The Food and Drug Administration (FDA) has suggested more clinical trials to back up Watson Pharmaceuticals' New Drug Application (NDA 22-139) for Progesterone Vaginal Gel 8%.

The product is used for reducing risk of pre-term birth in women with a singleton gestation and short uterine cervical length in the mid-trimester of pregnancy.

Watson Pharmaceuticals, Inc. (NYSE:WPI) and Columbia Laboratories, Inc. (Nasdaq: CBRX) have confirmed receiving a complete response letter from the FDA regarding the issue in a press release.

The FDA has said a single trial of the product is not enough to prove the effect of the treatment. So it cannot meet up the statistical level expected for the approval of the product in the U.S. market.

The strength of the efficiency of the drug in a small group compared to the overall efficiency of the trial has also been pointed out.

Paul M. Bisaro, Watson President and CEO, believes the need of a safe and effective medication to solve the pre-term birth issues and looks forward to work directly with the FDA to solve the issues raised by them.

According to Bisaro, pre-term birth affects approximately one-in-eight live born infants in the U.S.

Watson has conducted a pregnant study and compared the possibility of pre-term risk in pregnant women treated with Progesterone Gel 8% and those treated with Placebo. This study included women with and without a prior history of pre-term birth.