The label for the HIV drug <"http://www.yourlawyer.com/practice_areas/defective_drugs">Invirase has been updated to include information about a dangerous interaction with the drug Norvir, another HIV medication. According to the US Food & Drug Administration (FDA), the information will describe potentially life-threatening side effects on the heart when Invirase and Norvir are used together.
Invirase is an antiretroviral medication first approved in 1995, and used in combination with Norvir and other antiretroviral medicines to treat HIV in adults. Last February, the FDA warned patients and health care professionals that when used together, Invirase and Norvir could cause prolongation of the QT and PR intervals–indicators of heart rhythm activity seen on an electrocardiogram.
Prolongation of the QT interval may lead to a condition known as torsades de pointes, an abnormal heart rhythm. With torsades de pointes, 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. Prolongation of the PR interval may also lead to an abnormal heart rhythm known as heart block. With heart block, patients may experience lightheadedness, fainting or abnormal heartbeats.
This new risk information has been added to the Warnings and Precautions, Contraindications, and Clinical Pharmacology sections of the Invirase label. The FDA is also requiring a medication guide for patients using Invirase that will describe these potential risks. Patients at greater risk of developing one of the serious heart events described above include those with underlying heart conditions or those that have existing heart rate or rhythm problems.
The agency urged HIV patients to talk to their doctors and to make sure they disclose any other medications, vitamins or supplements they are taking in addition to their HIV drugs
According to a Reuters report, the European Medicines Agency announced separately that it had reviewed all the available data on potential heart risk and recommended that patients start off treatment with a lower dose of Invirase for a week as a precaution.