Hydrogel composition for use in the treatment of joint disorders

Abstract

The present disclosure relates to anionic cyclodextrin polymer- and chitosan-based hydrogel compositions for use in the treatment of joint disorders. In particular, the hydrogel combines a pharmacological action, in particular an analgesic action, with viscosupplementation (lubrication action).

Description

Technical Field

[0001] The present invention relates to anionic cyclodextrin polymer- and chitosan-based hydrogel compositions for use in the treatment of joint disorders. In particular, the present invention relates to cyclodextrin polymer- and chitosan-based hydrogel compositions for use in the treatment of joint disorders, which combine pharmacological action, particularly analgesic action, with viscosupplementation therapy, i.e., lubricating action.

Background Art

[0002] Temporomandibular disorders (TMDs), also known as temporomandibular joint dysfunction (TMJD), encompass disorders affecting the temporomandibular joint (the joint connecting the mandible to the skull). TMDs are myoarthroses of the masticatory apparatus that cause chronic pain symptoms and restricted mandibular movement. TMDs are the first cause of orofacial pain worldwide and are thought to affect 5-12% of the population in industrialized countries. According to the American Academy of Orofacial Pain, TDMs encompass a group of musculoskeletal and neuromuscular lesions involving the temporomandibular joint, masticatory muscles, and all related tissues. Among the pain symptoms, those with a more muscular onset (temporal and / or masseter muscles) can be distinguished from those with a more articular onset. In this case, there are often anatomical bases for the pain (e.g., disc displacements, whether reducible or irreducible, and degenerative joint diseases including osteoarthritis and degenerative arthritis).

[0003] There are numerous etiologies, with excessive mechanical stress, trauma in the granular area, dental malocclusion, systemic diseases, hormonal factors, and genetic factors being frequently associated (Tanaka E, Detamore MS, Mercuri LG. Degenerative disorders of the temporomandibular joint: etiology, diagnosis, and treatment. J Dent Res. Apr 2008;87(4):296~307. Wang XD, Zhang JN, Gan YH, Zhou YH. Current understanding of pathogenesis and treatment of TMJ osteoarthritis. J Dent Res. May 2015;94(5):666~73). All of these causes lead to the reconstruction of the dysfunction of the joint components. In fact, the hypoxic state induced by such factors results in an increase in the production of vascular endothelial growth factor (VEGF) (Tanaka E, Detamore MS, Mercuri LG. Degenerative disorders of the temporomandibular joint: etiology, diagnosis, and treatment. J Dent Res. Apr 2008;87(4):296~307). VEGF increases the production of matrix metalloproteinase (MMP) and decreases the production of tissue inhibitor of matrix metalloproteinase (TIMP). This imbalance of the activators of extracellular matrix remodeling accelerates bone resorption and cartilage resorption. The hypoxic state induced by overload also causes the release of oxygen free radicals and inflammatory cytokines such as interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNFα). These cytokines regulate the production of hyaluronic acid (HA), and in the case of such high levels of inflammatory cytokines, HA is degraded, leading to the breakdown of joint lubrication. The loss of synovial fluid and the resulting loss of viscosity impair the nutritional support to the cartilage, resulting in its progressive degeneration (Ernberg M.The role of molecular pain biomarkers in temporomandibular joint internal derangement. J Oral Rehabil. juin 2017;44(6):481~91). Similarly, IL-1β and TNF-α promote the production of MMP and collagenase by synoviocytes and chondrocytes (Tabeian H, Bakker AD, Betti BF, Lobbezoo F, Everts V, de Vries TJ. Cyclic Tensile Strain Reduces TNF-α Induced Expression of MMP-13 by Condylar Temporomandibular Joint Cells. J Cell Physiol. juin 2017;232(6):1287~94. Hutchinson NI, Lark MW, MacNaul KL, Harper C, Hoerrner LA, McDonnell J et al., In vivo expression of stromelysin in synovium and cartilage of rabbits injected intraarticularly with interleukin-1 beta. Arthritis Rheum. oct 1992;35(10):1227~33. Kubota E, Imamura H, Kubota T, Shibata T, Murakami K. Interleukin 1 beta and stromelysin(MMP3)activity of synovial fluid as possible markers of osteoarthritis in the temporomandibular joint. J Oral Maxillofac Surg.January 1997;55(1):20-7; discussion 27-28), and also promotes the activation of cyclooxygenase 1 and 2 (COX-1 / 2), which enhances inflammation by increasing the level of prostaglandin E2 (PGE2) (Satoh K, Ogura N, Akutsu M, Kuboyama N, Kuyama K, Yamamoto H et al., Expression of cyclooxygenase-1 and -2 in IL-1beta-induced synovitis of the temporomandibular joint. J Oral Pathol Med. August 2009;38(7):584-90. Emshoff R, Puffer P, Rudisch A, Gassner R. Temporomandibular joint pain: relationship to internal derangement type, osteoarthrosis, and synovial fluid mediator level of tumor necrosis factor-alpha. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. October 2000;90(4):442-9). All of these pathways play a role in the pathogenesis of TMJ osteoarthritis by accelerating cartilage and bone degradation, reducing synovial fluid volume, and causing chronic inflammation.

[0004] The symptoms are related to a persistent inflammatory process and osteoarthritis that constitutes degenerative joint disease of the temporomandibular joint. The main symptom is chronic orofacial pain, which is a result of chronic synovitis, reactive muscle spasm and degenerative joint disease (Ahmad M, Schiffman EL. Temporomandibular Joint Disorders and Orofacial Pain. Dent Clin North Am. janv 2016;60(1):105~24). Other symptoms are usually found in cases of TMJOA: limitation of jaw function, decreased jaw mobility, limitation of speech expression and chewing, limitation of opening, but there are also tenderness and neck pain, joint noises (Meloto CB, Slade GD, Lichtenwalter RN, Bair E, Rathnayaka N, Diatchenko L et al., Clinical predictors of persistent temporomandibular disorder in people with first-onset temporomandibular disorder: A prospective case-control study. J Am Dent Assoc. juill 2019;150(7):572~581.e10. Ohrbach R, Fillingim RB, Mulkey F, Gonzalez Y, Gordon S, Gremillion H et al., Clinical findings and pain symptoms as potential risk factors for chronic TMD: descriptive data and empirically identified domains from the OPPERA case-control study. J Pain. nov 2011;12(11 suppl):T27~45). The symptoms have various intensities over time, with exacerbation periods fluctuating but can also become chronic.

[0005] Numerous treatment approaches have been considered in the complex management of these TMDs. Conventional non-invasive treatments combine physical therapy sessions, occlusal therapy (often requiring an occlusal release splint), and systemic symptomatic medications that combine analgesics and muscle relaxants. Non-steroidal anti-inflammatory drugs (NSAIDs) are commonly prescribed orally to reduce chronic inflammation, but they are associated with negative side effects due to their systemic effects. For the joint type, when occlusal therapy fails, treatment modalities are often minimally invasive and require arthroscopic lavage (arthrocentesis) and / or intra-articular injection of various substances.

[0006] Well-known pharmacological substances used in intra-articular injections include hyaluronic acid with its lubricating properties, as well as corticosteroids, morphine and its derivatives, ketamine or botulinum toxin, or even platelet-rich plasma (PRP) that aids in regeneration, and these produce various outcomes.

[0007] Intra-articular injection of pharmacological substances avoids their systemic effects (gastric and renal tolerance of non-steroidal anti-inflammatory drugs, and metabolic disorders for corticosteroids) (Al-Moraissi EA et al., J Cranio-Maxillo-fac Surg 2020;48(1):9-23). To administer pharmacological substances controllably at the anatomical site of injection, carriers based on biocompatible materials (nanoparticles, microparticles or hydrogels) have been proposed (Systematic review of studies on drug-delivery systems for management of temporomandibular-joint osteoarthritis. Barry F, Chai F, Chijcheapaza-Flores H, Garcia-Fernandez MJ, Blanchemain N, Nicot R. J Stomatol Oral Maxillofac Surg. 2021 Aug 13:S2468-7855(21)00163-4. doi:10.1016 / j.jormas.2021.08.003. Online before print). However, as stated in the current state of the art, the release has to remain within the effective therapeutic range and the amount of active ingredient released has to be sufficient for long-term effectiveness, but is not considered very important for preventing local cytotoxicity in the joint and damage to the surrounding tissue (cartilage) (Cicognani M. et al., Pharmaceutics 2020;12(7):681. Deng Y et al., Sci Rep 2017; Kou L et al., Drug Deliv 2019;26(1):870-85).

[0008] Currently, there is no injectable substance available that combines the benefits of viscosupplementation (provided by hyaluronic acid) with an effective and safe pharmacological action. The pharmacological substances currently in use have a lack of sustained action (for non-steroidal anti-inflammatory drugs) or harmful local effects by inducing bone demineralization (for corticosteroids).

Summary of the Invention

[0009] Accordingly, there remains a need for an injectable composition for use in the treatment of TMD, and more generally for use in the treatment of joint disorders, that combines pain relief with a lubricating effect (viscosupplementation). More specifically, there remains a need for an injectable composition for use in the treatment of TMD, and more generally for use in the treatment of joint disorders, that combines a pharmacological effect with a lubricating effect (viscosupplementation) when such a dual effect is desired or required.

[0010] The present invention relates to a (a) (i) chitosan, (ii) an anionic cyclodextrin polymer hydrogel formed of a polymer network comprising wherein the anionic cyclodextrin polymer is a water-soluble anionic cyclodextrin polymer or a mixture of a water-soluble anionic cyclodextrin polymer and a water-insoluble anionic cyclodextrin polymer (CDPi), and the ratio of the weight of the water-soluble anionic cyclodextrin polymer to the weight of the water-insoluble cyclodextrin polymer is about 1:1, and the ratio of the weight of chitosan to the total weight of the anionic cyclodextrin polymer is about 2:1, (b) optionally, a pharmacological agent incorporated into the polymer network and a hydrogel composition comprising the same.

[0011] The present invention also relates to a method of preparing a hydrogel composition comprising a pharmacological agent, the method comprising the following steps: (i) providing a powder of a water-soluble anionic cyclodextrin polymer, and if applicable, a powder of a water-insoluble anionic cyclodextrin polymer, and a powder of chitosan; (ii) adding a pharmacological agent to the powder of the water-soluble anionic cyclodextrin polymer or to a mixture of the water-soluble and water-insoluble anionic cyclodextrin polymer powders by wet granulation; (iii) To form a powder mixture, a step of dry mixing the powder obtained in step (ii) with chitosan powder; (iv) Optionally, a step of sieving or co - grinding and sieving the powder mixture obtained in step (iii); (v) A step of suspending the powder mixture obtained in step (iv) in an aqueous medium having a pH that allows the anionic cyclodextrin polymer to dissolve without dissolving chitosan; (vi) A step of acidifying the suspension obtained in step (v) to form a hydrogel composition comprising.

[0012] A further aspect of the present invention is disclosed herein and in the claims.

Brief Description of the Drawings

[0013]

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Mode for Carrying Out the Invention

[0014] The present invention relates to the hydrogel composition disclosed herein for use in the treatment of joint disorders. This hydrogel composition makes it possible to provide both pain relief and a lubricating effect (viscosupplementation therapy), which does not require the administration of a pharmacological agent. Thus, in some embodiments, the hydrogel composition does not contain any pharmacological agent, particularly not the pharmacological agents disclosed hereinafter in this specification.

[0015] In some embodiments, local delivery of a pharmacological agent may be desired or required. In such cases, the hydrogel composition contains a pharmacological agent.

[0016] Examples of suitable joint disorders that can be treated by the hydrogel compositions of the present invention include, but are not limited to, osteoarthritis, osteoarthrosis (e.g., osteoarthritis of the knee), rheumatic disorders (e.g., rheumatoid arthritis or juvenile idiopathic arthritis), and degenerative meniscus injuries.

[0017] Osteoarthritis is one of the most common joint diseases and can affect all humans (shoulder, knee, and temporomandibular joints). In some embodiments, the hydrogel composition is for use in the treatment of temporomandibular joint disorders.

[0018] The pharmacological effect can be achieved through the release of the pharmacological agent. Preferably, an analgesic effect, i.e., pain reduction, is achieved through the release of an analgesic from the hydrogel. Examples of suitable analgesics include, but are not limited to, opioid analgesics and non-steroidal anti-inflammatory analgesics. Examples of opioid analgesics include codeine, oxycodone, and ultimately hydromorphone in severe pain. Examples of non-steroidal anti-inflammatory agents include naproxen, ibuprofen, diflunisal, and ketorolac. In the case of rheumatic disorders such as rheumatoid arthritis or juvenile idiopathic arthritis, the composition may contain an anti-TNFα drug.

[0019] In some embodiments, the present invention relates to a hydrogel composition as disclosed herein for use in the treatment of arthralgia, particularly for use in the treatment of temporomandibular joint pain. In some embodiments, the present invention relates to a hydrogel composition for use in postoperative pain management after arthroscopic or open joint surgery.

[0020] The composition of the present invention is based on a hydrogel. A hydrogel is made up of a polymer network that swells with water, especially a large amount of water. In a hydrogel, the bonds between polymer chains can be permanent (covalent bonds) or reversible (non-covalent bonds, such as hydrogen bonds, ionic bonds, hydrophobic bonds, or dipole-dipole bonds). Hydrogels with permanent bonds and hydrogels with reversible bonds are known as chemical hydrogels and physical hydrogels, respectively. The present invention relates to a composition based on a physical hydrogel crosslinked by ionic bonds between chitosan as a positive polyelectrolyte and a cyclodextrin polymer as a negative polyelectrolyte. These ionic bonds are weak non-covalent interaction that imparts viscoelasticity, shear thickening property and self-healing effect, and bring injectable properties to these mixtures.

[0021] As used herein, the term "cyclodextrin polymer" is understood to refer to an anionic cyclodextrin polymer, including when used in the expressions "water-soluble cyclodextrin polymer" and "water-insoluble cyclodextrin polymer".

[0022] The hydrogel composition of the present invention has been found to be biocompatible, stable during and after sterilization, and exhibits properties that make it suitable for administration by injection, for example using a syringe. The hydrogel composition of the present invention exhibits appropriate viscoelasticity (shear thinning and self-healing properties). When this hydrogel composition is exposed to mechanical shear stress, it fluidizes and, when it returns to the linear viscoelastic region, it recovers its viscoelasticity. Thus, in use, when the hydrogel composition is placed in the cylinder of a syringe, it flows under the action of the shear stress applied by the piston, and when the stress is released, i.e., when it is injected into the treatment zone, it resumes its aggregated state. The viscosity of the hydrogel composition is neither too low nor too high, thus enabling effective lubrication of the joint without interfering with the joint. The hydrogel composition of the composition has been found to exhibit lubricity equivalent to that of hyaluronic acid (Ostenil®).

[0023] The hydrogel composition of the present invention has appropriate tribological properties. It is strong enough to withstand joint forces for at least 2 to 3 weeks.

[0024] It has been found that the hydrogel composition of the present invention can reduce pain even in the absence of a pharmacological agent.

[0025] It has also been found that the hydrogel composition of the present invention can appropriately locally release a pharmacological agent over a long period of time. Combinations of pharmacological agents can also be released. Local administration avoids the undesirable effects that occur upon systemic administration of a pharmacological agent. The slow sustained release provided by the hydrogel composition of the present invention enables an effective amount of the pharmacological agent to be delivered while preventing any toxicity (the amount of the pharmacological agent released is below its toxicity threshold). Appropriately, the hydrogel composition of the present invention may be able to reduce pain over 2 to 3 weeks.

[0026] This combination of beneficial properties was achieved as a result of a specific formulation of the hydrogel composition.

[0027] Due to all of these properties, the hydrogel composition of the present invention is particularly suitable for the treatment of joint disorders, especially when a combination of pharmacological action and viscosupplementation therapy is desired or required.

[0028] The hydrogel composition of the present invention (a)(i) chitosan, (ii) a cyclodextrin polymer is a hydrogel made of a polymer network containing the cyclodextrin polymer is a water-soluble cyclodextrin polymer or a mixture of a water-soluble cyclodextrin polymer and a water-insoluble cyclodextrin polymer, and the ratio of the weight of the water-soluble cyclodextrin polymer to the weight of the water-insoluble cyclodextrin polymer is about 1:1, A hydrogel in which the ratio of the weight of chitosan to the total weight of the cyclodextrin polymer is about 2:1, and (b) optionally, a pharmacological agent, preferably an analgesic, incorporated into the polymer network is included.

[0029] The hydrogel composition according to the present invention is based on a physical hydrogel formed by the interaction between two complementary charged polymers, namely chitosan (cationic polymer) and cyclodextrin polymer (anionic polymer). Chitosan typically bears protonated amino groups in its glucosamine repeating units, and / or the anionic cyclodextrin polymers typically bear carboxylate groups in their polycarboxyl crosslinks.

[0030] The term "about" in the context of the present invention means that the value in question may be 10%, particularly 5%, particularly 1% lower or higher than the indicated value. It encompasses the indicated value and values that may be 10%, particularly 5%, particularly 1% lower or higher than the indicated value. By way of example, when a range is stated to vary from about X to about Y, it includes the range X to Y, and optionally values that may be 10%, particularly 5%, particularly 1% lower than X and values that may be 10%, particularly 5%, particularly 1% higher than Y.

[0031] Chitosan Chitosan is a linear polymer that exhibits an extended coil structure when dissolved, ensures the macromolecular structure of the hydrogel, and imparts the required rheological properties to the hydrogel.

[0032] Chitosan is a biocompatible and biodegradable cationic polymer. It is a linear polysaccharide composed of randomly distributed β-1,4-linked D-glucosamine (deacetylated units) and N-acetyl-D-glucosamine (acetylated units). Chitosan can be produced by deacetylation of chitin, a structural component of the exoskeleton of crustaceans, or it can be extracted directly from fungi.

[0033] Chitosan may be characterized by its degree of deacetylation, which represents the percentage of deacetylated glucosamine units on its polymer chain. Chitosan suitable for use in the present invention typically has a degree of deacetylation in the range of 60 to 95%, preferably 70% or more and preferably less than 90% or 76% or less.

[0034] Chitosan is commercially available in powder form or as flakes of various particle sizes.

[0035] Chitosan is insoluble in aqueous media having a pH of 4 or more, 4.5 or more, especially 5 or more. In contrast, chitosan dissolves in acidic aqueous media when the pH is less than 4. When the aqueous solution is sufficiently acidic, the amine functional group -NH2 of the D-glucosamine repeating unit of chitosan is protonated to the ammonium functional group -NH3 + . At a pH of 5 or less and 4 or more, the amine functional group of chitosan will be partially protonated, but it should be noted that this will not be a sufficient number to dissolve chitosan. The degree of protonation to be achieved to obtain solubilization also depends on the molecular weight and the degree of deacetylation of chitosan. When the degree of deacetylation is low, due to the hydrophobicity of the acetyl-D-glucosamine repeating unit, a higher ratio of amine functional groups must be protonated than when the degree of deacetylation is high. Chitosan having a degree of deacetylation (DDA) of 70% contains 4.04 mmol of amino groups per gram. The amino group content increases to 4.73 and 5.45 mmol per gram for chitosan having DDAs of 80% and 90% respectively.

[0036] The molecular weight of chitosan can be in the range of 200 to 300 kDa. Chitosan suitable for use in the present invention typically has a molecular weight of 256 kDa.

[0037] In some embodiments, the hydrogel comprises 1 to 3 wt% chitosan, based on the total weight of the hydrogel, and preferably, the hydrogel comprises about 2 wt% chitosan, based on the total weight of the hydrogel.

[0038] Cyclodextrin polymer The cyclodextrin polymer used in the present invention serves as a physical crosslinking agent by establishing ionic bonds with chitosan chain networks in the hydrogel composition. Such ionic bonds stabilize the hydrogel structure, render its elastic behavior quiescent, allow the ionic bonds to be broken when a strain is applied, resulting in shear-thinning properties, and immediately reconfigure in a quiescent state to provide self-healing properties. The cyclodextrin polymer ensures the cohesive force and viscoelasticity of the hydrogel, and the hydrogel cannot dissolve naturally or move in a physiological medium. The cyclodextrin polymer also forms an inclusion complex with a pharmacological agent, enabling the slow and local release of the pharmacological agent.

[0039] The cyclodextrin polymer is a polymer derived from cyclodextrin. Cyclodextrin is a cyclic oligomer composed of 6, 7, or 8 α-(1,4)-linked glucopyranose units, known as [alpha], [beta], and [gamma] cyclodextrin, respectively. The structure of cyclodextrin can be likened to a truncated cone, with its outer portion being hydrophilic, while its inner portion forms a hydrophobic cavity that can reversibly form an inclusion complex with a molecule, preferably a hydrophobic molecule.

[0040] The cyclodextrin polymer of the present invention is typically obtained from the polycondensation of natural cyclodextrin (alpha, beta, gamma cyclodextrin) or cyclodextrin derivatives (hydroxypropyl, methyl cyclodextrin) crosslinked with a polycarboxylic acid (such as citric acid or 1,2,3,4-butanetetracarboxylic acid).

[0041] The known cyclodextrin polymers obtained by the above-described route can be water-soluble or water-insoluble depending on their structure.

[0042] Suitable cyclodextrin polymers for use in the present invention include water-soluble cyclodextrin polymers and water-insoluble cyclodextrin polymers.

[0043] Water-soluble anionic cyclodextrin polymers and water-insoluble anionic cyclodextrin polymers can be prepared by a polycondensation reaction between (poly)carboxylic acids and natural cyclodextrins (alpha, beta, gamma) or their derivatives (methyl, hydroxypropyl cyclodextrin) as disclosed in EP1165621. Depending on the extent of the polycondensation reaction, the resulting polymer is either water-soluble or water-insoluble. The soluble forms of these cyclodextrin polymers exhibit a hyperbranched structure forming spherical objects of approximately 50 nanometers. The insoluble form is the result of a high degree of polymerization causing a crosslinked structure and resulting in water-insoluble properties. However, this insoluble form is highly hydrophilic and readily swells in water with a swelling ratio of 450 - 500% (meaning that the insoluble cyclodextrin polymer can absorb up to five times its own weight of water). The chemical structures of the soluble and insoluble forms are the same. The difference is an increase in the crosslinking rate that affects their molar mass. The cyclodextrin polymers used in the present invention, obtained by the process disclosed in particular in EP1165621, are characterized, for example, by a high cyclodextrin content of 40 - 65% by weight relative to the total weight of the polymer, and a large number of anionic carboxyl functional groups, for example, in the order of 3 - 5 mmol per gram of cyclodextrin polymer.

[0044] The cyclodextrin polymers used in the present invention, especially those obtained by the above-mentioned process, have a molar mass of about 15,000 to about 30,000 g / mol, especially about 20,000 to about 30,000 g / mol, preferably about 20,000 to about 25,000 g / mol. Therefore, the hydrogels of the present invention can provide a lubricating effect (viscosupplementation therapy) even in the absence of high-molar-mass polymers such as hyaluronic acid. The molar mass of the polymers disclosed herein refers to the number-average molar mass and is calculated using size exclusion chromatography (SEC) or gel permeation chromatography (GPC).

[0045] Both soluble and insoluble cyclodextrin polymers are typically obtained according to the process disclosed in EP1165621. The mixture obtained in the solid state from the polycondensation reaction between cyclodextrin and polycarboxylic acid is suspended in water and then separated by filtration through a sintered glass funnel. The insoluble part is washed with water and dried, while the filtrate is dialyzed and then lyophilized to obtain the soluble part as a powder. When preparing the hydrogel composition according to the present invention, powders in soluble and insoluble forms are weighed and mixed in a predetermined ratio.

[0046] Suitable cyclodextrin polymers used in the present invention contain, among other things, 3.5 to 4.5 mmol / g of carboxylic acid groups, typically about 4 mmol / g of carboxylic acid groups. The number of moles of carboxyl functional groups per gram of the cyclodextrin polymer can be measured by acid-base titration in the presence of a color-changing indicator. The measuring method involves dissolving a predetermined amount of the cyclodextrin polymer in a known volume of water in the presence of a color-changing indicator, for example, a few drops of phenolphthalein, and then gradually (drop by drop) adding a solution of sodium hydroxide at 0.1 mole per liter (mol / liter) to the solution, especially using a burette, while stirring (for example, using a magnetic stir bar) until the solution containing the color-changing indicator changes color. At that time, the number of moles of sodium hydroxide added corresponds to the number of moles of carboxylic acid groups neutralized.

[0047] In some embodiments, the polymer network of the hydrogel comprises only a water-soluble cyclodextrin polymer as the cyclodextrin polymer.

[0048] In some embodiments, the polymer network of the hydrogel comprises a mixture of a water-soluble cyclodextrin polymer and a water-insoluble cyclodextrin polymer as the cyclodextrin polymer, and the ratio of the weight of the water-soluble cyclodextrin polymer to the weight of the water-insoluble cyclodextrin polymer is 1:1.

[0049] In some embodiments, the hydrogel comprises 1 to 3% by weight of the cyclodextrin polymer based on the total weight of the hydrogel, and preferably, the hydrogel comprises 1% by weight of the cyclodextrin polymer based on the total weight of the hydrogel.

[0050] In some embodiments, the hydrogel comprises up to 3% by weight of the water-soluble cyclodextrin polymer based on the total weight of the hydrogel and does not contain the water-insoluble cyclodextrin polymer. Typically, the hydrogel comprises 1 to 3% by weight of the water-soluble cyclodextrin polymer based on the total weight of the hydrogel and does not contain the insoluble cyclodextrin polymer. Preferably, the hydrogel comprises 1% by weight of the water-soluble cyclodextrin polymer based on the total weight of the hydrogel and does not contain the insoluble cyclodextrin polymer.

[0051] In some embodiments, the hydrogel comprises 0.5% by weight of the water-soluble cyclodextrin polymer and 0.5% by weight of the water-insoluble cyclodextrin polymer based on the total weight of the hydrogel.

[0052] In some embodiments, the hydrogel comprises 1% to 3% by weight of chitosan, 1% to 3% by weight of the cyclodextrin polymer (soluble and / or insoluble part of the cyclodextrin polymer), and 94 to 98% by weight of water (typically water containing 1% by weight of an acid).

[0053] Hydrogel composition In some embodiments, the hydrogel composition does not contain a pharmacological agent. In some embodiments, the hydrogel composition consists of the hydrogels disclosed above herein.

[0054] In some embodiments, the hydrogel composition comprises 95% to 99.9% by weight of hydrogel, preferably 99% to 99.5% by weight of hydrogel, and 0.1 to 5% by weight of a pharmacological agent, preferably 0.1 to 1% or 0.5 to 1% by weight of a pharmacological agent, based on the total weight of the composition. Preferably, the pharmacological agent is an analgesic.

[0055] In some embodiments, the hydrogel composition comprises 1% by weight of a pharmacological agent, preferably 1% by weight of an analgesic, based on the total weight of the composition.

[0056] The pH of the hydrogel composition is typically in the range of 3 to 5, preferably 3.1 to 3.5 or 4.2 to 4.5.

[0057] Examples of suitable compositions include the following compositions.

[0058]

Table A

[0059] Preparation of the Hydrogel Composition A hydrogel composition containing a pharmacological agent can be suitably prepared by adding the pharmacological agent during the preparation of the hydrogel.

[0060] The hydrogel can be appropriately prepared according to the method disclosed in WOWO2017 / 001808. In the disclosed method, cyclodextrin polymers (soluble and insoluble cyclodextrin polymers) and chitosan are prepared as powders. As used herein, the term "powder" means a solid substance granulated at ambient temperature. The powders of cyclodextrin polymers (mixed insoluble and soluble forms, or soluble form only) and chitosan are dry mixed to form a powder mixture. The resulting powder mixture is suspended in an aqueous medium having a pH that allows the soluble cyclodextrin polymer to dissolve without dissolving the chitosan (nor the insoluble cyclodextrin polymer), for example, at a pH of 4 or higher, 4.5 or higher, or even 5 or higher, and then the resulting suspension is acidified to form a bulk viscoelastic hydrogel under strong stirring.

[0061] Based on this method, the hydrogel composition of the present invention can be prepared as described in detail below herein. The hydrogel composition can be prepared at room temperature.

[0062] Cyclodextrin polymers (soluble and insoluble cyclodextrin polymers) and chitosan are prepared as powders. The powders can be sterilized before use.

[0063] Preparation of Powders Chitosan and cyclodextrin polymers can be used as raw powders, i.e., as unprocessed particles. The cyclodextrin polymer powder and / or chitosan powder can be sieved before use. Sieving can be appropriately carried out through a sieve with a mesh size of 500 μm or less, for example, 300 μm or less, or even 200 μm or less, particularly 150 μm or less, and more specifically 125 μm or less. The chitosan powder and cyclodextrin polymer powder can be sieved using a vibrating sieve, for example, a vibrating sieve sold by Fritsch.

[0064] In some embodiments, the cyclodextrin polymer powder and / or chitosan powder can be milled using, for example, a Pulverisette 14® machine sold by Fritsch and provided with a 120 μm sieve, before being sieved. Milling can reduce the diameter of the solid particles and form smaller fragments. Control of the particle size of chitosan and insoluble cyclodextrin polymers can be important in the process of preparing the hydrogel. In fact, small particles are more easily suspended in water and, after acidification of the suspension, allow rapid dissolution of chitosan. These parameters can be important not only for the gel formation time, but also for the homogeneity of the bulk hydrogel (absence of lumps in the hydrogel).

[0065] In some embodiments, the water-soluble cyclodextrin polymer powder and the water-insoluble cyclodextrin polymer powder, if present, are milled in a mortar and sieved through a 125 μm sieve. Chitosan is milled separately using, for example, a Pulverisette 14® machine sold by Fritsch and provided with a 120 μm sieve, before being sieved. The resulting chitosan powder is then sieved again through a 125 μm sieve.

[0066] In some embodiments, the cyclodextrin polymer powder and / or chitosan powder are milled to obtain particles having an average diameter smaller than 125 microns. The particle size distribution of the chitosan powder and / or cyclodextrin polymer powder, or the particle size distribution of the mixture of chitosan powder and cyclodextrin polymer powder, can be measured using a Mastersizer S (Malvern Instruments, Orsay, France) using a 300 mm lens. The sample is dispersed in the dry state using compressed air at 4 bar.

[0067] Addition of the pharmacological agent The addition of the pharmacological agent can be made by any suitable method.

[0068] Pharmacological agents are typically added to cyclodextrin polymer powders by wet granulation. Since pharmacological agents can react with chitosan amino groups, this process prevents any interactions that could affect the formation and stability of the hydrogel. The pharmacological agent may be added to a water-soluble cyclodextrin polymer powder, which may have been pulverized and / or sieved before use, or to a mixture of water-soluble and water-insoluble cyclodextrin polymer powders. The pharmacological agent and the cyclodextrin polymer powder are prepared in the proportions shown above herein.

[0069] Wet granulation can be carried out by any method well known in the art. For example, the cyclodextrin polymer powder and the pharmacological agent may be placed in a mortar. Next, water is added, for example, at a ratio of 4:1 (w / w), and the resulting mixture is stirred. Next, the mixture is placed in an oven at 60 °C for 1 hour 30 minutes. Next, the resulting powder is pulverized and sieved to obtain particles having a diameter smaller than 125 microns.

[0070] The cyclodextrin polymer powder containing the pharmacological agent and the chitosan powder are then dry mixed. Dry mixing can be suitably done using a mixer mill.

[0071] In some embodiments, the resulting mixture can be sieved or co-pulverized and sieved. Sieving can be carried out as disclosed above.

[0072] In some embodiments, the cyclodextrin polymer powder and / or chitosan powder containing a pharmacological agent may be co-milled, for example, they can be co-milled manually in a mortar or using a Mixer Mill MM400 sold by Restch, Steinbach, Germany. The term "co-milling" refers to the simultaneous milling of at least two different powders. Co-milling and / or milling, followed by mixing, can reduce the diameter of the solid particles of the powder and can also result in a homogeneous mixing between the powders (for this reason, a better contact surface area is provided between the cyclodextrin polymer and chitosan, which is advantageous for electrostatic interactions). It has been observed that milling promotes the homogeneity of the aqueous dispersion formed using these powders in the next step of this method. The reproducibility in the formation of the hydrogel is also enhanced, similar to the homogeneity of the hydrogel without visible lumps.

[0073] Preparation and acidification of a suspension for forming a hydrogel composition After being dry-mixed and optionally sieved or milled and sieved, the resulting mixture of cyclodextrin polymer powder and chitosan powder, when a pharmacological agent is present, is then suspended in an aqueous medium having a pH that allows the cyclodextrin polymer to be dissolved without dissolving the chitosan. This suspension is preferably stirred. The pH of the aqueous medium is suitably in the range of 5 to 6, preferably 5.5 to 6. The pH values indicated in this document are measured using a pH meter at ambient temperature (i.e., 20 to 25 °C). The expression "without dissolving the chitosan" as used herein means that in the aqueous medium, none of the amine functional groups of the chitosan are protonated or only an insufficient number of the amine functional groups of the chitosan are protonated to cause dissolution of the chitosan powder. The aqueous medium is preferably water (e.g., distilled water or ultrapure water). Generally, an acid of at least 0.5% by volume, or at least 1% by volume, based on the total volume of the aqueous medium, may be added to the aqueous medium.

[0074] Next, the obtained suspension is acidified to form the hydrogel composition. When an acid is added, the pH of the suspension decreases to a pH of especially 5 or less, more particularly 3 or less, especially 4 or less, which causes solubilization of chitosan by protonation of the amine's ammonium functional groups of chitosan. The chitosan polymer unravels under the action of the intramolecular electrostatic repulsion forces between the formed ammonium groups and reaches an extended coil structure that occupies the entire volume of the aqueous medium when it reaches the "critical" concentration C* (generally represented by g / cm 3 ). This critical concentration C* corresponds to the concentration above which the polymer coils overlap. At the same time, ionic bonds are formed between the ammonium groups of chitosan and the anionic functional groups of the cyclodextrin polymer. Next, when the amine functional groups are protonated, the pH of the hydrogel rises to and stabilizes at a pH of preferably 4 or more, more preferably 4.5 or more, especially 5 or more.

[0075] Suitable acids that can be added to the suspension to form the hydrogel composition include, but are not limited to, acetic acid, especially glacial acetic acid, formic acid, tartaric acid, salicylic acid, glutamic acid, propanoic acid, hydrochloric acid, citric acid, lactic acid, and mixtures thereof. Preferred suitable acids include acetic acid, hydrochloric acid, lactic acid, and mixtures thereof. More preferred suitable acids include lactic acid and hydrochloric acid, especially lactic acid.

[0076] It has been observed that the hardness and stability of the injected hydrogel composition are better when using these acids, especially when using lactic acid. In addition, extremely diluted solutions of hydrochloric acid and lactic acid have the advantage of being odorless compared to acetic acid. The lactic acid added can be the aqueous solution containing at least 85% by weight of pure lactic acid relative to the volume of the aqueous solution.

[0077] Typically, the acidification is carried out by adding an aqueous composition containing at least 1% by weight of lactic acid. Furthermore, the acidification step must be accompanied by vigorous stirring. Shearing forces promote the rapid dissolution of chitosan and the formation of the hydrogel.

[0078] The present invention comprises the following steps: (i) preparing a water-soluble cyclodextrin polymer powder, and if applicable, a water-insoluble cyclodextrin polymer powder, and a chitosan powder; (ii) adding a pharmacological agent to the water-soluble cyclodextrin polymer powder or a mixture of water-soluble and water-insoluble cyclodextrin polymer powders by wet granulation; (iii) dry-mixing the powder obtained in step (ii) with the chitosan powder to form a powder mixture; (iv) optionally, sieving or co-milling and sieving the powder mixture obtained in step (iii); (v) suspending the powder mixture obtained in step (iv) in an aqueous medium having a pH that allows the water-soluble cyclodextrin polymer to dissolve without dissolving the chitosan, for example, at a pH of 4 or higher, 4.5 or higher, or even 5 or higher; (vi) acidifying the suspension obtained in step (v) to form a hydrogel composition and relates also to a method for providing a hydrogel composition as described herein.

[0079] Each step of this method is as disclosed in detail above herein.

[0080] In other words, the present invention comprises the following steps: (i) preparing a water-soluble cyclodextrin polymer powder, and if applicable, a water-insoluble cyclodextrin polymer powder, and a chitosan powder; (ii) adding a pharmacological agent to the water-soluble cyclodextrin polymer powder or a mixture of water-soluble and water-insoluble cyclodextrin polymer powders by wet granulation; (iii) dry-mixing the powder obtained in step (ii) with the chitosan powder to form a powder mixture; (iv) Optionally, the powder mixture obtained in step (iii) is sieved or co-milled and sieved, and (v) The powder mixture obtained in step (iv) is suspended in an aqueous medium having a pH that allows the water-soluble cyclodextrin polymer to dissolve without dissolving chitosan, for example at a pH of 4 or higher, at a pH of 4.5 or higher or even 5 or higher. (vi) Acidifying the suspension obtained in step (v) to form a hydrogel composition Also relates to a hydrogel composition obtainable by a method comprising.

[0081] Step (vi) is typically carried out with stirring at a high shear rate.

[0082] The disclosed method can be carried out using a device comprising a first syringe for receiving chitosan, a cyclodextrin polymer powder, and a pharmacological agent, and a second syringe for receiving a predetermined volume of acidified aqueous medium, said device comprising means for bringing the first syringe and the second syringe into fluid communication such that the acidified aqueous mixture can be combined with the mixture comprising chitosan, the cyclodextrin polymer powder and the pharmacological agent. Said means for fluid communication may optionally be removable from the first syringe and the second syringe. The first syringe and the second syringe may be in fluid communication at their respective injection ends via means for fluid communication (e.g., a luer lock), which allows the acidified aqueous medium to be introduced into the first syringe with the aid of the piston of the second syringe, and vice versa, made possible by the piston of the first syringe. The piston is moved several times (about 50 to about 70 repetitions) until the hydrogel is formed, and the shear force generated promotes the dissolution of the chitosan powder and the ionic interaction with the anionic cyclodextrin polymer to allow a stable and firm hydrogel to be easily formed.

[0083] Administration of the hydrogel composition The hydrogel composition can be suitably administered by injection, particularly by intra-articular injection. The injection can be made using a device containing the hydrogel. Said device is preferably a syringe containing at least one reservoir filled with the hydrogel composition, typically filled with a predetermined volume of the hydrogel composition.

[0084] In some embodiments, the device for administering the hydrogel composition comprises a first syringe containing a mixture comprising chitosan, cyclodextrin polymer powder, and, if present, a pharmacological agent, preferably a mixture comprising a suspension as described herein containing chitosan, cyclodextrin polymer powder, and, if present, a pharmacological agent, and a second syringe containing a predetermined volume of an acidified aqueous medium, and said device comprises means for bringing the first syringe and the second syringe into fluid communication such that the acidified aqueous medium can be combined with the mixture comprising chitosan, cyclodextrin polymer powder, and, if present, a pharmacological agent. When the hydrogel composition is formed as disclosed above herein, the syringe containing the hydrogel composition can be fitted with a needle and the hydrogel composition can be injected.

[0085] The present invention also relates to a method of treating joint disorders, including administration of an effective dose of the hydrogel composition disclosed herein to an individual in need thereof, particularly when a combination of pharmacological action and viscosupplementation therapy is desired or required. Administration of the hydrogel composition is typically carried out by injection, particularly by intra-articular injection.

[0086] The effective dose of the hydrogel composition varies depending on a number of parameters, such as body weight, age, gender, the progression of the disorder to be treated, and the sensitivity of the individual to be treated.

[0087] The present invention also relates to a hydrogel composition for use in the manufacture of a medicament for use in the treatment of joint disorders, particularly when a combination of pharmacological action and viscosupplementation therapy is desired or required.

[0088] Embodiments of the present invention are described herein by way of the following examples, which are provided for illustrative purposes only and do not limit the scope of the present disclosure.

Examples

[0089] Abbreviations CHT Chitosan PCDs Water-soluble anionic cyclodextrin polymer PCDi Water-insoluble anionic cyclodextrin polymer NaNX Naproxen sodium βCD Beta-cyclodextrin

[0090] Example 1: Stability of the hydrogel The hydrogel was prepared according to the method disclosed in WOWO2017 / 001808. The cohesive force of the following formulations was evaluated (Table 1).

[0091]

Table 1

[0092] After preparing the hydrogel, it was injected into vials and the cohesive force of the hydrogel was evaluated by inverting the vials. 1 mL of the hydrogel was injected into vials at 37°C and the flow resistance was visually evaluated over time.

[0093] A hyaluronic acid-based product (R.P.) called Ostenil® was used as a control and tested simultaneously (Figure 1).

[0094] All CHT / PCDs / PCDi formulations tested formed hydrogels.

[0095] The flow resistance of R.P. was low (less than 8 seconds) compared to one of the CHT / PCDs / PCDi formulations.

[0096] Various cohesive forces were observed between the samples. The 2:1:0 formulation showed a higher flow resistance (>2h) compared to the 1.5:1.5:0 (2h) formulation. The addition of PCDi led to a decreased flow resistance, reflecting weaker hydrogel cohesive forces (1.5:0.75:0.75 and 2:0.5:0.5).

[0097] The hydrogel was then injected into a buffer solution (phosphate buffered saline PBS, pH 7.4, 80 rpm, 37 °C) using an 18G needle, and the cohesive force of the hydrogel was tested in a medium mimicking physiological pH. Since R.P. is a hyaluronic acid-based solution, it did not form an aggregated product after injection (it formed a solution with PBS and the results are not presented).

[0098] The results are shown in Figure 2. String-like structures were observed in all samples. However, stronger cohesive forces were observed over 24 hours for the 2:1:0 and 2:0.5:0.5 hydrogels compared to the 1.5:0.75:0.75 and 2:0.5:0.5 hydrogels. More specifically, the 2:0.5:0.5 hydrogel showed the highest stability.

[0099] The 1.5:1.5:0 and 1.5:0.75:0.75 hydrogels showed weak cohesive forces over 24h. In fact, the 1.5:1.5:0 formulation lost its structure by shrinkage after 1 hour, while the 1.5:0.75:0.75 formulation partially lost its string-like structure and formed lumps.

[0100] In conclusion, stronger cohesive forces are observed for the hydrogels according to the invention, namely the 2:1:0 and 2:0.5:0.5 hydrogels. The hydrogels according to the invention are stable.

[0101] Despite the higher flow resistance of the 2:1:0 complex, the addition of PCDi improves the structural stability in the 2:0.5:0.5 complex.

[0102] Example 2: Viscoelasticity of Hydrogels Tests of G’ and G” (Pa) were carried out in the linear viscoelastic region (γ = 1%, frequency = 10 rad / s, 37 °C) using a rheometer by rheological measurement. The results are shown in Table 2 and Figure 3 below.

[0103] As shown in Table 2, in the CHT / PCDs / PCDi hydrogel, G’ is higher than G” (G’>G”), which demonstrates the formation of a viscoelastic solid.

[0104] It can be observed that the CHT / PCDs / PCDi hydrogel had excellent viscoelastic behavior compared to Ostenil® (referred to as R.P.). In fact, R.P. has behavior corresponding to a viscoelastic solid, but the difference between G’ and G” is quite small, and it can be concluded that R.P. exhibits weaker cohesive forces.

[0105] Tanδ (Table 2), also known as the loss factor, is a parameter that helps identify the internal energy (or interaction force) of a viscoelastic solid. In rheology, the value of Tanδ is calculated from the ratio G” / G’, and thus, tan d>100:1 = 100 is considered an ideal viscous liquid, 0.01 < tan d < 100 is considered viscoelastic behavior, and tan d < 1:100 = 0.01 is considered an ideal elastic solid.

[0106] For the CHT / PCDs / PCDi formulation, a lower value of tanδ (<0.82) was observed compared to R.P. (0.92). This is evidence of the higher solid elastic properties of the hydrogel. For the CHT / PCDs formulation, similar tanδ values (0.56) were observed as for the CHT / PCDs / PCDi formulation (0.82) (Figure 3).

[0107]

Table 2

[0108] In conclusion, the hydrogel CHT:PCDs / PCDi compositions in Table 2 behave as solid viscoelastic materials, while RP behaves as a viscous liquid.

[0109] Example 3: Injectability of Hydrogel (Test of Viscosity against Shear Rate) To test the injectability of the hydrogel, changes in viscosity against shear rate sweep were performed by rheological measurement (25 °C). The CHT / PCDs / PCDi hydrogel was tested in the same manner as R.P., and the effect of the addition of PCD to the formulation was observed. R.P. has a lower resistance to flow (0.16 Pa·s at 1000 s -1 ), while the CHT / PCDs / PCDi hydrogel had a slightly higher resistance (0.47 - 0.49 Pa·s at 1000 s -1 ) (Figure 4, Table 3). It can be concluded that CHT / PCDs / PCDi and R.P. are non-Newtonian and have shear-thinning behavior.

[0110] These characteristics demonstrate the injectability of the hydrogel.

[0111]

Table 3

[0112] Example 4: Self-Healing Action of Hydrogel (Recovery of G' Coefficient against Strain) Self-healing ability is the ability of some hydrogels to reconstitute their structure after internal bonds are broken under strain induced by mechanical stress. The recovery of the hydrogel under different shear stresses was evaluated to determine the recovery rate of the hydrogel. Weak (γ = 1%) and strong (γ = 500%) stress cycles at 25 °C were applied to all samples.

[0113] Figure 5 shows the G' and G" coefficients of CHT / PCDs / PCDi hydrogels and R.P as functions of applied shear amplitude cycles of 1% and 500%. At low shear amplitudes, G' is above G", and the gel has solid viscoelastic behavior. The influence of high stress causes a decrease in the G' coefficient below the value of G", which indicates fluid behavior. When returning to low shear amplitudes next, a recovery of G' is observed. CHT / PCDs / PCDi and R.P had a recovery rate of G' exceeding 90%. At low shear amplitudes, it is explained that chitosan, PCDs, and PCDi are in an interaction state by ionic bonds (they form polyelectrolyte complexes). At high shear amplitudes, the ionic interaction collapses, both polymers recover their mobility, and the system flows (G">G'). After low shear amplitude is applied again, the ionic bonds are rapidly reformed in a short time, and the initial parameters are restored.

[0114] Therefore, the CHT / PCDs / PCDi formulation can be considered a self-healing functional hydrogel.

[0115] Example 5: Formulation of Hydrogels with Pharmacological Agents Preparation of Hydrogel Compositions Containing Pharmacological Agents NaNX at a concentration of 1% w / w was added to the formulation by wet granulation of PCDs / PCDi / NaNX as described above.

[0116] Rheological Evaluation of Hydrogel Compositions Containing Pharmacological Agents The evaluation was performed for the hydrogels as disclosed above in this specification.

[0117] Evaluation of G' and G" over Time Rheological evaluations were performed to evaluate any changes after the addition of NaNX.

[0118] Figure 6 shows the formation of the hydrogel in both examples (G’ > G”). In fact, the inclusion of NaNX caused an increase in the G’ coefficient. The values of the G’ coefficient and G” coefficient, which are 230 Pa and 55 Pa respectively, were observed for formulation 2 + 1:0:1, and 130 Pa and 50 Pa respectively were observed for formulation 2 + 0.5:0.5:1 (Table 4).

[0119] The Tanδ values were similarly compared, and formulations with the pharmacological agent (<0.39) formed stronger hydrogels compared to formulations without the pharmacological agent (0.50 - 0.82).

[0120] In conclusion, the formation of stronger hydrogels is obtained after wet granulation between PCD and NaNX. This test demonstrated that the addition of NaNX makes it possible to maintain the viscoelasticity of the CHT + PCDs:PCDi hydrogel.

[0121]

Table 4

[0122] Test of viscosity against shear rate Figure 7 shows the viscosity test of the hydrogel composition containing NaNX. A significant increase in viscosity is observed at 0.01 s-1 with values of 415 and 268 (Table 5). An increase four times greater than the initial value of the hydrogel without NaNX is shown.

[0123] This result shows that the addition of NaNX makes it possible to maintain the non-Newtonian and shear-thinning behavior of the CHT + PCDs:PCDi hydrogel. As mentioned above, shear-thinning is related to the injectability of the hydrogel.

[0124]

Table 5

[0125] Recovery This test was performed using the same experimental parameters as those described above. Similar behavior was observed, and a recovery of approximately 90% of G’ was obtained. As described above, this test shows the loss of the polymer network structure at high shear amplitudes and the reconstruction of new ionic bonds upon return to low stress (Figure 8).

[0126] In vitro release test Release tests were performed to evaluate the kinetics of NaNX release. An amount of 0.8 g of the hydrogel composition (see Table 6) was injected into a 1 kDa regenerated cellulose dialysis membrane (Spectra / Por®, Spectrum Laboratories, Inc). The samples were then tested at 37 °C in 500 mL of phosphate buffered saline (PBS) in a USP1 elution system (Agilent, France). All tests were performed in triplicate.

[0127] All samples were analyzed by ultra-high performance liquid chromatography connected to a diode array detector (Shimadzu Nexera-i LC-2040 3D plus). The mobile phase was composed of an acetonitrile / orthophosphoric acid pH 2.25 (65:35) mixture and was injected at a flow rate of 1 mL / second into a C18 column (4 * 250 mm) stabilized at 25 °C. The injection volume was fixed at 20 μL and the detection wavelength was 225 nm. A retention time of 4.2 minutes was established to calculate the area under the curve (AUC).

[0128]

Table 6

[0129] First, similar release profiles were observed for both examples. Indeed, the plateau of release was reached after 36 hours. Some slight differences were also observed between the two formulations, with a higher amount of drug released in the 2+1:0:1 hydrogel (86.0 wt%) compared to the 2+0.5:0.5:1 hydrogel which released 78.1 wt% (Figure 9).

[0130] Example 6: Evaluation of cytotoxicity The cytotoxicity of hydrogel formulations 2:0.5:0.5 and 2:1:0 (see Table 1) was evaluated using a cell line of NIH / 3T3 fibroblasts by an extraction method (indirect contact) according to the ISO 10993-5 standard. The hydrogel was pre-treated in MEM-α culture medium at 37 °C and 80 rpm for 2 hours. The culture medium was removed and a concentration of 200 mg of hydrogel / 1 mL of medium was added. On the other hand, NIH 3T3 cells were seeded in a cell culture plate to form a cell carpet. The number of seeded cells was 4 × 103 cells per well in 100 μL of complete medium and incubated at 37 °C in an atmosphere of 5% CO2 for 24 hours. After incubation, each extraction medium (n = 2) was sterilized using a 0.22 μm filter. Subsequently, the cell layer culture medium was replaced with 100 μL of sterilized extraction medium. The cells were incubated for a further 24 hours at 37 °C in an atmosphere of 5% CO2. Finally, cell viability was evaluated by a fluorescence measurement method using AlamarBlue® reagent (Uptima, Interchim, France). Fluorescence readings were measured at an excitation wavelength of 530 nm and an emission wavelength of 590 nm. The metabolic activity of the cells was expressed as a percentage of the fluorescence intensity relative to the control value (Figure 10).

[0131] Figure 10 shows the percentage of cell survival after exposure to the hydrogel together with the culture medium. High cell viability was observed for both formulations compared to the control. This test demonstrates the safety of the administration of this hydrogel to humans.

[0132] Example 7: Tribological test The tribology test was performed on the 2:0.5:0.5 hydrogel (see Table 1) using a Tribo-Rheometer MCR301 (Anton Paar, Les Ulis, France) connected to a T-PID44 tribology cell and an SCFE7 measurement accessory. The lubricating action of the hydrogel and R.P was determined using an accessory of three pin shafts and a PTFE disk. A deflection angle of 50 mrad, an angular frequency of 6 rad / s, and a perpendicular resistance of 45 N were applied. Pre-stabilization was applied to depressurize the system before starting each cycle. This protocol consisted of a deflection angle of 0.014 mrad, an angular frequency of 1 rad / s, a perpendicular resistance of 15 N, and 5 minutes.

[0133] Torque was measured over 4 cycles for 30 minutes. At the same time, a sterilized sample of the formulation was tested and the results are shown in Figure 11.

[0134] The hydrogel 2:0.5:0.5 was also compared with a physiological solution (0.9% NaCl) as a negative control. In the first cycle, the negative control and the non-sterilized sample had similar behavior. Next, the negative control tended to increase over time, while the formulation 2:0.5:0.5 decreased over time, demonstrating the lubricating action of the formulation 2:0.5:0.5.

[0135] Example 8: Sterilization of the hydrogel Ethylene oxide (EtO) sterilization and gamma irradiation were used to sterilize the powders of CHT and PCD, respectively. The sterilization procedures were carried out in accordance with ISO 11135 and ISO 11137 standards for the sterilization of health products. Sterilization by EtO consisted of three parts, namely pre-packaging, sterilization (exposure to EtO for 3 hours), and aeration. The EtO gas was removed by using ventilation in the sterilization chamber to remove residual EtO particles.

[0136] Gamma irradiation sterilization was performed using a cobalt-60 (60Co) radiation source at a dose of 40 kGy.

[0137] The effect of sterilization on the hydrogel was carried out for the formulations CHT / PCDs / PCDi 2:0.5:0.5 and CHT + PCDs / PCDi / NaNX2 + 0.5:0.5:1. The evaluation consisted of tests of viscoelasticity (G’ and G”) and cell compatibility (only for the formulation without NaNX).

[0138] The results obtained are shown in Figure 12 and Table 7. The viscoelasticity was evaluated as described above (Figure 12, Table 7), and the results showed the predominance of the elastic coefficient over the viscous coefficient, which confirmed the formation of the hydrogel (G’>G”).

[0139]

Table 7

[0140] Next, the cell compatibility test was carried out according to ISO 10993-5 as described above. No difference in cell viability was observed after sterilization (Figure 13). In fact, a cell viability value of 100% (higher than the pre-sterilization cell viability of 93.8%) was obtained, demonstrating its cell compatibility.

[0141] Example 9: Preclinical Trials of Hydrogel A total of 20 male Wistar rats (6 weeks old) with an average body weight of 221.6 g per group (range 193 - 267 g) were used. The animals were housed in a temperature-controlled room (22 + / - 1°C) with a 12 - 12 hour light-dark cycle. After acceptance, each animal was placed in an individual cage and given free access to food and water. A single left temporomandibular joint (TMJ) injection of 0.5 mg of sodium iodoacetate (MIA, Sigma, Saint Louis, USA) dissolved in 50 μL of physiological saline was performed under general anesthesia to induce TMJ osteoarthritis. Using anatomical landmarks, the solution was injected into the upper compartment of the left TMJ with a 26-gauge needle. Two days after the MIA injection, the same injection method was used for both joints in the treatment groups (2:0.5:0.5 and R.P.).

[0142] Figure 14: The pain experienced by rats after intra-articular injection of a chemical agent was measured by a von Frey anesthesiometer before (-2 days, 0 day) and 2, 7, 14, 21, and 30 days after injection of the therapeutic agent. Briefly, using a hard plastic tip, the midpoint of the connection between the ear and the eye on the left side of the rat's head and face was stimulated. During the experimental procedure, the mechanical stimulus intensity was increased, and the behavior of the rat was observed simultaneously. When reactions such as licking the mouth, scratching the head, or a head withdrawal reflex were observed, the stimulus intensity (g) was recorded as the head withdrawal threshold (HWT), which was defined as the minimum pressure on the TMJ that induces nociception. The rat was then allowed to rest for several minutes, and then the same procedure was performed on the right side. The HWT was calculated as the mean value per joint for all rats / group tested.

[0143] (Left) side HWT significantly decreased 2 days after MIA injection, but HWT returned to its original level from D14 after 2:0.5:0.5 hydrogel injection, which emphasized the lubricating effect of the hydrogel. Compared to R.P, HWT was significantly higher in the hydrogel group from day 14 to day 30.

Claims

1. A hydrogel made of a polymer network containing (a)(i) chitosan, (ii) an anionic cyclodextrin polymer for use in the treatment of joint disorders, wherein the anionic cyclodextrin polymer is a water-soluble anionic cyclodextrin polymer or a mixture of a water-soluble anionic cyclodextrin polymer and a water-insoluble anionic cyclodextrin polymer (CDPi), and the ratio of the weight of the water-soluble anionic cyclodextrin polymer to the weight of the water-insoluble anionic cyclodextrin polymer is about 1:1, and the ratio of the weight of the chitosan to the total weight of the anionic cyclodextrin polymer is about 2:1, and (b) optionally, a pharmacological agent incorporated into the polymer network A hydrogel composition comprising.

2. The hydrogel composition for use according to claim 1, wherein the pharmacological agent is present and is an analgesic.

3. The hydrogel composition for use according to claim 2, wherein the analgesic is selected from the group consisting of opioid analgesics such as codeine, oxycodone and hydromorphone, and non-steroidal anti-inflammatory agents such as naproxen, ibuprofen, diflunisal and ketorolac.

4. The hydrogel composition for use according to any one of claims 1 to 3, wherein the joint disorder is osteoarthritis, osteoarthrosis, rheumatic disorder, and degenerative meniscus injury.

5. The hydrogel composition for use according to any one of claims 1 to 4, wherein the hydrogel composition is administered by intra-articular injection.

6. The hydrogel composition for use according to any one of claims 1 to 5, wherein the hydrogel contains 2% by weight of chitosan and 1% by weight of a water-soluble anionic cyclodextrin polymer based on the total weight of the hydrogel.

7. The hydrogel composition for use according to any one of claims 1 to 6, wherein the hydrogel contains 2% by weight of chitosan, 0.5% by weight of a water-soluble anionic cyclodextrin polymer, and 0.5% by weight of a water-insoluble anionic cyclodextrin polymer based on the total weight of the hydrogel.

8. The hydrogel composition according to any one of claims 1 to 7, which contains 0.1 to 5% by weight, preferably 0.1 to 1% by weight, of a pharmacological agent based on the total weight of the hydrogel composition.

9. A method for preparing a hydrogel composition according to any one of claims 1 to 8, which contains a pharmacological agent, the method comprising the following steps: (i) preparing a water-soluble anionic cyclodextrin polymer powder, if applicable, a water-insoluble anionic cyclodextrin polymer powder, and a chitosan powder; (ii) adding the pharmacological agent to the water-soluble anionic cyclodextrin polymer powder or a mixture of the water-soluble and water-insoluble anionic cyclodextrin polymer powders by wet granulation; (iii) dry-mixing the powder obtained in step (ii) with the chitosan powder to form a powder mixture; (iv) optionally, sieving or co-grinding and sieving the powder mixture obtained in step (iii); (v) suspending the powder mixture obtained in step (iv) in an aqueous medium having a pH that allows the anionic cyclodextrin polymer to dissolve without dissolving the chitosan; (vi) acidifying the suspension obtained in step (v) to form the hydrogel composition A method comprising.

10. The method according to claim 9, wherein step (vi) is carried out by adding an acid selected from the group consisting of acetic acid, formic acid, tartaric acid, salicylic acid, glutamic acid, propanoic acid, hydrochloric acid, citric acid, lactic acid, and mixtures thereof, preferably the acid being lactic acid or hydrochloric acid.

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