Polymethacrylate Coated Valsartan Tablets for Ileo-Colonic Delivery: Formulation Development and In Vitro and In Vivo Evaluations

The present study was aimed to develop timed/delayed release Eudragit coated tablets of valsartan for ileo-colonic release to treat early morning surge in blood pressure. The core-tablets containing 80 mg of valsartan were coated with different grades of methacrylate polymers viz., Eudragit S 100, Eudragit RS, Eudragit RS: RL combination (50:50 and 80:20) at different coating levels. The tablets were characterized for physical properties, in vitro release studies and in vivo release kinetics. The drug release studies indicated a very low drug release in the initial phase (0–6 h) followed by rapid release for next 12 h with the Eudragit S 100 and Eudragit RS alone coated tablets. The in vitro drug release studies showed that the coating was able to resist the environmental conditions in the gastric and duodenum and delayed the drug release until the tablet reached terminal ileum. In vivo pharmacokinetic study in rabbits and healthy human subjects showed rapid absorption of drug from conventional tablet, whereas absorption was delayed in the case of Eudragit coated tablets. Thus, a rapid release pattern obtained after a lag time of 6–7 h with Eudragit coated tablets could be an ideal approach for the treatment of morning surge using valsartan.