Development of a controlled release low dose class II drug-Glipizide

The purpose of this study was to develop a new monolithic matrix system to completely deliver glipizide, a Biopharmaceutics Classification System (BCS) Class II drug in a zero order manner over an extended time period. Two approaches were examined using drug in formulations that contain swellable hydroxypropylmethylcellulose (HPMC) or erodible polyethylene oxide (PEO). The matrices were prepared by dry blending selected ratios of polymers and ingredients using direct compression technique. Dissolution was assessed using modified USP apparatus II. Glucotrol XL push-pull osmotic pump (PPOP) was used as the reference. The interrelationship between matrix hydration, erosion and textural properties were determined and analyzed under the dissolution test conditions. Linear and reproducible release similar to that of Glucotrol XL was achieved for optimized matrices (f2>50) independent of hydrodynamic conditions. The kinetics of drug delivery was directly related to the synchronization of swelling, erosion and fractional release. HPMC matrices showed a significantly greater degree of hydration and swelling and stronger texture property relative to PEO matrices. Results indicate that in the case of low dose/low soluble drug, total drug release in a zero order manner heavily depends on the synchronization of erosion and swelling fronts during the entire dissolution study.