Absence of in vivo and in vitro interactions of an aluminum hydroxide, magnesium hydroxide containing antacid with cimetidine in patients with peptic ulcer.

In view of contradictory reports on the bioavailability of cimetidine in the presence of concomitantly administered antacids we studied the areas under the plasma concentration time curves (AUC) of cimetidine, the maximal concentrations (cmax) and the time, at which cmax was reached (tmax) in eight patients (five patients with duodenal ulcer, three patients with gastric ulcer) with and without the administration of an aluminum hydroxide magnesium hydroxide containing antacid (Maaloxan). No significant effects of the antacid on AUC, cmax and tmax of cimetidine were found. In vitro studies also showed no adsorption of cimetidine to aluminum hydroxide, magnesium hydroxide or the antacid.