[Comparison of the M1-blocker with the H2-blocker regarding their effects on gastric pH and viscosity under general anesthesia].

In a prospective, controlled, randomized trial measuring the gastric juice pH and viscosity, 30 patients under general anesthesia received M1-blocker; pirenzepine or H2-blocker; ranitidine. The gastric juice pH value was significantly higher (P less than 0.05) both in the pirenzepine and the ranitidine group than in the control group. While in the pirenzepine group the viscosity of gastric juice was unchanged, in the ranitidine group it was reduced. The results suggest that pirenzepine offers more effective prophylaxis against stress ulcer than ranitidine.