The controversy over the circumstances surrounding

Merck's

(MRK) - Get Report

withdrawal of its drug Vioxx may yield some tangible changes in regulatory policy.

The Food and Drug Administration Friday announced a review to strengthen its safety program for marketed drugs.

The FDA's top official said, "Experience has shown that the full magnitude of some potential risks has not always emerged during the mandatory clinical trials conducted before approval that evaluate these products for safety and effectiveness." Dr. Lester M. Crawford, acting FDA commissioner, added, "Occasionally, serious adverse effects are identified after approval either in post-marketing clinical trials or through spontaneous reporting of adverse events."

Crawford authorized the agency's Center for Drug Evaluation and Research to undertake a number of measures. Among other things, they would implement a program for reconciling differences of professional opinion, sponsor an Institute of Medicine study of the drug safety system, and publish risk management guidance documents.

In sum, the measures are meant to improve the chances of learning more about the side affects of drugs in actual use, a key issue in the controversy over Vioxx.

Merck withdrew the drug from the market on Sept. 30, citing a recently completed, company-sponsored study that raised questions about heart attack risks. Prior to that, however, other medical studies raised questions about the safety of the painkiller. Since the recall, reports have also questioned what Merck knew about the drug prior to making its decision. The FDA has also come under fire for approving the drug in the first place.

The recall has slammed Merck's stock, erasing more than a third of its value, and raised questions about the tenure of its Chairman and CEO Raymond Gilmartin.