Design and evaluation of mucoadhesive microspheres of repaglinide for oral controlled release

Gastro retentive dosage forms have potential for use as controlled-release drug delivery systems. Multiple unit systems avoid the “all-or-none gastric” emptying nature of single-unit systems. A controlled release system designed to increase its residence time in the stomach with contact with the mucosa was achieved through the preparation of mucoadhesive microspheres by the emulsion solvent evaporation technique consisting of (I) chitosan mucoadhesive (ii) repaglinide, an oral hypoglycemic agent; and (iii) Eudragit RS-100 as polymer. The microspheres were evaluated for surface morphology and particle shape by scanning electron microscope. The microspheres were also evaluated for their microencapsulation efficiency, in vitro wash-off mucoadhesion test, in vitro drug release and in vivo study. The microspheres were found to be spherical and free flowing. The microencapsulation efficiency was in the range of 61.44±1.16 to 79.90±1.17and microspheres exhibited good mucoadhesive property in the in vitro wash off test. The drug-polymer concentration of dispersed phase influences the particle size and drug release properties. All the formulations were followed by Matrix-Peppas model. The drug release was also found to be slow and extended for 24 h. In vivo testing of the mucoadhesive microspheres in diabetic albino rats demonstrated significant antidiabetic effect of repaglinide. The hypoglycemic effect obtained by mucoadhesive microspheres was for more than 16 whereas repaglinide produced an antidiabetic effect for only 10 h suggesting that mucoadhesive microspheres are a valuable system for the long term delivery of repaglinide.Keywords: Controlled Release, Repaglinide, Solvent Evaporation, Microspheres, Mucoadhesive