Optimer Pharmaceuticals Inc’s experimental antibiotic is safe and effective in treating a bacterial infection that causes diarrhea, a U.S. advisory panel said on Tuesday.

The advisory panel of 13 independent experts voted unanimously that the drug was effective but said there were concerns regarding the drug’s use in pregnant women and children.

However, the panel was divided on whether the oral drug, fidaxomicin, was also effective in lowering the risks of recurrence of infection-related diarrhea.

Last week, the U.S. Food and Drug Administration staff said the drug was effective in fighting an infection that causes a life-threatening diarrhea.

The FDA is expected to give its decision on the drug by May 30. A positive vote by the panel does not guarantee an approval, but the agency usually follows panel recommendations.

The drug aims to treat diarrhea caused by C. difficile infection (CDI,) a serious illness caused by infection of the lining of the colon. It afflicts more than 700,000 people each year in the United States, according to the company.

Late-stage trials of the drug had shown that it was as effective as the only FDA-approved drug for treating CDI - ViroPharma Inc’s Vancocin.

Optimer has a deal with Japan’s Astellas Pharma Inc on the drug. Astellas holds the rights to develop and sell the drug in Europe and parts of the Middle East and Africa.

Trading in the company’s shares was halted pending news of the panel’s decision.

(Reporting by Esha Dey and Lisa Richwine)

###

SILVER SPRING, Maryland