EFFECT OF AN EVENING DOSE OF REGULAR AND EFFERVESCENT FORMULATIONS OFRANITIDINE OR CIMETIDINE ON INTRAGASTRIC PH IN HEALTHY-VOLUNTEERS

Aims: To compare the effects on intragastric acidity of a single eveni ng 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 ambu latory intragastric pH monitoring technique. The subjects received a s tandard evening meal at 17.00 hours and one of the H-2-receptor antago nist formulations was given at 23.00 hours. Results: Both effervescent formulations caused a transient rapid increase in intragastric pH, re aching a maximum at about 3 min after ingestion. After both effervesce nt formulations a significantly higher pH was measured during the firs t 45 min after ingestion (P < 0.05), compared to the regular formulati ons. The onset of action of the H-2-receptor antagonists was similar f or both formulations of ranitidine and the effervescent cimetidine, bu t 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 durat ion of action (taken as time with pH > 4) of both ranitidine formulati ons was longer than that of both cimetidine formulations (P < 0.002). Conclusions: A single evening dose of 300 mg ranitidine produces a str onger decrease of nocturnal gastric acid secretion than 800 mg cimetid ine. The effervescent formulations of both drugs offer the advantage o f a rapid decrease (within minutes) of intragastric acidity, with pres ervation of the sustained systemic effect.