New directly acting
antivirals (DAAs) that inhibit hepatitis C virus (HCV) replication are increasingly used for the treatment of
chronic hepatitis C. A marked pharmacokinetic variability and a high potential for
drug-drug interactions between DAAs and numerous
drug classes have been identified. In addition,
ribavirin (RBV), commonly associated with
hemolytic anemia, often requires dose adjustment, advocating for therapeutic
drug monitoring (TDM) in patients under combined
antiviral therapy. However, an assay for the simultaneous analysis of RBV and DAAs constitutes an analytical challenge because of the large differences in polarity among these drugs, ranging from hydrophilic (RBV) to highly lipophilic (
telaprevir [TVR]). Moreover, TVR is characterized by erratic behavior on standard octadecyl-based reversed-phase column chromatography and must be separated from VRT-127394, its inactive
C-21 epimer metabolite. We have developed a convenient assay employing simple
plasma protein precipitation, followed by high-performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS) for the simultaneous determination of levels of RBV,
boceprevir, and TVR, as well as its metabolite VRT-127394, in plasma. This new, simple, rapid, and robust HPLC-MS/MS assay offers an efficient method of real-time TDM aimed at maximizing efficacy while minimizing the toxicity of
antiviral therapy.