The label of the hepatitis C antiviral drug telaprevir has been changed to include new dosing recommendations and contraindications, described in a "Dear Healthcare Professional" letter issued by the manufacturer.
Telaprevir is a hepatitis C virus (HCV) NS3/4A protease inhibitor approved in 2011 for the treatment of genotype 1 chronic HCV infection in adults with compensated liver disease, in combination with peginterferon alfa and ribavirin. It is marketed as Incivek, by Vertex Pharmaceuticals.
The recommended dose is now 1,125 mg (three 375-mg tablets) taken orally twice a day, 10-14 hours apart with food that is not low fat, according to the Oct. 28 letter. "This change in dosing frequency was based on data from a clinical trial demonstrating similar sustained virologic response and safety profile between the twice-daily dosing and the every-8-hour dosing," the letter stated.
In addition, carbamazepine, phenobarbital, and phenytoin are now on the list of contraindicated drugs, based on a pharmacokinetics study that found coadministration of these drugs with telaprevir "has the potential to lower exposure and, thus, may result in a loss of efficacy" of telaprevir, according to the letter.
New twice-daily-dosing packaging will be available at the end of January 2014. Until then, the current packaging that contains six tablets per blister strip – with three blister sections containing two tablets each – can be used for the twice-daily recommendation. Two tablets from one blister section and one tablet from another section can be taken for the three-pill dose, administered twice a day, the letter pointed out.
The updated label is available at http://pi.vrtx.com/files/uspi_telaprevir.pdf.
Vertex can be contacted for questions at 877-824-4281. Serious adverse events associated with telaprevir should be reported to Vertex at that number, or to the Food and Drug Administration at 800-332-1088 or at www.fda.gov/medwatch.
