Studies on influence of process variables on performance of gliclazide mucoadhesive microcapsules

Abstract

Microencapsulation is a unique technique of controlled drug delivery system and is of major importance for effective alteration of drug release required to produce a novel formulation with desired characteristics to overcome the disadvantages of the conventional therapeutic dosage forms. Microcapsules offer efficient absorption and enhanced bioavailability owing to their higher surface area, however, mucoadhesive microcapsules render more intimate contact with
the mucus membrane thereby leading to increase in the gastro intestinal residence time. Gliclazide is an oral hypoglycemic second generation sulfonyl urea, which is useful for a long-term treatment of non-insulin dependent diabetes mellitus. In the present investigation, the gliclazide microcapsules are formulated to control the release rate and improve the absorption across gastrointestinal membrane by employing ionic gelation method.The effect of various process variables such as curing time, stirring speed, stirring time, volume and concentration of curing reagent on entrapment efficiency, and drug release
rate was studied. The microcapsules were evaluated for drug content, encapsulation efficiency, in vitro drug release studies. The optimized formulation was selected based on the entrapment efficiency and drug release rate.The optimized formulation of gliclazide microcapsules were evaluated for rheological properties, moisture content, swelling index, erosion studies,
wall thickness and in vitro wash off test. The microcapsules formulated with 2:1 coat:core ratio by using 150 ml of 0.1M Cacl2 solution as curing reagent, at a stirring speed of 400 rpm for 60 minutes and a curing period of 48 hrs were found to be the optimum formulation. The drug release followed zero order kinetics and was controlled by peppas mechanism. The pharmacodynamic activity of optimized gliclazide microcapsules was conducted by measuring blood glucose levels in healthy albino rabbits. The percentage glucose reduction was calculated and the data was treated statistically. The hypoglycemic activity was extended up to 10 hours in case of microcapsules.