Abbott HIV drug being studied for possible heart harm

Two HIV drugs made by Abbott Laboratories and Roche Holding AG may be linked to heart-rhythm disorders when used together, U.S. regulators said, citing data gathered as part of a broader look at a class of medicines.

The combination of the two drugs, Abbott's Norvir and Roche's Invirase, may cause "prolonged" QT and PR intervals, measures of the heart's electrical activity, the Food and Drug Administration said today in an e-mailed statement. This may lead to a "serious" abnormal rhythm called torsades de pointes or a signaling malfunction called a heart block.

Roche, based in Basel, Switzerland, provided data in response to the agency's request that all makers of drugs known as protease inhibitors study the drugs' effect on the heart's electrical signals, the FDA said. Invirase, a member of that group, "showed a potential" for causing heart-rhythm irregularities, Terry Hurley, a spokesman for Roche's South San Francisco, California-based Genentech unit, said in an e-mailed statement.

"Health care professionals should be aware of this potential risk for changes to the electrical activity of the heart," the FDA said in its advisory. The analysis is "ongoing."

Patients shouldn't halt Invirase without talking to their doctors, the agency said. Patients who take drugs to control heart rhythm, such as quinidine or amiodarone, shouldn't take Invirase, the FDA said.

Protease InhibitorsInvirase was approved in 1995 and like other protease inhibitors it helps prevent HIV, the virus that causes AIDS, from replicating in the body. Norvir is used to boost the power of Invirase, the FDA said.Additional drugs on an FDA list of protease inhibitors, not part of the statement, are Agenerase, from London-based GlaxoSmithKline Plc; Aptivus, from German drugmaker Boehringer Ingelheim GmbH; Crixivan, from Whitehouse Station, New Jersey- based Merck Co.; Kaletra, from Abbott; Lexiva, from Glaxo; Prezista, from New Brunswick, New Jersey-based Johnson Johnson; Reyataz, from New York-based Bristol-Myers Squibb Co.; and Viracept, from Pfizer Inc., based in New York.The shares of Abbott, which is based in Abbott Park, fell 43 cents, less than 1 percent, to $53.97 at 4 p.m. in New York Stock Exchange composite trading. The American depositary receipts of Roche fell 93 cents, or 2.2 percent, to $41.30. Each receipt equals one-quarter of a regular share.Spokesmen for Abbott couldn't immediately be reached for comment.