Comparison of dissolution profiles of theophylline extended-release dosage forms.

Dissolution testing is a very important tool used to demonstrate the similarity between different formulations. Due to a narrow therapeutic range of theophylline, it is crucial to investigate the differences in the rate of release of this drug between the products. The aim of study was to compare the dissolution profiles of theophylline extended-release dosage forms available on Polish market: Theoplus, Theovent, Theospirex retard, and Euphyllin long. The investigation of theophylline release from tablets was performed by the basket apparatus type DT700 (Erweka). The difference and similarity factor was used to compare the obtained dissolution profiles. The obtained values showed that dissolution profiles of investigated formulations were not equivalent to each other. The tablets differed by the mechanism of drug release also.