- Although current concepts of ulcer pathophysiology postulate an imbalance between the principal aggressive factors of acid and pepsin and an impairment of mucosal defence, effective acid reduction by a variety of antisecretory drugs is associated with a significant acceleration of duodenal and gastric ulcer healing in controlled clinical trials. The healing of duodenal ulcer is related to the degree and duration of acid reduction with currently available H2-receptor antagonists. The highly significant correlation between the reduction of nocturnal acidity and ulcer healing reflects the ability of these drugs to inhibit basal and nocturnal acid secretion to a greater extent than stimulated daytime secretion. The extent to which the addition of daytime acid inhibition to that of nocturnal acid inhibition is responsible for further accelerating ulcer healing has not yet been determined, although a model has been proposed recently to explore this effect. Omeprazole has a marked effect on the duration and the degree of inhibition of intragastric acidity which is dose-dependent. In clinical trials of duodenal ulcer treatment, this efficacy and duration of effect is associated with an increased rate of healing and a leftward shift of the healing time curve.