GASTRIC-ACID SUPPRESSION IS GREATER DURING INTRAVENOUS RANITIDINE INFUSION VERSUS BOLUS INJECTIONS OF FAMOTIDINE

It has been proposed that famotidine may be effective in maintaining i ntragastric pH greater than or equal to 4 for up to 12 h with a single i.v. 20 mg bolus injection and thereby prevent acute stress-related m ucosal haemorrhage. The present study was designed to compare a raniti dine continuous i.v. infusion (6.25 mg/h) vs. famotidine bolus injecti on (20 mg every 12 h) on 24-h intragastric pH and gastric acid secreti on. Twenty-eight healthy volunteers (15 males, 13 females: 20-56 years ) participated in two 24-h treatment periods; each test was in random order separated by 7-10 days. After an overnight fast, subjects were i ntubated and gastric pH and acid secretion measured hourly. Whereas ra nitidine maintained gastric pH above 4 for the entire 24-h period, mea n pH steadily decreased to a nadir of 2.9 and 3.7, respectively, 12 h after each famotidine injection (P < 0.01 vs. ranitidine). Furthermore , gastric acid secretion increased to 4.4 +/- 1.2 mmol/h 12 h after fa motidine injection compared to 1.1 +/- 0.3 mmol/h with ranitidine (P < 0.01). We conclude that ranitidine delivered as a continuous i.v. inf usion (6.25 mg/h) is superior to bolus famotidine injections (20 mg) a t 12-h intervals in suppressing gastric acid secretion and maintaining an intragastric pH greater than or equal to 4. More frequent famotidi ne dosing, or delivery by continuous i.v. infusion, may be required to provide prolonged acid suppression.