The effects of single doses of cimetidine, famotidine, and ranitidine on gastric acid and fluid secretions in 12 critically ill, mechanically ventilated patients were evaluated in a prospective, randomized, crossover, single-blind trial. Each patient received an intravenous dose of cimetidine 300 mg, famotidine 20 mg, or ranitidine 50 mg diluted in 50 mL of normal saline and infused over 30 minutes. Each agent was administered in crossover fashion on consecutive days after the pH returned to baseline. Analysis of gastric fluids and pH measurements were determined from gastric samples collected every 15 minutes. Cimetidine, famotidine, and ranitidine treatment resulted in significant increases in gastric pH and decreased fluid production and total aspirated fluid volume. Famotidine maintained a gastric pH ≥4.0 for a mean duration of 16.5 ± 4.1 hours, significantly longer (P < 0.01) than cimetidine (2.3 ± 1.3 hours) or ranitidine (4.9 ± 0.8 hours). The percent of pH readings ≥4.0 was significantly (P < 0.01) greater for famotidine (88.0%) compared with cimetidine (38.5%) and ranitidine (55.6%). In critically ill patients given a single intravenous dose, famotidine suppressed acid secretion to a greater degree and for longer time periods than with either cimetidine or ranitidine.
ASJC Scopus subject areas
- Pharmacology (medical)