Biodegradable microspheres based on gelatin-porcine mucin admixtures: in vitro and in vivo delivery studies

Soluble mucus glycoprotein (S-mucin) processed from the small intestines (ileal region) of freshly slaughtered pigs via homogenization, dialysis, centrifugation and lyophilization and their admixtures with type B gelatin were used to prepare cefaclor-loaded microspheres by the emulsification-crosslinking method. The microspheres were evaluated for the in vitro delivery of cefaclor in both simulated intestinal fluid (SIF) without pancreatin (pH 7.4) and simulated gastric fluid (SGF) without pepsin (pH 1.2). Results obtained indicated that the microspheres formulated were highly mucoadhesive and that release of cefaclor in both release media was non-Fickian and was much higher and more rapid in SGF than in SIF and from microspheres based on gelatin alone when compared to those based on gelatin-procine mucin admixtures. The mean area under the plasma level versus time curves (AUC) was shown to be dependent on the formulation with values of 172.3 mug.h/ml for the control, 278.5 mug.h/ml for microspheres based on gelatin only and 353.0 mug.h/ml for microspheres formulated with equal parts of gelatin and mucin indicating that the rectal route may provide a therapeutically viable alternative to the oral route for the delivery of cefaclor. Further indications also emerged of a possibility of site-specific delivery of cefaclor to the small intestine through a careful selection of gelatin type and porcine mucin admixtures prior to formulation of the microspheres. On the whole, the inclusion of S-mucin in the composition of the microspheres had an enhancer effect on the release and rectal bioavailability of cefaclor which may be exploited in the design of a rectal delivery system of the drug.