Feds Issue Med Warning

The U.S. Food and Drug Administration announced preliminary data suggesting that Invirase (saquinavir) in combination with Norvir (ritonavir) may have potentially important adverse effects on the heart.

When used together, the drugs may cause prolongation of the QT and PR intervals on an electrocardiogram. Prolongation of the QT interval may lead to a condition known as torsades de pointes, an abnormal heart rhythm. Prolongation of the PR interval may also lead to an abnormal heart rhythm known as heart block. With torsades de pointes or with heart block, patients may experience lightheadedness, fainting, or abnormal heart beats. In some cases, torsades de pointes may progress to a life-threatening irregular heart beat known as ventricular fibrillation.

Review of the data is ongoing. Preliminary findings suggest that some patients using Invirase and Norvir may be at an increased risk for heart abnormalities leading to irregular heart rhythms. For example, the risk for torsades de pointes may be increased in patients who are also using medications known to cause a heart disturbance called QT interval prolongation. The risk may also be increased in patients who have a history of QT interval prolongation.

Patients using Invirase should talk to their health care professional about any questions or concerns they have about Invirase. Patients and health care professionals should report any side effects from the use of Invirase to the FDA's MedWatch program. Invirase is an antiretroviral medication that was first approved in 1995. Invirase is used in combination with Norvir and other antiretroviral medicines to treat HIV in adults. Invirase does not cure HIV infection, may not prevent you from developing HIV-related illnesses, and may not prevent you from spreading HIV to other people.

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

Invirase is marketed by San Francisco-based Genentech, a subsidiary of the Roche Group. Norvir is marketed by Abbott Park, Ill.-based Abbott Laboratories.