In vitro testing of controlled release theophylline preparations: Theolair ®, Theograd® and Theolin®

Abstract

Three dissolution methods,i.e. a paddle type, theusp disintegration and a column method, were used to characterize the release from three controlled release theophylline preparations,i.e. Theolair Retard® 250, Theolin Retard® 300 and Theograd® 350. The release profiles proved to be dependent upon agitation intensity and pH or a combination of both, but the sensitivity towards these variables differed markedly between the products tested.