The US Food and Drug Administration (FDA) is warning physicians against prescribing itraconazole (Sporanox) to treat fungal nail infections in patients who have congestive heart failure (CHF) or a history of CHF (www.fda.gov/cder/drug/advisory/sporanox-lamisil/advisory.htm). It also warns that itraconazole and terbinafine hydrochloride (Lamisil) have been associated with serious liver problems.
Recent studies indicate that itraconazole may weaken the force of the heart's contractions. This effect was observed when the drug was injected into anesthetized dogs and healthy human volunteers. In these studies, the adverse effect resolved once use of the drug stopped.
Since becoming aware of those findings, the FDA analysed US and international postmarketing adverse event reports involving itraconazole that were received between its approval in 1992 and April 2001. It received 94 reports in which patients receiving the drug developed CHF, and thinks itraconazole contributed to or may have been the cause of CHF in 58 of the 94 patients.
The advisory also alerts physicians about rare cases of serious liver disease, including liver failure, associated with the use of itraconazole products and terbinafine tablets. It says physicians should obtain nail specimens for laboratory testing to confirm the diagnosis of fungal nail infections before prescribing either medication.
CMAJ now posts FDA warnings at www.cma.ca/cmaj/FDA-Advisory/index.htm.