PLGA nanospheres should be more suitable for delivery to inflamed synovial tissue than microspheres due to their ability to penetrate the synovium. PLGA particulate systems with biocompatibility in the joint can provide local-therapy action in joint disease in a different manner depending on the size of the system.

Direct intra-articular injection of a PLGA nanosphere system with a water-soluble steroid provided a prolonged pharmacological efficacy in the joints of arthritic rabbits. The local anesthetic in the knee-joints was evaluated to be safe and without biologic damage.

Some acidic nonsteroidal anti-inflammatory drugs (NSAIDs) are poorly soluble in the stomach. In this study, M-5011, d-2-[4-(3-methyl-2-thienyl) phenyl] propionic acid, was used as a model substance. To increase the dissolution rate of M-5011, a solid dispersion of M-5011 was prepared by the powder mixing method using Eudragit E-100 (aminoacryl methacrylate copolymer) as a carrier. Evaluation by X-ray diffraction and differential scanning calorimetry (DSC) revealed that M-5011 easily formed a solid dispersion with E-100. The dissolution behavior of a physical mixture prepared immediately after mixing and the mixture stored for 14 days at 40 degrees C were examined. It was observed that the former, containing a great deal of E-100, showed a fairly good dissolution behavior, and the latter had a better dissolution rate. The mechanism of the interaction of M-5011 and E-100 was investigated by infrared (IR) spectroscopy and nuclear magnetic resonance (NMR). The interaction was simulated by NMR using a monomer of Eudragit E-100.

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Permeation of 22-oxacalcitriol-1α, 25-dihydroxyvitamin D(3) (OCT) through excited hairless mouse skin was determined after application of OCT as solutions and O/W lotions consisted of different polarities of solvents: medium-chain fatty acid triglyceride (MCT), myristate isopropyl (IPM), 1,3-butylene glycol (1,3-BG), and propylene glycol (PG). OCT concentration in skin was also followed after applying these formulations. A two-layer diffusion model was composed to analyze dermatopharmacokinetic profiles of OCT for each vehicle. In the OCT solutions, skin permeation profile of OCT differed depending on solvent polarity. The O/W lotion with a high MCT content led to a low amount of OCT in skin. On the other hand, the O/W lotion with a high 1,3-BG content led to a high amount of OCT in skin. This dermatopharmacokinetic analysis indicated that addition of MCT to the formulation decreases the skin/vehicle partition coefficient of OCT and increases the diffusion coefficient of OCT in skin. However, the opposite effects on these two parameters were found in the case of 1,3-BG. Thus, skin permeability of OCT differed depending on the solvents used in the formulation. These results indicate that skin permeability of OCT is influenced by the physicochemical properties (i.e. polarity) of OCT, solvent, and skin. Our findings on the solvent effects of the skin permeability of OCT are thus useful for designing topical drug formulation, especially in aiming for bioequivalent dosage formulas.