Some HIV and Hep C Drugs Less Effective Together: FDA

Federal drug regulators are warning that combining the hepatitis C drug Victrelis with medications from a family of HIV drugs, which includes Norvir, Reyataz, Prezista and Kaletra, may result in reduced effectiveness for both medications. 

The FDA issued a drug safety communication on February 8, following an analysis of data from a recent drug interaction study.

Merck and Co., sent out a Dear Healthcare Professional letter (pdf) with the same warning on February 6.

According to the FDA, the problem occurs when Victrelis is used in combination with either Reyataz, Prezista or Kaletra, known as HIV Protease Inhibitors, which are then boosted by Norvir. The drug interaction study showed that once the triple drug combination was taken, the blood levels of the HIV drugs and Victrelis dropped from 49 to 59%.

Healthcare professionals are being warned that this could cause a resurgence of the hepatitis C virus and HIV in patients that had previously improved under treatment.

The FDA is advising doctors to discuss the findings with patients to whom the drugs might be co-administered and to monitor those patients for possible Hepatitis C and HIV rebounds. However, patients are being advised not to stop taking the drugs without first talking to their healthcare professional.

Victrelis (boceprevir) is a hepatitis C protease inhibitor used to treat chronic hepatitis C infections in adults. It was approved for use by the FDA in May 2011. Merck, the makers of Victrelis, advised against using it with HIV drugs and warns that Victrelis is not indicated for use in patients who have both HIV and hepatits C.

The FDA is calling for healthcare professionals and patients who have suffered adverse side effects from this drug combination to report such incidents to MedWatch, the FDA’s adverse event reporting program.