In vitro interaction studies of diltiazem with H2 receptor antagonists

Abstract

Diltiazem is a well-known cardiovascular drug that is used clinically for the treatment of angina pectoris and hypertension. H2-receptor antagonists are used to treat gastroesophageal reflux, gastric and duodenal ulceration. In vitro interaction studies of diltiazem with H2-receptor antagonists (cimetidine, ranitidine, and famotidine) were investigated by using spectrophotometric and RP-HPLC techniques. The availability of diltiazem was found to be influenced considerably in presence of H2-receptor antagonists. The effect of various dissolution mediums, simulating body environments with respect to pH on these interactions was examined to elucidate the mechanism of these interactions. Moreover, diltiazem-H2 receptor complexes were synthesized to confirm the interaction of these drugs. The complexes formed were then characterized by IR spectroscopy and verified by computational molecular modeling.