Chitosan-Hydroxypropyl Methylcellulose Matrices as Carriers for Hydrodynamically Balanced Capsules of Moxifloxacin HCl

Background: In recent years, gastroretentive, hydrodynamically balanced system (HBS) for stomach-specific floating sustained drug release has gained a lot of importance in improving absorption of drugs especially those absorbed from stomach and small intestine. Objective: The objective of the current investigation is to evaluate chitosan-hydroxypropyl methylcellulose (HPMC) based on polymeric matrices as a carrier for single-unit capsules based on HBS for stomach- specific floating sustained drug release using moxifloxacin HCl (MX) as a model drug. Method: Various HBS capsules of MX were prepared by physical blending of MX with chitosan (low or medium molecular mass) or HPMC (K4M or K15M) or chitosan-HPMC combinations in varying proportions followed by encapsulation into size 0 capsules made of hard gelatin. The in vitro buoyancy and drug release in 0.1 N HCl (pH 1.2) were evaluated. Results: HBS capsules based on chitosan (low and medium molecular weight and their combination) as polymer matrix failed to float on 0.1 N HCl (pH 1.2). Whereas, formulations containing HPMC (K4M or K15M) or their mixture with chitosan, remained buoyant and released MX over 9 h in the acidic dissolution medium following zero-order kinetics. Conclusion: HPMC (K4M, K15M, blend of K4M and K15M) or their mixture with low/medium molecular mass chitosan may constitute excellent carrier systems for the stomach-specific sustained delivery of MX over a longer period. Keywords: Chitosan, drug release, HPMC, hydrodynamically balanced system.