Comparison of an intravenous bolus of famotidine and Mylanta II for the control of gastric pH in critically ill patients.

The effects of the intravenous bolus administration of famotidine versus the administration of Mylanta II liquid every 2 hours on the pH of the gastric antrum, body, and fundus for 24 hours were compared in 10 critically ill patients admitted to the intensive care unit with isolated cranial trauma. Patients received 30 mL of Mylanta II every 2 hours via nasogastric tube for 24 hours, followed by administration of 20 mg of intravenous bolus famotidine every 12 hours for the subsequent 24-hour period. pH of the gastric antrum, body, and fundus was monitored continuously using a three antimony pH electrode/nasogastric tube assembly. Gastric pH data were analyzed for the percentage of time pH was less than 4 and median pH for the antrum, body, and fundus for each 24-hour period. The percentage of time pH was less than 4 was significantly less in the antrum and body of the stomach during famotidine therapy (8.9% +/- 3.6% and 24.9% +/- 6.9%, respectively) compared with Mylanta II (39.1% +/- 6.7% and 57.6% +/- 8.5%, respectively, both p < 0.005), but was not significantly different in the fundus (famotidine: 25.3% +/- 7.8%; Mylanta II: 28.3% +/- 6.5%). Median gastric pH for 24 hours was significantly greater in the antrum and body of the stomach during famotidine therapy (7.8 +/- 0.2 and 6.8 +/- 0.6, respectively) compared with Mylanta II (4.5 +/- 0.6 and 3.7 +/- 0.9, respectively, p < 0.005 and p < 0.01, respectively), but was not significantly different in the fundus (famotidine: 5.9 +/- 0.8; Mylanta II: 5.4 +/- 0.7). The data indicate that an intravenous bolus of famotidine every 12 hours is more effective than Mylanta II liquid every 2 hours administered via a nasogastric tube in maintaining gastric pH above 4 in critically ill patients. Famotidine produces a uniform increase in gastric pH throughout the stomach, whereas Mylanta II controls only proximal gastric pH, probably related to fundic pooling of antacid in the supine position.