Intravenous cimetidine or two regimens of ranitidine to reduce fasting gastric acidity.

Fasting gastric pH (acidity) was measured over a 10-hour period in six patients with duodenal ulcer disease. Fasting pH was measured in a control study during which no medications were administered and in response to 300 mg of intravenous cimetidine given every 6 hours or 50 mg of intravenous ranitidine given every 6 or 8 hours. Each regimen produced gastric pH levels significantly higher than those obtained when no medication was given. Although patterns of gastric pH differed among the medication regimens, and although the ranitidine regimens maintained pH at or above 5.0 more reliably than cimetidine, there were no significant differences in mean pH, median pH, or mean hydrogen ion concentration.