FORMULATION BY DESIGN: UNDERSTANDING THE FORMULATION VARIABLES AND OPTIMISATION OF GLIPIZIDE BUOYANT BIOADHESIVE MICROCARRIERS BY CENTRAL COMPOSITE DESIGN

In this study, a combination of statistical and analytical approach have been used in the formulation development and optimisation guided by “formulation by design” (FbD) for air entrapped microcarriers of alginate of glipizide. Microcarriers of glipizide were prepared by ionotropic-gelation technique, taking concentrations of sodium alginate (SA) and calcium carbonate (CC) as independent variables. The effects of the polymers were evaluated on dependent variables that is drug release (DR), entrapment efficiency (EE), bioadhesive strength (BS), microcarrier size (MS) and total floating time (TFT). Various batches exhibited rough, spherical microcarriers with nominal size variation having sufficient drug EE, very short lag time, while the microcarriers shows the buoyancy over a period of 6–18 hours based on the formulation variables. The DR from the microcarriers was also sustained for more than 10 hours, in 0.1N HCl (pH 1.2). Higuchi’s and the first order kinetic modelling indicated a diffusion-controlled release of drug from the microcarriers. The study also demonstrated the influence of SA and CC on drug EE (71.00%–80.30%) and in vitro release (87.10%–99.89%). Higher level of air increased EE but retarded DR rate as compared to a lower level of air containing microcarriers. The concentration of SA and CC had highly significant effect on buoyancy, DR and other dependent variables as level of significance is ≤0.05. The effects studied will pave the way for developing optimised microcarriers.