UPDATE 1-Optimer says diarrhea drug effective in trial

(New throughout, adds share detail)

July 16 (Reuters) - Optimer Pharmaceuticals Inc (OPTR.O) said its experimental treatment for infectious diarrhea, Prulifloxacin, was effective in a late-stage trial.

The San Diego-based company said patients taking the drug did not have unformed stool for about 24 hours, which was significantly different from patients on a dummy treatment, meeting the main goal of the study.

Prulifloxacin, taken orally once daily over three days, was generally well tolerated and had a safety profile similar to placebo, the company said.

The study was conducted in Mexico and Peru, and tested adult travelers suffering from infectious diarrhea.

The company said it was the first of two clinical studies being carried out in preparation for a New Drug Application to the U.S. Food and Drug Administration.

Shares of Optimer closed at $7.88 Tuesday on Nasdaq. (Reporting by Varsha Tickoo in Bangalore; Editing by Bernard Orr)