Sustained-Release Formulations of Nifedipine

Abstract

The effects of various polymers on the release of nifedipine from their matrices have been evaluated. In vitro release profile of nifedipine from Eudragit RS matrices showed that increasing the concentration of Eudragit RS resulted in a reduction in the release rate of nifedipine. In vitro release profiles of nifedipine matrices containing methylcellulose showed that more than 90% of the drug was released after 2 h at PH 1.2 indicating that methylcellulose could not produce sustained release matrices of nifedipine. A linear relationship was established between the T90% and the percent Eudragit RS, used. Relationships, such as predicted by the Korsmeyer equation (Q=Ktn), were considered appropriate to describe accurately the quantity of drug released. Values of n were 0.564-0.629, indicating that release was controlled by both diffusion and erosion.