Sustained fasting achlorhydria: a comparison of medical regimens.

The effects on fasting gastric pH of eight medical regimens were evaluated during a 10-h period in 8 duodenal ulcer patients. Our goal was to find a regimen that would produce sustained, fasting achlorhydria (pH greater than 7.0) in every patient. The effects of commonly prescribed bolus doses of cimetidine, antacid, or their combination were studied first. Mean gastric pH with cimetidine (300 mg/6 h intravenously), antacid (30 ml/h intragastrically), and their combination was 3.5, 4.6, and 6.8, respectively. Although mean pH with the combination was significantly higher than with either drug alone (p less than 0.05), sustained achlorhydria was not achieved. Next we tested constant-infusion regimens of cimetidine (50 mg/h intravenously), antacid (0.5 ml/min intragastrically), and their combination. Whereas infusions of cimetidine or antacid alone produced mean pH levels of 4.3 and 5.2, respectively, not significantly different from their bolus counterparts, the combination regimen resulted in a mean pH of 7.4. However, sustained achlorhydria was still not produced in each patient. Only when the dose of cimetidine infusion was doubled to 100 mg/h and administered with a constant infusion of antacid was sustained achlorhydria achieved in each patient.