New Warning of Cardiac Risk Added to Saquinavir Label


October 21, 2010

October 21, 2010 — The US Food and Drug Administration (FDA) is revising the label of saquinavir (Invirase; Genentech) to warn that taking the anti-HIV drug with ritonavir (Norvir; Abbott Laboratories) could lead to life-threatening abnormal heart rhythms, the agency announced today.

The 2 drugs, both protease inhibitors, are given together to treat HIV infection, with ritonavir serving to boost the level of saquinavir in the body.

In February, the agency announced that it was studying clinical trial data about the potential risk of the drug combination altering the heart's electrical activity. A review of the data eventually showed that saquinavir and ritonavir may prolong either the PR or QT intervals of the heart, possibly leading to abnormal heart rhythms, the FDA said.

Specifically, prolongation of the QT interval may cause torsades de pointes, which may progress to potentially fatal ventricular fibrillation. Prolongation of the PR interval may trigger an abnormal rhythm called heart block.

Patients with either torsades de pointes or heart block may experience light-headedness, fainting, or abnormal heartbeats. The agency is advising clinicians to instruct patients who are receiving the combination therapy to seek medical care immediately if they have such symptoms.

Clinicians also should perform an electrocradiogram before treating patients with saquinavir and ritonavir, according to the FDA. Patients with a QT interval greater than 450 msec should not start on the drug combination. Patients given the drug combination should receive an electrocradiogram after 3 or 4 days of therapy. If the QT interval exceeds 480 msec, or if prolongation increases by 20 msec more than the pretreatment level, patients should discontinue treatment.

In addition to the label change for saquinavir, the FDA is requiring that patients receive a medication guide explaining the cardiovascular risks associated with the 2 drugs.

More information about today's announcement is available on the FDA Web site.

To report adverse events related to saquinavir, contact MedWatch, the FDA's safety information and adverse event reporting program, by telephone at 1-800-FDA-1088, by fax at 1-800-FDA-0178, online at, or by mail to MedWatch, FDA, 5600 Fishers Lane, Rockville, Maryland 20852-9787.


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