Reuters (04.26.12) - Monday, April 30, 2012

The Food and Drug Administration (FDA) said Thursday it is changing the label for Merck & Co.'s hepatitis C virus (HCV) treatment Victrelis following studies indicating it should not be taken with some common HIV drugs.

"Co-administration [of the two drugs] ... is not recommended at this time because of the possibility of reducing the effectiveness of the medicines, permitting the amount of HCV or HIV ... in the blood to increase," FDA said.

Victrelis (boceprevir) was approved last May. FDA and Merck first warned about the issue in February after results of a drug interaction study of healthy patients who took Victrelis and the widely used HIV drug Norvir (ritonavir) as part of a combination protease inhibitor regimen. The study found Victrelis reduced the concentrations of HIV drugs in the blood.

A second, small clinical trial of 98 people presented last month also contributed to FDA's labeling decision, though its results were not as conclusive as the drug interaction study. Some of the HCV/HIV co-infected patients were given Victrelis plus peginterferon/ribavirin, while others received only peginterferon/ribavirin; all patients were given a type of HIV drug. Of 64 patients taking Victrelis, three had a rebound in their HIV, compared to four of the 34 taking the older combination HCV treatment.

Merck said it plans to conduct a larger drug interaction study of Victrelis with other HIV drugs. FDA said it will report any new information about Victrelis and those treatments when it becomes available.

To view the announcement, visit http://www.fda.gov/Drugs/DrugSafety/ucm301616.htm?utm_campaign =Google2&utm_source=fdaSearch&utm_medium=website&utm_term=vict relis&utm_content=6.