Postmarketing case reports of sudden hearing loss have prompted the Food and Drug Administration (FDA) to request a revision to the labeling of the erectile dysfunction drugs sildenafil (Viagra), vardenafil (Levitra), and tadalafil (Cialis). The revision will also be made to the labeling of Revatio, the formulation of sildenafil used to treat pulmonary arterial hypertension.

While loss of hearing had been identified as a possible adverse effect of the drugs, which inhibit the enzyme phosphodiesterase type 5 (PDE5), the statement was buried amidst label information on all possible, rare adverse effects. It's now more prominently displayed under the Postmarketing Experience subheading in the Adverse Reactions section. Although it has not been confirmed that the drugs cause hearing loss, an association seems clear enough to warrant the label revision.

According to the reports, the loss of normal hearing occurred usually in one ear, was either partial or complete, and was temporary in one-third of cases. In the rest it was either ongoing or the outcome was not described. Nurses should inform patients taking one of the PDE5 inhibitors that they should discontinue using it and contact the prescriber if sudden loss of hearing occurs. Patients who take a PDE5 inhibitor to treat pulmonary hypertension should not discontinue use of the drug if the effect occurs; pulmonary hypertension is possibly life threatening. But such patients should be instructed to contact the prescribing provider.

The FDA has also received 30 postmarketing reports of acute pancreatitis in patients taking exenatide (Byetta), an injectable noninsulin drug used in the treatment of type 2 diabetes mellitus in adults. The drug's labeling will be revised to include in the Precautions section information concerning the elevated risk. Nurses should assess patients taking exenatide for symptoms and signs of acute pancreatitis--persistent severe abdominal pain that can radiate to the back, possibly accompanied by nausea and vomiting, and elevated serum levels of amylase or lipase (or both). The use of exenatide should be discontinued if acute pancreatitis is suspected and not resumed if the condition is confirmed without identification of another cause.

Center for Drug Evaluation and Research. FDA alert: Information for healthcare professionals. Exenatide (marketed as Byetta). Rockville, MD: U.S. Food and Drug Administration; 2007 Oct. http://www.fda.gov/cder/drug/InfoSheets/HCP/exenatideHCP.htm; FDA announces revisions to labels for Cialis, Levitra and Viagra: Potential risk of sudden hearing loss with ED drugs to be displayed more prominently. FDA News 2007 Oct 18. http://www.fda.gov/bbs/topics/NEWS/2007/NEW01730.html.