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

•UPLC–MS/MS method for the quantification of SOF, GS-331007 and DCV in a small plasma samples.•Assay validation following FDA guidelines.•The method is sensitive, specific, robust, and time-saving.•The method may be useful to prevent therapeutic failure and DDI in 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