The practice of off-label use of prescription medications occurs in approximately 1 in every 5 scripts filled in the United States. This practice is potentially risky because 75% of these off-label uses do not have extensive scientific support, according to study results reported in the Archives of Internal Medicine (May 8, 2006). Once the FDA approves a drug for 1 indication, physicians can prescribe it for other uses.

For the study, the researchers determined the frequency of and reasons for off-label use by looking at a 2001 survey that examined patterns for 160 routinely prescribed drugs from office-based physicians. That year, there were an estimated 150 million off-label scripts written, or 21% of the total. Of those, 27% were for indications supported by scientific evidence. Yet, the remaining 73% (109 million prescriptions) had little or no evidence supporting the use in question.

The investigators concluded that off-label use needs better scrutiny. Physicians, too, need to be alert to the potential positive and negative outcomes. This type of surveillance, lead author Randall Stafford, MD, PhD, said, "would be particularly important for off-label uses which haven't gone through that initial step of being reviewed by the FDA."