Formulation design and in vitro evaluations for stomach specific drug delivery system of anti retroviral drug-acyclovir

Abstract

Floating matrix tablets or stomach specific drug delivery systems are designed to prolong the gastric residence time after oral administration, at a particular site and controlling the release of drug, especially useful for achieving controlled plasma level as well as improving bioavailability. Due to low gastric retention time, the bioavailability of acyclovir is low as the large portion of drug misses the absorption window. The objective of this study was to develop a stomach specific drug delivery system of acyclovir using gas‐forming agent like sodium bicarbonate and polymers like different grades of HPMC and xanthun gum. Tablets were prepared by direct compression using different concentrations of HPMC and xanthun gum. Tablets were evaluated for their physical characteristics, viz., hardness, friability, weight variation and floating properties. The floating lag time of all the formulations was within the prescribed limit (<10 minutes). All the formulations showed good buoyancy and swelling index properties. From in vitro drug release studies, it is concluded that all the formulation retarded the release of drug for twelve hours except AF-1 formulation. AF-8 formulation with 30% xanthun gum shows more controlled release of 60.22% at the end of 12hrs when compared to all other formulations.