To the Editor.
—The article by Dr Feldman1 compares the acid-reducing capacities of over-the-counter famotidine with calcium carbonate antacid. We have confidence in Feldman's overall findings as they pertain to the relative duration of effects of each agent on gastric acidity; however, one should exercise great caution before extrapolating the findings from a highly controlled, pharmacodynamic assessment of gastric acidity to an interpretation of clinically relevant symptom relief.The results of several large symptom-based heartburn studies contradict the reported delayed onset of famotidine's antisecretory action in the article by Feldman. These studies clearly demonstrated the efficacy of low-dose famotidine both in treating and in preventing heartburn symptoms in a far earlier time frame than suggested by Feldman's pharmacodynamic data. In 2 such studies2 (N. Laird, PhD, written communication, March 26, 1996), data collected from 1100 patients with heartburn demonstrated significant symptom relief (vs placebo) as early as 15