Abstract
The ultimate goal is to design a new chronotherapeutic system for theophylline (TPH) with high potential benefits in treating nocturnal asthma. TPH core tablets were prepared by wet granulation using a developed formula. Compression coating over core tablets containing 200 mg TPH was done using granulated chitosan with 10% PVP K30. Different formulae F1, F2 and F3 were prepared using coat weights 260, 300 and 360 mg, respectively. The in vitro release characteristics in both variant pH media mimicking the gastrointestinal media and in media containing rat cecal content were monitored. The in vivo performance of the optimum formula was compared with Avolen (R) SR in Beagle dogs. F3 with high coat thickness exhibited a minimal release after 5-h release study. Both F2 and F3 showed more than 50% drug release after 4 h in the rat cecal medium. This reflects the colon selectivity of the system. The C-max values were found to be 5.49 +/- 0.46 and 5.12 +/- 0.85 mu g/mL for F3 and Avolen (R) SR, respectively, F3 showed higher mean plasma concentration than Avolen (R) SR from the beginning and continued till 7 h post administration indicating high potential as chronotherapeutic treatment of nocturnal asthma.