Tom Murphy
Newswire21.org

A popular drug "cocktail" used to treat HIV may cause heart problems, the Food and Drug Administration reported.

The use of Invirase with Norvir raised the risk of abnormal heart rhythms, according to preliminary analysis of new data, the agency said.

The FDA said the drug could prolong the QT and PR intervals in an electrocardiogram. A longer QT interval can trigger an abnormal rhythm called torsades de pointes, while a prolonged PR interval can cause a problem called heart block.

With either condition, patients may faint or feel lightheaded, and in some cases, torsades de pointes may develop into a life-threatening problem called ventricular fibrillation, in which the muscles around the heart's ventricle quiver instead of contracting properly.

The agency didn't say how many people are believed to be taking the drugs in combination. About 1.1 million Americans were living with HIV at the end of 2006, according to the CDC.

The warning comes as Congress is delving in why the FDA and GlaxoSmithKline allowed the diabetes drug Avandia to remain on the market after finding it triggered 83,000 heart attacks from 1999 to 2007. Invirase is made by Genentech, a division of Roche, while Norvir comes from Abbott Labs. 

The agency didn't say whether this early warning on the HIV drugs - based on preliminary findings - was triggered by recent criticism, but suggested the agency will aggressively release information about possible risks.

"This early communication is in keeping with FDA's commitment to inform the public about ongoing safety reviews of drugs," the agency's statement said. "FDA will communicate its findings to the public as soon as the review is complete."

Antiretrovirals
Invirase, known by the generic name saquinavir, belongs to a class of drugs called antiretroviral medications and was first approved 15 years ago. it is sued with Norvir and other antiretroviral drugs to manage HIV in adults, but neither cures nor prevents the development of HIV-related illnesses.

"Patients using Invirase should talk to their health care professional about any questions or concerns they have about Invirase," the FDA said in a statement, urging patients and health professionals to report any side effects to the FDA's MedWatch program.

The agency also released its data on this issue and provided and toll-free number for consumer who have questions: 888-Info-FDA.