<qa>  What was the major outcome parameter?During short-term study, adult U.S. students in Mexico n 310 with acute diarrhea 3 unformed stools with enteric symptoms were enrolled in a double-blind, randomized trial wherein they were given rifaximin 200 mg three times a day for 3 days R n 102, loperamide 4 mg initially followed by 2 mg after each unformed stool not to exceed 8 mgday for 2 days L n 104 or both drugs in the same dosage schedule LR n 104. The major outcome parameter was time from initiation of therapy until passage of the last unformed stool before becoming well TLUS. 