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

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Abstract
SUMMARY: 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.