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COMPARISON OF NEW AND OLD OVER-THE-COUNTER REMEDIES FOR GASTRIC ACID.

Now that histamine blockers are available over the counter at non-prescription strength, people must often choose between these newer agents and older antacids. This randomized, double-blind, placebo-controlled trial compared famotidine (Pepcid AC, 10 mg), calcium carbonate antacid tablets (Tums), and placebo in 18 healthy volunteers.

The subjects were given two meals at 2.5 and 6 hours after taking the medications, while intragastric pH was maintained at 4.0 through an infusion of sodium bicarbonate. The amount of sodium bicarbonate required to maintain this pH was used to assess the effectiveness of the therapy.

Both famotidine and calcium carbonate lowered the need for sodium bicarbonate by about the same amount, but with different time profiles: calcium carbonate had its peak effects during the first 30 minutes after administration and lasted only 60 minutes, while the onset of famotidine's effect began at 90 minutes and lasted at least 6 hours.

Comment: These data indicate that calcium carbonate may be the right over-the-counter medication when immediate relief is sought, but famotidine can be used for longer relief or prevention. Their combination cannot be recommended, since antacids may reduce absorption of the histamine blocker.

— TH Lee

Published in Journal Watch General Medicine May 31, 1996

Citation(s):

Feldman M. Comparison of the effects of over-the-counter famotidine and calcium carbonate antacid on postprandial gastric acid: a randomized controlled trial. JAMA 1996 May 8 275 1428-1431.

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