Microsphere-based injectable rofecoxib formulation

Abstract

This invention provides a biodegradable microsphere, wherein the microsphere (i) has a diameter of from 1 μm to 500 μm; (ii) comprises a polylactic-co-glycolic acid (PLGA) matrix; (iii) carries pharmaceutical rofecoxib; and (iv) when present in a suitable joint-related tissue or suitable soft tissue, releases rofecoxib for at least one month. This invention also provides related compositions, treatment methods, and kits.

Description

[0001] MICROSPHERE-BASED INJECTABLE ROFECOXIB FORMULATION

[0002] This application claims the benefit of U.S. Provisional Application No. 63 / 570,345, filed March 27, 2024, the contents of which are incorporated herein by reference.

[0003] Throughout this application, various publications are cited. The disclosure of these publications is hereby incorporated by reference into this application to describe more fully the state of the art to which this invention pertains.

[0004] Field of the Invention

[0005] The present invention relates to methods for treating joint-related and soft tissue-related disorders via localized injection of rofecoxib-containing biodegradable microspheres.

[0006] Background of the Invention

[0007] Non-steroidal anti-inflammatory drugs (NSAIDs) treat inflammation and pain. For treating localized inflammatory diseases in the joint and soft tissue, oral NSAIDs have been widely used to decrease pain and improve physical function. However, the vast majority of NSAIDs cause severe side effects due to inhibition of COX-1 and COX-2 targets. Indeed, each such side effect-causing drug carries a black-box warning on its product label, as required by the FDA. These labels also state that patients should use the lowest effective dosage for the shortest duration. In addition to the cardiovascular and gastrointestinal adverse effects listed in the black-box warnings, the labels also warn of other systemic toxicities such as hepatotoxicity and renal toxicity.

[0008] Rofecoxib is a potent and selective COX-2 inhibitor that was approved to treat osteoarthritis, rheumatoid arthritis, juvenile rheumatoid arthritis, acute pain, primary dysmenorrhea and migraine under the commercial name, VIOXX. Oral rofecoxib showed clinically superior pain relief than other NSAIDs such as celecoxib in many settings such as osteoarthritis pain and dental pain. However, due to its severe cardiovascular thrombotic side effects including heart attack and stroke, oral rofecoxib was withdrawn from the market by its manufacturer, Merck Laboratories. To avoid its systemic side effects, an extended-release formulation of rofecoxib that can be directly injected to the sites of inflammation or pain is desirable. Such an ideal formulation should exhibit a stable and continuous rofecoxib release over at least one month. Furthermore, a high percentage of drug loading in the formulation can reduce injection burden and improve patient compliance.

[0009] PLGA Microspheres Generally

[0010] An important biodegradable material commonly used for extended-release drug delivery is polylactic co-glycolic acid (PLGA). PLGA can be made of purely polylactic acid (PLA) units, purely polyglycolic acid (PGA) units, and typically both. If PLGA is made of 100% polylactic acid units, it can be described as PLGA100:0. If PLGA is made of 100% polyglycolic acid units, it can be described as PLGA0:100. As an FDA- approved polymer, it has been extensively investigated in many medical and pharmaceutical fields due to its biodegradability and biocompatibility. PLGA-containing microspheres have shown sustained release characteristics due to degradation and diffusion mechanisms. The drug release profile of a PLGA microsphere preparation is dependent on certain factors, such as the specific properties of the drug, the ratio of PLA to PGA, the type of end cap of the polymer (i.e. , ester or acid), the molecular weight / inherent viscosity of the polymer, the loading ratio of drug to the polymer, and the size of the microspheres.

[0011] As a general matter, PLGA-based microparticles are difficult to develop due to the unpredictable nature of the development process because the mechanisms of PLGA microparticle formation are not fully understood (Park, et al.). In the absence of a mechanistic understanding, the development of injectable long-acting formulations has been based on a trial-and-error approach (Park, et al.). The interactions among drug, PLGA, and solvent affect the microparticle properties in unpredictable ways, as their impacts are not linear (Park, et al.). Thus, repeated experimentation is required to develop a sustained-release PLGA microsphere for any compound.

[0012] Rofecoxib-Containing PLGA Microspheres

[0013] Hahn, et al., discloses microspheres composed of PLGA50:50 (30 kDa and 40 kDa) and celecoxib (a different COX-2 inhibitor with drug loading ratios of 7.32% and 8.01 %), which showed a celecoxib release duration of 14-21 days, and microspheres composed of PLGA75:25 (30 kDa) and celecoxib (with a drug loading ratio of 8.3%), which showed a celecoxib release duration of 28 days. However, this publication does not disclose any rofecoxib-containing microspheres or any microspheres with continuous drug release over one month.

[0014] Li discloses microspheres composed of PLGA and celecoxib, which showed a celecoxib release duration of at least one month. However, this publication does not mention rofecoxib or disclose any microspheres containing rofecoxib.

[0015] Due to the unmet need for a superior way to treat joint-related and soft tissue-related disorders, a novel delivery formulation of rofecoxib with a long duration of continuous drug release is needed to maximize its local anti-inflammatory effects, minimize its side effects associated with systemic delivery, and enhance patient compliance.

[0016] Summary of the Invention

[0017] This invention provides a biodegradable microsphere, wherein the microsphere (i) has a diameter of from 1 pm to 500 pm; (ii) comprises a polylactic-co-glycolic acid (PLGA) matrix; (iii) carries pharmaceutical rofecoxib; and (iv) when present in a suitable joint- related tissue, releases rofecoxib for at least one month.

[0018] This invention also provides a plurality of biodegradable microspheres, wherein the microspheres (i) have a dio value of at least 1 pm and a dgo value of 500 pm or less; (ii) comprise a polylactic-co-glycolic acid (PLGA) matrix; (iii) carry a therapeutically effective amount of pharmaceutical rofecoxib; and (iv) when present in a suitable joint- related tissue, release rofecoxib for at least one month.

[0019] This invention further provides an injectable formulation comprising (a) a pharmaceutically acceptable carrier and (b) a plurality of biodegradable microspheres wherein the microspheres (i) have a dio value of at least 1 pm and a dgo value of 500 pm or less; (ii) comprise a polylactic-co-glycolic acid (PLGA) matrix; (iii) carry a therapeutically effective amount of pharmaceutical rofecoxib; and (iv) when present in a suitable joint-related tissue, release rofecoxib for at least one month. This invention still further provides a method for treating a joint-related disorder in a subject comprising introducing biodegradable microspheres into suitable tissue in or around one or more of the subject’s joints, wherein the microspheres (i) have a dio value of at least 1 pm and a dgo value of 500 pm or less; (ii) comprise a polylactic-co- glycolic acid (PLGA) matrix; (iii) carry a therapeutically effective amount of pharmaceutical rofecoxib; and (iv) when present in a suitable joint-related tissue, release rofecoxib for at least one month.

[0020] This invention further provides an article of manufacture (kit) comprising, in separate compartments, (a) one of, and ideally both of, (i) a diluent and (ii) a label instructing the user to introduce the biodegradable microspheres into suitable tissue in or around one or more of a subject’s joints, and (b) a plurality of biodegradable microspheres, wherein the microspheres (i) have a dio value of at least 1 pm and a dgo value of 500 pm or less;

[0021] (ii) comprise a polylactic-co-glycolic acid (PLGA) matrix; (iii) carry a therapeutically effective amount of pharmaceutical rofecoxib; and (iv) when present in a suitable joint- related tissue, release rofecoxib for at least one month.

[0022] This invention provides a biodegradable microsphere, wherein the microsphere (i) has a diameter of from 1 pm to 500 pm; (ii) comprises a polylactic-co-glycolic acid (PLGA) matrix; (iii) carries pharmaceutical rofecoxib; and (iv) when present in a suitable soft tissue, releases rofecoxib for at least one month.

[0023] This invention also provides a plurality of biodegradable microspheres, wherein the microspheres (i) have a dio value of at least 1 pm and a dgo value of 500 pm or less; (ii) comprise a polylactic-co-glycolic acid (PLGA) matrix; (iii) carry a therapeutically effective amount of pharmaceutical rofecoxib; and (iv) when present in a suitable soft tissue, release rofecoxib for at least one month.

[0024] This invention further provides an injectable formulation comprising (a) a pharmaceutically acceptable carrier and (b) a plurality of biodegradable microspheres wherein the microspheres (i) have a dio value of at least 1 pm and a dgo value of 500 pm or less; (ii) comprise a polylactic-co-glycolic acid (PLGA) matrix; (iii) carry a therapeutically effective amount of pharmaceutical rofecoxib; and (iv) when present in a suitable soft tissue, release rofecoxib for at least one month. This invention still further provides a method for treating a soft tissue disorder in a subject comprising introducing biodegradable microspheres into the soft tissue and / or its surrounding tissue, wherein the microspheres (i) have a dio value of at least 1 pm and a dgo value of 500 pm or less; (ii) comprise a polylactic-co-glycolic acid (PLGA) matrix; (iii) carry a therapeutically effective amount of pharmaceutical rofecoxib; and (iv) when present in a suitable soft tissue, release rofecoxib for at least one month.

[0025] This invention further provides an article of manufacture (kit) comprising, in separate compartments, (a) one of, and ideally both of, (i) a diluent and (ii) a label instructing the user to introduce the biodegradable microspheres into suitable soft tissue, and (b) a plurality of biodegradable microspheres, wherein the microspheres (i) have a dio value of at least 1 pm and a dgo value of 500 pm or less; (ii) comprise a polylactic-co-glycolic acid (PLGA) matrix; (iii) carry a therapeutically effective amount of pharmaceutical rofecoxib; and (iv) when present in a suitable soft tissue, release rofecoxib for at least one month.

[0026] Brief Description of the Figures

[0027] Figures 1A and 1 B

[0028] Figures 1 A (12.5 mg rofecoxib group) and 1 B (25 mg rofecoxib group) show that microspheres with PLGA65:35, 0.4 dl / g, acid-terminated and PLGA75:25, 0.4 dl / g, acid- terminated demonstrated continuous rofecoxib release for at least one month.

[0029] Microspheres made from PLGA75:25, 0.6 dl / g, ester-term inated showed a release gap in days 40-48 in the 12.5 mg rofecoxib group but showed continuous rofecoxib release over at least 85 days in the 25 mg rofecoxib group.

[0030] Figure 2

[0031] This figure shows a mixer (Model L5MA, Silverson, Massachusetts, US) with an in-line mixing chamber and general-purpose disintegrating head that was used to continuously create oil-in-water emulsions and generate microspheres.

[0032] Figures 3A-3I

[0033] Figure 3A shows continuous rofecoxib release for over two months for all mixing speeds in the 200 mg rofecoxib+200 mg PLGA75:25, 0.4 dl / g, acid-terminated group. Figure 3B shows continuous rofecoxib release for over two months for the 800 rpm, 1 ,200 rpm and 2,400 rpm mixing speeds in the 200 mg rofecoxib+200 mg PLGA75:25, 0.6 dl / g, ester-term inated group. Figure 3C shows continuous rofecoxib release for over three months for the 1 ,600 rpm and 2,400 rpm mixing speeds in the 200 mg rofecoxib+200 mg PLGA75:25, 0.9 dl / g, ester-term inated group. However, the 800 rpm mixing speed resulted in microspheres with a release gap from day 44 to 62. Figure 3D shows continuous rofecoxib release for four months for the 1 ,600 rpm and 2,400 rpm mixing speeds in the 200 mg rofecoxib+200 mg PLGA75:25, 1.2 dl / g, ester-term inated group. However, the 800 rpm and 1 ,200 rpm mixing speeds resulted in microspheres with a release gap from day 53 to 62. Figure 3E shows continuous rofecoxib release for six months for the 1 ,600 rpm and 2,400 rpm mixing speeds in the 200 mg rofecoxib+200mg PLGA85:15, 1.5 dl / g, ester-term inated group. However, the 800 rpm mixing speed resulted in microspheres with a release gap from day 53 to 62. Figures 3F, 3G, 3H, and 3I show continuous rofecoxib release for at least 44 days for all mixing speeds in the 200 mg rofecoxib+100 mg PLGA (all types tested) groups.

[0034] Figures 4A and 4B

[0035] These figures show that all formulations exhibited continuous rofecoxib release over at least three months, with the 2,400 rpm and 3,200 rpm groups exhibiting more uniform release kinetics.

[0036] Figures 5A and 5B

[0037] These figures show over four months of continuous rofecoxib release across all formulations tested with relatively uniform release kinetics.

[0038] Figures 6A-6C

[0039] These figures show that all formulations tested exhibited continuous rofecoxib release over five months in vitro with relatively uniform release kinetics. Notably, higher drug loading was associated with a faster release rate.

[0040] Figures 7A and 7B

[0041] These figures show that all formulations tested exhibited continuous rofecoxib release over at least five months in vitro with relatively uniform release kinetics. Notably, unirradiated microspheres from PLGA75:25, 0.9 dl / g and 1.2 dl / g, ester-term inated showed continuous rofecoxib release over six months. Microspheres of PLGA85:15, 1.5 dl / g, ester-term inated showed continuous rofecoxib release over nine months in the un-irradiated group and over seven months in the 25 kGy E-beam irradiated group.

[0042] Detailed Description of the Invention

[0043] This invention provides rofecoxib-containing biodegradable microspheres and methods for using them to treat joint-related disorders and soft tissue disorders.

[0044] Definitions

[0045] In this application, certain terms are used which shall have the meanings set forth as follows.

[0046] As used herein, a “biodegradable microsphere” comprises a polylactic-co-glycolic acid (PLGA) matrix, which matrix can include solely polylactic acid (PLA or PLGA100:0), solely polyglycolic acid (PGA or PLGA0:100), or a polymeric combination of lactic acid and glycolic acid units. In general, for certain lactic acid to glycolic acid ratios (e.g., 50:50 to 100:0), the higher a microsphere’s lactic acid content, the slower it degrades and, thus, the more stable it is. Conversely, for such ratios, the higher a microsphere’s glycolic acid content, the faster it degrades and the less stable it is. In one embodiment, the biodegradable microsphere contains a combination of lactic acid and glycolic acid units wherein the molar ratio of lactic acid to glycolic acid units (i.e. , the “lactic acid to glycolic acid ratio”, or “L:G ratio”) is 0:100, 5:95, 10:90, 15:85, 20:80, 25:75, 30:70, 35:65, 40:60, 45:55, 50:50, 55:45, 60:40, 65:35, 70:30, 71 :29, 72:28, 73:27, 74:26, 75:25, 76:24, 77:23, 78:22, 79:21 , 80:20, 81 :19, 82:18, 83:17, 84:16, 85:15, 86:14, 87:13, 88:12, 89:11 , 90:10, 95:5, or 100:0. In another embodiment, the biodegradable microsphere contains a combination of lactic acid and glycolic acid units wherein the molar ratio of lactic acid to glycolic acid is from 5:95 to 20:80, from 20:80 to 40:60, from 40:60 to 50:50, from 50:50 to 60:40, from 60:40 to 70:30, from 70:30 to

[0047] 80:20, from 80:20 to 90:10, from 90:10 to 100:0, from 50:50 to 70:30, from 60:40 to

[0048] 80:20, from 65:35 to 85:15, from 70:30 to 90:10, from 75:25 to 95:5, from 80:20 to

[0049] 100:0, from 50:50 to 75:25, from 60:40 to 85:15, from 65:35 to 90:10, from 70:30 to

[0050] 95:5, from 75:25 to 100:0, from 50:50 to 80:20, from 60:40 to 90:10, from 70:30 to 100:0, from 50:50 to 90:10, from 60:40 to 100:0, from 50:50 to 100:0, from 71 :29 to

[0051] 76:24, from 72:28 to 77:23, from 73:27 to 78:22, from 74:26 to 79:21 , from 71 :29 to 79:21 , from 72:28 to 78:22, from 73:27 to 77:23, from 74:26 to 76:24, from 81 :19 to

[0052] 86:14, from 82:18 to 87:13, from 83:17 to 88:12, from 84:16 to 89:11 , from 81 :19 to

[0053] 89:11 , from 82:18 to 88:12, from 83:17 to 87:13, from 84:16 to 86:14, from 71 :29 to

[0054] 89: 11 , from 72:28 to 88: 12, from 73:27 to 87: 13, from 74:26 to 86: 14, or from 75:25 to

[0055] 85:15. The population of biodegradable microspheres used in this invention can be homogeneous or heterogeneous with respect to the microspheres’ molar ratio of lactic acid to glycolic acid. In one embodiment, the population of biodegradable microspheres is homogeneous with respect to the microspheres’ molar ratio of lactic acid to glycolic acid (e.g., the population includes only microspheres wherein the molar ratio of lactic acid to glycolic acid is 75:25 or 85:15). In another embodiment, the population of biodegradable microspheres is heterogeneous (e.g., the population includes both (i) microspheres wherein the molar ratio of lactic acid to glycolic acid is 70:30, and (ii) microspheres wherein the molar ratio of lactic acid to glycolic acid is 80:20). In a preferred embodiment, the instant microspheres contain PLGA having an inherent viscosity of 0.1 to 2.4 dl / g (e.g., 0.16 to 1 .7 dl / g), and a molecular weight from 1 ,000 (or 1 kDa) to 600,000 (or 600 kDa) (e.g., from 7,000 to 240,000). In one embodiment, the biodegradable microsphere contains PLGA having a viscosity of 0.1 dl / g, 0.2 dl / g, 0.3 dl / g, 0.4 dl / g, 0.5 dl / g, 0.6 dl / g, 0.7 dl / g, 0.8 dl / g, 0.9 dl / g, 1.0 dl / g, 1.1 dl / g, 1.2 dl / g, 1.3 dl / g, 1.4 dl / g, 1.5 dl / g, 1.6 dl / g, 1.7 dl / g, 1.8 dl / g, 1.9 dl / g, 2.0 dl / g, 2.1 dl / g, 2.2 dl / g, 2.3 dl / g, or 2.4 dl / g. In another embodiment, the biodegradable microsphere contains PLGA having a viscosity of from 0.1 dl / g to 0.2 dl / g, from 0.2 dl / g to 0.3 dl / g, from 0.3 dl / g to 0.4 dl / g, from 0.4 dl / g to 0.5 dl / g, from 0.5 dl / g to 0.6 dl / g, from 0.6 dl / g to 0.7 dl / g, from 0.7 dl / g to 0.8 dl / g, from 0.8 dl / g to 0.9 dl / g, from 0.9 dl / g to 1.0 dl / g, from 1.0 dl / g to 1.1 dl / g, from 1.1 dl / g to 1.2 dl / g, from 1.2 dl / g to 1.3 dl / g, from 1 .3 dl / g to 1 .4 dl / g, from 1 .4 dl / g to 1 .5 dl / g, from 1 .5 dl / g to 1 .6 dl / g, from 1 .6 dl / g to 1 .7 dl / g, from 1 .7 dl / g to 1 .8 dl / g, from 1 .8 dl / g to 1 .9 dl / g, from 1 .9 dl / g to 2.0 dl / g, from 2.0 dl / g to 2.1 dl / g, from 2.1 dl / g to 2.2 dl / g, from 2.2 dl / g to 2.3 dl / g, or from 2.3 dl / g to 2.4 dl / g. In a further embodiment, the biodegradable microsphere contains PLGA having a viscosity of from 0.1 dl / g to 0.5 dl / g, from 0.5 dl / g to 1.0 dl / g, from 1.0 dl / g to 1 .5 dl / g, from 1 .5 dl / g to 2.0 dl / g, from 2.0 dl / g to 2.4 dl / g, from 0.5 dl / g to 1 .3 dl / g, from 0.7 dl / g to 1 .3 dl / g, from 0.9 dl / g to 1 .3 dl / g, or from 1 .3 dl / g to 1 .7 dl / g. Preferred embodiments of the present microspheres are PLGA75:25, 0.5-1.3 dl / g and PLGA85: 15, 1 .3-1 .7 dl / g. In a further embodiment, the drug loading ratio for the present biodegradable microsphere is from 20% to 30%, from 25% to 35%, from 30% to 40%, from 35% to 45%, from 40% to 50%, from 45% to 55%, from 50% to 60%, from 55% to 65%, from 60% to 70%, from 65% to 75%, from 20% to 35%, from 30% to 45%, from 40% to 55%, from 50% to 65%, from 20% to 40%, from 30% to 50%, from 40% to 60%, from 50% to 70%, from 20% to 50%, from 30% to 60%, from 40% to 70%, from 20% to 60%, from 30% to 70%, from 41 % to 50%, from 42% to 50%, from 43% to 50%, from 44% to 50%, from 45% to 50%, from 41 % to 51 %, from 42% to 51 %, from 43% to 51 %, from 44% to 51 %, from 45% to 51 %, from 46% to 51 %, from 42% to 52%, from 43% to 52%, from 44% to 52%, from 45% to 52%, from 46% to 52%, from 47% to 52%, from 43% to 53%, from 44% to 53%, from 45% to 53%, from 46% to 53%, from 47% to 53%, from 48% to 53%, from 44% to 54%, from 45% to 54%, from 46% to 54%, from 47% to 54%, from 48% to 54%, from 49% to 54%, from 40% to 49%, from 40% to 48%, from 40% to 47%, from 40% to 46%, from 41 % to 49%, from 41 % to 48%, from 41 % to 47%, from 41 % to 46%, from 42% to 49%, from 42% to 48%, from 42% to 47%, from 43% to 49%, from 43% to 48%, from 44% to 49%, from 40% to 51 %, from 40% to 52%, from 40% to 53%, from 40% to 54%, from 40% to 55%, from 40% to 56%, from 40% to 57%, from 40% to 58%, from 40% to 59%, from 41 % to 52%, from 41 % to 53%, from 41 % to 54%, from 41 % to 55%, from 41 % to 56%, from 41 % to 57%, from 41 % to 58%, from 41 % to 59%, from 41 % to 60%, from 50% to 55%, from 50% to 56%, from 50% to 57%, from 50% to 58%, from 50% to 59%, from 50% to 61 %, from 50% to 62%, from 50% to 63%, or from 50% to 64%. In yet a further embodiment, the molecular weight of the PLGA contained in the microspheres is from 10 kDa to 20 kDa, from 20 kDa to 30 kDa, from 30 kDa to 40 kDa, from 40 kDa to 50 kDa, from 50 kDa to 60 kDa, from 60 kDa to 70 kDa, from 70 kDa to 80 kDa, from 80 kDa to 90 kDa, from 90 kDa to 100 kDa, from 100 kDa to 110 kDa, from 110 kDa to 120 kDa, from 120 kDa to 130 kDa, from 130 kDa to 140 kDa, from 140 kDa to 150 kDa, from 150 kDa to 160 kDa, from 160 kDa to 170 kDa, from 170 kDa to 180 kDa, from 180 kDa to 190 kDa, from 190 kDa to 200 kDa, from 200 kDa to 210 kDa, from 210 kDa to 220 kDa, from 220 kDa to 230 kDa, from 230 kDa to 240 kDa, from 30 kDa to 240 kDa, from 35 kDa to 240 kDa, from 40 kDa to 240 kDa, from 50 kDa to 240 kDa, from 60 kDa to 240 kDa, from 70 kDa to 240 kDa, from 80 kDa to 240 kDa, from 90 kDa to 240 kDa, from 100 kDa to 240 kDa, from 110 kDa to 240 kDa, from 120 kDa to 240 kDa, from 30 kDa to 190 kDa, from 35 kDa to 190 kDa, from 40 kDa to 190 kDa, from 50 kDa to 190 kDa, from 60 kDa to 190 kDa, from 70 kDa to 190 kDa, from 80 kDa to 190 kDa, from 90 kDa to 190 kDa, from 100 kDa to 190 kDa, from 110 kDa to 190 kDa, from 120 kDa to 190 kDa, from 30 kDa to 115 kDa, from 35 kDa to 115 kDa, from 40 kDa to 115 kDa, from 50 kDa to 115 kDa, from 60 kDa to 115 kDa, from 70 kDa to 115 kDa, from 80 kDa to 115 kDa, from 90 kDa to 115 kDa, from 100 kDa to 115 kDa, from 30 kDa to 76 kDa, from 40 kDa to 76 kDa, from 50 kDa to 76 kDa, or from 60 kDa to 76 kDa.

[0056] The subject biodegradable microsphere (i) has a diameter from 1 pm to 500 pm, (ii) can non-covalently carry a therapeutic agent (e.g., rofecoxib), and (iii) depending on its polymeric composition, degrades over a period lasting, for example, from one month to over six months when placed in suitable joint-related tissue or suitable soft tissue. Microsphere diameters, set forth as ranges from d to doo (as defined herein), include, for example, the following: from 1 pm to 20 pm, from 20 pm to 40 pm, from 40 pm to 60 pm, from 60 pm to 80 pm, from 80 pm to 100 pm, from 100 pm to 120 pm, from 120 pm to 140 pm, from 140 pm to 160 pm, from 160 pm to 180 pm, from 180 pm to 200 pm, from 200 pm to 250 pm, from 250 pm to 300 pm, from 300 pm to 350 pm, from 350 pm to 400 pm, from 400 pm to 450 pm, and from 450 pm to 500 pm. Microsphere diameters also include, for example, the following: 10 pm , 20 pm, 30 pm , 40 pm, 50 pm, 60 pm, 70 pm, 80 pm, 90 pm, 100 pm, 120 pm, 140 pm, 160 pm, 180 pm, 200 pm, 250 pm, 300 pm, 350 pm, 400 pm, 450 pm, and 500 pm. Microsphere diameters, set forth as ranges from dw to doo (as defined herein), also include, for example, the following: from 5 pm to 20 pm, from 5 pm to 30 pm, from 5 pm to 40 pm, from 5 pm to 50 pm, from 5 pm to 60 pm, from 5 pm to 70 pm, from 5 pm to 80 pm, from 5 pm to 90 pm, from 5 pm to 100 pm, from 5 pm to 150 pm, from 10 pm to 20 pm, from 10 pm to 30 pm, from 10 pm to 40 pm, from 10 pm to 50 pm, from 10 pm to 60 pm, from 10 pm to 70 pm, from 10 pm to 80 pm, from 10 pm to 90 pm, from 10 pm to 100 pm, from 10 pm to 150 pm, from 20 pm to 30 pm, from 20 pm to 40 pm, from 20 pm to 50 pm, from 20 pm to 60 pm, from 20 pm to 70 pm, from 20 pm to 80 pm, from 20 pm to 90 pm, from 20 pm to 100 pm, from 20 pm to 150 pm, from 30 pm to 40 pm, from 30 pm to 50 pm, from 30 pm to 60 pm, from 30 pm to 70 pm, from 30 pm to 80 pm, from 30 pm to 90 pm, from 30 pm to 100 pm, from 30 pm 150 pm, from 40 pm to 50 pm, from 40 pm to 60 pm, from 40 pm to 70 pm, from 40 pm to 80 pm, from 40 pm to 90 pm, from 40 pm to 100 pm, from 40 pm to 150 pm, from 50 pm to 100 pm, and from 50 pm to 150 pm. In a further embodiment, the dw values for the present microsphere diameters include the following: (i) 5 pm, 10 pm, 15 pm, 20 pm, 25 pm, 30 pm, 35 pm, and 40 pm; (ii) from 5 pm to 10 pm, from 10 pm to 15 pm, from 15 pm to 20 pm, from 20 pm to 25 pm, from 25 pm to 30 pm, from 30 pm to 35 pm, and from 30 pm to 40 pm; (iii) from 5 pm to 15 pm, from 10 pm to 20 pm, from 15 pm to 25 pm, from 20 pm to 30 pm, and from 25 pm to 40 pm; (iv) from 5 pm to 20 pm, from 10 pm to 25 pm, from 15 pm to 30 pm, from 20 pm to 35 pm, from 25 pm to 40 pm; (v) from 5 pm to 25 pm, from 10 pm to 30 pm, from 15 pm to 35 pm, from 20 pm to 40 pm , from 25 pm to 40 pm, from 10 pm to 35 pm, from 10 pm to 40 pm, and from 5 pm to 40 pm.

[0057] In a further embodiment, the doo values for the present microsphere diameters include the following: (i) 20 pm, 30 pm, 40 pm, 50 pm, 60 pm, 70 pm, 80 pm, 90 pm, 100 pm, 110 pm, and 120 pm; (ii) from 20 pm to 30 pm, from 30 pm to 40 pm, from 40 pm to 50 pm, from 50 pm to 60 pm, from 60 pm to 70 pm, from 70 pm to 80 pm, from 80 pm to 90 pm, from 90 pm to 100 pm, from 100 pm to 110 pm, and from 110 pm to 120 pm; (iii) from 20 pm to 40 pm, from 40 pm to 60 pm, from 60 pm to 80 pm, from 80 pm to 100 pm, or from 100 pm to 120 pm; or (iv) from 20 pm to 60 pm, from 60 pm to 100 pm, and from 20 pm to 120 pm.

[0058] The subject biodegradable microspheres can further comprise polyethylene glycol (PEG). Biodegradable PLGA microspheres (including homogeneous and heterogeneous populations thereof having defined molar ratios of lactic acid to glycolic acid units) are commercially available from, among other sources, Millipore-Sigma in the form of Degradex® products (Burlington, MA) and Evonik Industries in the form of Resomer® products (Essen, Germany).

[0059] As used herein, the term “carry”, with respect to pharmaceutical rofecoxib and a biodegradable microsphere, means that the pharmaceutical rofecoxib is non-covalently bound to, or otherwise contained in or on, the biodegradable microsphere in a manner permitting release from the microsphere during its biodegradation.

[0060] As used herein, the term “rofecoxib” shall mean 4-[4 (methylsulfonyl)phenyl]-3-phenyl- 2(5 / - / )-furanone, with CAS number 162011-90-7. Rofecoxib is a nonsteroidal antiinflammatory drug. It is commercially known and was sold by Merck under the trade name VIOXX®.

[0061] As used herein, the term “diluent” includes, without limitation, sodium chloride, carboxymethylcellulose sodium, polysorbate 80, mannitol (which can optionally be incorporated on and / or into the microspheres to improve suspendability), and water. As used herein, the term “dgo value”, with respect to the present microspheres, means the 90thpercentile diameter in the microsphere population on a volume-weighted basis. The term “dso value” means the 50thpercentile diameter in the microsphere population on a volume-weighted basis. The term “dio value” means the 10thpercentile diameter in the microsphere population on a volume-weighted basis.

[0062] As used herein, “introducing”, with respect to biodegradable microspheres, means delivering to a specified part of the body, such as joint fluid or soft tissue. Methods of introducing biodegradable microspheres to joint fluid are known and include, for example, intra-articular injection. See, e.g., the Zilretta® label. Methods for injecting biodegradable microspheres into discs are known and can be performed based on known animal studies. For example, polyester amide microspheres were injected to the intervertebral discs in a canine model of disc degeneration and were shown to have good cytocom patability and biocompatibility. In a rat discitis model, intra-discal vancomycin-loaded PLGA microspheres were shown to control and reduce infective discitis, with superior efficacy to intravenous vancomycin. See, e.g., Williems, et al., and Wang, et al. In a rat Achilles tendinopathy model, a methacrylate gelatin microsphere loaded with heparin-dopamine conjugate and hepatocyte growth factor was injected to the injured tendon to promote tissue regeneration (Han, et al.).

[0063] A “joint-related disorder” includes, without limitation, osteoarthritis, synovitis, hemophilic arthropathy, rheumatoid arthritis, psoriatic arthritis, juvenile rheumatoid arthritis, gouty arthritis, adhesive capsulitis, shoulder impingement syndrome, septic or infectious arthritis, reactive arthritis, reflex sympathetic dystrophy, scleroderma, ankylosing spondylitis, algodystrophy, achondroplasia, Paget’s disease, Tietze syndrome or costochondritis, fibromyalgia, neurogenic or neuropathic arthritis, arthropathy, sarcoidosis, amyloidosis, cartilage injury, hydrarthrosis, periodical disease, rheumatoid spondylitis, osteochondritis dissecans, hypertrophic arthritis, Yersinia arthritis, pyrophosphate arthritis, an endemic form of arthritis, fibromyalgia, systemic lupus erythematosus, scleroderma, ankylosing spondylitis, degenerative disc disease, lower back pain, neck pain, hip dysplasia, osteochondrosis, elbow dysplasia, joint injury caused by trauma, acute and subacute bursitis, acute and subacute nonspecific tenosynovitis and epicondylitis, acute rheumatic carditis and ankylosing spondylitis, tenosynovitis, epicondylitis, synovitis, sciatica, and other forms of radicular pain. In one embodiment, a joint-related disorder includes discomfort, inflammation or other indication associated with recovery from a surgical joint procedure such as a total or partial knee replacement, a total or partial hip replacement, a total or partial ankle replacement, an arthroscopic or open joint surgery, a microfracture, an autologous chondrocyte implantation, mosaicplasty, debridement and lavage, a ligament repair, a tendon repair, a rotator cuff repair, meniscus surgery, or synovectomy.

[0064] As used herein, the term “pharmaceutical rofecoxib” includes, without limitation, rofecoxib and pharmaceutical salts and esters thereof.

[0065] “Pharmaceutically acceptable carriers” are well known and include, without limitation, the diluents described herein.

[0066] As used herein, a biodegradable microsphere “releases” rofecoxib when some or all of the rofecoxib contained by the microsphere is freed into the microsphere’s surrounding milieu. Preferably, the release is continuous. For example, in a plurality of rofecoxib- carrying biodegradable microspheres having an average release per day of X mg, the rofecoxib released per day is, e.g., from 0.1X mg to 10X mg, from 0.2X mg to 5X mg, or from 0.5X mg to 2X mg. In another example, in a plurality of rofecoxib-carrying biodegradable microspheres having an average release per week of X mg, the rofecoxib released per week is, e.g., from 0.2X mg to 10X mg, or from 0.5X mg to 2X mg. Rofecoxib release into joint-related tissue or soft tissue can precede, and is distinct from, its efficacy in that tissue. For example, biodegradable microspheres that release a therapeutically effective amount of pharmaceutical rofecoxib into a joint’s synovial fluid for two months might yield a therapeutic effect for three months.

[0067] A “soft tissue-related disorder” includes, without limitation, tendonitis, tendinopathy, fasciitis including plantar fasciitis, tenosynovitis, trigger finger, ligament sprain, adhesive capsulitis, bursitis, carpal tunnel, peripheral nerve entrapment, inflammation of the nervous tissue, myofascial pain, epicondylitis, post-surgical inflammation and pain, inflammation and pain from injury or trauma, and inflammation and pain in the muscle. Methods of administration of the microspheres include injection or instillation to the tissue.

[0068] As used herein, the term “subject” includes, without limitation, a mammal such as a human, a non-human primate, a dog, a cat, a horse, a sheep, a goat, a cow, a rabbit, a pig, a rat, and a mouse. Preferably, the subject is human. In another preferred embodiment, the subject is a cat, a dog, or a horse.

[0069] As used herein, the phrase “suitable joint-related tissue” includes any portion of a joint, the joint’s surrounding tissue, an intervertebral disc, or the intervertebral disc’s surrounding tissue that is capable of holding the instant rofecoxib-containing biodegradable microspheres such that the rofecoxib released therefrom can act on the joint. Suitable joint-related tissue includes, without limitation, (i) articular and periarticular spaces; (ii) the bursa, synovial cavity, joint capsule with synovial lining, and the fluids contained therein; and (iii) connective and contractile tissue (e.g., articular cartilage, ligaments, tendons and muscles).

[0070] As used herein, a “suitable matrix” for a biodegradable microsphere includes, without limitation, a polylactic-co-glycolic acid (PLGA) matrix (including a poly-lactic acid matrix (PLA or PLGA100:0)); a hydrogel matrix (e.g., one based on poly D,L-lactide and polyethylene glycol (PEG)); a poly-caprolactone matrix; an ethylcellulose matrix; a PLGA-polythioester matrix; a solid lipid nanoparticle matrix; an acetyl-capped PCLA- PEG-PCLA thermogel matrix; a polyester amide (PEA) matrix; and a chitosan matrix. In the preferred embodiment, the suitable matrix is a polylactic-co-glycolic acid (PLGA) matrix.

[0071] As used herein, the term “therapeutically effective amount”, with respect to pharmaceutical rofecoxib carried in biodegradable microspheres, refers to the amount of pharmaceutical rofecoxib collectively carried by the total dose of biodegradable microspheres introduced into soft tissue or into or around one of a subject’s joints. In one embodiment, the effective amount is 1 pg, 5 pg, 10 pg, 15 pg, 20 pg, 25 pg, 30 pg, 40 pg, 50 pg, 60 pg, 70 pg, 80 pg, 90 pg, 100 pg, 150 pg, 200 pg, 250 pg, 300 pg, 350 pg, 400 pg, 450 pg, 500 pg, 550 pg, 600 pg, 650 pg, 700 pg, 750 pg, 800 pg, 850 pg, 900 pg, 950 pg, 1 mg, 5 mg, 10 mg, 15 mg, 20 mg, 25 mg, 30 mg, 40 mg, 50 mg, 60 mg, 70 mg, 80 mg, 90 mg, 100 mg, 150 mg, 200 mg, 250 mg, 300 mg, 350 mg, 400 mg, 450 mg, 500 mg, 550 mg, 600 mg, 650 mg, 700 mg, 750 mg, 800 mg, 850 mg, 900 mg, 950 mg, 1 ,000 mg, 1 ,050 mg, 1 ,100 mg, 1 ,150 mg, 1 ,200 mg, 1 ,250 mg, 1 ,300 mg, 1 ,350 mg, 1 ,400 mg, 1 ,450 mg, 1 ,500 mg, 1 ,550 mg, 1 ,600 mg, 1 ,650 mg, 1 ,700 mg,

[0072] 1 ,750 mg, 1 ,800 mg, 1 ,850 mg, 1 ,900 mg, 1 ,950 mg, 2,000 mg, 2,050 mg, 2,100 mg,

[0073] 2,150 mg, 2,200 mg, 2,250 mg, 2,300 mg, 2,350 mg, 2,400 mg, 2,450 mg, 2,500 mg, 2.550 mg, 2,600 mg, 2,650 mg, 2,700 mg, 2,750 mg, 2,800 mg, 2,850 mg, 2,900 mg, 2,950 mg, or 3,000 mg. In another embodiment, the effective amount is from 1 pg to 10 pg, from 10 pg to 50 pg, from 50 pg to 100 pg, from 100 pg to 150 pg, from 150 pg to 200 pg, from 200 pg to 250 pg, from 250 pg to 300 pg, from 300 pg to 350 pg, from 350 pg to 400 pg, from 400 pg to 450 pg, from 450 pg to 500 pg, from 500 pg to 550 pg, from 550 pg to 600 pg, from 600 pg to 650 pg, from 650 pg to 700 pg, from 700 pg to 750 pg, from 750 pg to 800 pg, from 800 pg to 850 pg, from 850 pg to 900 pg, from 900 pg to 950 pg, from 950 pg to 1 mg, 1 mg to 10 mg, from 10 mg to 50 mg, from 50 mg to 100 mg, from 100 mg to 150 mg, from 150 mg to 200 mg, from 200 mg to 250 mg, from 250 mg to 300 mg, from 300 mg to 350 mg, from 350 mg to 400 mg, from 400 mg to 450 mg, from 450 mg to 500 mg, from 500 mg to 550 mg, from 550 mg to 600 mg, from 600 mg to 650 mg, from 650 mg to 700 mg, from 700 mg to 750 mg, from 750 mg to 800 mg, from 800 mg to 850 mg, from 850 mg to 900 mg, from 900 mg to 950 mg, from 950 mg to 1 ,000 mg, from 1 ,000 mg to 1 ,050 mg, from 1 ,050 mg to 1 ,100 mg, from

[0074] 1 , 100 mg to 1 , 150 mg, from 1 , 150 mg to 1 ,200 mg, from 1 ,200 mg to 1 ,250 mg, from

[0075] 1 ,250 mg to 1 ,300 mg, from 1 ,300 mg to 1 ,350 mg, from 1 ,350 mg to 1 ,400 mg, from

[0076] 1 ,400 mg to 1 ,450 mg, from 1 ,450 mg to 1 ,500 mg, from 1 ,500 mg to 1 ,550 mg, from

[0077] 1 .550 mg to 1 ,600 mg, from 1 ,600 mg to 1 ,650 mg, from 1 ,650 mg to 1 ,700 mg, from

[0078] 1 ,700 mg to 1 ,750 mg, from 1 ,750 mg to 1 ,800 mg, from 1 ,800 mg to 1 ,850 mg, from

[0079] 1 ,850 mg to 1 ,900 mg, from 1 ,900 mg to 1 ,950 mg, from 1 ,950 mg to 2,000 mg, from

[0080] 2,000 mg to 2,050 mg, from 2,050 mg to 2,100 mg, from 2,100 mg to 2,150 mg, from

[0081] 2,150 mg to 2,200 mg, from 2,200 mg to 2,250 mg, from 2,250 mg to 2,300 mg, from

[0082] 2,300 mg to 2,350 mg, from 2,350 mg to 2,400 mg, from 2,400 mg to 2,450 mg, from

[0083] 2,450 mg to 2,500 mg, from 2,500 mg to 2,550 mg, from 2,550 mg to 2,600 mg, from

[0084] 2,600 mg to 2,650 mg, from 2,650 mg to 2,700 mg, from 2,700 mg to 2,750 mg, from

[0085] 2,750 mg to 2,800 mg, from 2,800 mg to 2,850 mg, from 2,850 mg to 2,900 mg, from

[0086] 2,900 mg to 2,950 mg, or from 2,950 mg to 3,000 mg. In a further embodiment, the effective amount is from 1 pg to 250 pg, from 250 pg to 500 pg, from 500 pg to 750 pg, from 750 pg to 1 mg, 1 mg to 250 mg, from 250 mg to 500 mg, from 500 mg to 750 mg, from 750 mg to 1 ,000 mg, from 1 ,000 mg to 1 ,250 mg, from 1 ,250 mg to 1 ,500 mg, from 1 ,500 mg to 1 ,750 mg, from 1 ,750 mg to 2,000 mg, from 2,000 mg to 2,250 mg, from 2,250 mg to 2,500 mg, from 2,500 mg to 2,750 mg, or from 2,750 mg to 3,000 mg. In yet a further embodiment, the effective amount is from 1 pg to 500 pg, from 500 pg to 1 mg, 1 mg to 500 mg, from 10 mg to 500 mg, from 500 mg to 1 ,000 mg, from 1 ,000 mg to 1 ,500 mg, from 1 ,500 mg to 2,000 mg, from 2,000 mg to 2,500 mg, or from 2,500 mg to 3,000 mg.

[0087] As used herein, “treating” a subject afflicted with a disorder shall include, without limitation, (i) slowing, stopping or reversing the disorder's progression, (ii) slowing, stopping or reversing the progression of the disorder’s symptoms (e.g., pain), (iii) reducing the likelihood of the disorder’s recurrence, and / or (iv) reducing the likelihood that the disorder’s symptoms will recur. In the preferred embodiment, treating a subject afflicted with a disorder means (i) reversing the disorder's progression, ideally to the point of eliminating the disorder, and / or (ii) reversing the progression of the disorder’s symptoms, ideally to the point of eliminating the symptoms.

[0088] Embodiments of the Invention

[0089] This invention solves an unmet need in the art by providing an unexpectedly superior way to treat joint-related disorders and soft tissue disorders using rofecoxib. The invention does this via rofecoxib-carrying microspheres that release rofecoxib over time.

[0090] Joint-Related Embodiments

[0091] Specifically, this invention provides a biodegradable microsphere, wherein the microsphere (i) has a diameter of from 1 pm to 500 pm; (ii) comprises a polylactic-co- glycolic acid (PLGA) matrix; (iii) carries pharmaceutical rofecoxib; and (iv) when present in a suitable joint-related tissue, releases rofecoxib for at least one month.

[0092] In one embodiment of the instant biodegradable microsphere, it has a lactic acid to glycolic acid molar ratio of from 100:0 to 50:50. Preferably, the instant microsphere (i) has a d value of at least 5 pm and a dgo value of 200 pm or less (when present as a plurality); and (ii) has a lactic acid to glycolic acid molar ratio of 85:15. Preferably, in the instant biodegradable microsphere, the lactic acid to glycolic acid molar ratio is 75:25 or 85:15, the dw is 5-40 pm, and the doo is 20-120 pm.

[0093] In another embodiment of the instant biodegradable microsphere, it further comprises polyethylene glycol (PEG). The PEG can be any type suitable for use in forming biodegradable microspheres (e.g., PEG1450 (Polysciences, Inc., Warrington, PA)). Moreover, the ratio of PEG to PLGA can be any ratio suitable for use in forming biodegradable microspheres (e.g., 25:100, 50:100, 75:100 or 100:100).

[0094] In yet another embodiment of the instant biodegradable microsphere, when it is present in a suitable joint-related tissue, it releases rofecoxib for longer than one month. Preferably, the microsphere, when present in a suitable joint-related tissue, releases rofecoxib for at least two months, at least three months, at least four months, at least five months, at least six months, at least seven months, at least eight months, at least nine months, at least ten months, at least eleven months, or at least twelve months.

[0095] The following rofecoxib-containing biodegradable microspheres are preferred embodiments of this invention. The microsphere population comprises PLGA75:25 (i.e., wherein the L:G ratio is 75:25), 0.5-1.3 dl / g, MW: 35,000-190,000, ester- terminated, with rofecoxib loading of 40%-60% (calculated as rofecoxib / total weight of microsphere). The microsphere population may also comprise PLGA85:15 (i.e., wherein the L:G ratio is 85:15), 1.3-1.7 dl / g, MW: 190,000-240,000, ester-term inated, with rofecoxib loading of 40%-60% (calculated as rofecoxib / total weight of microsphere). For example, these microsphere populations can be prepared by mixing 24 ml dichloromethane solution containing 1 .2 g rofecoxib and 1 .2 g PLGA (L:G ratio of 75:25 or 85:15, 0.5-1.7 dl / g, ester-term inated) and 0.11 % polyvinyl alcohol 4-88 in an in-line mixing chamber (model L5MA, Silverson, Massachusetts, US) at the infusion rates of 4 ml / min and 800 ml / min, respectively, and at a mixing speed of 2,400 rpm, followed by solidification on top of 5 L water under stirring at 300 rpm for at least 30 minutes and washing with water.

[0096] This invention also provides a plurality of biodegradable microspheres, wherein the microspheres (i) have a dio value of at least 1 pm and a dgo value of 500 pm or less; (ii) comprise a polylactic-co-glycolic acid (PLGA) matrix; (iii) carry a therapeutically effective amount of pharmaceutical rofecoxib; and (iv) when present in a suitable joint- related tissue, release rofecoxib for at least one month.

[0097] In an embodiment of the instant plurality of biodegradable microspheres, the microspheres further comprise polyethylene glycol (PEG). In another embodiment of the instant plurality of biodegradable microspheres, the microspheres, when present in a suitable joint-related tissue, release rofecoxib for longer than one month. Preferably, the microspheres, when present in a suitable joint- related tissue, release rofecoxib for at least two months, at least three months, at least four months, at least five months, at least six months, at least seven months, at least eight months, at least nine months, at least ten months, at least eleven months, or at least twelve months.

[0098] In a further embodiment of the instant plurality of biodegradable microspheres, the microspheres (i) have a dio value of at least 5 pm and a dgo value of 200 pm or less; (ii) have a lactic acid to glycolic acid molar ratio of from 100:0 to 50:50; and (iii) carry from 1 pg to 3,000 mg of pharmaceutical rofecoxib.

[0099] This invention further provides an injectable formulation comprising (a) a pharmaceutically acceptable carrier and (b) a plurality of biodegradable microspheres wherein the microspheres (i) have a dio value of at least 1 pm and a dgo value of 500 pm or less; (ii) comprise a polylactic-co-glycolic acid (PLGA) matrix; (iii) carry a therapeutically effective amount of pharmaceutical rofecoxib; and (iv) when present in a suitable joint-related tissue, release rofecoxib for at least one month.

[0100] In an embodiment of the instant formulation, the microspheres further comprise polyethylene glycol (PEG).

[0101] In another embodiment of the instant formulation, the microspheres, when present in a suitable joint-related tissue, release rofecoxib for longer than one month. Preferably, the microspheres, when present in a suitable joint-related tissue, release rofecoxib for at least two months, at least three months, at least four months, at least five months, at least six months, at least seven months, at least eight months, at least nine months, at least ten months, at least eleven months, or at least twelve months.

[0102] This invention still further provides a method for treating a joint-related disorder in a subject comprising introducing biodegradable microspheres into suitable tissue in or around one or more of the subject’s joints, wherein the microspheres (i) have a dio value of at least 1 pm and a dgo value of 500 pm or less; (ii) comprise a polylactic-co- glycolic acid (PLGA) matrix; (iii) carry a therapeutically effective amount of pharmaceutical rofecoxib; and (iv) when present in a suitable joint-related tissue, release rofecoxib for at least one month.

[0103] In an embodiment of the instant method, the microspheres further comprise polyethylene glycol (PEG).

[0104] In a preferred embodiment of the instant method, the subject is human. In another preferred embodiment of the instant method, the subject is a cat, a dog, or a horse. In another preferred embodiment of the instant method, the disorder is arthritis (e.g., osteoarthritis or rheumatoid arthritis).

[0105] In this invention, the biodegradable microspheres can be introduced into the suitable tissue in or around one or more of the subject’s joints using any known method appropriate for the tissue in question. For example, in a preferred embodiment of the instant method where the tissue is synovial fluid in the knee joint, the method comprises intra-articularly injecting the biodegradable microspheres into the synovial fluid of one or both of the subject’s knees. In another embodiment, the instant method is performed a plurality of times (e.g., two times, three times, four times, five times, or more). In that embodiment, each subsequent time the method is performed, it is performed after a suitable period has lapsed since the preceding time the method was performed. This suitable time can be, for example, one month, two months, three months, four months, five months, six months, seven months, eight months, nine months, ten months, eleven months, one year, or longer. Microsphere-based drug products and methods of delivering them are known, at least generally (e.g., Zilretta® (triamcinolone acetonide extended-release injectable suspension for intra-articular use (Flexion)); and Sandostatin LAR® Depot (octreotide acetate for injectable suspension) (Novartis)).

[0106] In a further preferred embodiment of the instant method, the microspheres (i) have a dio value of at least 5 pm and a dgo value of 200 pm or less (e.g., from 10 pm to 120 pm);

[0107] (ii) have a lactic acid to glycolic acid molar ratio of from 100:0 to 50:50 (e.g., 75:25 or 85:15); and (iii) carry from 1 pg to 3,000 mg of pharmaceutical rofecoxib.

[0108] In yet another embodiment of the instant method, the microspheres, when present in a suitable joint-related tissue, release rofecoxib for longer than one month. Preferably, the microspheres, when present in a suitable joint-related tissue, release rofecoxib for at least two months, at least three months, at least four months, at least five months, at least six months, at least seven months, at least eight months, at least nine months, at least ten months, at least eleven months, or at least twelve months.

[0109] This invention further provides an article of manufacture (kit) comprising, in separate compartments, (a) one of, and ideally both of, (i) a diluent and (ii) a label instructing the user to introduce the biodegradable microspheres (described below) into suitable tissue in or around one or more of a subject’s joints, and (b) a plurality of biodegradable microspheres, wherein the microspheres (i) have a dio value of at least 1 pm and a dgo value of 500 pm or less (e.g., from 5 pm to 200 pm, or from 10 pm to 120 pm); (ii) comprise a polylactic-co-glycolic acid (PLGA) matrix (preferably having a lactic acid to glycolic acid molar ratio of from 100:0 to 50:50 (e.g., 75:25 or 85:15)); (iii) carry a therapeutically effective amount of pharmaceutical rofecoxib (e.g., from 1 pg to 3,000 mg of pharmaceutical rofecoxib); and (iv) when present in a suitable joint-related tissue, release rofecoxib for at least one month (and optionally release rofecoxib for at least two months, at least three months, at least four months, at least five months, at least six months, at least seven months, at least eight months, at least nine months, at least ten months, at least eleven months, or at least twelve months). In one embodiment of the instant kit, the microspheres further comprise polyethylene glycol (PEG). Where applicable, the embodiments described above for the instant methods are also envisioned for this article of manufacture.

[0110] In a preferred embodiment, the instant kit is supplied as a single-dose kit and contains (i) a single dose vial of rofecoxib-carrying biodegradable microspheres, and (ii) a single dose vial of diluent (e.g., sterile, clear liquid solution of 0.9% w / w sodium chloride, 0.5% - 1 % w / w sodium carboxymethylcellulose, and 0.1 % w / w polysorbate-80).

[0111] This invention provides a biodegradable microsphere, wherein the microsphere (i) has a diameter of from 1 pm to 500 pm; (ii) comprises a suitable matrix (e.g., a polylactic- co-glycolic acid (PLGA) matrix); (iii) carries pharmaceutical rofecoxib; and (iv) when present in a suitable joint-related tissue, releases rofecoxib for at least one month. The biodegradable microsphere components, dimensions, features, and rofecoxib release duration described above are envisioned, mutatis mutandis, for this biodegradable microsphere. This invention also provides a plurality of biodegradable microspheres, wherein the microspheres (i) have a dio value of at least 1 pm and a dgo value of 500 pm or less; (ii) comprise a suitable matrix (e.g., a polylactic-co-glycolic acid (PLGA) matrix); (iii) carry a therapeutically effective amount of pharmaceutical rofecoxib; and (iv) when present in a suitable joint-related tissue, release rofecoxib for at least one month. The biodegradable microsphere components, dimensions, features, rofecoxib dosing, and rofecoxib release duration described above are envisioned, mutatis mutandis, for this plurality of biodegradable microspheres.

[0112] This invention further provides an injectable formulation comprising (a) a pharmaceutically acceptable carrier and (b) a plurality of biodegradable microspheres wherein the microspheres (i) have a dio value of at least 1 pm and a dgo value of 500 pm or less; (ii) comprise a suitable matrix (e.g., a polylactic-co-glycolic acid (PLGA) matrix); (iii) carry a therapeutically effective amount of pharmaceutical rofecoxib; and (iv) when present in a suitable joint-related tissue, release rofecoxib for at least one month. The biodegradable microsphere components, dimensions, features, rofecoxib dosing, and rofecoxib release duration described above are envisioned, mutatis mutandis, for this injectable formulation.

[0113] This invention still further provides a method for treating a joint-related disorder in a subject comprising introducing biodegradable microspheres into suitable tissue in or around one or more of the subject’s joints, wherein the microspheres (i) have a dio value of at least 1 pm and a dgo value of 500 pm or less; (ii) comprise a suitable matrix (e.g., a polylactic-co-glycolic acid (PLGA) matrix); (iii) carry a therapeutically effective amount of pharmaceutical rofecoxib; and (iv) when present in a suitable joint-related tissue, release rofecoxib for at least one month. The (i) biodegradable microsphere components, dimensions, features, rofecoxib dosing, and rofecoxib release duration, and (ii) therapeutic indications, subjects, and modes of administration described above are envisioned, mutatis mutandis, for this method.

[0114] This invention further provides a kit comprising, in separate compartments, (a) a diluent, and (b) plurality of biodegradable microspheres, wherein the microspheres (i) have a dio value of at least 1 pm and a dgo value of 500 pm or less; (ii) comprise a suitable matrix (e.g., a polylactic-co-glycolic acid (PLGA) matrix); (iii) carry a therapeutically effective amount of pharmaceutical rofecoxib; and (iv) when present in a suitable joint-related tissue, release rofecoxib for at least one month. The diluents, biodegradable microsphere components, dimensions, features, rofecoxib dosing, and rofecoxib release duration described above are envisioned, mutatis mutandis, for this kit.

[0115] Soft Tissue-Related Embodiments

[0116] This invention provides a biodegradable microsphere, wherein the microsphere (i) has a diameter of from 1 pm to 500 pm; (ii) comprises a polylactic-co-glycolic acid (PLGA) matrix; (iii) carries pharmaceutical rofecoxib; and (iv) when present in a suitable soft tissue, releases rofecoxib for at least one month.

[0117] In one embodiment of the instant biodegradable microsphere, it has a lactic acid to glycolic acid molar ratio of from 100:0 to 50:50. Preferably, the instant microsphere (i) has a diameter of from 5 pm to 200 pm; and (ii) has a lactic acid to glycolic acid molar ratio of 75:25 or 85:15.

[0118] In another embodiment of the instant biodegradable microsphere, it further comprises polyethylene glycol (PEG). The PEG can be of any type described above in the joint- related embodiments section.

[0119] In yet another embodiment of the instant biodegradable microsphere, when it is present in a suitable soft tissue, it releases rofecoxib for longer than one month. Preferably, the microsphere, when present in a suitable soft tissue, releases rofecoxib for at least two months, at least three months, at least four months, at least five months, at least six months, at least seven months, at least eight months, at least nine months, at least ten months, at least eleven months, or at least twelve months.

[0120] The following rofecoxib-containing biodegradable microspheres are preferred embodiments of this invention. The microsphere population comprises PLGA75:25 (i.e., wherein the L:G ratio is 75:25), 0.5-1.3 dl / g, MW: 35,000-190,000, ester- terminated, with rofecoxib loading of 40%-60% (calculated as rofecoxib / total weight of microsphere). The microsphere population may also comprise PLGA85:15 (i.e., wherein the L:G ratio is 85:15), 1.3-1.7 dl / g, MW: 190,000-240,000, ester-term inated, with rofecoxib loading of 40%-60% (calculated as rofecoxib / total weight of microsphere). For example, these microsphere populations can be prepared by mixing 24 ml dichloromethane solution containing 1 .2 g rofecoxib and 1 .2 g PLGA (L:G ratio of 75:25 or 85:15, 0.5-1.7 dl / g, ester-term inated) and 0.11 % polyvinyl alcohol 4-88 in an in-line mixing chamber (model L5MA, Silverson, Massachusetts, US) at the infusion rates of 4 ml / min and 800 ml / min, respectively, and at a mixing speed of 2,400 rpm, followed by solidification on top of 5 L water under stirring at 300 rpm for at least 30 minutes and washing with water.

[0121] This invention also provides a plurality of biodegradable microspheres, wherein the microspheres (i) have a dio value of at least 1 pm and a dgo value of 500 pm or less; (ii) comprise a polylactic-co-glycolic acid (PLGA) matrix; (iii) carry a therapeutically effective amount of pharmaceutical rofecoxib; and (iv) when present in a suitable soft tissue, release rofecoxib for at least one month.

[0122] In an embodiment of the instant plurality of biodegradable microspheres, the microspheres further comprise polyethylene glycol (PEG).

[0123] In another embodiment of the instant plurality of biodegradable microspheres, the microspheres, when present in a suitable soft tissue, release rofecoxib for longer than one month. Preferably, the microspheres, when present in a suitable soft tissue, release rofecoxib for at least two months, at least three months, at least four months, at least five months, at least six months, at least seven months, at least eight months, at least nine months, at least ten months, at least eleven months, or at least twelve months.

[0124] In a further embodiment of the instant plurality of biodegradable microspheres, the microspheres (i) have a dio value of at least 5 pm and a dgo value of 200 pm or less; (ii) have a lactic acid to glycolic acid molar ratio of from 100:0 to 50:50; and (iii) carry from 1 pg to 3,000 mg of pharmaceutical rofecoxib.

[0125] This invention further provides an injectable formulation comprising (a) a pharmaceutically acceptable carrier and (b) a plurality of biodegradable microspheres wherein the microspheres (i) have a dio value of at least 1 pm and a dgo value of 500 pm or less; (ii) comprise a polylactic-co-glycolic acid (PLGA) matrix; (iii) carry a therapeutically effective amount of pharmaceutical rofecoxib; and (iv) when present in a suitable soft tissue, release rofecoxib for at least one month.

[0126] In an embodiment of the instant formulation, the microspheres further comprise polyethylene glycol (PEG).

[0127] In another embodiment of the instant formulation, the microspheres, when present in a suitable soft tissue, release rofecoxib for longer than one month. Preferably, the microspheres, when present in a suitable soft tissue, release rofecoxib for at least two months, at least three months, at least four months, at least five months, at least six months, at least seven months, at least eight months, at least nine months, at least ten months, at least eleven months, or at least twelve months.

[0128] This invention still further provides a method for treating a soft tissue disorder in a subject comprising introducing biodegradable microspheres into the soft tissue and / or its surrounding tissue, wherein the microspheres (i) have a dio value of at least 1 pm and a dgo value of 500 pm or less; (ii) comprise a polylactic-co-glycolic acid (PLGA) matrix; (iii) carry a therapeutically effective amount of pharmaceutical rofecoxib; and (iv) when present in a suitable soft tissue, release rofecoxib for at least one month.

[0129] In an embodiment of the instant method, the microspheres further comprise polyethylene glycol (PEG).

[0130] In a preferred embodiment of the instant method, the subject is human. In another preferred embodiment of the instant method, the subject is a cat, a dog, or a horse. In another preferred embodiment of the instant method, the disorder is tendonitis, plantar fasciitis, adhesive capsulitis, bursitis, carpal tunnel, or site of injury, site of trauma, or site of surgery.

[0131] In this invention, the biodegradable microspheres can be introduced into the suitable tissue in or around one or more of the subject’s soft tissues using any known method appropriate for the tissue in question. For example, in a preferred embodiment of the instant method where the tissue is tendon, the method comprises injecting the biodegradable microspheres into or around the tendon. In another preferred embodiment of the instant method where the tissue is bursa, the method comprises injecting the biodegradable microspheres into or around the bursa. In yet another preferred embodiment of the instant method where the tissue is the site of injury, the site of trauma, or the site of surgery, the method comprises instilling the biodegradable microspheres into or around the site. In another embodiment, the instant method is performed a plurality of times (e.g., two times, three times, four times, five times, or more). In that embodiment, each subsequent time the method is performed, it is performed after a suitable period has lapsed since the preceding time the method was performed. This suitable time can be, for example, one month, two months, three months, four months, five months, six months, one year, or longer. Microsphere-based drug products and methods of delivering them are known, at least generally (e.g., Zilretta® (triamcinolone acetonide extended-release injectable suspension for intraarticular use (Flexion)); and Sandostatin LAR® Depot (octreotide acetate for injectable suspension) (Novartis)).

[0132] In a further preferred embodiment of the instant method, the microspheres (i) have a dio value of at least 5 pm and a dgo value of 200 pm or less (e.g., from 10 pm to 120 pm);

[0133] (ii) have a lactic acid to glycolic acid molar ratio of from 100:0 to 50:50 (e.g., 75:25 or 85:15); and (iii) carry from 1 pg to 3,000 mg of pharmaceutical rofecoxib.

[0134] In yet another embodiment of the instant method, the microspheres, when present in a suitable soft tissue, release rofecoxib for longer than one month. Preferably, the microspheres, when present in a suitable soft tissue, release rofecoxib for at least two months, at least three months, at least four months, at least five months, at least six months, at least seven months, at least eight months, at least nine months, at least ten months, at least eleven months, or at least twelve months.

[0135] This invention further provides an article of manufacture (kit) comprising, in separate compartments, (a) one of, and ideally both of, (i) a diluent and (ii) a label instructing the user to introduce the biodegradable microspheres (described below) into suitable soft tissue, and (b) a plurality of biodegradable microspheres, wherein the microspheres (i) have a dio value of at least 1 pm and a dgo value of 500 pm or less (e.g., from 5 pm to 200 pm, or from 10 pm to 120 pm); (ii) comprise a polylactic-co-glycolic acid (PLGA) matrix (preferably having a lactic acid to glycolic acid molar ratio of from 100:0 to 50:50 (e.g., 75:25 or 85:15)); (iii) carry a therapeutically effective amount of pharmaceutical rofecoxib (e.g., from 1 pg to 3,000 mg of pharmaceutical rofecoxib); and (iv) when present in a suitable soft tissue, release rofecoxib for at least one month (and optionally release rofecoxib for at least two months, at least three months, at least four months, at least five months, at least six months, at least seven months, at least eight months, at least nine months, at least ten months, at least eleven months, or at least twelve months). In one embodiment of the instant kit, the microspheres further comprise polyethylene glycol (PEG). Where applicable, the embodiments described above for the instant methods are also envisioned for this article of manufacture.

[0136] In a preferred embodiment, the instant kit is supplied as a single-dose kit and contains (i) a single dose vial of rofecoxib-carrying biodegradable microspheres, and (ii) a single dose vial of diluent (e.g., sterile, clear liquid solution of 0.9% w / w sodium chloride, 0.5% - 1 % w / w sodium carboxymethylcellulose, and 0.1 % w / w polysorbate-80).

[0137] This invention provides a biodegradable microsphere, wherein the microsphere (i) has a diameter of from 1 pm to 500 pm; (ii) comprises a suitable matrix (e.g., a polylactic- co-glycolic acid (PLGA) matrix); (iii) carries pharmaceutical rofecoxib; and (iv) when present in a suitable soft tissue, releases rofecoxib for at least one month.

[0138] This invention also provides a plurality of biodegradable microspheres, wherein the microspheres (i) have a dio value of at least 1 pm and a dgo value of 500 pm or less; (ii) comprise a suitable matrix (e.g., a polylactic-co-glycolic acid (PLGA) matrix); (iii) carry a therapeutically effective amount of pharmaceutical rofecoxib; and (iv) when present in a suitable soft tissue, release rofecoxib for at least one month.

[0139] This invention further provides an injectable formulation comprising (a) a pharmaceutically acceptable carrier and (b) a plurality of biodegradable microspheres wherein the microspheres (i) have a dio value of at least 1 pm and a dgo value of 500 pm or less; (ii) comprise a suitable matrix (e.g., a polylactic-co-glycolic acid (PLGA) matrix); (iii) carry a therapeutically effective amount of pharmaceutical rofecoxib; and (iv) when present in a suitable soft tissue, release rofecoxib for at least one month.

[0140] This invention still further provides a method for treating a soft tissue disorder in a subject comprising introducing biodegradable microspheres into the soft tissue and / or its surrounding tissue, wherein the microspheres (i) have a dio value of at least 1 pm and a dgo value of 500 pm or less; (ii) comprise a suitable matrix (e.g., a polylactic-co- glycolic acid (PLGA) matrix); (iii) carry a therapeutically effective amount of pharmaceutical rofecoxib; and (iv) when present in a suitable soft tissue, release rofecoxib for at least one month.

[0141] Finally, this invention provides a kit comprising, in separate compartments, (a) a diluent, and (b) plurality of biodegradable microspheres, wherein the microspheres (i) have a d value of at least 1 pm and a dgo value of 500 pm or less; (ii) comprise a suitable matrix (e.g., a polylactic-co-glycolic acid (PLGA) matrix); (iii) carry a therapeutically effective amount of pharmaceutical rofecoxib; and (iv) when present in a suitable soft tissue, release rofecoxib for at least one month.

[0142] The subject biodegradable microspheres, formulations, methods, and kits are envisioned in this invention for (a) administration to (i) epidural and perineural spaces, (ii) the foramenal space at or near the site of a patient’s pain or inflammation, and (iii) sites of injury or surgery, as well as (b) treatment of non-joint-related indications such as post-surgical pain relief (e.g., relief of pain due to hernia repair, abdominoplasty, or bunionectomy), mutatis mutandis, as they are for suitable joint-related tissue.

[0143] This invention will be better understood by reference to the examples which follow, but those skilled in the art will readily appreciate that the specific examples detailed are only illustrative of the invention as described more fully in the claims which follow thereafter.

[0144] Examples

[0145] Example 1 . Preparation of rofecoxib microspheres with a stir bar

[0146] PLGA refers to poly-lactic-co-glycolic acid; PDLA refers to poly-D-lactic acid, which is one kind of poly-lactic acid (PLA); DMSO refers to dimethyl sulfoxide; PVA refers to polyvinyl alcohol; PBS refers to phosphate buffered saline, pH 7.4; and MW refers to molecular weight. The magnetic stir bar used in all of the following examples is 2 cm in length and 0.7 cm in diameter.

[0147] (i) PLGA50:50, 0.2 dl / g, acid-terminated: Intrinsic viscosity = 0.16-0.24 dl / g. MW:7, GOO- 17, 000; (ii) PLGA50:50, 0.2 dl / g, ester-term inated: Intrinsic viscosity = 0.16-0.24 dl / g. 1 MW:7, 000-17,000; (iii) PLGA50:50, 0.4 dl / g, acid-terminated: Intrinsic viscosity = 0.32- 0.44 dl / g. MW:24, 000-38, 000; (iv) PLGA50:50, 0.4 dl / g, ester-term inated: Intrinsic viscosity = 0.32-0.44 dl / g. MW:24, 000-38, 000; (v) PLGA50:50, 0.5 dl / g, acid- terminated: Intrinsic viscosity = 0.45-0.6 dl / g. MW: 38, 000-54, 000; (vi) PLGA50:50, 0.5 dl / g, ester-term inated: Intrinsic viscosity = 0.45-0.6 dl / g. MW:38, 000-54, 000; (vii) PLGA50:50, 0.6 dl / g, ester-term inated: Intrinsic viscosity = 0.50-0.65 dl / g; (viii) PLGA50:50, 0.7 dl / g, ester-term inated: Intrinsic viscosity = 0.61-0.74 dl / g. MW:54, GOO- 69, 000; (ix) PLGA65:35, 0.4 dl / g, acid-terminated: Intrinsic viscosity = 0.32-0.44 dl / g. MW:24, 000-38, 000; (x) PLGA75:25, 0.2 dl / g, acid-terminated: Intrinsic viscosity = 0.14- 0.22 dl / g. MW: 4,000-15,000; (xi) PLGA75:25, 0.2 dl / g, ester-term inated: Intrinsic viscosity = 0.16-0.24 dl / g. MW: 4,000-15,000; (xii) PLGA75:25, 0.4 dl / g, acid- terminated: Intrinsic viscosity = 0.32-0.44 dl / g. MW: 15,000-35,000; (xiii) PLGA75:25, 0.4 dl / g, ester-term inated: Intrinsic viscosity = 0.32-0.44 dl / g. MW: 15,000-35,000; (xiv) PLGA75:25, 0.6 dl / g, ester-term inated: Intrinsic viscosity = 0.5-0.7 dl / g. MW: 35, GOO- 76, 000 with average about 61 ,100; (xv) PLGA75:25, 0.65 dl / g, ester-term inated: Intrinsic viscosity = 0.55-0.75 dl / g. MW: about 97,000; (xvi) PLGA75:25, 0.9 dl / g, ester- terminated: Intrinsic viscosity = 0.71-1.0 dl / g. MW:76, 000-115,000; (xvii) PLGA75:25, 1.2 dl / g, ester-term inated: Intrinsic viscosity = 0.9-1.3 dl / g. MW: 115,000-190,000; (xviii) PLGA85:15, 1.5 dl / g, ester-term inated: Intrinsic viscosity = 1.3-1.7 dl / g. MW: 190,000- 240,000.

[0148] In experiments described herein, one type of PVA (i.e. , of one molecular weight and degree of hydrolysis) at one concentration (i.e., 1 %) is used to produce microspheres. However, in this invention, other types of PVA and other PVA concentrations are also envisioned to yield the same microspheres. For example, where 0.11 % PVA4-88, 200 pl dichloromethane, and 1 ,400 rpm stirring, is used to produce a certain population of microspheres, 0.05% PVA4-88, 300 pl dichloromethane, and 1 ,000 rpm stirring, may also be used to produce essentially the same population of microspheres. Surfactants other than PVA can also be used in this invention to produce microspheres. These other surfactants include, for example, the commonly known surfactants vitamin E, Tween-20, Tween-80, poloxamers, poloxamines, pluronic polymers (such as F68 and F127), and sodium cholate. Similarly, in experiments described herein, dichloromethane is used to produce microspheres. However, in this invention, other types of organic solvents (e.g., ethyl acetate, chloroform, acetone, propylene carbonate, and tetrahydrofuran) may be used instead of dichloromethane to yield essentially the same microspheres, assuming other experimental parameters are adjusted accordingly. Moreover, in this invention, any of a plurality of physical methods for preparing PLGA microspheres (e.g., spinning disk, spray drying, and microfluidics) may be used to yield the subject microspheres.

[0149] In one experiment, 12.5 mg or 25 mg rofecoxib and 12.5 mg PLGA were dissolved in 1 ml dichloromethane (DCM). The solution was injected into 50 ml 0.11 % polyvinyl alcohol 4-88 (PVA488) and emulsified at 1 ,200 rpm for 2 minutes with a stir bar. The emulsion was then stirred at 300 rpm for 1 hour before centrifugation at 300 g for 2 minutes to collect the microspheres and the supernatant.

[0150] The supernatant was tested for UV absorption at 230 nm (OD230) to determine the amount and percentage of rofecoxib leaked to the supernatant during emulsification, as shown in Table 1 . The encapsulation efficiency of rofecoxib in the microspheres was calculated as one minus the percentage leaked. Drug loading was calculated as (rofecoxib input x encapsulation efficiency) / (rofecoxib input x encapsulation efficiency + PLGA input).

[0151] The microspheres were further washed in water twice and added to 250 ml phosphate- buffered saline (PBS, pH=7.4) for continuous shaking at 60 rpm at 37 °C. A sample of 600 pl was taken out to determine OD230 every 1-7 days, which was used to determine the amount of rofecoxib released from the microsphere into PBS. To maintain sink conditions, 200 ml of existing PBS were replaced with 200 ml fresh PBS every 3-4 weeks.

[0152] PLGA used in this study included: PLGA50:50, 0.4 dl / g, acid-terminated; PLGA65:35, 0.4 dl / g, acid-terminated; PLGA75:25, 0.4 dl / g, acid-terminated; PLGA75:25, 0.6 dl / g, ester-term inated.

[0153] Table 1 . Encapsulation efficiency of rofecoxib microspheres. Figures 1 A (12.5 mg rofecoxib group) and 1 B (25 mg rofecoxib group) show that microspheres with PLGA65:35, 0.4 dl / g, acid-terminated and PLGA75:25, 0.4 dl / g, acid- terminated demonstrated continuous rofecoxib release for at least one month.

[0154] Microspheres made from PLGA75:25, 0.6 dl / g, ester-term inated showed a release gap in days 40-48 in the 12.5 mg rofecoxib group but showed continuous rofecoxib release over at least 85 days in the 25 mg rofecoxib group.

[0155] Example 2. Preparation of rofecoxib microspheres in a mixing chamber

[0156] To increase the scale of microsphere preparation, a mixer (Model L5MA, Silverson, Massachusetts, US) with in-line mixing chamber (Figure 2) was used to continuously create oil-in-water emulsions and generate microspheres. 200 mg rofecoxib and 100 or 200 mg PLGA were dissolved in 4 ml DCM to form the oil phase. The oil phase was pumped into the mixing chamber at a rate of 4 ml / min while 0.11 % PVA4-88 (water phase) was pumped into the mixing chamber at 800 ml / min. Different mixing speeds at 800 rpm, 1 ,200 rpm, 1 ,600 rpm and 2,400 rpm were used to create microspheres of different sizes. The emulsions were collected on top of 800 ml water in a 2 L beaker and allowed to solidify into microspheres under continuous stirring at 500 rpm for 1 hour. The microspheres were filtered through a 200 pm sieve to remove large particulates and collected on a 10 pm PTFE membrane in a vacuum filter flask. The microspheres were washed in water twice, lyophilized, and irradiated with 15 kGy E- beam. PLGA used in this study included: PLGA75:25, 0.4 dl / g, acid-terminated; PLGA75:25, 0.6 dl / g, ester-term inated, PLGA75:25, 0.9 dl / g, ester-term inated; PLGA75:25, 1.2 dl / g, ester-term inated; PLGA 85:15, 1.5 dl / g, ester-term inated.

[0157] Microsphere size was determined with a laser-diffraction particle size analyzer (Beckman Coulter LS13320, New Jersey, US) and expressed as d , dso and doo (Table 2).

[0158] Rofecoxib loading in microsphere was determined with HPLC with a Zorbax SB-Phenyl 5-micron, 4.6 x 250 mm column (Agilent Technologies, California, US) (Table 2). About 20 mg microspheres were dissolved in 1 ml acetonitrile (ACN) and precipitated in 24 ml methanol before injection to HPLC (Injection volume: 15 pl; Mobile phase: 50% ACN in water; Flow rate: 3.5 ml / min; Column temperature: 30 °C; Detection wavelength: 230 nm). These microspheres showed high drug loading above 40%. Table 2. Particle size and drug loading of rofecoxib microspheres.

[0159] Rofecoxib release was determined by adding 5 mg microspheres to 250 ml PBS and shaken at 60 rpm at 37 °C. A sample of 600 pl was taken out to determine OD230 every 1-7 days, which measures released rofecoxib. To maintain sink conditions, 200 ml of existing PBS were replaced with 200 ml fresh PBS every 3-4 weeks.

[0160] Figure 3 shows that all formulations in the 1 ,600 rpm and 2,400 rpm groups exhibited continuous rofecoxib release over at least one month. In general, smaller microspheres formed from higher mixing speeds had shorter total duration of release and a more uniform release kinetics. Unexpectedly, all microspheres made from 200 mg rofecoxib+100 mg PLGA showed continuous rofecoxib release until at least day 44, but some microspheres from 200 mg rofecoxib+200 mg PLGA showed release gaps. This result suggests that higher drug loading may be associated with continuous release of rofecoxib microspheres.

[0161] Example 3. Effects of microsphere size on rofecoxib release profile

[0162] To further evaluate the effects of microsphere size on rofecoxib release, smaller microspheres were prepared from higher mixing speeds in the Silverson L5MA in-line mixing chamber (Figure 2). 800 mg rofecoxib and 800 mg PLGA were dissolved in 16 ml DCM to form the oil phase, which was pumped into the mixing chamber at a speed of 4 ml / min. The water phase of 0.11 % PVA 4-88 was pumped into the mixing chamber at 800 ml / min. The oil phase and water phase were mixed at 1 ,600 rpm, 2,400 rpm, 3,200 rpm and 4,000 rpm to create an emulsion, which was added on top of 800 ml water in a 2 L beaker under continuous stirring at 500 rpm for 1 hour. The microspheres were filtered through a 100 pm sieve to remove large particulates and collected on a 5 pm PTFE membrane in a vacuum filter flask. The microspheres were washed in water twice, lyophilized and irradiated with 15 kGy E-beam. PLGA used in this study included: PLGA75:25, 0.6 dl / g, ester-term inated; PLGA75:25, 0.9 dl / g, ester- terminated; PLGA75:25, 1.2 dl / g, ester-term inated; PLGA 85:15, 1.5 dl / g, ester- term inated.

[0163] Microsphere size was determined with a laser-diffraction particle size analyzer (Beckman Coulter LS13320, New Jersey, US) and expressed as d , dso and doo (Table 3). Rofecoxib release was determined by adding 5 mg microspheres to 250 ml PBS and shaken at 60 rpm at 37 °C. A sample of 600 pl was taken out to determine OD230 every 1 -7 days, which measures released rofecoxib. To maintain sink conditions, 200 ml of existing PBS were replaced with 200 ml fresh PBS every 3-4 weeks.

[0164] Table 3. Particle size of rofecoxib microspheres.

[0165] In figure 4, all microsphere formulations showed continuous rofecoxib release over at least three months. Surprisingly, microspheres from PLGA 85:15, 1.5 dl / g, ester- term inated showed continuous rofecoxib release over six months. In general, microsphere from the 2,400 rpm and 3,200 rpm groups showed relatively uniform release kinetics, which is highly desirable to maintain long-term anti-inflammatory effects while avoiding toxic side effects of rofecoxib. Example 4. Reducing microsphere size by decreasing the size of sieving pores

[0166] A smaller needle size is desired by patients and increases compliance with pharmaceutical treatments. Sieving the microspheres through smaller pores can remove excessively large microspheres from a population but may also reduce total duration of release. Thus, a smaller pore size of 75 pm was used in the sieving step in this study, lower than the 100 pm pore size in Example 3.

[0167] 0.6 g rofecoxib and 0.39 g or 0.48 g or 0.6 g of PLGA were dissolved in 12 ml DCM to form the oil phase, which was pumped into the Silverson L5MA in-line mixing chamber (Figure 2) at a speed of 4 ml / min. The water phase of 0.11 % PVA 4-88 was pumped into the mixing chamber at 800 ml / min. The oil phase and water phase were mixed at 2,400 rpm, 3,200 rpm, and 4,000 rpm to create an emulsion, which was added on top of 800 ml water in a 2 L beaker under stirring at 500 rpm for 1 hour. The microspheres were filtered through a 75 pm sieve to remove large particulates and collected on a 5 pm PTFE membrane in a vacuum filter flask. The microspheres were washed in water twice, lyophilized, and irradiated with 15 kGy E-beam. PLGA used in this study included: PLGA75:25, 0.9 dl / g, ester-term inated; PLGA75:25, 1.2 dl / g, ester-term inated. Microsphere size was determined with a laser-diffraction particle size analyzer (Beckman Coulter LS13320, New Jersey, US) and expressed as d , dso and doo (Table 4). Rofecoxib release was determined by adding 5 mg microspheres to 250 ml PBS and shaken at 60 rpm at 37 °C. A sample of 600 pl was taken out to determine OD230 every 1 -7 days, which measures released rofecoxib. To maintain sink conditions, 200 ml of existing PBS were replaced with 200 ml fresh PBS every 3-4 weeks.

[0168] Table 4. Particle size of rofecoxib microsphere after sieving through 75 pm pores.

[0169] Table 4 shows smaller particle sizes compared to microspheres in Example 3 (with the same PLGA type and mixing speed). Smaller microsphere sizes are generally associated with a shorter duration of release due to faster rate of hydrolysis of PLGA. Unexpectedly, figure 5 still shows over four months of continuous rofecoxib release across all formulations with relatively uniform release kinetics. Comparing microspheres from Table 4 to Table 3, given the same PLGA type, the same input ratio of PLGA: rofecoxib in making microspheres and the same mixing speed, the smaller microspheres in Table 4 showed a similar duration of release to the larger microspheres in Table 3. Since smaller microspheres are generally hydrolyzed faster and show a shorter duration of drug release, this result of rofecoxib microsphere is unexpected.

[0170] Example 5. In vivo rofecoxib release from microspheres after injection to Sprague Dawley rats

[0171] From microspheres prepared in Example 2, the following samples were further injected subcutaneously to male Sprague Dawley rats at a dose of 100 mg microspheres per rat (Table 5). Plasma samples were collected periodically until day 182 and plasma rofecoxib concentrations were analyzed with an LC-MS / MS system (SCIEX ExionLC, Triple Quad 6500+ with Analyst 1 .7.2 AB Sciex). Table 6 shows continuous rofecoxib release over two months for all formulations (A-F) and over six months for formulations C, D, E and F. Table 5. Microsphere formulations from Example 2 injected to rats.

[0172] Table 6. Plasma rofecoxib concentration in rats after subcutaneous injection of microspheres A-F.

[0173] Example 6. Optimizing the loading ratio of rofecoxib microspheres based on an intraarticular injection study in dogs

[0174] To evaluate the release profile of rofecoxib microspheres as injections to knee joints, the following microspheres were prepared using a Silverson L5MA in-line mixing chamber (Figure 2). 1.2 g rofecoxib and 0.78 g, or 0.96 g, or 1 .2 g PLGA were dissolved in 24 ml DCM to form the oil phase, which was pumped into the mixing chamber at a rate of 4 ml / min. The water phase, 0.11 % PVA 4-88, was pumped into the mixing chamber at 800 ml / min. Emulsions were formed at a mixing speed of 2,400 rpm and the emulsions were collected on top of 5 L water under stirring at 300 rpm for at least 30 minutes. The solidified microspheres were filtered with a 75 pm sieve to remove large particulates and collected on 10 pm PTFE membranes in a vacuum filter flask. The microspheres were then washed with water three times, lyophilized, and irradiated with 15 kGy E-beam. PLGA used in this study included: PLGA75:25, 0.6 dl / g, ester-term inated; PLGA75:25, 0.9 dl / g, ester-term inated; PLGA75:25, 1.2 dl / g, ester- term inated.

[0175] Microsphere size was determined with a laser-diffraction particle size analyzer (Beckman Coulter LS13320, New Jersey, US) and expressed as d , dso and doo (Table 7). Rofecoxib loading in microsphere was determined with HPLC with a Zorbax SB- Phenyl 5-micron, 4.6 x 250 mm column (Agilent Technologies, California, US) (Table 7). About 10 mg microspheres were dissolved in 1 ml ACN and precipitated in 9 ml methanol before injection to HPLC (Injection volume: 15 pl; Mobile phase: 50% ACN in water; Flow rate: 3.5 ml / min; Column temperature: 30 °C; Detection wavelength: 230 nm). All microspheres showed high drug loading above 40%.

[0176] Table 7. Particle size and drug loading of rofecoxib microspheres.

[0177] In vitro rofecoxib release was determined by adding 5 mg microspheres to 250 ml PBS and shaken at 60 rpm at 37 °C. A sample of 600 pl was taken out to determine OD230 every 1 -7 days, which measures released rofecoxib. To maintain sink conditions, 200 ml of existing PBS were replaced with 200 ml fresh PBS every 3-4 weeks. Figure 6 shows that all formulations exhibited continuous rofecoxib release over at least five months in vitro. A higher drug loading was associated with a faster release rate of rofecoxib.

[0178] Rofecoxib microspheres were injected to bilateral knee joints of male Beagle dogs. The dose per joint was 100 mg microsphere, 300 mg microsphere and 600 mg microsphere for the 0.78 g PLGA groups, the 0.96 g PLGA groups, and the 1 .2 g PLGA groups, respectively. Plasma samples were collected periodically until day 168 and analyzed for rofecoxib concentrations with an LC-MS / MS system (SHIMADZU LC40, Triple Quad 6500+ with Analyst 1 .7.2 AB Sciex). In Table 8, all rofecoxib microspheres showed at least 16 weeks of continuous release after injection to knee joints in dogs. Microspheres with rofecoxib loading between 40-55% showed a longer duration of release than microspheres with rofecoxib loading above 55%. A higher drug loading is a desirable feature for injectable drugs because, for each injection, a greater amount of drug can be administered. However, as this dog study shows, rofecoxib loading above 55% reduced the total duration of rofecoxib release. Thus, a rofecoxib loading ratio between 40-55% combines three desirable features of relatively high drug loading, continuous drug release and a long duration of release.

[0179] Table 8. Plasma rofecoxib concentration after injection of microspheres to knee joints of dogs.

[0180] Example 7. Long-term rofecoxib release from microspheres after knee injections in dogs

[0181] To evaluate the long-term release of rofecoxib microspheres after injection to knee joints, the following microspheres were prepared using a Silverson L5MA in-line mixing chamber (Figure 2). 3.6 g rofecoxib and 3.6 g PLGA were dissolved in 72 ml DCM to form the oil phase, which was pumped into the mixing chamber at a rate of 4 ml / min. The water phase, 0.11 % PVA 4-88, was pumped into the mixing chamber at 800 ml / min. Emulsions were formed at a mixing speed of 2,400 rpm and the emulsions were collected on top of 22 L water under stirring at 300 rpm for at least 30 minutes. The solidified microspheres were filtered with a 75 pm sieve to remove large particulates and collected on 10 pm PTFE membranes in a vacuum filter flask. The microspheres were then washed with water three times and lyophilized. A portion of the microspheres were irradiated with 15 kGy E-beam or 25 kGy E-beam. PLGA used in this study included: PLGA75:25, 0.6 dl / g, ester-term inated; PLGA75:25, 0.9 dl / g, ester-term inated; PLGA75:25, 1.2 dl / g, ester-term inated; and PLGA85:15, 1.5 dl / g, ester-term inated.

[0182] Microsphere size was determined with a laser-diffraction particle size analyzer (Beckman Coulter LS13320, New Jersey, US) and expressed as d , dso and doo (Table 9). Rofecoxib loading in microspheres was determined with HPLC with a Zorbax SB- Phenyl 5-micron, 4.6 x 250 mm column (Agilent Technologies, California, US) (Table 9). About 10 mg microspheres were dissolved in 1 ml ACN and precipitated in 9 ml methanol before injection to HPLC (Injection volume: 15 pl; Mobile phase: 50% ACN in water; Flow rate: 3.5 ml / min; Column temperature: 30 °C; Detection wavelength: 230 nm). All microspheres showed a high drug loading above 40%.

[0183] Table 9. Particle size and drug loading of rofecoxib microspheres (un-irradiated)

[0184] In vitro rofecoxib release was determined by adding 5 mg microspheres to 250 ml PBS and shaking at 60 rpm at 37 °C. A sample of 600 pl was taken out to determine OD230 every 1 -7 days, which measures released rofecoxib. To maintain sink conditions, 200 ml of existing PBS were replaced with 200 ml fresh PBS every 3-4 weeks. Figure 7 shows that all formulations exhibited continuous rofecoxib release over at least five months in vitro, with PLGA75:25, 0.9 dl / g and 1.2 dl / g, ester-term inated (un-irradiated) showing six months of continuous rofecoxib release and PLGA85:15, 1 .5 dl / g, ester- term inated (un-irradiated) showing nine months of continuous rofecoxib release.

[0185] 300 mg rofecoxib microspheres (made from PLGA75:25, 0.9 dl / g, ester-term inated, irradiated with 15 kGy E-beam) were injected to one knee of two replicate male Beagle dogs. 600 mg rofecoxib microspheres (made from PLGA85:15, 1 .5 dl / g, ester- terminated, un-irradiated) were injected to one knee of three replicate Beagle dogs. Plasma samples were collected periodically until day 224 and analyzed for rofecoxib concentrations with an LC-MS / MS system (SHIMADZU LC40, Triple Quad 6500+ with Analyst 1.7.2 AB Sciex). In Table 10, rofecoxib microspheres (made from PLGA75:25, 0.9 dl / g, ester-term inated, irradiated with 15 kGy E-beam) showed continuous in vivo release over 182 days, and rofecoxib microspheres (made from PLGA85:15, 1.5 dl / g, ester-term inated, un-irradiated) showed continuous in vivo release over at least 224 days.

[0186] Table 10. Plasma rofecoxib concentration after injection of microspheres to knee joints of dogs.

[0187] References

[0188] FDA Label for VIOXX® (rofecoxib).

[0189] FDA Label for Zilretta® (a PLGA-triamcinolone-acetonide microsphere formulation).

[0190] Han, et al. (2024) Antioxidant and anti-inflammatory injectable hydrogel microspheres for in situ treatment of tendinopathy. Regen Biomater. 11 .

[0191] Park, et al. (2019) Injectable, long-acting PLGA formulations: Analyzing PLGA and understanding microparticle formation. Journal of Controlled Release. Vol. 304, pp. 125-134.

[0192] Wang, et al. (2011 ) Intra-discal vancomycin-loaded PLGA microsphere injection for MRSA discitis: an experimental study. Arch Orthop Trauma Surg. 131 :111 -119.

[0193] Williems, et al. (2017) Safety of intradiscal injection and biocompatibility of polyester amide microspheres in a canine model predisposed to intervertebral disc degeneration. Journal of Biomedical Materials Research Part B. 105(4)707-714.

[0194] Hahn, et al., U.S. Patent No. 11 ,793,762, “Composition and method for reducing joint pain associated with hemarthrosis and hemophilic arthropathy.”

[0195] Li, U.S. Publication No. 2022 / 0257565, “Microsphere-Based Injectible Celecoxib Formulation.”

Claims

What is claimed is:1 . A biodegradable microsphere, wherein the microsphere (i) has a diameter of from 1 pm to 500 pm; (ii) comprises a polylactic-co-glycolic acid (PLGA) matrix; (iii) carries pharmaceutical rofecoxib; and (iv) when present in a suitable joint-related tissue, releases rofecoxib for at least one month.

2. The biodegradable microsphere of claim 1 , wherein the microsphere has a lactic acid to glycolic acid molar ratio of from 100:0 to 50:50.

3. The biodegradable microsphere of claim 1 or 2, wherein the microsphere (i) has a diameter of from 5 pm to 200 pm; and (ii) has a lactic acid to glycolic acid molar ratio of 75:25 or 85:15.

4. The biodegradable microsphere of any of claims 1 -3, wherein the microsphere further comprises polyethylene glycol (PEG).

5. The biodegradable microsphere of any of claims 1-4, wherein the microsphere, when present in a suitable joint-related tissue, releases rofecoxib for at least two months.

6. A plurality of biodegradable microspheres, wherein the microspheres (i) have a d value of at least 1 pm and a dgo value of 500 pm or less; (ii) comprise a polylactic- co-glycolic acid (PLGA) matrix; (iii) carry a therapeutically effective amount of pharmaceutical rofecoxib; and (iv) when present in a suitable joint-related tissue, release rofecoxib for at least one month.

7. The plurality of biodegradable microspheres of claim 6, wherein the microspheres further comprise polyethylene glycol (PEG).

8. The plurality of biodegradable microspheres of claim 6 or 7, wherein the microspheres, when present in a suitable joint-related tissue, release rofecoxib for at least two months.

9. The plurality of biodegradable microspheres of any of claims 6-8, wherein the microspheres (i) have a dw value of at least 5 pm and a dgo value of 200 pm or less; (ii) have a lactic acid to glycolic acid molar ratio of from 100:0 to 50:50; and (iii) carry from1 pg to 3,000 mg of pharmaceutical rofecoxib.

10. An injectable formulation comprising (a) a pharmaceutically acceptable carrier and (b) a plurality of biodegradable microspheres wherein the microspheres (i) have a d value of at least 1 pm and a dgo value of 500 pm or less; (ii) comprise a polylactic- co-glycolic acid (PLGA) matrix; (iii) carry a therapeutically effective amount of pharmaceutical rofecoxib; and (iv) when present in a suitable joint-related tissue, release rofecoxib for at least one month.11 . The formulation of claim 10, wherein the microspheres further comprise polyethylene glycol (PEG).

12. The formulation of claim 10 or 11 , wherein the microspheres, when present in a suitable joint-related tissue, release rofecoxib for at least two months.

13. A method for treating a joint-related disorder in a subject comprising introducing biodegradable microspheres into suitable tissue in or around one or more of the subject’s joints, wherein the microspheres (i) have a d value of at least 1 pm and a dgo value of 500 pm or less; (ii) comprise a polylactic-co-glycolic acid (PLGA) matrix; (iii) carry a therapeutically effective amount of pharmaceutical rofecoxib; and (iv) when present in a suitable joint-related tissue, release rofecoxib for at least one month.

14. The method of claim 13, wherein the microspheres further comprise polyethylene glycol (PEG).

15. The method of claim 13 or 14, wherein the subject is human.

16. The method of claim 13 or 14, wherein the subject is a cat, a dog, or a horse.

17. The method of any of claims 13-16, wherein the disorder is arthritis.

18. The method of any of claims 13-17, wherein the arthritis is osteoarthritis.

19. The method of any of claims 13-17, wherein the arthritis is rheumatoid arthritis.

20. The method of any of claims 13-19, wherein the method comprises intraarticularly injecting the biodegradable microspheres into one or both of the subject’s knees.21 . The method of any of claims 13-20, wherein the microspheres (i) have a dio value of at least 5 pm and a dgo value of 200 pm or less; (ii) have a lactic acid to glycolic acid molar ratio of from 100:0 to 50:50; and (iii) carry from 1 pg to 3,000 mg of pharmaceutical rofecoxib.

22. The method of any of claims 13-21 , wherein the microspheres have an average lactic acid to glycolic acid molar ratio of 75:25 or 85:15.

23. The method of any of claims 13-22, wherein the biodegradable microspheres have a dio value of at least 10 pm and a dgo value of 120 pm or less.

24. The method of any of claims 13-23, wherein the microspheres release rofecoxib for at least two months.

25. The method of any of claims 13-24, wherein the microspheres release rofecoxib for at least three months.

26. The method of any of claims 13-25, wherein the microspheres release rofecoxib for at least six months.

27. A kit comprising, in separate compartments, (a) a diluent, and (b) plurality of biodegradable microspheres, wherein the microspheres (i) have a dio value of at least 1 pm and a dgo value of 500 pm or less; (ii) comprise a polylactic-co-glycolic acid (PLGA) matrix; (iii) carry a therapeutically effective amount of pharmaceutical rofecoxib; and (iv) when present in a suitable joint-related tissue, release rofecoxib for at least one month.

28. A biodegradable microsphere, wherein the microsphere (i) has a diameter of from 1 pm to 500 pm; (ii) comprises a polylactic-co-glycolic acid (PLGA) matrix; (iii)carries pharmaceutical rofecoxib; and (iv) when present in a suitable soft tissue, releases rofecoxib for at least one month.

29. The biodegradable microsphere of claim 28, wherein the microsphere has a lactic acid to glycolic acid molar ratio of from 100:0 to 50:50.

30. The biodegradable microsphere of claim 28 or 29, wherein the microsphere (i) has a diameter of from 5 pm to 200 pm; and (ii) has a lactic acid to glycolic acid molar ratio of 75:25 or 85:15.31 . The biodegradable microsphere of any of claims 28-30, wherein the microsphere further comprises polyethylene glycol (PEG).

32. The biodegradable microsphere of any of claims 28-31 , wherein the microsphere, when present in a suitable soft tissue, releases rofecoxib for at least two months.

33. A plurality of biodegradable microspheres, wherein the microspheres (i) have a d value of at least 1 pm and a dgo value of 500 pm or less; (ii) comprise a polylactic- co-glycolic acid (PLGA) matrix; (iii) carry a therapeutically effective amount of pharmaceutical rofecoxib; and (iv) when present in a suitable soft tissue, release rofecoxib for at least one month.

34. The plurality of biodegradable microspheres of claim 33, wherein the microspheres further comprise polyethylene glycol (PEG).

35. The plurality of biodegradable microspheres of claim 33 or 34, wherein the microspheres, when present in a suitable soft tissue, release rofecoxib for at least two months.

36. The plurality of biodegradable microspheres of any of claims 33-35, wherein the microspheres (i) have a d value of at least 5 pm and a dgo value of 200 pm or less; (ii) have a lactic acid to glycolic acid molar ratio of from 100:0 to 50:50; and (iii) carry from1 pg to 3,000 mg of pharmaceutical rofecoxib.

37. An injectable formulation comprising (a) a pharmaceutically acceptable carrier and (b) a plurality of biodegradable microspheres wherein the microspheres (i) have a d value of at least 1 pm and a dgo value of 500 pm or less; (ii) comprise a polylactic- co-glycolic acid (PLGA) matrix; (iii) carry a therapeutically effective amount of pharmaceutical rofecoxib; and (iv) when present in a suitable soft tissue, release rofecoxib for at least one month.

38. The formulation of claim 37, wherein the microspheres further comprise polyethylene glycol (PEG).

39. The formulation of claim 37 or 38, wherein the microspheres, when present in a suitable soft tissue, release rofecoxib for at least two months.

40. A method for treating a soft tissue disorder in a subject comprising introducing biodegradable microspheres into the soft tissue and / or its surrounding tissue, wherein the microspheres (i) have a d value of at least 1 pm and a dgo value of 500 pm or less;(ii) comprise a polylactic-co-glycolic acid (PLGA) matrix; (iii) carry a therapeutically effective amount of pharmaceutical rofecoxib; and (iv) when present in a suitable soft tissue, release rofecoxib for at least one month.41 . The method of claim 40, wherein the microspheres further comprise polyethylene glycol (PEG).

42. The method of claim 40 or 41 , wherein the subject is human.

43. The method of claim 40 or 41 , wherein the subject is a cat, a dog, or a horse.

44. The method of any of claims 40-43, wherein the disorder is selected from the group consisting of tendonitis, plantar fasciitis, adhesive capsulitis, bursitis, carpal tunnel, site of injury, site of trauma, and site of surgery.

45. The method of any of claims 40-44, wherein the microspheres (i) have a dw value of at least 5 pm and a dgo value of 200 pm or less; (ii) have a lactic acid to glycolic acid molar ratio of from 100:0 to 50:50; and (iii) carry from 1 pg to 3,000 mg of pharmaceutical rofecoxib.

46. The method of any of claims 40-45, wherein the microspheres have an average lactic acid to glycolic acid molar ratio of 75:25 or 85:15.

47. The method of any of claims 40-46, wherein the biodegradable microspheres have a dio value of at least 10 pm and a dgo value of 120 pm or less.

48. The method of any of claims 40-47, wherein the microspheres release rofecoxib for at least two months.

49. The method of any of claims 40-48, wherein the microspheres release rofecoxib for at least three months.

50. The method of any of claims 40-49, wherein the microspheres release rofecoxib for at least six months.51 . A kit comprising, in separate compartments, (a) a diluent, and (b) plurality of biodegradable microspheres, wherein the microspheres (i) have a dio value of at least 1 pm and a dgo value of 500 pm or less; (ii) comprise a polylactic-co-glycolic acid (PLGA) matrix; (iii) carry a therapeutically effective amount of pharmaceutical rofecoxib; and (iv) when present in a suitable soft tissue, release rofecoxib for at least one month.

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