HIV antiviral medication Invirase (saquinavir) when taken in combination with Norvir (ritonavir), also an HIV antiviral, can increase the risk of life-threatening heart rhythm abnormalities, triggering the FDA (Food and Drug Administration) to announce the addition of new safety information to Invirase’s labeling. Saquinivir is a protease inhibitor class medication which is marketed in two formulations, hard-ger capsule formulation of the mesylate (Invirase) – taken with ritonavir to increase saquiavir’s bioavailability, and a soft-gel capsule (Fortovase).
In February of this year the FDA warned clinicians and patients that the drug combination could cause QT and PR interval prolongation (electrocardiogram heart rhythm activity indicators). QT interval refers to a measure (time) between the start of the Q wave and the end of the T wave in the heart’s electrical cycle. The PR interval shows how long the electrical impulse takes to travel from the sinus node through the AV node and entering the ventricles (in the heart).
Patients with QT prolongation can develop torsades de pointes, a type of ventricular tachycardia that exhibits distinct characteristics on the electrocardiogram (abnormal heart rhythm). There is a higher risk of ventricular fibrillation, an irregular heart rhythm which can be fatal. Patients with torsades de pointes may experience lightheadedness or fainting.
PR interval prolongation can lead to heart block (or AV block), and the patient may experience lightheadedness, syncope (fainting), and palpitations. Heart block is an electrical fault in the heart.
The FDA announced that there will also be a medication guide for individuals taking Invirase; the guide will explain these possible risks. Patients with existing heart rate/rhythm problems, as well as those with underlying heart conditions are have a higher risk of developing one of the serious heart events described above.
Edward Cox, M.D., M.P.H, director, Office of Antimicrobial Products in FDA’s Center for Drug Evaluation and Research, said:
“These heart conditions could potentially be life-threatening and we want to assure that health care providers and patients are adequately informed of the risks. Patients should talk to their doctor if they have any concerns about their treatment. Certain drugs may interact with Invirase and increase the risk of developing these side effects, so patients should be sure to tell their doctor about other medicines they may be taking, including non-prescription medicines, vitamins, and herbal supplements.
Side effects from Invirase use experienced by patients or identified by clinicians should be reported to the FDA’s
Invirase, which is sometimes used with other medications for HIV treatment, apart from Norvir, was approved by the FDA in 1995.
In a communiqué, the FDA emphasizes that Invirase does not cure or prevent HIV infection, neither does it prevent the transmission of HIV infection to other people.
Invirase is manufactured and marketed by Genentech (part of Roche Group), San Francisco, California, and Norvir is manufactured and marketed by Abbot Laboratories, Abbot Park, Illinois.
Source: FDA
Written by Christian Nordqvist