Medical researchers and doctors often discover effective "off-label" uses for drugs in addition to the narrow purposes approved by the Food and Drug Administration (FDA) and printed on the label or package insert. Off-label uses are tested by other researchers, published in medical journals, discussed in symposia and even appear in medical textbooks and are taught to medical students.

However, since 1991, the FDA has prohibited drug manufacturers from telling doctors about drugs' off-label uses. The FDA threatens product seizure, injunctions and prosecution. Manufacturers must even be careful about distributing reprints from medical journals. This particularly affects the poor, whose doctors may lave less access to expensive research journals or on-line services. As a result:

• Tens of thousands of middle-aged men died of heart attacks because for years the FDA prevented manufacturers from informing doctors about the many studies that showed that taking aspirin daily reduced the risk of heart attack.

• Research indicates that Doxil, an FDA-approved drug for AIDS patients, may be effective in treating ovarian cancer, but manufacturers cannot inform doctors of that finding.

The American Medical Association estimates that up to 60 percent of all drug prescriptions are for off-label uses. In cancer therapy, up to 70 percent of prescriptions are for off-label uses, and in pediatrics the figure may be as high as 90 percent.