Cimetidine Versus Ranitidine: Single-Dose, Oral Regimen for Reducing Gastric Acidity and Volume in Ambulatory Surgery Patients

Abstract

This placebo-controlled trial compared the efficacy of single oral doses of cimetidine or ranitidine in maintaining intragastric pH and volume >2.5 and <25 ml, respectively, in ambulatory surgery patients requiring general anesthesia. Patients were randomized to receive either placebo, ranitidine HC1 150 mg, or cimetidine HCI 400 mg upon rising on the morning of surgery. At induction, the cimetidine and ranitidine groups had significantly higher (p<0.05) gastric pH values than the placebo group. At extubation, the ranitidine group had a significantly higher (p < 0.05) gastric pH than either the cimetidine or placebo group. Both H,-blocker groups had lower volumes when compared with the placebo group at extubation (p < 0.05). There were more patients at risk for aspiration pneumonitis (pH < 2.5 and/or volume >25 ml) in the cimetidine group (4ft percent) than in the ranitidine group (15 percent). All placebo-treated patienis were at risk for aspiration pneumonitis. Wc did not find subjective clinical evidence of aspiration pneumonitis in our patients. We conclude that both ranitidine and cimclidinc arc superior to placebo, but ranitidine may be the preferred agent because ol its more consistent effcct on gastric pH and volume