Effect of Tablet Surface Area and Surface Area/Volume on Drug Release from Lamivudine Extended Release Matrix Tablets

Abstract

The purpose of this study was to investigate the influence of tablet surface area/ volume (SA/Vol) on drug release from extended-release matrix tablets of lamivudine prepared with hydroxy propyl methylcellulose (HPMC). Highly soluble drug such as lamivudine was utilized in this study to give predominantly diffusion-controlled release. Drug release from HPMC matrix tablets with similar values of SA/Vol was comparable within the same tablet shaped tablet. Tablets having the same surface area but different SA/Vol values did not result in similar drug release, tablets with larger SA/Vol values had faster release profiles. Utility of SA/Vol to affect drug release was demonstrated by changing drug doses, and altering tablet shape to adjust SA/Vol. When SA/Vol was held constant, similar release profiles were obtained. Thus, surface area/volume is one of the key variables in controlling drug release from HPMC matrix tablets. Proper use of this variable has practical application by formulators who may need to duplicate drug release profiles from tablets of different sizes and different shapes.