The FDA has released a statement notifying physicians and patients that the combination of saquinavir and ritonavir can lead to abnormal heart rhythm.
The FDA has notified the public that new risk information has been added to the label of the antiviral drug Invirase (saquinavir) describing a potential change in the electrical activity of the heart when it is used with another antiviral medication, Norvir (ritonavir). Changes in the electrical activity of the heart may lead to abnormal heart rhythms, it said in a statement last week.
Earlier this year, the FDA announced it was reviewing clinical trial data about a potentially serious effect on the heart from the use of Invirase in combination with Norvir.
The new risk data has been added to the “Warnings and Precautions, Contraindications, and Clinical Pharmacology” sections of the Invirase label. In addition, the FDA will require that a Medication Guide that includes information on the risk of abnormal heart rhythms is given to patients when picking up a prescription for Invirase.
The medications are given together to treat HIV infection; Norvir must be given at a low dose in order to increase the level of Invirase in the body. However, when used together, the two drugs can cause prolongation of the QT and/or PR intervals. Each of these changes in the heart's normal electrical activity can be detected readily on an electrocardiogram, or EKG.
According to the FDA, prolongation of the QT interval can precipitate torsades de pointes, a type of ventricular tachyarrhythmia that may be self-limited or progress to ventricular fibrillation. Prolongation of the PR interval can lead to heart block of varying degree (first, second or third). Recent data from the Framingham Heart Study indicate that even first-degree heart block, once considered largely benign, increases a patient's risk of developing atrial fibrillation, of needing a pacemaker inserted or of early death.
Patients with either type of prolongation may experience lightheadedness, fainting, or heart palpitations. Those who have underlying heart conditions or existing heart rate or rhythm problems are at greater risk for these cardiovascular events.
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