The Food and Drug Administration is responsible for making sure that the drugs we take are safe and effective. But these terms are not as absolute as many people think. We talk with Dr. Alastair Wood, professor of pharmacology and medicine at Vanderbilt University School of Medicine. He chaired the expert panel that considered the safety issues surrounding Bextra, Celebrex and Vioxx. The committee recommended that Vioxx be returned to the market. We also talk with Dr. Jerry Avorn. He is a pharmacoepidemiologist at Harvard Medical School. His new book is Powerful Medicines:Benefits, Risks and Costs of Prescription Drugs.