Mucoadhesion has been a topic of interest in the design of drug delivery system to prolong the residence time of the dosage form with the under lying absorption surface to improve and enhance the bioavailability of drugs. The objective of this study is to develop, characterize, and evaluate mucoadhesive microspheres of Metronidazole employing various mucoadhesive polymers for prolonged gastrointestinal absorption. Metronidazole, an effective antiprotozoal drug that requires controlled release was used as the core in microencapsulation.
Microsphere containing Metronidazole were prepared employing sodium alginate in combination with four mucoadhesive polymers – sodium CMC, Methylcellulose, Carbopol and HPMC-K4M as coat materials with different polymers ratios. Further Chitosan coating was employed for better mucoadhesive property. The microspheres were filled in capsules for in-vivo evaluation. The microspheres were found to discrete, spherical, free flowing, and of the monolithic matrix type. The mucoadhesive property of the microcapsules was evaluated by an in nitro adhesion testing method known as wash-off method. Scanning Electron Microscopy indicated coarser surface texture which improves the adhesion through stronger mechanical interaction of the microspheres. The mucoadhesive microspheres were evaluated by in vitro and in vivo methods using Gamma Scintigraphy for controlled release.
Microspheres coated with HPMC-K4M and Carbopol polymer upon Chitosan coating retained spherical shapes which produced best drug release. The microspheres having good in vitro properties were used for in vivo evaluation. These mucoadhesive microspheres are, thus, suitable for oral controlled release of Metronidazole.