Composition for the treatment of osteoarthritis

Abstract

The present invention relates to a composition for intra-articular use for the treatment of osteoarthritis (OA), comprising cross-linked hyaluronic acid or a salt or derivative thereof, clodronic acid or an equivalent salt thereof, and acetate buffer.

Description

Technical Field

[0001] The present invention relates to a composition containing cross-linked hyaluronic acid or its salt or derivative, clodronic acid or its equivalent salt, and an acetate buffer solution, and is preferably used for the treatment of osteoarthrosis (OA), including osteoarthritis, by intra-articular administration.

Background Art

[0002] Arthrosis or osteoarthrosis (OA) is a progressive chronic disease that particularly affects joints that are most susceptible to mechanical stress, such as the hip and knee. When this symptom occurs, the entire joint is affected by a series of degradation and repair processes, and ultimately, the structure and function of the joint change, affecting all components of the joint, such as cartilage, subchondral bone, and synovial tissue. Therefore, the state of "arthrosic" is the result of a series of interrelationships between systemic factors (e.g., aging and obesity) and local factors (e.g., trauma and overuse), changing successively due to a number of predisposing factors, or combined with infectious and inflammatory events caused by various etiologies.

[0003] In this complex event, attempts have been made for many years to perform therapeutic interventions by addressing and suppressing individual causative processes. Also, in practice, various treatments aimed at managing the resulting inflammatory events and pain have been relied upon. Mainly, intra-articular injections of various drugs such as analgesics, local or systemic anti-inflammatory agents, or bisphosphonates, hyaluronic acid, anthraquinone, chondroitin sulfate, etc. have been used.

[0004] In order to obtain a more effective composition, combinations of the above active ingredients have also been attempted. For example, patent EP1976538 by the same applicant describes a combination of linear hyaluronic acid and sodium clodronate, which yields excellent results in reducing pain symptoms in patients with osteoarthritis. Furthermore, the combination of the two active ingredients, through a synergistic effect, reduces both the effective amount of hyaluronic acid used in the final formulation, thereby reducing undesirable effects such as stimulation of inflammatory cytokine production, and the amount of clodronate reduces side effects mainly due to its acidity, thereby improving overall patient compliance.

[0005] After decades of clinical use of hyaluronic acid, it is now known that the effectiveness of linear hyaluronic acid is far superior to that of cross-linked hyaluronic acid, which is characterized by its longer retention time within the joint compared to linear hyaluronic acid.

[0006] Scientific studies show that linear hyaluronic acid has a residence time of only about 2-3 days, compared to approximately 1-4 weeks (Conrozier, Joint Bone Spine 83, 2016, 1-2). The paper resubmits that this is due to its unique chemical structure, which makes it less susceptible to degradation by hyaluronidase naturally present in the joint cavity.

[0007] Furthermore, it is known that a combination of clodronic acid or its salts, such as sodium salt, with cross-linked hyaluronic acid has therapeutic effects. For example, Palmieri, Drug Design, Development and Therapy 2013:7 7-12, reported favorable results using two active ingredients to treat pain symptoms of osteoarthritis in the knee. In this study, the authors mixed solutions of commercially available drugs containing separate active ingredients immediately before use to obtain an immediate solution of their combination.

[0008] However, once the two active ingredients come into contact with each other, they are not very stable, and the drugs tend to decompose rapidly. Therefore, drugs prepared in this way, that is, instant drugs, need to be used quickly. [Overview of the project] [Problems that the invention aims to solve]

[0009] Therefore, in practice, even today, the primary treatment goal in the management of osteoarthritis (OA) is the control and reduction of the pain symptoms that always accompany the condition, which is crucial to the quality of life of affected patients. This goal should also be achieved through the least invasive treatment methods possible.

[0010] Therefore, the object of the present invention is to solve the problems reported above by obtaining a novel alternative treatment for the treatment of OA and, in particular, the treatment of pain symptoms of OA, while being effective, safe, and satisfactory in terms of patient compliance. [Means for solving the problem]

[0011] To our surprise, the inventors have discovered that by using cross-linked hyaluronic acid or its salt or derivative, clodronic acid or an equivalent amount of its salt in combination with acetate buffer, the above-mentioned effective alternative therapeutic means can be obtained. In fact, the addition of compositions containing cross-linked hyaluronic acid or its salts or derivatives, and clodronic acid or its equivalent salts, to acetate buffer demonstrated that they were effective and safe for patients, exhibited excellent compliance, and made the compositions remarkably stable. Surprisingly, the presence of acetate buffer can effectively stabilize compositions of cross-linked hyaluronic acid, or its salts or derivatives, and clodronic acid, or its equivalent salts. In sterilization processes required during pharmaceutical manufacturing, the absence of acetate buffer or the use of other buffers would rather lead to rapid degradation of the solution, but the associated stability problems could also be overcome.

[0012] Therefore, the present invention is - Cross-linked hyaluronic acid or its salts or derivatives, - Clodronic acid or an equivalent amount of its salt, and - Acetate buffer This relates to compositions containing the following:

[0013] In the present invention, the term "acetic acid buffer" refers to an aqueous solution of acetic acid and an alkali or alkaline earth metal acetate. Examples of acetate buffers include aqueous solutions of acetic acid-sodium acetate, acetic acid-potassium acetate, acetic acid-calcium acetate, and acetic acid-magnesium acetate. The preferred acetate buffer according to the present invention is an aqueous solution of acetic acid-sodium acetate.

[0014] The compositions of the present invention optionally include a pharmaceutically acceptable carrier and / or a suitable excipient. In a preferred embodiment, the composition of the present invention is in gel form. In a more preferred embodiment, the composition of the present invention is preferably gel-like: - 1.8 to 2.2 mg / mL, preferably 1.9 to 2.1 mg / mL, more preferably about 2 mg / mL of sodium clodronate or an equivalent amount thereof of clodronic acid or another salt thereof; - 16-24 mg / mL, preferably 18-22 mg / mL, more preferably about 20 mg / mL of cross-linked sodium hyaluronate; - 0.6 to 1.2 mg / mL, preferably 0.8 to 1 mg / mL of sodium acetate and 0.028 to 0.052 mg / mL of acetic acid, - water Includes.

[0015] The gel-like composition of the present invention optionally contains an excipient. In a more preferred embodiment, the composition is preferably in gel form: - 1.8 to 2.2 mg / mL, preferably 1.9 to 2.1 mg / mL, more preferably about 2 mg / mL of sodium clodronate or an equivalent amount of clodronic acid or other salt thereof; - 17-21 mg / mL, preferably 18-20 mg / mL, more preferably 19 mg / mL of cross-linked sodium hyaluronate; - Sodium acetate at 0.6 to 1.2 mg / mL, preferably 0.8 to 1 mg / mL, and acetic acid at 0.028 to 0.052 mg / mL; - Sodium hyaluronate at 0.5 to 2 mg / mL, preferably about 1 mg / mL; and - Water are included. Optionally, the composition of the present invention further contains an excipient.

[0016] In another aspect, the present invention relates to a single-dose form containing 1 to 5 mL, preferably 2 mL of the above gel-like composition.

[0017] In a further aspect, the present invention relates to the use of the composition of the present invention, alone or in combination, i.e., as a combined therapeutic agent in a fixed-dose combination or in combination therapy with separately formulated active ingredients, for the treatment of osteoarthritis by intra-articular administration.

[0018] In the present invention, when referring to "osteoarthritis", "arthrosis" shall also be included.

[0019] The inventors have also found that the composition of the present invention can improve the symptoms of osteoarthritis. Therefore, the present invention relates to a medical device containing the composition of the present invention and an excipient. The medical device, and thus the composition of the present invention, can be used to improve the symptoms of osteoarthritis related to aspects particularly related to joint pain. The medical device, and thus the composition of the present invention, can be used in combination therapy with known drugs for the treatment of osteoarthritis. In another aspect, the present invention relates to a method for producing the above composition.

Embodiments for Carrying out the Invention

[0020] In the present invention, the following terms: - "Chlodronic acid or an equivalent salt thereof" shall include all polymorphs thereof, both amorphous and crystalline, and cocrystalline forms, as well as the anhydrous, hydrated, and solvated forms of chlordronic acid or a salt thereof. The salt is formed with any pharmaceutically acceptable cation, the preferred cation being sodium.

[0021] - "Acetic acid buffer" refers to an aqueous solution of acetic acid and an alkali or alkaline earth metal acetate. Examples of acetate buffers include aqueous solutions of acetic acid-sodium acetate, acetic acid-potassium acetate, acetic acid-calcium acetate, and acetic acid-magnesium acetate. The preferred acetate buffer according to the present invention is an aqueous solution of acetic acid-sodium acetate.

[0022] - "Cross-linked hyaluronic acid or its salts or derivatives" means hyaluronic acid that has been crosslinked by, for example, divinyl sulfone (DVS), glutaraldehyde (GTA), 1,4-butanediol diglycidyl ether (BDDE) or other chemical crosslinking methods, or by physical crosslinking methods (e.g., photocrosslinking or thermal crosslinking), or its salts with any pharmaceutically acceptable cation; the preferred cation is sodium; or hyaluronic acid that has been derivatized with a compound selected from the group consisting of, for example, carbodiimide, carbodiimidazole, and hydrazine sulfate; derivatives also include organic and inorganic salts of hyaluronic acid crosslinked or derivatized in the manner described above. The preferred cross-linked hyaluronic acid in the present invention is cross-linked hyaluronic acid obtained by crosslinking with 1,4-butanediol diglycidyl ether (BDDE).

[0023] - "Linear hyaluronic acid or a salt thereof" means hyaluronic acid that has not undergone any cross-linking treatment, and a salt thereof means a salt with any pharmaceutically acceptable cation, the preferred cation being sodium.

[0024] - "Pharmacologically acceptable carrier" means a carrier suitable for the final formulation, preferably water, and more preferably water for intra-articular administration.

[0025] - "Osteoarthritis (OA)" refers to degenerative and / or inflammatory processes affecting the joints, including osteoarthritis.

[0026] - G', or the modulus of elasticity, represents the energy stored in the elastic structure of a solid (e.g., a gel) during deformation. A larger G' indicates greater material hardness. The modulus of elasticity G' is typically used to describe the solid component of a gel. In the context of this invention, the elastic modulus G' is measured preferably at room temperature, typically at 25°C, with the help of a rheometer using a 40 mm plate / plate geometry and a 250 μm gap, in this case a Kinexus Pro type. The sample is subjected to preliminary shearing and resting time to erase its "rheological memory," and then the linear viscoelastic region is measured by amplitude sweep at a fixed frequency, for example, 1 Hz. Next, the elastic modulus G' can be measured from the curve obtained in the linear viscoelastic region where stress and displacement have a linear relationship.

[0027] The term "extrusion force" refers to the force required to push a product out of a syringe through a needle. In this invention, the extrusion force is measured using an MTS Adamel Lhomargy DY30 type universal material testing machine (or universal testing machine). Following the protocol used, connect the needle to the syringe, apply a speed of 1 cm / min to the syringe plunger, and record the average extrusion force between displacements of 10 mm and 30 mm.

[0028] In the context of this specification and the subsequent claims, all numerical values ​​indicating quantities, parameters, percentages, etc., are intended to be preceded by the term “approximately” in all contexts unless otherwise specified. Furthermore, all numerical ranges include all possible combinations of maximum and minimum values, and all possible intermediate ranges, in addition to the ranges specifically shown in the following description. Preferably, the compositions of the present invention for use in the treatment of osteoarthritis (OA) are directed toward the treatment of pain symptoms of osteoarthritis (OA).

[0029] Therefore, the present invention is - Cross-linked hyaluronic acid or its salts or derivatives, - Clodronic acid, or an equivalent amount of its salt, and - Acetate buffer This relates to compositions containing the following:

[0030] Therefore, the composition of the present invention comprises chlordronic acid or an equivalent amount of salt thereof. The salt of chlordronic acid is preferably a salt of chlordronic acid with a pharmaceutically acceptable cation. Preferably, the cation is sodium. Therefore, the composition preferably contains sodium chlordronate.

[0031] Therefore, the composition of the present invention comprises crosslinked hyaluronic acid or a salt or derivative thereof. Preferably, the crosslinked hyaluronic acid is in the form of a salt, more preferably an alkali or alkaline earth metal salt, and more preferably a sodium salt. Therefore, the crosslinked hyaluronic acid of the present invention is preferably in the form of sodium hyaluronate.

[0032] The crosslinked hyaluronic acid of the present invention, or its salt or derivative, is hyaluronic acid that has been subjected to a crosslinking process using a crosslinking agent. The crosslinking agent is preferably selected from the group consisting of 1,4-butanediol diglycidyl ether (BDDE), divinyl sulfone (DVS), and glutaraldehyde (GTA), and more preferably 1,4-butanediol diglycidyl ether (BDDE).

[0033] The composition of the present invention comprises an acetate buffer. According to the present invention, an acetate buffer is an aqueous solution of acetic acid and an alkali or alkaline earth metal acetate. Examples of acetate buffers include aqueous solutions of acetic acid-sodium acetate, acetic acid-potassium acetate, acetic acid-calcium acetate, and acetic acid-magnesium acetate. A preferred acetate buffer according to the present invention is an aqueous solution of acetic acid-sodium acetate, and more preferably an aqueous solution containing acetic acid, sodium acetate, and sodium chloride.

[0034] Surprisingly, the presence of acetate buffer can effectively stabilize compositions of cross-linked hyaluronic acid or its salts or derivatives, and chlordronic acid or its equivalent salts. As will be evident from the experiments below, it also overcomes the stability issues associated with the sterilization process required during the pharmaceutical manufacturing stage, which would otherwise lead to the rapid degradation of active chlordronic acid / chloronate if acetate buffer were absent or other buffers were used.

[0035] Clearly, the chemical equilibrium between different species of a composition is not solely related to the definition of a pH value that can potentially stabilize the species in question, but rather to a complex equilibrium in which each is highly stable at entirely different pH levels. Regardless of the selected pH value, temperature can induce other reasonable equilibria and reactions, particularly during the sterilization stage of difficult-to-handle compositions, leading to chemical reactions and decompositions that depend precisely on the chemical species present. In fact, as will become clear from the experiments described below, buffer solutions capable of providing the same pH value surprisingly could not guarantee the same stability performance for the prepared pharmaceutical compositions throughout the entire manufacturing cycle, including the subsequent sterilization process. Here, the manufacturing cycle includes not only the preparation of initial stable solutions of cross-linked hyaluronic acid, or its salt or derivative, and clodronic acid, or its salt, which themselves require careful handling due to the different stability requirements for the two active ingredients, but also the subsequent sterilization process.

[0036] In fact, the inventors of the present invention have surprisingly discovered that, downstream of the sterilization step, seemingly stable compositions obtained thanks to the use of buffers with similar but different pH values ​​are subjected to different stresses that have an unexpected effect on the stability of these compositions, and decompose only in the presence of acetate buffer, due to an acceptable impurity profile.

[0037] Therefore, surprisingly, acetate buffer plays a fundamental role in the chemical properties of the compositions of cross-linked hyaluronic acid, or its salt or derivative, and clodronic acid, or its equivalent salt, to stabilize the compositions both in the formulation stage and the subsequent sterilization stage, and at the same time ensures a suitable G' value, i.e., elastic modulus, for their use in gel form, preferably administered using a pre-filled syringe, thus enabling safe and reliable manufacturing and commercialization.

[0038] Preferably, the acetate buffer solution of the present invention is an aqueous solution of sodium acetate / acetic acid.

[0039] The composition of the present invention preferably also includes linear hyaluronic acid or a salt thereof.

[0040] The compositions of the present invention preferably include excipients, more preferably pharmaceutically acceptable excipients for intra-articular administration.

[0041] The compositions of the present invention may also include a pharmaceutically acceptable carrier, which is preferably water.

[0042] Appropriate pharmaceutically acceptable excipients for intra-articular administration include, for example, pH adjusters, isotonic agents, stabilizers, chelating agents, preservatives, and antioxidants. Excipients present in the composition may include, for example, sodium chloride.

[0043] In another embodiment, the composition of the present invention is in gel form. In a preferred embodiment, the composition is preferably gel-like: - 1.8 to 2.2 mg / mL, preferably 1.9 to 2.1 mg / mL, more preferably about 2 mg / mL of sodium clodronate or an equivalent amount thereof of clodronic acid or another salt thereof; - 16-24 mg / mL, preferably 18-22 mg / mL, more preferably about 20 mg / mL of cross-linked sodium hyaluronate; - 0.6 to 1.2 mg / mL, preferably 0.8 to 1 mg / mL of sodium acetate, and 0.028 to 0.052 mg / mL of acetic acid; and - water Includes. Optionally, the compositions of the present invention may include suitable excipients.

[0044] In a more preferred embodiment, the composition is preferably gel-like: - 1.8 to 2.2 mg / mL, preferably 1.9 to 2.1 mg / mL, more preferably about 2 mg / mL of sodium clodronate or an equivalent amount thereof of clodronic acid or another salt thereof. - 17-21 mg / mL, preferably 18-20 mg / mL, more preferably about 19 mg / mL of cross-linked sodium hyaluronate, - 0.5 to 2 mg / mL, preferably about 1 mg / mL of linear sodium hyaluronate, - 0.6 to 1.2 mg / mL, preferably 0.8 to 1 mg / mL of sodium acetate, and 0.028 to 0.052 mg / mL of acetic acid. - water Includes. Optionally, the composition may contain a suitable excipient.

[0045] In a preferred embodiment, the composition of the present invention, preferably including the addition of linear sodium hyaluronate, is advantageous in that it may have a gel extrusion force in the range of 18 to 65 N, preferably 30 N or less, more preferably about 30 N, measured on a universal material tester at a speed of 1 cm / min; the product is extruded from a 2 mL volume syringe having a 21 G 1" 1 / 2 type needle.

[0046] The resulting gel-like composition was most suitable for intra-articular administration.

[0047] The gel-like composition can be prepared by a manufacturing method comprising the following steps: a. Linear hyaluronic acid is hydrated and crosslinked using an aqueous solution containing a crosslinking agent to obtain a gel; b. The gel obtained in step (a) is neutralized by adding an acid solution to obtain a neutralized gel; c. The neutralized gel from step (b) is subjected to a dialysis purification process to obtain a dialyzed gel; d. Add a solution containing sodium clodronate, acetate buffer, and optionally linear hyaluronic acid to the dialyzed gel from step (c); e. Mix the components from step (d) to obtain a homogeneous gel.

[0048] In step (a), linear hyaluronic acid is hydrated and then crosslinked by adding it to an aqueous solution containing a crosslinking agent, preferably to a basic hydration solution containing water and a crosslinking agent. In a preferred embodiment of the present invention, the basic aqueous solution of the crosslinking agent is a basic aqueous solution of 1,4-butanediol diglycidyl ether (BDDE), which is the crosslinking agent. The basic solution containing 1,4-butanediol diglycidyl ether (BDDE) is preferably an aqueous solution of sodium hydroxide.

[0049] In step (b), the gel obtained in step (a) is preferably neutralized with a hydrochloric acid solution diluted with a buffer.

[0050] In step (d), the acetate buffer is preferably an aqueous solution of sodium chloride, sodium acetate, and acetic acid.

[0051] The composition for use of the present invention in gel form may be subject to further processing steps to be administered in a suitable dosage form, which is advantageous.

[0052] In a preferred embodiment of the present invention, the composition for use in gel form is subjected to a sterilization process after being inserted into an administration form, such as a syringe.

[0053] Preferably, the sterilization process is carried out in an autoclave at a temperature of 125°C for 250 seconds.

[0054] In a preferred embodiment, the gel-like composition has a pH in the range of 4.8 to 5.4, preferably 5 to 5.2.

[0055] In another preferred embodiment, the gel-like composition has an elastic modulus G' value of 50 Pa or higher at 1 Hz, as measured with a plate rheometer having a gap of 250 μm at 1 Hz.

[0056] In a more preferred embodiment, the composition for use of the present invention has an osmotic pressure in the range of 250 to 400 mOsm / L, preferably 270 to 380 mOsm / L.

[0057] In a more preferred embodiment, the gel-like composition of the present invention is in a single-dose form with a volume of 1 to 5 mL, more preferably 2 mL. This single-dose form is preferably a syringe.

[0058] The composition of the present invention or the aforementioned single-dose form preferably contains approximately 38 mg of cross-linked sodium hyaluronate, approximately 2 mg of linear sodium hyaluronate, approximately 4 mg of sodium clodronate, approximately 1.8 mg of sodium acetate, approximately 0.08 mg of acetic acid, and approximately 18 mg / mL of sodium chloride.

[0059] The composition of the present invention, or preferably the single-dose form described above, is advantageous for use as a pharmaceutical, preferably in the treatment of osteoarthritis.

[0060] In another embodiment, the compositions of the present invention may be used alone or in combination in the treatment of osteoarthritis, i.e., as combination therapy in a fixed-dose formulation, or as combination therapy with separately formulated active ingredients.

[0061] In yet another aspect, the present invention relates to a medical device comprising the composition of the present invention and optionally a suitable excipient.

[0062] The medical device is preferably used to improve the symptoms of osteoarthritis, and such improvement includes the reduction of joint pain.

[0063] As will be demonstrated from the following experimental results, the compositions for use of the present invention are stable, reproducible, and can be used to prepare single-dose forms such as pre-filled syringes.

[0064] The present invention will be described by several illustrative examples, but will not be limited thereto. [Examples]

[0065] Experiment Department Example 1. Preparation of a gel composition according to the present invention, comprising cross-linked hyaluronic acid, sodium clodronate, and acetate buffer.

[0066] The gel composition according to the present invention was prepared using the following procedure: a. Linear hyaluronic acid with an average molecular weight of approximately 3 MDa was hydrated and crosslinked by adding a basic aqueous solution of sodium hydroxide with a pH of approximately 13 containing 25% 1,4-butanediol diglycidyl ether (BDDE) until a crosslinked hyaluronic acid gel was formed. b. Next, the gel obtained in step (a) was neutralized by adding a hydrochloric acid solution diluted in acetate buffer. c. Next, the neutralized gel from step (b) was subjected to a dialysis purification process to obtain a purified gel with a pH of approximately 4.98. d. To the dialyzed gel from step (c), an aqueous solution containing sodium chlordronate at a concentration of 100 mg / mL and an aqueous solution of acetate buffer (obtained by mixing 100 mg / mL acetic acid, 100 mg / mL sodium acetate, and 100 mg / mL sodium chloride) were added, and the mixture was then thoroughly mixed until a homogeneous gel according to the present invention was obtained.

[0067] When the gel was measured using a plate rheometer with a gap of 250 μm at 1 Hz and a pH of approximately 4.81, it showed a G' value of approximately 267.2 Pa. Next, this gel was subjected to sterilization, which involves a process at a temperature of approximately 125°C for 250 seconds. At the end of the sterilization process, the gel's G' value had decreased to approximately 77.1 Pa, retaining only about 28.5% of its initial value. The pH did not show any significant change, remaining at approximately 4.88. Accelerated stability testing was performed using sterile gel at a temperature of 60°C and humidity of 96%, and under these stress conditions, the G' value further decreased to approximately 36.3 Pa.

[0068] Example 2. Preparation of a gel composition containing cross-linked hyaluronic acid, sodium clodronate, and citrate buffer.

[0069] The same composition as in Example 1 was prepared, but the only difference was that the acetate buffer of the present invention was replaced with a citrate buffer. Specifically, the added citrate buffer solution was an aqueous solution containing 0.98 mg / mL of citric acid, 3.54 mg / mL of sodium citrate, and 9 mg / mL of sodium chloride. In this case as well, a cross-linked hyaluronic acid gel was obtained, and this gel had a G' value of approximately 406.8 Pa and a pH of approximately 5.0, as measured at 1 Hz using a plate rheometer with a 250 μm gap. Next, the gel was sterilized, meaning it was treated at a temperature of approximately 125°C for 250 seconds. At the end of the sterilization process, the G' value of the gel decreased to approximately 159.2 Pa, retaining only about 39.0% of its initial value. The pH remained unchanged and was still approximately equal to 5.0. Similarly, the sterile gel was also subjected to accelerated stability testing at a temperature of 60°C and a humidity of 96%, and under these stress conditions, the G' value further decreased to approximately 113.1 Pa.

[0070] Example 3. Comparison of results obtained from tests conducted on the compositions of Example 1 and Example 2 according to the present invention. Analysis of the impurity profile of the gel after sterilization. Next, we compared the G' results before and after sterilization for the two compositions, Example 1 (COMP1inv) and Example 2 (COMP2). These results are shown in Table 1 below.

[0071] [Table 1] Table 1 - G' values ​​of the gels of the compositions of Example 1 and Example 2 before and after the sterilization process.

[0072] As is evident from the results reported in the table, the composition of Example 2, which included citrate buffer, showed an even better profile with respect to parameter G'. To test the potential of using two buffers in gel formulations, the impurity profiles of each gel were analyzed after sterilization, a process notorious for leading to significant degradation of the active ingredients, particularly sodium chlordronate. Impurity measurements were performed by ion chromatography (Thermo Fisher Scientific instrument). In relation to clodronic acid, the impurities listed in the European Pharmacopoeia (Monograph 1777) are known to consist of so-called impurity D and phosphates. Surprisingly, in the analysis conducted by the inventors, previously unlisted impurities were also discovered, which were named Unk1, Unk2, and Unk3 (where the prefix "Unk" is, of course, an abbreviation for Unknown). The results obtained from these analyses (performed three times, with the average value reported) are shown in Table 2 for the composition using the citrate buffer in Example 2, and in Table 3 for the composition using the acetate buffer in Example 1 according to the present invention. Impurity D was below the instrument's detection threshold in both cases and is therefore not shown in these tables.

[0073] [Table 2] Table 2 - Changes in clodronate titer and impurity profiles in COMP2 composition after sterilization.

[0074] [Table 3] Table 3 - Changes in clodronate titer and impurity profiles in COMP1inv composition after sterilization.

[0075] As can be seen from Tables 2 and 3, the results obtained demonstrate the reproducibility and reliability of this method. Regarding the overall degradation of chlordronate, the results appeared comparable in both cases, although the composition of Example 2, containing citrate buffer, yielded slightly better results than the acetate buffer of Example 1 according to the present invention. In fact, approximately 1% more of the active ingredient was degraded in the latter case. However, to our great surprise, the resulting profile of impurities was completely different. In reality, despite the fact that the compositions of the two starting gels were identical except for the buffer solution, and the pH values ​​before and after sterilization were almost the same (approximately 5 for the citrate buffer and approximately 4.9 for the acetate buffer solution according to the present invention), completely different values ​​for individual impurities were obtained. This is evidence that unpredictable chemical and physical equilibrium and chemical reactions within the gel are established primarily by the role of the buffers present within it. In fact, the chemical species forming the buffer not only control the pH of the composition, but also, similarly in both cases, influence other properties of the system, namely the stability of chlordronate in the gel and the tendency of decomposition following reaction kinetics, which are clearly quite different in the two cases, even if the same pH value is obtained. Therefore, the ability of citrate buffer and acetate buffer according to the present invention to interact with hyaluronic acid and clodronate gels is completely different, and this versatility is clearly represented by the rheological differences of clodronate, which, once placed in contact with one or the other sample, yielded different impurity profiles. In particular, in the case of citrate buffer (COMP2, Table 2), the percentage value of a component called UNK3 reached as high as 2.48%.

[0076] As is well known, in the pharmaceutical field, the ICH guidelines recommend against using active ingredients at concentrations exceeding 1% that may lead to the release of unclassified or unclassifiable substances through degradation. Therefore, although citrate buffer appears to be a nearly optimal buffer based on the results obtained for the G' parameter even under stress conditions, it can never be used for the preparation of hyaluronic acid and clodronic acid compositions due to its unsuitable impurity profile. On the other hand, in the case of the acetate buffer of the present invention, impurity Unk3 was detected at a concentration of 0.97%, which was within the acceptable limit. The same applies to the other two impurities, Unk1 and Unk2, both of which were below the identification threshold of 0.5%; however, this excludes phosphates, which are known impurities not considered to be hazardous to human health under any circumstances. Therefore, the presence of the acetate buffer makes the composition of the present invention the only one suitable for pharmaceutical development.

[0077] Example 4. Preparation of a formulation according to the present invention, further comprising linear hyaluronic acid. A gel-like composition according to the present invention was also prepared, comprising hyaluronic acid, sodium clodronate, acetate buffer, and linear sodium hyaluronate. Table 4 below shows the detailed qualitative and quantitative composition:

[0078] [Table 4] Table 4 - A gel-like composition according to the present invention, further comprising linear hyaluronic acid.

[0079] The gel-like compositions of the present invention for intra-articular use shown in Table 4 are prepared by the same procedure as already described in the above examples, the only difference being the addition of linear hyaluronic acid with an average molecular weight of 1.5 MDa to the reaction mixture in step (d), in conjunction with the addition of sodium clodronate solution.

[0080] The gel formulation of the present invention has been proven to be completely stable over time, even after the sterilization step, with impurity levels and sodium clodronate degradation that are fully acceptable according to pharmacopoeia standards. Furthermore, its G' value is approximately 383 Pa, making it easy to administer from pre-filled syringes and enabling the composition to be marketed in a pharmaceutical form that is highly compliant with patient needs.

Claims

1. - Cross-linked hyaluronic acid or its salts or derivatives, - Clodronic acid or an equivalent amount of its salt, and - Acetate buffer A composition containing the following:

2. The composition according to claim 1, wherein the crosslinked hyaluronic acid or its salt or derivative is sodium hyaluronate crosslinked with butanediol diglycidyl ether (BDDE).

3. The composition according to claim 1 or 2, wherein the chlordronic acid or salt thereof is sodium chloronate.

4. The composition according to any one of claims 1 to 3, wherein the acetate buffer is an aqueous solution of acetate / sodium acetate, preferably an aqueous solution of sodium chloride, sodium acetate, and acetate.

5. A composition according to any one of claims 1 to 4, which is in the form of a gel.

6. The aforementioned composition is: - 1.8 to 2.2 mg / mL, preferably 1.9 to 2.1 mg / mL, more preferably about 2 mg / mL of sodium clodronate or an equivalent amount thereof of clodronic acid or other salt thereof; - 16-24 mg / mL, preferably 18-22 mg / mL, more preferably about 20 mg / mL of cross-linked sodium hyaluronate; - 0.6 to 1.2 mg / mL, preferably 0.8 to 1 mg / mL of acetate ions and 0.028 to 0.052 mg / mL of acetate; and - water A composition according to any one of claims 1 to 5, comprising:

7. The aforementioned composition is: - 1.8 to 2.2 mg / mL, preferably 1.9 to 2.1 mg / mL, more preferably about 2 mg / mL of sodium clodronate or an equivalent amount thereof of clodronic acid or other salt thereof; - 17–21 mg / mL, preferably 18–20 mg / mL, more preferably about 19 mg / mL of cross-linked sodium hyaluronate; - 0.5 to 2 mg / mL, preferably about 1 mg / mL of linear sodium hyaluronate; - 0.6 to 1.2 mg / mL, preferably 0.8 to 1 mg / mL of acetate ions and 0.028 to 0.052 mg / mL of acetate, - water A composition according to any one of claims 1 to 5, comprising:

8. The composition according to any one of claims 1 to 7, wherein the extrusion force measured using a universal material tester (or universal tester) at a speed of 1 cm / min with a 21G1"1 / 2 needle is in the range of 18 to 65 N, preferably 30 N or less, more preferably about 30 N.

9. The composition according to any one of claims 1 to 8, wherein the composition has a pH in the range of 4.8 to 5.4, preferably 5 to 5.

2.

10. The composition according to any one of claims 1 to 9, wherein the composition has an elastic modulus G' of 50 Pa or more at 1 Hz, as measured using a plate rheometer with a gap of 250 μm at 1 Hz.

11. The composition according to any one of claims 1 to 10, wherein the composition has an osmotic pressure in the range of 250 to 400 mOsm / L, preferably 270 to 380 mOsm / L.

12. A single-dose form comprising 1 to 5 mL, preferably about 2 mL, of the composition according to any one of claims 1 to 11.

13. The single-dose administration method according to claim 12, wherein the administration method is a syringe.

14. A composition according to any one of claims 1 to 11, or a single-dose form according to claim 12 or 13, comprising approximately 38 mg of cross-linked sodium hyaluronate and approximately 2 mg of linear sodium hyaluronate, for use as a pharmaceutical.

15. A composition according to any one of claims 1 to 11, or a single-dose form according to claim 12 or 13, for use in the treatment of osteoarthritis.

16. The composition according to any one of claims 1 to 11, for use alone or in combination, i.e., as a combination therapy agent in a fixed-dose formulation, or for use in combination therapy of separately formulated active ingredients, in the treatment of osteoarthritis.

17. A medical device comprising the composition according to any one of claims 1 to 11 and optionally a suitable excipient.

18. A medical device comprising a composition according to any one of claims 1 to 11 for use in improving the symptoms of osteoarthritis, wherein the improvement includes the reduction of joint pain.

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