Antacid versus cimetidine in preventing acute gastrointestinal bleeding. A randomized trial in 75 critically ill patients.

Over a 15-month period, 75 critically ill patients at risk of acute gastrointestinal bleeding were randomized into two groups: one group (38 patients) received the H2-blocker cimetidine intravenously at an initial dosage of 300 mg every six hours, and the other group (37 patients) received antacid (Mylanta II) through a nasogastric tube at an intial dosage of 30 ml every hour. Gastric pH was measured hourly and titrated above 3.5. Upper-gastrointestinal-tract bleeding occurred in seven of 38 cimetidine-treated patients but in none of 37 antacid-treated patients (P less than 0.01). When antacid titration was added to the cimetidine regimen in four of seven patients with bleeding, all four stopped bleeding. Renal failure, sepsis, peritonitis, hypotension, respiratory failure, jaundice, multiple trauma, and major operative procedures were associated with an increased incidence of bleeding. Cimetidine does not adequately protect seriously ill patients from acute upper-gastrointestinal-tract bleeding. Antacid is better for this purpose.