Continuous intragastric pH monitoring: a real progress in the assessment of antisecretory drugs

Abstract

24 hour intragastric pH recording by means of an indwelling minielectrode which is connected to an ambulatory apparatus is unquestioned in the assessment of the pharmacodynamic properties of potent antisecretory drugs. pH measurements obtained with this continuous monitoring have been shown to be more accurate than those provided by the traditional hourly nasogastric aspiration method. We used this technique to evaluate the effects on gastric acidity of placebo, ranitidine 150mg, famotidine 20mg and nizatidine 150mg in fifteen patients with healed duodenal ulcer. These medications were orally administered at 22:00hr in a double-blind fashion on four separate occasions at least one week apart. All H2-receptor blockers were more effective than placebo in suppressing both circadian (p less than 0.001) and nocturnal (p less than 0.0001) gastric acidity, while there was no significant difference between the effects of the three active agents in the same time periods. During morning hours (8:00-12:00) both ranitidine and nizatidine did not differ from placebo, and famotidine produced more acid inhibition than nizatidine (p less than 0.03). However, in the same period the percent of time spent above pH 4.0 was significantly superior (p less than 0.00001) for both famotidine (33%) and ranitidine (14.2%) with respect to nizatidine (6%) and placebo (8.4%). Therefore, after bedtime dosing, the action of nizatidine is more confined to the nocturnal period than those of ranitidine and famotidine.