UPLC-MS/MS method for the simultaneous quantification of sofosbuvir, sofosbuvir metabolite (GS-331007) and daclatasvir in plasma of HIV/HCV co-infected patients

Direct-acting antiviral agents (DAAs) represent the major advance in hepatitis C virus (HCV) infection treatment leading to extremely high eradication rates in HCV mono- and HIV/HCV co-infected patients. In this scenery, availability of Therapeutic Drug Monitoring (TDM) is of interest to assess plasma concentrations to prevent either therapeutic failure due to suboptimal medication adherence and drug-drug interactions or avoid adverse events. Aim of this study was to develop and validate an Ultra-Performance Liquid Chromatography Mass Spectrometry (UPLC-MS/MS) method for the simultaneous quantification of sofosbuvir, sofosbuvir metabolite (GS-331007), and daclatasvir in human plasma. A simple protein precipitation was applied by adding 200 μL acetonitrile with internal standard 6,7-Dimethyl- 2,3-di(2-pyridyl) quinoxaline to 100 μL plasma sample. Drug separation was performed on analytical C-18 Luna Omega column (50 mm × 2.1 mm I.D.) with particle size of 1.6 μm. The mobile phase consisting of water containing 0.1% formic acid and acetonitrile at flow 0.4 mL/min and a gradient run time of 3.5 min. The injection volume was 10 μL. Anti-HCV drugs were detected in positive electrospray ionization mode. The full scan mass spectral analyses of sofosbuvir, GS-331007, daclatasvir and quinaxoline showed protonated molecule ions and transitions m/z: 530.098 → 243.02, 260.93 → 112.94, 739.4 → 339.27 and 313.03 → 77.99 respectively. The linearity of standard curves was excellent (r² > 0.99), the absolute recovery of anti-HCV drugs ranged between 95 and 98%, and both imprecision and inaccuracy were <15% according to FDA guidelines. The UPLC-MS/MS method was applied to 16 plasma samples of as many HIV/HCV co-infected patients treated with sofosbuvir and daclatasvir. While sofosbuvir was not detectable in all samples, the median plasma concentrations of daclatasvir and GS-331007 were 223.6 ± 319.56 ng/mL and 537.11 ± 242.09 ng/mL, respectively. In conclusion, we describe an UPLC-MS/MS method allowing the simultaneous quantification of sofosbuvir, GS-331007 and daclatasvir in plasma samples. The method was sensitive, specific, robust, and time-saving.