pharmaceutical composition. 13. The pharmaceutical composition according to any one of embodiments 2-12, wherein the bioadhesive polymer is selected from the group consisting of: chitosan, hyaluronic acid and its salts, cellulose derivatives, polyvinyl alcohol, polyvinylpyrrolidone, polyacrylic acid, polyethylene oxides, tragacanth, sodium alginate, xanthan gum, gelatin, pectin and mixtures thereof. 14.The pharmaceutical composition according to any one of embodiments 2-13, wherein the bioadhesive polymer is a cellulose derivative selected from the group consisting of: methylcellulose, hydroxypropyl methylcellulose, hydroxypropyl cellulose, sodium carboxymethylcellulose and mixtures thereof.15. The pharmaceutical composition according to any one of embodiments 2-14, wherein the bioadhesive polymer is sodium carboxymethylcellulose.16. The pharmaceutical composition according to any one of embodiments 2-15, wherein the bioadhesive polymer is present in an amount of from about 0.01% to about 2.0% by weight relative to the weight of the pharmaceutical composition, preferably in an amount of from about 0.05% to about 0.1% by weight relative to the weight of the pharmaceutical composition.17.A pharmaceutical composition according to any of the previous embodiments, wherein the pharmaceutical composition further comprises at least one pharmaceutically acceptable excipient selected from the group consisting of: an antioxidant, a preservative, and a combination thereof; and / or optionally, wherein the composition has a pH in the range from 6.5 to 7.5, preferably from 6.8 to 7.2. 18. A pharmaceutical composition according to any of the previous embodiments, comprising from about 0.1% to about 5% by weight of rifamycin SV or a pharmaceutically acceptable salt thereof relative to the weight of the pharmaceutical composition; preferably from about 0.25% to about 3.0% by weight of rifamycin SV or a pharmaceutically acceptable salt thereof relative to the weight of the pharmaceutical composition, such as from about 0.25% to about 2.5% by weight relative to the weight of the pharmaceutical composition.A pharmaceutical composition comprising a therapeutically effective amount of rifamycin SV or a pharmaceutically acceptable salt thereof and a polymer mixture for use in the treatment of pouchitis, proctitis and / or ulcerative colitis of the distal portions (including proctosigmoiditis), wherein the pharmaceutical composition is administered rectally, is a liquid at room temperature and forms a gel in situ at the body temperature of said patient. 20. A pharmaceutical composition for use according to embodiment 19, wherein said pharmaceutical composition is an enema. 21. A pharmaceutical composition for use according to embodiment 19 or 20 for the relief and / or amelioration of one or more clinical symptoms selected from the group consisting of: increased frequency of stool, change in stool consistency, rectorrhagia, pain, abdominal cramps, urgency, tenesmus, fecal incontinence, fever and extraintestinal manifestations. 22.A pharmaceutical composition for use according to embodiment 19 or 20 for alleviating and / or reducing the incidence of one or more endoscopic symptoms selected from the group consisting of: mucosal edema, granular structure, contact bleeding, loss of vascular pattern, bleeding, and ulceration. 23. A pharmaceutical composition for use according to any one of claims 19-22, wherein said pharmaceutical composition is administered daily or twice daily. 24. A pharmaceutical composition for use according to any one of claims 19-23, wherein said rectal administration occurs for at least two weeks. 25.A method for treating pouchitis, proctitis and / or ulcerative colitis of the distal regions (including proctosigmoiditis) in a patient in need of such treatment, comprising: rectal administration to said patient of a pharmaceutical composition comprising a therapeutically effective amount of rifamycin SV or a pharmaceutically acceptable salt thereof and a polymer mixture; wherein the pharmaceutical composition is a liquid at room temperature and forms a gel in situ at the body temperature of said patient. 26. The method of claim 25, wherein said pharmaceutical composition is an enema. 27. The method of claim 25, wherein said pharmaceutical composition comprises from about 0.1% to about 5% by weight of rifamycin SV or a pharmaceutically acceptable salt thereof, based on the weight of the pharmaceutical composition. 28. The method of claim25, wherein rectal administration of the pharmaceutical composition causes and / or alleviates one or more clinical symptoms selected from the group consisting of: increased frequency of bowel movements, change in stool consistency, rectorrhagia, pain, abdominal cramps, urgency, tenesmus, fecal incontinence, fever, and extraintestinal manifestations. 29. The method of claim 25, wherein rectal administration of the pharmaceutical composition alleviates and / or reduces the incidence of one or more endoscopic symptoms selected from the group consisting of: mucosal edema, granular structure, contact bleeding, loss of vascular pattern, hemorrhage, and ulceration. 30. The method of claim 25, wherein said pharmaceutical composition is administered daily. 31. The method of claim 25, wherein said pharmaceutical composition is administered twice daily. 32. The method according to claim 30, wherein said rectal administration is carried out for at least two weeks.33. The method according to claim31, wherein said rectal administration is carried out for at least two weeks.34. Use of a pharmaceutical composition according to any one of claims 1 to 18 in the manufacture of a medicament for the treatment of pouchitis, proctitis and / or ulcerative colitis of the distal regions (including proctosigmoiditis).EXAMPLES

[00149] The following examples are included for the purpose of illustrating certain aspects and aspects of the invention and are not intended to limit the invention.Example 1 Simplex centroid design with or without rifamycin

[00150] A pharmaceutical composition was prepared containing rifamycin SV and a polymer mixture containing poloxamer, sodium alginate and sodium carboxymethylcellulose. The pharmaceutical composition is intended for application to the reservoir, distal intestine and rectum. The DoE method, "simplex centroid design", is used to better understand the interactions and relationships between a polymer (carrier) mixture with and without rifamycin SV.The response variables considered are:

[00151] 1) the viscosity of the polymer mixture at room temperature (25°C), ensuring ease of administration;

[00152] 2) the viscoelastic properties after administration, ensuring the sustained release effect of the polymer mixture at the site of application; and

[00153] 3) the mucoadhesion at 37°C, ensuring the in situ maintenance of the polymer mixture after administration.

[00154] Table 1 and Fig. 1 show the measurement area and experimental points of the simplex centroid design.

[00155] The mixture design shown in Fig. 1 includes: 3 individual mixture components corresponding to the corners of a triangle; 3 binary combinations graphically represented as points at the edges of the triangle; 1 ternary combination that intersects with the center of the triangle, and 3 ternary combinations in the region inside the triangle [Brereton, 2003]. Two parallel centroid designs for the mixture were performed: one with the addition of the active ingredient (rifamycin SV at a concentration of 0.5% w / w, equivalent to 5 mg / g) and one without the addition of the active ingredient, according to the scheme of Table 1, to obtain the main points of the simplex centroid design.The reason for this duplication of the design (with and without drug) was to test whether rifamycin and the gelling properties of the selected polymer blend interact in a specific way and, if any chemical and / or physical interactions occur, whether such interactions lead to an improvement or deterioration in rheological properties.

[00156] The polymer blends at the 10 points presented in Table 1 (with and without rifamycin SV) were characterized for viscosity at increasing shear rates (0.1-300 s-1). -1) using a rotational rheometer (Kinexus Pro+) at 25°C and 37°C. All polymer blends (with and without rifamycin SV) were tested for viscoelastic properties (oscillation test) at 25°C and 37°C using the same rotational rheometer (Kinexus Pro+), and mucoadhesion properties were determined. To characterize the mucoadhesion properties, all rifamycin-containing carriers were evaluated at 37°C using a TA-XT plus texture analyzer. This test measures the peel force (Fmax, mN) and adhesion force (AUC, mN-mm) required to separate a carrier layer from a filter disc impregnated with an 8% w / w suspension of commercial gastric mucin (type II, Sigma, I) compared to purified water as a control solution. Data were also normalized between mucin and control to better assess the adhesion of the compositions when comparing the two substrates.The normalized force and work of adhesion (AUC) were calculated using the following equations: ΔFmax / Fmax_control=(Fmax_mucin - Fmax_control) / Fmax_control and Δ AUC / AUC_control npo6a=(AUC_mucin - AUC_control) / AUC_controlWhere Fmax_mucin and AUC_mucin are the force and work of adhesion, respectively, obtained in the presence of 8% w / w gastric mucin dispersion, and Fmax_control and AUC_control are the force and work of adhesion, respectively, obtained from the measurement of the control sample.

[00157] The following response variables were measured:

[00158] 1) the viscosity of the polymer mixture at 25°C and 37°C, at a shear rate of 10 s -1;

[00159] 2) with respect to the viscoelastic property measurements:1) Elastic (storage) moduli (G');2) Viscosity (loss) moduli (G'');3) Loss tangent (tan delta), calculated as the ratio between the loss modulus, which is an indicator of the viscous properties (G''), and the elastic (storage) modulus (G');

[00160] with respect to the mucoadhesion measurements:1) Maximum peel force (Fmax)2) Work of adhesion (AUC)3) Normalized force data (Δ Fmax / Fmax_ control sample)4) Normalized work data (Δ AUC / AUC_ control sample).

[00161] Each response variable can be related to the polymer blend composition by means of a suitable mathematical model. For this purpose, the experimental data were subjected to multiple linear regression analysis, testing a series of models (linear, quadratic and special cubic) [Draper and Smith (1981)].To determine the best-fit model for each response variable, statistical analysis (ANOVA) was performed using the statistical software package (Minitab® 19, 2020).

[00162] Viscosity curves were obtained for each experiment with or without rifamycin SV, and at temperatures of 25°C and 37°C. Representative viscosity curves at 25°C and 37°C for the experiment with rifamycin are shown in Fig. 2. A comparison of the viscosity data obtained in Experiments 1-10 (placebo and rifamycin SV formulations) shows that:The viscosity data in Experiments 7 and 10 are similar for both the placebo and rifamycin formulations, showing higher viscosity values ​​at a rate of 10 s. -1(100 times higher than others at 25°C and 37°C), with no difference between the viscosity curves at 25°C and 37°C, probably due to the higher concentration of poloxamer, meaning that no transition occurs with temperature; In experiment 2 and experiment 3, with a poloxamer content of 15% in the formula, a difference is shown between the viscosity profiles from 25°C to 37°C. Both formulas exhibit Newtonian properties at 25°C and pseudoplastic properties at 37°C. In addition, the viscosity values ​​at 37°C, at a rate of 10 s -1, higher compared to the values ​​at 25°C. Similar properties are shown in each sample run for the placebo and rifamycin SV samples, even though the rifamycin SV samples show a decrease in viscosity values ​​compared to the corresponding vehicle runs.

[00163] Considering the viscoelastic data, run 7 and run 10 (both with a poloxamer concentration >20%) do not show a switch in the G' and G" moduli from 25°C to 37°C. In fact, both the viscosity curves of run 7 and run 10 at 25°C show higher values ​​compared to the other runs. On the other hand, run 2 and run 3 show a switch in the G' and G" moduli around 28°C. Figure 3 shows the temperature range for run 2.

[00164] The results of mucoadhesion in relation to Fmax in experiments with the inclusion of rifamycin SV show that experiments 3, 4, 7, 8 and experiment 10 demonstrate an increase in mucoadhesive properties after interaction with mucin, as shown in Fig. 4.The adhesion results (AUC) confirmed the results obtained from the Fmax values, mainly in runs 7 and 10, which showed high values ​​for both substrates, indicating high interaction under both conditions. This interaction is due to the high concentration of poloxamers in both runs. See Fig. 5. The normalized results make it easier to understand the data: the combination of the three polymers provided high mucoadhesion, as shown in run 4. Fig. 6 shows the contour plot of the normalized work (AUC) extrapolated from the blend plan. The highest work of adhesion values ​​are in the region with the combination of all three polymers (dark green), with poloxamer 407 contents of approximately below 15%, sodium alginate of approximately above 0.5%, and sodium carboxymethylcellulose of approximately below 0.17%.

[00165] Based on the results of this first blend design, the optimization region for the polymer blend was determined to be between approximately 14% and 15% w / w poloxamer 407, between approximately 0.4% and 0.1% sodium alginate, and between approximately 0.4 and 0.01 sodium carboxymethylcellulose. A further three-factorial full factorial design was performed using the selected polymer ranges to better determine the optimal composition of the formulation. EXAMPLE 2 FULL FACTORIAL Determination of Optimal Quantitative Composition of Polymer Blend

[00166] The pharmaceutical composition is intended for application to the J-reservoir, distal bowel, and rectum. The DoE "factorial full design" method was used to determine the optimal quantitative composition of the polymer blend. The response variables considered were as follows:

[00167] 1) viscosity of the polymer blend at room temperature (25°C), providing ease of administration.

[00168] 2) viscoelastic properties after administration, providing a delayed release effect of the polymer mixture at the site of application; and

[00169] 3) mucoadhesion at a temperature of 37°C, providing in-situ maintenance of the polymer mixture after administration.

[00170] Table 2 and Figure 7 show the measurement area and experimental points of the face-centered factorial full design.

[00171] The DoE set includes three factors that correspond to three polymers. Each factor has two levels, which also contain a point on the axis (face-centered). Each factor has a lower level (-1), an upper level (+1), and an axial (0).

[00172] Polymer blends at 14 points presented in Table 2 (with rifamycin SV) are characterized by viscosity with increasing shear rate (0.1-300 s -1) using a rotational rheometer (Kinexus Pro+) at 25°C. All polymer blends (with and without rifamycin SV) are subjected to viscoelastic properties (oscillation test) at 25°C and 37°C using the same rotational rheometer (Kinexus Pro+), and mucoadhesion characteristics are determined.

[00173] The following response variables are determined:[0017 4] 1) Viscosity of the polymer blend at 25°C and 37°C, at a shear rate of 10 s -1;

[00175] 2) With respect to viscoelastic property measurements:1) Elastic (storage) moduli (G');2) Viscosity (loss) moduli (G'');3) Loss tangent (tan delta) is calculated as the ratio between the loss modulus, which is an indicator of viscous properties (G''), and the elastic (storage) modulus (G').[0017 6] With respect to mucoadhesion measurements:1) Maximum peel force (Fmax)2) Work of adhesion (AUC)3) Normalized force data (Δ Fmax / Fmax control)4) Normalized work data (Δ AUC / AUC control)

[00177] Each response variable can be related to the polymer blend composition using a suitable mathematical model. For this purpose, the experimental data were subjected to multiple linear regression analysis, testing a series of models (linear, quadratic and special cubic) [Draper and Smith (1981)].To determine the best-fit model for each response variable, statistical analysis (ANOVA) was performed using a statistical software package (Minitab® 19, 2020).

[00178] Viscosity curves were obtained for each run with rifamycin SV at 25°C. Representative viscosity curves at 25°C are shown in Fig. 8. Comparison of the viscosity data obtained in Runs 1–14 showed that Run 2, with all polymers at lower levels, showed the lowest viscosity; on the other hand, Run 1, with a higher level for all three polymers, showed the highest viscosity.

[00179] From the experiments, it is clear that lower levels of poloxamer 407 and sodium carboxymethylcellulose have an effect on the viscosity of the vehicle at 25°C and a speed of 10 s. -1, in fact, the carriers with the lowest level of the two polymers mentioned are characterized by low viscosity (e.g., experiment 4). However, the addition of sodium alginate to these carriers sharply increases the viscosity.

[00180] Taking into account the viscoelasticity data, it was established that the poloxamer is the main one responsible for the gelation of the composition under physiological conditions due to its thermogelation properties. In the case where the concentration of poloxamer 407 was 12% w / w, thermogelation did not occur in most of the studied experiments, with the exception of experiment 2. On the other hand, in the case where the concentration was 18% w / w, the composition demonstrated properties similar to those of a solid already at room temperature.When Poloxamer 407 was at its pivot point (15% w / w), a switch in the G' and G" moduli occurred in the range from 27 to 37°C depending on the formulation; this switch provided the formulations with properties similar to those of a solid. An example of this trend is shown in Figs. 9 and 10.

[00181] The results of the mucoadhesion study in terms of adhesion work of both series confirmed the data obtained for the mucoadhesion strength. The normalized Fmax and adhesion work (AUC) results were analyzed by means of a factorial complete design, and it was found that the most statistically significant factor was Poloxamer 407 and the blend of the three polymers based on the Pareto diagram. In addition, the contour plot of the normalized force and work was extrapolated from the factorial complete design.High values ​​of adhesion force and work were observed at a content of poloxamer 407 of approximately 15%, sodium alginate of approximately below 1.0% and sodium carboxymethylcellulose of approximately below 0.5%. Fig. 11 shows the effective adhesion work in the case where the content of poloxamer P 407 is approximately 15%, sodium alginate of approximately below 1.0% and sodium carboxymethylcellulose of approximately below 0.5%. Example 3 Sample 7568

[00182] An aqueous solution of sample 7568 was prepared as follows. .

[00183] Purified water (95% of the total amount) is placed in a suitable vessel equipped with a stirrer; then, ascorbic acid and sodium ascorbate are added with stirring until complete dissolution is achieved. Then, sodium alginate is added to the above mixture with stirring until a homogeneous mixture is achieved. Then, sodium carboxymethylcellulose is added to the above mixture with stirring until a homogeneous mixture is achieved. Then, potassium metabisulfite is added to the above mixture with stirring until a homogeneous mixture is achieved. Then, potassium sorbate is added to the above mixture with stirring until complete dissolution is achieved. Then, sodium benzoate is added to the above mixture with stirring until complete dissolution is achieved. Then, the pH of the solution is checked and, if necessary, its value is adjusted to a value of 6.0-6.5. Then, rifamycin SV is added to the above mixture with stirring until complete dissolution is achieved. The solution is then cooled to a temperature of 5°C to 20°C; then, poloxamer is added.The mixture is kept under stirring until complete dissolution is achieved and then warmed to room temperature. The pH is then checked and, if necessary, its value is adjusted to 7.0. The mixture is brought to the final weight by adding purified water.

[00184] The following properties were considered:1) Viscosity of the composition after increasing the temperature from 25°C to 37°C at a frequency of 10 Hz;2) With regard to the measurements of the viscoelastic properties:1) Elastic (storage) moduli (G');2) Viscosity (loss) moduli (G'');3) The loss tangent (tan delta) is maintained as the relationship between the loss moduli, which is an indicator of the viscous properties (G'') and the elastic (storage) modulus (G').

[00185] The temperature range at a frequency of 10 Hz shows a switch between the moduli G' and G'', starting from approximately 27°C to 29°C. This transition is associated with increased elasticity of the sample.

[00186] The loss tangent (tan 5) was determined as a function of frequency at temperatures of 25°C and 40°C.Tangent δ<1 exhibits gel-like properties, which means that elastic properties predominate over viscous properties at a temperature of 40°C. Meanwhile, at a temperature of 25°C, tangent δ>1 exhibits properties similar to those of a liquid, which confirms the transformation of the sol into a gel. Fig. 12 shows a graph of the loss tangent (tangent δ) for sample 7568. This graph is representative of the loss tangent. Example 4 Sample 7569

[00187] An aqueous solution of sample 7569 was prepared as follows. .[0 0188] Purified water (95% of the total amount) is placed in a suitable vessel equipped with a stirrer; then ascorbic acid and sodium ascorbate are added with stirring until complete dissolution is achieved. Then sodium alginate is added to the above mixture with stirring until a homogeneous mixture is obtained. Then sodium carboxymethylcellulose is added to the above mixture with stirring until a homogeneous mixture is obtained. Then potassium metabisulfite is added to the above mixture with stirring until a homogeneous mixture is obtained. Then the pH of the solution is checked and, if necessary, it is adjusted to 6.0-6.5. Then rifamycin SV is added to the above mixture with stirring until complete dissolution is achieved. Then the solution is cooled to a temperature of from 5°C to 20°C; then poloxamer is added. The mixture is kept with stirring until complete dissolution is achieved and then warmed to room temperature. Then 96% ethanol is added to the above mixture with stirring until a homogeneous mixture is obtained.The pH is then checked and adjusted to 7.0 if necessary. The mixture is brought to the final weight by adding purified water.

[00189] The following properties were considered:1) Viscosity of the composition after increasing the temperature from 25°C to 37°C at a frequency of 10 Hz;2) Regarding the viscoelastic properties measurements:1) Elastic (storage) moduli (G');2) Viscosity (loss) moduli (G'');3) The loss tangent (tan delta) is calculated as the ratio between the loss modulus, which is an indicator of the viscous properties (G''), and the elastic (storage) modulus (G').

[00190] The temperature range at a frequency of 10 Hz shows a switch between G' and G' ' moduli, starting from approximately 26°C to 29°C. This transition is associated with increased elasticity of the sample.

[00191] Tangent δ<1 exhibits shadow-like properties, which means that elastic properties predominate over viscous ones at a temperature of 40°C.At the same time, at a temperature of 25°C, tangent δ>1 shows properties similar to those of a liquid, which confirms the transformation of the sol into a gel. Example 5 Sample 7572

[00192] An aqueous solution of sample 7572 was obtained as follows.

[00193] Purified water (95% of the total amount) is added to a suitable vessel equipped with a stirrer; then, ascorbic acid and sodium ascorbate are added while stirring until complete dissolution is achieved. Then, sodium alginate is added to the above mixture while stirring until a homogeneous mixture is obtained. Then, sodium carboxymethylcellulose is added to the above mixture while stirring until a homogeneous mixture is obtained. Then, potassium metabisulfite is added to the above mixture while stirring until a homogeneous mixture is obtained. Then, the pH of the solution is checked and, if necessary, it is adjusted to 6.0-6.5. Then, rifamycin SV is added to the above mixture while stirring until complete dissolution is achieved. The solution is then cooled to a temperature of from 5°C to 20°C; then, poloxamer is added. The mixture is kept under stirring until complete dissolution is achieved, and then warmed to room temperature. Then, 96% ethanol is added to the above mixture while stirring until a homogeneous mixture is obtained.The pH is then checked and adjusted to 7.0 if necessary. The mixture is brought to the final weight by adding purified water.

[00194] The following properties were examined:1) Viscosity of the composition after increasing the temperature from 25°C to 37°C, at a frequency of 10 Hz;2) Regarding the viscoelastic properties measurements:1) Elastic (storage) moduli (G');2) Viscosity (loss) moduli (G'');3) The loss tangent (tan delta) is calculated as the ratio between the loss modulus, which is an indicator of the viscous properties (G''), and the elastic (storage) modulus (G').

[00195] The temperature range at a frequency of 10 Hz shows a switch between G' and G'' moduli, starting from approximately 26°C to 31°C. This switch is associated with increased elasticity of the sample.

[00196] Tangent δ<1 demonstrates gel-like properties, which means that elastic properties predominate over viscous ones at a temperature of 40°C.At the same time, at a temperature of 25°C, tangent δ>1 shows properties similar to those of a liquid, which confirms the transformation of the sol into a gel. Example 6 Sample 7567

[00197] An aqueous solution of sample 7567 was obtained as follows.

[00198] Purified water (95% of the total amount) is placed in a suitable vessel equipped with a stirrer; then hydroxypropyl cellulose is added to the above mixture while stirring until a homogeneous mixture is obtained. Then, ascorbic acid and sodium ascorbate are added while stirring until completely dissolved. Then, potassium metabisulfite is added to the above mixture while stirring until a homogeneous mixture is obtained. Then, the solution is cooled to a temperature of from 5°C to 20°C; then, poloxamer is added until a homogeneous mixture is obtained. The mixture is kept under stirring until completely dissolved, and then warmed to room temperature. Then, the pH of the solution is checked and, if necessary, adjusted to 6.0-6.5. Then, rifamycin SV is added to the above mixture while stirring until completely dissolved. Then, gellan gum is added to the above mixture while stirring until a homogeneous mixture is obtained. Then, the pH is checked and, if necessary, its value is adjusted to 7.0.The mixture is brought to the final weight by adding purified water.

[00199] The following properties were considered:1) Viscosity of the composition after increasing the temperature from 25°C to 37°C at a frequency of 10 Hz;2) Regarding the measurements of the viscoelastic properties:1) Elastic (storage) moduli (G');2) Viscosity (loss) moduli (G'');3) The loss tangent (tan delta) is calculated as the ratio between the loss modulus, which is an indicator of the viscous properties (G''), and the elastic (storage) modulus (G')

[00200] The temperature range at a frequency of 10 Hz does not show a switch between G' and G'' moduli, which probably began before the temperature from 25°C to 30°C. However, the G' modulus is much larger than G''.

[00201] Tangent δ<1 demonstrates gel-like properties, which means that elastic properties predominate over viscous ones at both 25°C and 40°C. Tangent δ<1 shows that the transformation of the sol into a gel is not observed in this temperature range.Example 7 Sample 7570

[00202] An aqueous solution of sample 7570 was obtained as follows.

[00203] Purified water (95% of the total amount) is placed in a suitable vessel equipped with a stirrer; then, ascorbic acid and sodium ascorbate are added with stirring until complete dissolution is achieved. Then, sodium alginate is added to the above mixture with stirring until a homogeneous mixture is obtained. Then, sodium carboxymethylcellulose is added to the above mixture with stirring until a homogeneous mixture is obtained. Then, potassium metabisulfite is added to the above mixture with stirring until a homogeneous mixture is obtained. Then, the pH of the solution is checked and, if necessary, its value is adjusted to 6.0-6.5. Then, rifamycin SV is added to the above mixture with stirring until complete dissolution is achieved. Then, the solution is cooled to a temperature of 5°C to 20°C; then, poloxamer is added. The mixture is stirred until complete dissolution is achieved and then warmed to room temperature. Then, the pH is checked and, if necessary, its value is adjusted to pH 7.0.The mixture is brought to the final weight by adding purified water.

[00204] The following properties were considered:1) Viscosity of the composition after increasing the temperature from 25°C to 37°C at a frequency of 10 Hz;2) Regarding the measurements of viscoelastic properties:1) Elastic (storage) moduli (G');2) Viscosity (loss) moduli (G'');3) The loss tangent (tan delta) is calculated as the ratio between the loss modulus, which is an indicator of the viscous properties (G''), and the elastic (storage) modulus (G').

[00205] The temperature range at a frequency of 10 Hz shows a switch between G' and G'' moduli, starting from approximately 26°C to 28°C. This switch is associated with increased elasticity of the sample. The temperature range at 10 Hz of the carrier without rifamycin SV shows a switch between the G' and G' ' moduli, starting from approximately 24°C to 26°C.

[00206] The tangent δ<1 shows gel-like properties, which means that elastic properties predominate over viscous ones at 40°C.At the same time, at a temperature of 25 °C, the tangent δ>1 shows properties similar to those of a liquid, which confirms the transformation of the sol into a gel.

[00207] Rifamycin SV compositions and the corresponding placebo compositions were subjected to a constant frequency and shear stress for 20 minutes at a constant temperature of 37 °C to assess the occurrence of a time dependence. Fig. 13.

[00208] Surprisingly, it was found that only compositions containing Rifamycin SV exhibit a time dependence, meaning an increase in the modulus G' over time. The time dependence confirms an increase in the retention time of the drug at the site of action, preventing the destruction of the three-dimensional structure of the gel. Example 8 Sample 7574

[00209] An aqueous solution of sample 7574 was prepared as follows.

[00210] Purified water (95% of the total amount) is placed in a suitable vessel equipped with a stirrer; then, ascorbic acid and sodium ascorbate are added with stirring until complete dissolution is achieved. Then, sodium alginate is added to the above mixture with stirring until a homogeneous mixture is obtained. Then, sodium carboxymethylcellulose is added to the above mixture with stirring until a homogeneous mixture is obtained. Then, the pH of the solution is checked and, if necessary, adjusted to a pH of 6.0-6.5. Then, rifamycin SV is added to the above mixture with stirring until complete dissolution is achieved. The solution is then cooled to a temperature of 5°C to 20°C; then, poloxamer is added. The mixture is kept with stirring until complete dissolution is achieved and then warmed to room temperature. Then, 96% ethanol is added to the above mixture with stirring until a homogeneous mixture is obtained. Then, the pH is checked and, if necessary, adjusted to 7.0.The mixture is brought to the final weight by adding purified water.

[00211] The following properties were considered:1) Viscosity of the composition after increasing the temperature from 25°C to 37°C at a frequency of 10 Hz;2) Regarding the measurements of viscoelastic properties:1) Elastic (storage) moduli (G');2) Viscosity (loss) moduli (G'');3) The loss tangent (tan delta) is calculated as the ratio between the loss modulus, which is an indicator of the viscous properties (G''), and the elastic (storage) modulus (G').

[00212] The temperature range shows a transition between G' and G'' moduli, starting from approximately 26°C to 29°C. This transition is associated with increased elasticity of the sample.

[00213] Tangent δ<1 demonstrates gel-like properties, indicating the predominance of elastic properties over viscous ones at a temperature of 40°C. At the same time, at a temperature of 25°C, tangent δ>1 exhibits properties similar to those of a liquid, confirming the transformation of the sol into a gel.

[00214] Both placebo and rifamycin formulations were subjected to a constant frequency and shear stress for 20 minutes at a constant temperature of 37°C to assess the development of a time dependence. Surprisingly, only formulations containing rifamycin were found to exhibit a time dependence, indicating an increase in the G' modulus over time. The time dependence confirms an increase in the retention time of the drug at the site of action, preventing the destruction of the three-dimensional structure of the gel. Example 9 Sample 7601

[00215] This sample corresponds to the optimized formulation extrapolated by the factorial full design. An aqueous solution of sample 7601 was prepared as follows.

[00216] Purified water (95% of the total amount) is placed in a suitable vessel equipped with a stirrer; then, ascorbic acid and sodium ascorbate are added with stirring until complete dissolution is achieved. Then, sodium alginate is added to the above mixture with stirring until a homogeneous mixture is obtained. Then, sodium carboxymethylcellulose is added to the above mixture with stirring until a homogeneous mixture is obtained. Then, the pH of the solution is checked and, if necessary, adjusted to a pH of 6.0-6.5. Then, SV rifamycin is added to the above mixture with stirring until complete dissolution is achieved. Then, the solution is cooled to a temperature of from 5°C to 20°C; then, poloxamer is added. The mixture is kept with stirring until complete dissolution is achieved, and then warmed to room temperature. Then, 96% ethanol is added to the above mixture with stirring until a homogeneous mixture is obtained. Then, the pH is checked and, if necessary, adjusted to 7.0.The mixture is brought to the final weight by adding purified water.

[00217] The following properties were considered:1) Viscosity of the composition after increasing the temperature from 25°C to 37°C at a frequency of 10 Hz;2) With regard to the measurements of viscoelastic properties:1) Elastic (storage) moduli (G');2) Viscosity (loss) moduli (G'');3) The loss tangent (tan delta) is calculated as the ratio between the loss modulus, which is an indicator of viscous properties (G''), and the elastic (storage) modulus (G').

[00218] The temperature range shows a transition between G' and G'' moduli, starting from 32°C to 35°C. This transition is associated with increased elasticity of the sample.

[00219] Tan δ<1 shows gel-like properties, which means that elastic properties predominate over viscous properties at a temperature of 37°C. Moreover, at a temperature of 25°C, tan δ>1 demonstrates liquid-like properties, confirming the transformation of the sol into a gel.

[00220] The composition was subjected to a constant frequency and shear stress for 20 minutes at a constant temperature (37°C) to assess whether a time dependence emerged.

[00221] The time dependence confirms an increase in the retention time of the drug at the site of action, preventing the destruction of the three-dimensional structure of the gel. Example 10 Sample 7604

[00222] This sample corresponds to the optimized composition extrapolated by the factorial full design. An aqueous solution of sample 7604 was prepared as follows.

[00223] Purified water (95% of the total amount) is placed in a suitable vessel equipped with a stirrer; then, ascorbic acid and sodium ascorbate are added with stirring until complete dissolution is achieved. Then, sodium alginate is added to the above mixture with stirring until a homogeneous mixture is obtained. Then, sodium carboxymethylcellulose is added to the above mixture with stirring until a homogeneous mixture is obtained. Then, potassium sorbate and sodium benzoate are added with stirring until complete dissolution is achieved. Then, the pH of the solution is checked and, if necessary, its value is adjusted to 6.0-6.5. Then, rifamycin SV is added to the above mixture with stirring until complete dissolution is achieved. The solution is then cooled to a temperature of 5°C to 20°C; then, poloxamer is added. The mixture is kept with stirring until complete dissolution is achieved, and then warmed to room temperature. Then, 96% ethanol is added to the above mixture with stirring until a homogeneous mixture is obtained.Then the pH is checked and, if necessary, adjusted to pH 7.0. The mixture is brought to the final weight by adding purified water.

[00224] The following properties were considered:1) Viscosity of the composition after increasing the temperature from 25°C to 37°C at a frequency of 10 Hz;2) Regarding the viscoelastic properties measurements:1) Elastic (storage) moduli (G');2) Viscosity (loss) moduli (G'');3) The loss tangent (tan delta) is calculated as the ratio between the loss modulus, which is an indicator of the viscous properties (G''), and the elastic (storage) modulus (G').

[00225] The temperature range shows a transition between G' and G'' moduli, starting from 29°C to 31°C. This transition is associated with increased elasticity of the sample.

[00226] Tangent δ<1 exhibits gel-like properties, meaning that elastic behavior predominates over viscous behavior at 37°C.Meanwhile, at a temperature of 25°C, tan δ>1 exhibits properties similar to those of a liquid, confirming the transformation of the sol into a gel.

[00227] The composition was subjected to a constant frequency and shear stress for 20 minutes at a constant temperature (37°C) to evaluate the occurrence of a time dependence.

[00228] The time dependence confirms an increase in the retention time of the drug at the site of action, preventing the destruction of the three-dimensional structure of the gel.Example 11 Sample 7611

[00229] Sample 7611 aqueous solution was prepared as follows.

[00230] Purified water (95% of the total amount) is placed in a suitable vessel equipped with a stirrer; then, ascorbic acid and sodium ascorbate are added with stirring until complete dissolution is achieved. Then, sodium alginate is added to the above mixture with stirring until a homogeneous mixture is obtained. Then, sodium carboxymethylcellulose is added to the above mixture with stirring until a homogeneous mixture is obtained. Then, the pH of the solution is checked and, if necessary, its value is adjusted to 6.0-6.5. Then, rifamycin SV is added to the above mixture with stirring until complete dissolution is achieved. Then, the solution is cooled to a temperature of from 5°C to 20°C; then, poloxamer is added. The mixture is kept with stirring until complete dissolution is achieved, and then warmed to room temperature. Then, 96% ethanol is added to the above mixture with stirring until a homogeneous mixture is obtained. Then, the pH is checked and, if necessary, its value is adjusted to 7.0.The mixture is brought to the final weight by adding purified water.

[00231] Fig. 14 shows the effect of rifamycin concentration on viscosity properties.Example 12 Sample 7615

[00232] An aqueous solution of sample 7 615 was prepared as follows.

[00233]

[00234] Purified water (95% of the total amount) is placed in a suitable vessel equipped with a stirrer; then, ascorbic acid and sodium ascorbate are added with stirring until complete dissolution is achieved. Then, sodium alginate is added to the above mixture with stirring until a homogeneous mixture is obtained. Then, sodium carboxymethylcellulose is added to the above mixture with stirring until a homogeneous mixture is obtained. Then, the pH of the solution is checked and, if necessary, its value is adjusted to 6.0-6.5. Then, rifamycin SV is added to the above mixture with stirring until complete dissolution is achieved. Then, the solution is cooled to a temperature of from 5°C to 20°C; then, poloxamer is added. The mixture is kept with stirring until complete dissolution is achieved and then warmed to room temperature. Then, 96% ethanol is added to the above mixture with stirring until a homogeneous mixture is obtained. Then, the pH is checked and, if necessary, its value is adjusted to 7.0.The mixture is brought to the final mass by adding purified water. Example 13 Sample 7616

[00235] An aqueous solution of sample 7616 was obtained as follows.

[00236] Purified water (95% of the total amount) is placed in a suitable vessel equipped with a stirrer; then, ascorbic acid and sodium ascorbate are added with stirring until complete dissolution is achieved. Then, sodium alginate is added to the above mixture with stirring until a homogeneous mixture is obtained. Then, sodium carboxymethylcellulose is added to the above mixture with stirring until a homogeneous mixture is obtained. Then, the pH of the solution is checked and, if necessary, its value is adjusted to pH 6.0-6.5. Then, rifamycin SV is added to the above mixture with stirring until complete dissolution is achieved. Then, the solution is cooled to a temperature of from 5°C to 20°C; then, poloxamer is added. The mixture is kept with stirring until complete dissolution is achieved and then warmed to room temperature. Then, 96% ethanol is added to the above mixture with stirring until a homogeneous mixture is obtained. Then, the pH is checked and, if necessary, its value is adjusted to 7.0.The mixture is brought to the final weight by adding purified water. Example 14 Antibacterial activity of rifamycin SV

[00237] In patients who have undergone ileoanal anastomosis surgery, biopsies obtained from the upper ileostomy site during stoma closure revealed a predominance of facultative anaerobes (such as lactobacilli, enterococci, and coliforms), low numbers of sulfate-reducing bacteria, and low levels of Clostridium perfringens. On the other hand, during episodes of pouchitis, an increase in Enterobacteriaceae and a decrease in Bacteroides and Faecalibacterium prausnitzii have been described.

[00238] Rifamycin is a topical antibiotic and, in fact, exhibits antibacterial activity against microorganisms causing gastrointestinal infections, but not systemic infections. Moreover, it is released in the gastrointestinal tract and is excreted mainly unchanged in the feces.

[00239] The minimum inhibitory concentration (MIC) is defined as the lowest concentration, expressed in mg / L (equivalent to μg / mL), of an antimicrobial ingredient or agent that is bacteriostatic (prevents visible bacterial growth). MIC is used to evaluate the antimicrobial efficacy of various compounds by measuring the effect of decreasing antibiotic concentrations over a specified period in terms of inhibiting the growth of a microbial population. MIC is generally considered the most basic laboratory indicator of the activity of an antimicrobial agent against an organism. Because a lower MIC value indicates that less drug is required to inhibit the growth of an organism, drugs with lower MIC values ​​are more effective antimicrobials.

[00240] The antimicrobial properties of rifamycin sodium salt were evaluated against a panel of selected bacteria implicated in the pathogenesis of pouchitis, and a standard liquid culture dilution method was used to determine the MIC of rifamycin. Briefly, two-fold dilutions of the test compounds were distributed into 96-well round-bottom plates, and each dilution was treated with liquid culture medium appropriate for the bacterial species being tested. Bacterial inocula were prepared by suspending the microbial strain in sterile saline and adjusted to a McFarland standard of 0.5, corresponding to 1.5 x 10. 8 CFU / ml. A final concentration of bacteria of 0.5-1×10 was distributed into each well. 5CFU / ml. Each plate was incubated at the appropriate temperature and oxygen concentration for the bacterial species tested (aerobic or anaerobic). Incubation times ranged from a minimum of 24 to a maximum of 72 hours. MICs were recorded when visible growth was observed in the positive growth control column (bacterial inoculum without the test substance). The in vitro antimicrobial susceptibility results for the selected bacteria (aerobes and anaerobes) compared to the test rifamycin are shown in Table 3. As shown by the results presented in Table 3 and Fig. 15, rifamycin exhibits potent in vitro antimicrobial activity with a broad spectrum against gram-positive and gram-negative, aerobic and anaerobic bacteria involved in the pathogenesis of a number of gastrointestinal diseases, including pouchitis. Example 15 Antibacterial activity of rifamycin SV in situ gelling enema compositions

[00241] The antibacterial activities of rifamycin SV in situ gelling enema compositions, sample 7570 and sample 7574, and their related placebo compositions (7571 and 7575) were determined by the agar diffusion method on solid inoculated culture medium. The agar well diffusion method is widely used to evaluate the activity of antibiotics and, in this case, allows for a combined study of antibacterial activity together with the diffusion capacity of the composition.

[00242] Briefly, agar medium was prepared according to the manufacturer's instructions and autoclaved at 121°C for 15 minutes. The temperature was then lowered to just above the agar point using a thermostatted bath, and then live bacterial inoculum was added to the medium at a final concentration of 1×10. 5CFU / ml. The inoculated medium was dispensed into Petri dishes and allowed to solidify. Holes (6 mm in diameter) were then made in each Petri dish to dispense the test substance (40 µl). Finally, the dishes were incubated at the appropriate temperature and oxygen concentration for the bacterial species being studied (aerobic or anaerobic) to ensure bacterial growth and compound diffusion through the agar plate. Incubation times ranged from a minimum of 2 to a maximum of 72 hours. Antimicrobial sensitivity was assessed as the inhibition zone size (mm) of the test compound inhibiting microbial growth. Experiments were performed in duplicate, and results are expressed as mean and standard deviation. The gel composition and corresponding placebo were tested in parallel.The in vitro antimicrobial susceptibility results, determined by the agar diffusion method, of selected bacteria (aerobes and anaerobes) compared to the test compositions are shown in Table 5; a larger inhibition zone diameter corresponds to higher antibacterial activity.

[00243] Two pharmaceutical compositions were prepared and tested: (1) 7570 rifamycin SV sample with its related 7571 placebo sample (without rifamycin SV) and (2) 757 4 rifamycin SV sample and 7575 placebo sample (without rifamycin SV). The concentration of rifamycin SV in the pharmaceutical compositions is 5 mg / mL or 7 mM with additional components indicated in Table 3.

[00244] The two samples tested (7570 and 7574) showed significant inhibition of bacterial growth. As shown in Fig. 16, the results confirmed the correspondence between the MIC values ​​obtained for rifamycin as a salt only (shown in Table 3) and the zone of inhibition of rifamycin SV (in situ gelation) in the 7570 and 7574 sample enemas; in fact, for the same bacterial strains, lower MIC values ​​correspond to zones of inhibition with a larger diameter. In addition, the two placebo formulations (7571 and 7575) did not show any antimicrobial activity against the tested microbial strains, confirming the specific antibacterial activity of the rifamycin SV formulation.Example 16 Anti-inflammatory Activity of a Pharmaceutical Composition of Rifamycin SV via PXR Activation

[00245] The anti-inflammatory activities of the enema compositions (in situ gelling) with Rifamycin SV, Sample 7570 and Sample 7574 and their related placebo compositions (7571 and 7575) were determined using in vitro assays to determine the activation of the transcription factor pregnane X receptor (PXR), the inhibition of the transcription factor nuclear factor kB (NFkB) and the inhibition of the mechanistic target of rapamycin pathway (mTOR).

[00246] In addition to its role in detoxification mechanisms, the transcription factor PXR has been shown to indirectly inhibit inflammation through the repression of another transcription factor, NFkB. Ultimately, this results in a reduction in the expression of multiple inflammatory cytokines, including IL8, in intestinal cells [Rosette et al., 2019].A human embryonic kidney reporter cell line (HEK293t) expressing a PXR fusion protein was used to compare the anti-inflammatory activity of in situ gel-forming enema formulations of rifamycin with rifamycin sodium salt. Cells were seeded on 96-well collagen-coated plates and treated with the test solutions for 24 hours using a 7-point logarithmic titration. Luminescence proportional to PXR activity was quantified using a luminometer. As shown in Figure 17, both in situ gel-forming enema formulations containing rifamycin SV demonstrated increased stimulatory efficacy on PXR transcriptional activity compared to rifamycin when tested at a concentration of 3 × 10. -6 M. The maximum activity of rifampicin (100% stimulation) was used for comparison, since it is the reference standard for PXR activation in this reporter assay system. Concentration 3×10 -6M is readily achieved in the proposed pouchitis enema gel formulation containing 7 mM active ingredient, which is 200-fold higher than the concentration of the highest tested level in the PXR assay. Furthermore, the maximum antibacterial MIC value of 200 μg / mL (0.3 mM) is 23-fold lower than that of the proposed pouchitis enema formulation containing 7 mM active ingredient. Thus, the required concentrations for both anti-inflammatory (PXR activity) and antibacterial (MIC) activity are significantly lower than the 7 mM rifamycin concentration in the gel formulation. Both placebo (also referred to as vehicle) gel formulations and DMSO alone did not induce PXR transcriptional activity, confirming the specificity of the formulation's activity (data not shown).Example 17 Anti-inflammatory activity of rifamycin SV via inhibition of the mTOR pathway

[00247] The mechanistic target of rapamycin (mTOR) is serine / threonine kinase, which exists as the catalytic subunit of two biochemically distinct complexes called mTOR complex 1 (mTORC1) and mTORC2. Typically, mTORC1 controls cell growth in response to nutrients and growth factors. However, recent evidence has implicated immune cell-specific mTORC1 in various inflammatory diseases [Lin X (2018)]. The mTOR pathway promotes the expression of key effector and regulatory cytokines involved in ulcerative colitis (UC), such as IL10, IFNγ, and IL17 [Xie et al (2020)], demonstrates an important role for epithelial mTORC1 in the pathogenesis of UC, and establishes a link between colonic epithelium and immune cells in the development of UC.This study used two genetic mouse models and, importantly, biopsies from patients with ulcerative colitis. mTOR inhibitors such as rapamycin have anti-inflammatory effects in models of experimental colitis, and the antibiotic rifaximin has been shown to inhibit the mTOR pathway in vitro in colonic epithelial cells.

[00248] The inflamed J-reservoir has inflammatory features similar to those in the colons of patients with ulcerative colitis, suggesting that they are driven by similar inflammatory mechanisms and, therefore, may respond to similar therapeutics. Thus, mTOR inhibitors may also be effective in the treatment of pouchitis.

[00249] To assess the activity of rifamycin on the mTOR pathway, primary colon epithelial cells were serum-starved for 24 hours and restimulated with serum for 48 hours to induce phosphorylation of mTOR and its downstream target protein S6R. Serum-stimulated cells were treated with rifamycin SV, rifaximin, rapamycin as a positive control, or DMSO vehicle as a negative control. Cells were fixed, stained with antibodies against pmTOR and pS6R, and then analyzed by flow cytometry. The percentage of cells staining positively for both antibodies was quantified and normalized to the DMSO control (set to 100%).

[00250] Figure 18 shows the percentage of cells staining positively for anti-pmTOR and anti-pS6R relative to DMSO. The ranking of activity on the mTOR pathway is as follows: Rapamycin > Rifamycin SV > Rifaximin (IC. 505.3×10-7, 9.9×10-6, 4.3×10-5, respectively). Thus, rifamycin SV is 4-fold more potent than rifaximin and only 20-fold less potent than the standard reference mTOR pathway inhibitor, rapamycin. Example 18 Compositions with rifamycin SV in aqueous solution were prepared as follows:

[00251] The following pharmaceutical compositions were prepared: (1) Samples 7639 and 7663 with rifamycin SV (the composition of sample 7663 is similar to the composition of sample 7639) with related placebo samples 7642 (without rifamycin SV) and placebo samples 7679 (without rifamycin SV + red dye staining).

[00252] Purified water (95% of the total amount) is placed in a suitable vessel equipped with a stirrer; then, ascorbic acid and sodium ascorbate are added with stirring until complete dissolution is achieved. Potassium metabisulfite is then added to the above mixture with stirring until a homogeneous mixture is obtained.

[00253] Sodium alginate is then added to the above mixture with stirring until a homogeneous mixture is obtained.

[00254] Sodium carboxymethylcellulose is then added to the above mixture with stirring until a homogeneous mixture is obtained.

[00255] The solution is then cooled to a temperature in the range of 5°C to 20°C; then poloxamer is added until a homogeneous mixture is obtained.

[00256] The pH of the solution is then checked and, if necessary, its value is adjusted to 6.0-6.5.

[00257] Rifamycin SV is then added to the above mixture with stirring until complete dissolution is achieved.

[00258] The pH is then checked and, if necessary, its value is adjusted to 7.0.

[00259] 96% ethanol is then added to the above mixture with stirring until a homogeneous mixture is achieved.

[00260] The mixture is brought to the final weight by adding purified water. Example 19

[00261] Preclinical in vitro and in vivo studies were performed using the new optimized (in situ gelling) enema compositions, which are described below to better illustrate and support the invention without limiting its scope.

[00262] For the following examples, the composition identified as sample 7639 (whose composition and method of preparation are included in Example 18) also corresponds to sample 7663 and is also designated by the reference code CB0125 in the figures below.

[00263] In vitro studies: One rifamycin enema composition (in situ gelling) (sample 7639) of the present invention and a related placebo composition (sample 7642) according to Table 6 above were tested by the agar diffusion method and were shown to inhibit the growth of bacteria specifically involved in the pathogenesis of pouchitis.The agar diffusion method is widely used to assess the activity of antibiotics and, in this case, allows combining the study of antibacterial activity with the diffusion ability of the drugs being studied.

[00264] Composition 7639 demonstrated significant inhibition of the growth of a representative group of bacteria involved in the pathogenesis of inflammatory bowel diseases, such as pouchitis. The results confirmed the correspondence between the MIC values ​​obtained for rifamycin (presented in Table 3) and the zone of inhibition of the composition 7639 with rifamycin for enema (in situ gelling). It should be noted that, for the same bacterial strains, lower MIC values ​​correspond to zones of inhibition with a larger diameter. Therefore, in this case, the combination of rifamycin in the composition as an in situ gelling solution did not affect or reduce the antibacterial activity of rifamycin when tested on a panel of bacteria involved in inflammatory bowel diseases, such as pouchitis.

[00265] As expected, the placebo formulation 7642 (without rifamycin) did not demonstrate any antibacterial activity confirming specificity.

[00266] The antibacterial activity of rifamycin enema formulations (7639 and 7640) (in situ gelling) was investigated using an agar penetration assay. This is a sensitive and quantitative antibacterial test in which different concentrations of each formulation are applied to microorganisms grown on a solid agar support. This assay allows not only to quantify the effective antimicrobial activity but, more importantly, to determine the ability of the formulation to penetrate a physical barrier in vivo, similar to what can happen with intestinal epithelial mucus in the reservoir and in the intestine. Two different agar concentrations (0.8% and 1.5% w / v agar) were tested to determine the percentage penetration of the rifamycin enema formulations (in situ gelling) into agar of different densities.

[00267] The data presented in Table 8 indicate that different agar concentrations did not affect the antibiotic activity of the tested (in situ gelling) enema; the small differences observed between different samples of the rifamycin compositions and different agar concentrations were not considered significant. Accordingly, the antibacterial activity of the rifamycin compositions is not dependent on the agar density, and the compositions should exhibit similar antibacterial activity in vivo regardless of the density of mucus and intestinal epithelium.

[00268] The anti-inflammatory activity of compositions 7637, 7639, 7640 was determined using a human embryonic kidney reporter cell line (HEK293t) expressing the PXR fusion protein. This in vitro anti-inflammatory activity was compared with the anti-inflammatory activity of rifamycin alone as an active ingredient (dissolved in DMSO).

[00269] The results presented in Fig.19 show that almost all of the gel solutions (except 7637) have enhanced agonist activity on PXR transcriptional activity compared to rifamycin in DMSO.

[00270] In vivo Study: The in vivo physicochemical characteristics of the 7639 in situ gel enema formulation, such as gelation, surface contact area, release properties and biocompatibility, were determined and characterized. The study was performed to demonstrate that the rifamycin enema formulation (in situ gel) changed from a liquid state to a gel / solid state at 37°C after enema administration. Briefly, rats were anesthetized and an enema of 7639 formulation (2 ml / rat) was administered into the rectum via a catheter. All rats were euthanized by CO2 inhalation at predetermined time points. Immediately after euthanasia, animals were subjected to laparotomy, and the intestines were exposed.The colon was removed entirely from the cecum to the anus, carefully cleaned of vessels and mesenteric fat with scissors, cut longitudinally, and examined to assess the presence of the gel composition.

[00271] Figure 20 shows that after a single administration via enema, composition 7639 readily formed a gel in the colon after 5 minutes (not shown), and the gel persisted for at least 4 hours. The enema coated the intestinal surface and formed a gel film. Gel persistence was inversely proportional to time, with a gradual decrease in gel persistence over a period of 0.5 to 4 hours. After 6 hours, the gel was no longer present. Following a single enema administration of composition 7639, the concentration of rifamycin in colon homogenates and plasma was determined by HPLC / MS-MS in samples collected at different time points.

[00272] In Fig.21 It was shown that in colon homogenate samples, rifamycin was detectable at all time points analyzed, with peak concentrations at 2-4 hours post-administration; at 6 hours post-administration, rifamycin was detected at a mean concentration of 123 ng / g. The concentration of rifamycin in the colon appears to correlate with the retention of the gel in the colon.

[00273] When blood samples were studied, rifamycin concentrations at all time points (30 minutes, 1 hour, 2 hours, 4 hours, and 6 hours) were always lower than the lower limit of quantification (LLOQ) of the method (1 ng / mL) at all time points studied, indicating the absence of systemic absorption following enema administration.

[00274] Thus, the composition of the invention exhibits gelling at 37°C in situ with a gel retention time of at least 4 hours after administration; this translates into therapeutic concentrations of rifamycin in colon tissue, while systemic absorption is insignificant. This convincingly confirms the effectiveness of the local treatment of rectal pathologies by means of the composition of the present invention, reducing the risks of systemic side effects.

[00275] The in vivo efficacy of the 7663 in situ gel enema composition sample (a composition similar to sample 7639) was studied in a mouse model of acute colitis induced by dextran sodium sulfate (DSS). This animal model is perhaps the most widely used mouse model of colitis and uses DSS, a chemical colitogen with anticoagulant properties, to induce a disease that closely resembles ulcerative colitis in humans.DSS-induced intestinal inflammation results in damage to the epithelial monolayer lining the colon, leading to dissemination of proinflammatory intestinal contents (e.g., bacteria and their products) into the underlying tissues.[0027 6] For this study, one group of mice was administered an enema with sample 7663 (labeled CB0125 in the figures) (dose 45 mg / kg), one group was administered an enema with placebo sample 7679 as a comparator for 7663, and one group was administered an enema with powdered rifamycin dissolved in water (67 mg / kg). One group of mice was orally administered 5-ASA at a dose of 100 mg / kg; this group served as a positive control. 5-ASA is the gold standard therapy for inflammatory bowel diseases, including ulcerative colitis, distal ulcerative colitis, and proctitis. One group was administered an enema with only the vehicle (H2O) as a negative control.

[00277] Briefly, DSS (2%) was dissolved in water (w / v) and given to mice instead of regular drinking water.Water with DSS was provided ad libitum for 5 days and changed daily. This period was followed by a "washout" period of 5 days with water only. Mice were weighed daily and monitored for clinical status, including hunching, mobility, soft stools, and / or diarrhea. At the end of the study, mice were euthanized by CO2 inhalation. Immediately after euthanasia, animals were laparotomized and the intestines were externalized. The colon was dissected intact from the cecum to the anus, placed on a ruler in an unstretched state, and then measured and weighed after rinsing the lumen with saline. Weight was normalized to colon length by calculating a ratio.

[00278] As shown in Fig. 22A, treatment with composition 7663 (CB0125) showed improved body weight change compared to vehicle and placebo 1619.Treatment with rifamycin in water enema, as well as treatment with oral 5-ASA (positive control), showed similar results in improving body weight compared to vehicle (H2O)-treated mice.

[00279] Importantly, treatment with the 7663 formulation showed a significant improvement in colon weight / colon length (CW / CL) compared to vehicle and placebo. Specifically, treatment with rifamycin in water and 5-ASA showed less efficacy than 7663 (Figure 22B).

[00280] Additionally, treatment with the 7663 formulation showed a significant improvement in clinical assessment of AUC compared to vehicle and placebo; treatment with rifamycin in water and 5-ASA showed less efficacy than 7663 (Figure 22C).

[00281] Finally, treatment with enema formulation 7663 (in situ gelling) and rifamycin in water showed a significant improvement in stool totals compared to vehicle (Figure 22D).Treatment with 7679 placebo significantly improved stool scores compared to vehicle, but to a lesser extent than 7663 enema with rifamycin (in situ gelling).

[00282] For histological examination of colon samples, approximately 2 cm of mid-section of the separated colon was fixed in 10% formalin. Each fixed fragment was embedded in paraffin. Slides were stained with hematoxylin and eosin and scored for histological scores.

[00283] Figure 23 shows that the significant clinical effects observed with 7663 / CB0125 treatment were confirmed by histological examination. A significant reduction in histological score was observed in mice treated with 7663 compared to placebo and vehicle; Treatment with rifamycin in water, as well as 5-ASA, showed a slight improvement in histological examination score compared to 7663.

[00284] For the pharmacokinetic (PK) study, colon samples were cut into pieces and washed three times with phosphate-buffered saline (PBS) to remove surface contaminants.

[00285] Figure 24 shows that in mice receiving either the 7663 enema formulation (in situ gelling) or rifamycin in water, rifamycin was consistently detected in the colon homogenate; rifamycin concentrations in the colon tissue of animals receiving rifamycin in water were lower than in animals receiving the 7663 formulation at all time points in the study, despite the fact that rifamycin in water was administered at a higher dose (67 mg / kg versus 45 mg / kg). The data clearly demonstrate that the composition of the invention is capable of improving the local penetration of rifamycin into colon tissue and its retention in the same tissue.

[00286] A stability study was performed on the new optimized formulations, in particular on the 7639 enema (in situ gelling) sample, the composition of which is described in Example 18. The study demonstrates good stability of the product packaged in polyethylene (PE) vessels for up to 6 months when stored at 5°C, and significantly higher stability at 25°C compared to a commercially available rifamycin solution (Rifocin® 5 g / 100 g, sample A9073). The data are presented in the following tables, which summarize the known (rifamycin S) and unknown impurities in the composition:. As can be seen from the above data, the stability of the compositions of the invention is significantly improved compared to Rifocin®. It is important to note that the stability data of the composition of the invention after 6 months is much better than the stability data of Rifocin® after 1 month. Thus, the composition of the present invention shows a lower degree of degradation after 6 months than Rifocin® after 1 month, which allows for longer storage at room temperature. References 1. Li, Y. and Shen, B. (2014). Management of acute and chronic pouchitis. Medical Therapy of Ulcerative Colitis, Springer, New York, pp. 367–376. 2. Isaacs, K., et al. (2007). Rifaximin for the treatment of active pouchitis: a randomized, double-blind, placebo-controlled pilot study. Inflamm. Bowel Dis, 2007; 13: 1250–1255. 3. Nguyen N, Zhang B, Holubar SD, Pardi DS, Singh S. (2019). Treatment and prevention of pouchitis after ileal pouch-anal anastomosis for chronic ulcerative colitis.Cochrane Database of Systematic Reviews, Issue 11. Art. No.: CD001176.4. Akiyama, S., et al. (2021). Pouchitis in inflammatory bowel disease: a review of diagnosis, prognosis, and treatment. Intest Res 19(1):1-11. doi:10.5217 / ir.2020.000475. Schieffer, K.M., et al. (2016). Review article: the pathogenesis of pouchitis. Aliment Pharmacol Ther 2016, 44:817-835.6. Hoy, SM. (2019) Rifamycin SV MMX: a review in the treatment of traveler's diarrhea. Clin Drug Investig Jul., 39(7):691-697.7. Rosette, C, et al. (2019). Rifamycin SV exhibits strong anti-inflammatory in vitro activity through pregnane X receptor stimulation and NFkB inhibition. Drug Metabolism and Pharmacokinetics, 34(3): 172-180.8. Rosette, C. et al. (2013). Anti-inflammatory and immunomodulatory activities of rifamycin SV. Int J Antimicrob Agents 42:182-186.9. Fumery, M., et al. (2018). Natural History of Adult Ulcerative Colitis in Population-based Cohorts: A Systematic Review. Clin Gastroenterol Hepatol.2018 March; 16(3): 343-356.10. Brereton, R.G., (2003). Chemometries: data analysis for the laboratory and chemical plant. John Wiley & Sons Ltd, Chichester.11. Draper, N.R. and Smith, H. (1981), Applied regression analysis. New York: Wiley & sons, 412-419.12. Rosette, C, et al. (2019). Rifamycin SV exhibits strong anti-inflammatory in vitro activity through pregnane X receptor stimulation and NFkB inhibition. Drug Metabolism and Pharmacokinetics, 34(3): 172-180.13. Lin, X., et al. (2018). Colonic epithelial mTORC1 promotes ulcerative colitis through COX-2'-mediated Thl7 responses. Mucosal Immunol.Nov; 11(б):1663-1673.14. Xie, Y., et al. (2020). Gut epithelial TSC1 / mTOR controls RXPK3-dependent necroptosis in intestinal inflammation and cancer. J Clin Invest 130:2111.

Claims

1. Use of a pharmaceutical composition in the treatment of pouchitis, proctitis and / or ulcerative colitis of the distal areas, including proctosigmoiditis, wherein the pharmaceutical composition contains: a therapeutically effective amount of rifamycin SV or a pharmaceutically acceptable salt thereof; and a polymer mixture; wherein the pharmaceutical composition is formulated in such a way that it is suitable for rectal administration, is a liquid at room temperature and forms a gel in situ at the body temperature of the said patient; wherein the polymer mixture contains: at least one heat-sensitive polymer; at least one ion-sensitive polymer; and at least one bioadhesive polymer.

2. Use according to paragraph 1, wherein the pharmaceutical composition is an enema.

3. The use according to claim 1 or 2, wherein the thermosensitive polymer is selected from the group consisting of: block copolymers of polyoxyethylene and polyoxypropylene, block copolymers of poly(ethylene glycol) / poly(lactide-co-glycolide) (PEG-PLGA), poly(ethylene glycol)-poly(lactic acid)-poly(ethylene glycol) (PEG-PLA-PEG), poly(N-isopropylacrylamide) and cellulose derivatives.

4. The use according to claim 1, 2 or 3, wherein the heat-sensitive polymer is a block copolymer of polyoxyethylene and polyoxypropylene selected from the group consisting of: poloxamer 124, poloxamer 188, poloxamer 237, poloxamer 338 and poloxamer 407.

5. The use according to any one of claims 1 to 4, wherein the heat-sensitive polymer is a cellulose derivative selected from the group consisting of methylcellulose (MC), hydroxypropylmethylcellulose (HPMC) and mixtures thereof.

6. The use according to any one of claims 1 to 4, wherein the heat-sensitive polymer is poloxamer 188, poloxamer 407 or mixtures thereof.

7. The use according to any one of claims 1 to 4, wherein at least one temperature-sensitive polymer is present in an amount of from about 1% to about 25% by weight relative to the weight of the pharmaceutical composition; preferably from about 12% to about 18% by weight relative to the weight of the pharmaceutical composition.

8. Uses according to any one of claims 1 to 5, wherein the ion-sensitive polymer is a polysaccharide.

9. The use according to any one of claims 1 to 8, wherein the ion-sensitive polymer is selected from the group consisting of: carrageenan, gellan gum, pectin, alginic acid, their salts and mixtures thereof.

10. The use according to any one of claims 1 to 9, wherein the ion-sensitive polymer is sodium alginate.

11. The use according to any one of claims 1 to 6, wherein at least one ion-sensitive polymer is present in an amount of from about 0.01% to about 3% by weight relative to the weight of the pharmaceutical composition; preferably from about 0.1% to about 2.0% by weight relative to the weight of the pharmaceutical composition.

12. The use according to any one of claims 1 to 7, wherein the bioadhesive polymer is selected from the group consisting of: chitosan, hyaluronic acid and its salts, cellulose derivatives, polyvinyl alcohol, polyvinylpyrrolidone, polyacrylic acid, polyethylene oxides, tragacanth, sodium alginate, xanthan gum, gelatin, pectin and mixtures thereof.

13. The use according to any one of claims 1 to 12, wherein the bioadhesive polymer is a cellulose derivative selected from the group consisting of: methylcellulose, hydroxypropyl methylcellulose, hydroxypropyl cellulose, sodium carboxymethylcellulose and mixtures thereof.

14. The use according to any one of claims 1 to 13, wherein the bioadhesive polymer is sodium carboxymethylcellulose.

15. The use according to any one of claims 1 to 8, wherein the bioadhesive polymer is present in an amount of from about 0.01% to about 2.0% by weight relative to the weight of the pharmaceutical composition, preferably in an amount of from about 0.01% to about 0.1% by weight relative to the weight of the pharmaceutical composition.

16. The use according to any one of the preceding claims, wherein the pharmaceutical composition further comprises at least one pharmaceutically acceptable excipient selected from the group consisting of: an antioxidant, a preservative and a combination thereof; and / or optionally, wherein the composition has a pH value in the range from 6.5 to 7.5, preferably from 6.8 to 7.

2.

17. The use according to any one of the preceding claims, containing from about 0.1% to about 5% by weight of rifamycin SV or a pharmaceutically acceptable salt thereof relative to the weight of the pharmaceutical composition; preferably from about 0.25% to about 3.0% by weight of rifamycin SV or a pharmaceutically acceptable salt thereof relative to the weight of the pharmaceutical composition, for example from about 0.25% to about 2.5% by weight relative to the weight of the pharmaceutical composition.

18. The use according to claim 1, wherein the treatment is intended to alleviate and / or reduce one or more clinical symptoms selected from the group consisting of: increased frequency of bowel movements, changes in stool consistency, rectorrhagia, pain, abdominal cramps, urges, tenesmus, fecal incontinence, fever and extraintestinal manifestations.

19. The use according to claim 1, wherein the treatment is intended to alleviate and / or reduce the incidence of one or more endoscopic symptoms selected from the group consisting of: mucosal edema, granular structure, contact bleeding, loss of vascular pattern, bleeding and ulceration.

20. The use according to claim 1, wherein said pharmaceutical composition is administered daily or twice a day; optionally, said pharmaceutical composition is administered daily or twice a day for at least two weeks.

21. The use according to claim 1, wherein the pharmaceutical composition comprises from about 0.1% to about 5% by weight of rifamycin SV or a pharmaceutically acceptable salt thereof relative to the weight of the pharmaceutical composition; and a polymer mixture containing: at least one thermosensitive polymer present in an amount of from about 1% to about 25% by weight relative to the weight of the pharmaceutical composition; at least one ion-sensitive polymer present in an amount of from about 0.01% to about 3% by weight relative to the weight of the pharmaceutical composition; at least one bioadhesive polymer present in an amount of from about 0.01% to about 2.0% by weight relative to the weight of the pharmaceutical composition.

22. The use according to claim 1, wherein the pharmaceutical composition comprises from about 0.1% to about 5% by weight of rifamycin SV or a pharmaceutically acceptable salt thereof relative to the weight of the pharmaceutical composition; and a polymer mixture containing: at least one thermosensitive polymer present in an amount of from about 12% to about 18% by weight relative to the weight of the pharmaceutical composition; at least one ion-sensitive polymer present in an amount of from about 0.1% to about 2.0% by weight relative to the weight of the pharmaceutical composition; at least one bioadhesive polymer present in an amount of from about 0.05% to about 0.1% by weight relative to the weight of the pharmaceutical composition.

23. The use according to claim 1, wherein the pharmaceutical composition comprises from about 0.25% to about 2.5% by weight of rifamycin SV or a pharmaceutically acceptable salt thereof relative to the weight of the pharmaceutical composition; and a polymer mixture containing: at least one thermosensitive polymer present in an amount of from about 12% to about 18% by weight relative to the weight of the pharmaceutical composition; at least one ion-sensitive polymer present in an amount of from about 0.1% to about 2.0% by weight relative to the weight of the pharmaceutical composition; at least one bioadhesive polymer present in an amount of from about 0.05% to about 0.1% by weight relative to the weight of the pharmaceutical composition.

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