Evaluation of ranitidine as an oral antacid in outpatient anesthesia.

We studied the effects of preanesthetic ranitidine on gastric contents in 60 outpatients scheduled for elective surgery, with random allocation into three groups of 20 patients each. Patients in group 1 did not receive ranitidine and served as controls. Patients in groups 2 and 3 received ranitidine orally, 150 and 300 mg, respectively, one to five hours before induction of anesthesia. In the control group, mean pH and volume of gastric contents were 1.90 and 27.7 ml respectively. Ninety percent of the control subjects had gastric pH less than or equal to 2.5, and 65% of the patients had pH less than or equal to 1.8; 65% of the patients had gastric volumes of 20 ml or greater. Ranitidine in 150 and 300 mg doses markedly raised mean gastric pH to 6.40 and 5.87 respectively and reduced the proportion of patients with gastric pH less than or equal to 2.5 to 10% in group 2 and 0% in group 3. Mean gastric volume and proportion of patients with volume greater than or equal to 20 ml were significantly reduced in both treatment groups. Proportions of patients with combination of pH less than or equal to 2.5 and volume greater than or equal to 20 ml were significantly low in both treatment groups, as there was only one patient in group 2 and none in group 3 with both low pH and high volume. With respect to reduction of gastric acidity and volume, 300 mg of ranitidine had no advantage over 150 mg.