Enteric coated capsules of eprosartan mesylate with pH-modifier for augmenting the dissolution

Eprosartan mesylate, an antihypertensive, exhibits low oral bioavailability due to its ionization at alkaline pH. An attempt has been made to prepare enteric coated capsule containing drug and maleic acid, as dosage form. Male-ic acid acts as pH-modifier, facilitates the absorption of drug by reducing the pH of intestinal environment (prefer-ably duodenum) so as to reduce the ionization of eprosartan, once the capsule reaches the duodenum. The capsules were coated with eudragit L100-55 (enteric coating agent) by dip method and evaluated for % weight gain to ensure coating. The capsules coated with 300 mg eudragit L100-55 in 5 ml acetone showed 9-10% weight gain and maximum drug release at the end of the 180 min. This was considered optimized formulation. The coated capsules were filled with drug and maleic acid and evaluated for drug release in the acid (pH 1.2) and alkaline (pH 6.2) media. The optimized capsules exhibited optimum dissolution profile with the maximum release of drug in the alkaline medium.