Effect of an evening dose of regular and effervescent formulations of ranitidine or cimetidine on intragastric pH in healthy volunteers.

ABSTRACT

AIMS: To compare the effects on intragastric acidity of a single evening dose of either standard or effervescent formulations of ranitidine (300 mg) or cimetidine (800 mg). METHODS: Twelve healthy subjects were studied, using a four-period randomized cross-over design and an ambulatory intragastric pH monitoring technique. The subjects received a standard evening meal at 17.00 hours and one of the H2-receptor antagonist formulations was given at 23.00 hours. RESULTS: Both effervescent formulations caused a transient rapid increase in intragastric pH, reaching a maximum at about 3 min after ingestion. After both effervescent formulations a significantly higher pH was measured during the first 45 min after ingestion (P < 0.05), compared to the regular formulations. The onset of action of the H2-receptor antagonists was similar for both formulations of ranitidine and the effervescent cimetidine, but tended to be slower for the regular cimetidine (P = 0.06). Nocturnal intragastric pH was significantly increased by all four formulations, but more effectively so by the two ranitidine formulations. The duration of action (taken as time with pH > 4) of both ranitidine formulations was longer than that of both cimetidine formulations (P < 0.002). CONCLUSIONS: A single evening dose of 300 mg ranitidine produces a stronger decrease of nocturnal gastric acid secretion than 800 mg cimetidine. The effervescent formulations of both drugs offer the advantage of a rapid decrease (within minutes) of intragastric acidity, with preservation of the sustained systemic effect.