CHARACTERIZATION OF THE IN-VITRO DISSOLUTION OF SOME COMMERCIAL SUSTAINED-RELEASE THEOPHYLLINE DOSAGE FORMS

A dissolution study of five commercial sustained release theophylline dosage forms, concerning their pH dependency, is described. The experiment was carried out in a flow through dissolution apparatus, at constant pH and at pH gradient, being the pH values of 1,2, 6,5 and 7,5. In both cases, they were treated in terms of the dissolution profile and the dissolution rate, complemented with the dissolution efficiency at pH gradient in order to make a correlation with the in vivo experiments that will be done in the future. The absorbance was measured at a wavelength of 264 nm. According to the results obtained, was selected the best pharmaceutical form, concerning the pH dependency and taking as a basis, just, the in vitro experiments.