Biorelevant and screening dissolution methods for minocycline hydrochloride microspheres intended for periodontal administration.

Currently, there is no compendial-level method to assess dissolution of particulate systems administered in the periodontal pocket. This work seeks to develop dissolution methods for extended release poly(lactic-co-glycolic acid) (PLGA) microspheres applied in the periodontal pocket. Arestin®, PLGA microspheres containing minocycline hydrochloride (MIN), is indicated for reduction of pocket depth in adult periodontitis. Utilizing Arestin® as a model product, two dissolution methods were developed: a dialysis set-up using USP apparatus 4 and a novel apparatus fabricated to simulate in vivo environment of the periodontal pocket. In the biorelevant method, the microspheres were dispersed in 250 μL of simulated gingival crevicular fluid (sGCF) which was enclosed in a custom-made dialysis enclosure. sGCF was continuously delivered to the device at a biorelevant flow rate and was collected daily for drug content analysis using UPLC. Both methods could discriminate release characteristics of a panel of MIN-loaded PLGA microspheres that differed in composition and process conditions. A mechanistic model was developed, which satisfactorily explained the release profiles observed using both dissolution methods. The developed methods may have the potential to be used as routine quality control tools to ensure batch-to-batch consistency and to support evaluation of bioequivalence for periodontal microspheres.