Failure to demonstrate effectiveness of an anticholinergic drug in the symptomatic treatment of acute travelers' diarrhea.

Seventy adults in the United States with acute diarrhea who were attending classes in Guadalajara, Mexico, enrolled in a double-blind placebo-controlled treatment study of an anticholinergic drug, mepenzolate bromide (MZB). Thirty-five patients received MZB (50 mg) and 35 received placebo each taken 4 times daily for 48 hours. No significant difference was detected between the MZB- and placebo-treated patients in symptoms or in the frequency or character of stools. Recovery rates of 24.1% and 31% for placebo- and MZB-treated patients were similar. Despite the occurrence of anticholinergic side effects in 51% of MZB- versus 14% of placebo-treated patients (P less than 0.001), therapeutic efficacy was not detected. We do not recommend anticholinergic drugs for therapy in acute infectious diarrhea.