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On February 23, 2010, The U.S. Food and Drug Administration (FDA) issued a warning about potential heart risks when combining two HIV drugs.(1) FDA is reviewing clinical trial data about a potentially serious effect on the heart from the use of Invirase (saquinavir) in combination with Norvir (ritonavir). The data suggest that together the two drugs may affect the electrical activity of the heart. In some cases, the problem can cause irregular heart rhythms, leading to lightheadedness, fainting, and even death.
Invirase was approved in 1995 and is marketed by Genentech, the biotech unit of Swiss drug maker Roche, and the drug is used in combination with Norvir and other anti-viral drugs to control HIV in adults. Norvir is given at a low dose to boost the level of Invirase in the body.
The FDA made its announcement after reviewing data submitted by Roche about the heart activity of patients using its drug with Abbott’s Norvir. The agency said its review is ongoing and patients should not stop taking Invirase without talking to their doctor.
Data Summary
The clinical trial study data were submitted by Roche, the manufacturer of Invirase, based on FDA's request that all manufacturers of protease inhibitors, including Invirase, conduct a thorough QT study to evaluate the effect these drugs have on the QT and PR intervals.
The preliminary data show that when Invirase boosted with Norvir (1000mg/100mg) was given to healthy patients, ages 18 to 55 years, there was a dose-dependent prolongation of the QT and PR intervals. The magnitude of the effect and clinical implications of QT and PR interval prolongation are still being reviewed by FDA.
These findings suggest that some patients using Invirase boosted with Norvir may be at an increased risk for developing abnormal heart rhythms. In particular, this risk may be increased in patients using other medications known to cause QT interval prolongation, such as Class IA and Class III antiarrhythmic drugs or in patients with a history of QT interval prolongation.
FDA recommends that healthcare professionals:
- Not use Invirase in patients with a history of QT interval prolongation, preexisting conduction system disease, ischemic heart disease, cardiomyopathy, or underlying structural heart disease.
- Not use Invirase in patients who are currently using Class IA (such as quinidine) or Class III (such as amiodarone) antiarrhythmic drugs or other drugs that may prolong the QT or PR interval.
- Report any adverse events associated with the use of Invirase to FDA's MedWatch program.
Reference
1. FDA Drug Safety Communication: Ongoing safety review of Invirase (saquinavir) and possible association with abnormal heart rhythms. Safety Announcement # 02-23-2010. http://www.fda.gov/Drugs/DrugSafety/PostmarketDrugSafetyInformationforPatientsandProviders/ucm201221.htm (accessed February 25, 2010)
Ken Korber is a PA in Chicago and the architect of the first PA postgraduate fellowship curriculum for cardiovascular care in the United States. He can be reached at his email address, kenneth.korber@gmail.com, for any comments or questions.
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