Abstract
The dissolution behavior of two marketed sustained-release theophylline preparations was studied using the USP basket method. The pH of the medium was changed from simulated gastric fluid (pH 1.2) to simulated intestinal fluid (pH 7.5) after 1 h. A marked difference in the release pattern between the two brands was observed and was attributed to the difference in the nature and the method of manufacturing of both products. The bioavailability of these preparations was studied, using the salivary concentration, in six healthy male volunteers and the results were analyzed by the statistical moment theory. A significant difference in the absorption parameters was found, but there was no significant differences in the extent of absorption indicating that the two brands are bioequivalent. A direct correlation between the percent in-vivo absorbed and the percent in-vitro dissolved was observed for each brand.