The FDA has notified healthcare professionals that drug interactions between the hepatitis C virus (HCV) protease inhibitor Victrelis (boceprevir; Merck) and certain ritonavir-boosted human immunodeficiency virus (HIV) protease inhibitors can potentially reduce the effectiveness of these medicines when they are used together.

A drug interaction study showed that taking Victrelis with Norvir (ritonavir; Abbott) in combination with Reyataz (atazanavir; Bristol-Myers Squibb), or Prezista (darunavir; Janssen Therapeutics), or with Kaletra (lopinavir/ritonavir; Abbott) reduced the blood levels of these HIV medicines and boceprevir in the body, possibly permitting the amount of HCV or HIV virus in the blood to increase. The Victrelis drug label will be updated to include information about these drug interactions.

Victrelis is a hepatitis C virus (HCV) protease inhibitor used to treat chronic hepatitis C infection in adults. Reyataz, Prezista, and Kaletra are HIV protease inhibitors indicated to treat HIV infection. Ritonavir is also an HIV protease inhibitor used to “boost” other HIV protease inhibitors, increasing their levels in the blood and making them more effective.

For more information visit http://www.fda.gov/Safety/MedWatch/SafetyInformation/SafetyAlertsforHumanMedicalProducts/ucm291144.htm.