The US Food and Drug Administration (FDA) is cautioning physicians to avoid use of the drug boceprevir to treat hepatitis C in patients who are concurrently taking one of several protease inhibitors used to treat HIV/AIDS. Use of boceprevir in such patients can reduce the effectiveness of these medications, the FDA said.

Many patients with HIV are also infected with hepatitis C virus (HCV), particularly those who have a history of injecting illicit drugs. The presence of both viruses can contribute to poorer outcomes for coinfected patients, such as more rapid onset of HCV complications such as liver disease and liver cancer, according to the US Centers for Disease Control and Prevention (http://tinyurl.com/6u7eqb8).

Recently, information has emerged suggesting that interactions between boceprevir, a protease inhibitor, and other protease inhibitors used to treat HIV may result in reduced blood levels of the drugs and may lead to increased viral loads (http://tinyurl.com/6o7nrc3). This information has led the FDA to update the label of boceprevir to indicate that interactions between this drug and ritonavir in combination with atazanavir, darunavir, or lopinavir can lead to reduced levels of the HIV medications in patients' blood and should be avoided. Additionally, use of ritonavir alone with boceprevir can lead to decreased concentrations of boceprevir in the blood.