Comparison of low-dose antacids, cimetidine, and placebo on 24-hour intragastric acidity in healthy volunteers.

Low-dose aluminium (Al) antacids are effective in promoting ulcer healing and symptomatic relief in peptic ulcer patients, although the effect on intragastric acidity is very weak. In this randomized, double-blind study, 24-hr intragastric acidity was compared in 11 healthy volunteers, treated with a low-dose Al antacid regimen (1 tablet four times a day), cimetidine (800 mg at bedtime) and placebo, using the double-dummy technique. Standardized meals were given at 8 AM, noon, and 5 PM. Medication was given 1 hr after meals and at bedtime. Intragastric acidity was recorded with a nasogastric monocrystant antimony pH catheter, connected to an ambulatory digital data recorder. No significant difference in intragastric acidity was observed between antacid and placebo treatment. Treatment with cimetidine reduced circadian and nocturnal (but not diurnal) intragastric acidity significantly, as compared to both placebo and antacid treatment. The results support the hypothesis that Al antacids promote peptic ulcer healing by other mechanisms than acid neutralization.