The number of look- or sound-alike drug names is growing, according to the 8th annual national MEDMARX Data Report released by the U.S. Pharmacopeia (USP). For the 2008 report, researchers reviewed more than 26,000 records submitted to the MEDMARX database from 2003 to 2006 and compiled a list of 3,170 pairs of drug names that look or sound alike. That figure is nearly twice the 1,750 pairs researchers identified in 2004. Among their other findings:

* The top 10 most commonly prescribed drugs in the U.S. are often confused with at least 1 other drug.

* Some drug names sound or look very similar to more than one other drug, such as Vioxx, Ziox, and Zyvox.

* The antibiotic cefazolin has been confused with 15 other drugs.

* Only about 1% of drug errors harmed patients according to this study, but researchers believe that this figure is low because drug errors are underreported.

In response to their findings, USP is asking prescribers and pharmacists to include an "indication for use" on all prescriptions. Also, USP recommends that prescribers use trustworthy decision-support tools, such as Epocrates Rx drug reference, to help prevent errors.