Antacids: the past, the present, and the future.

Antacids have served us well for over a century. The attitude in the late 1950s to 1970s that antacids should be taken only on demand was unjustified and was based on what can be seen nowadays as misinterpretation of scientific data. Twelve recent endoscopic controlled studies have confirmed the efficacy of antacids in the healing of duodenal ulcer, achieving about 75% healing in 4 weeks. Like H2-receptor antagonists, the efficacy of antacids in the healing of gastric ulcers is controversial, most probably related to the even greater pathogenetic heterogeneity of this condition. Antacids should be given at least four times a day and at least 1 hour after meals, since their therapeutic success most likely depends on neutralization of postprandial acid secretion. In vivo, the newer tablet forms are indistinguishable from the liquid forms in terms of neutralizing efficiency and healing efficacy. The ideal dose is one that neutralizes 400 mmol of acid. Combination with an anticholinergic drug is effective and a recent report suggests that this may lead to longer remission than with H2-receptor antagonists. As a long-term therapy, antacids appear to work but need to be taken in multiple daily doses, a regimen which is unlikely to meet with long-term patient compliance. The success of antacids in duodenal ulcer healing should alert us to the importance of controlling the meal-stimulated acid secretion in ulcer therapy, and to the hard fact that acid is a non-permissive factor in ulcer healing.