The initially recommended dosage of prescription drugs is often twice that needed for safe and effective use in clinical practice, according to two new studies by researchers in the United States and the Netherlands. Both studies were recently published in the online version of the journal Pharmacoepidemiology and Drug Safety.
In one study, researchers at the Food and Drug Administration (FDA) in Rockville, Md, and Georgetown University Center for Drug Development Science in Washington, DC, studied label changes for 354 "new molecular entities" (new drugs containing an active substance not previously approved for marketing in any form in the United States) that received FDA approval between 1980 and 1999 (Pharmacoepidemiol Drug Saf. DOI: 10.1002/pds.744). They discovered that the initially recommended dosage for 21% of the drugs was later changed, and that the overwhelming proportion of such changes (70%) were dosage decreases made for safety reasons.
Stephenson J. New Drugs' Dosages Often Too High. JAMA. 2002;288(13):1578. doi:10.1001/jama.288.13.1578-JMN1002-3-1