Dr. John Jenkins, director of the Office of New Drugs at the agency, said he did not know why the drug might cause heart problems.

Jenkins directs the Office of New Drugs at the FDA's Center for Drug Evaluation and Research.

John Jenkins, director, Office of New Drugs, Center for Drug Evaluation and Research.

But Dr. John Jenkins, director of the Office of New Drugs at the agency, said that many drug companies who promised to undertake trials "are taking that commitment very seriously."

But she said she did not see the need for an independent safety agency, given the separation between the Office of Drug Safety and the Office of New Drugs.

Dr. John Jenkins, director of the Office of New Drugs at the F.D.A., said the science had changed.

The agency's Office of New Drugs had asked Ms. Green to determine whether eye problems that sometimes resulted from taking Avandia and a similar drug, Actos, were a serious issue.

John Jenkins, director of the Office of New Drugs in the Center for Drug Evaluation and Research, looks at changes in the way new drugs are evaluated.

This makes the Office of Drug Safety "captive," he said, to the Office of New Drugs.

Both the Office of New Drugs and the Office of Drug Safety report directly to me as the Director of the Center.