Development and validation of LC-MS/MS method for quantification of bictegravir in human plasma and its application to an intracellular uptake study.

A sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for quantification of bictegravir in human plasma. A small volume of only 50 μL aliquot of plasma was precipitated with acetonitrile containing an internal standard (IS). Chromatographic separation was performed on a Kinetex EVO C18 column, 50 × 3.0 mm, 5 μm using an isocratic mobile phase containing 80:20 acetonitrile-water with 0.1% formic acid. A mass spectrometer was operated in ESI positive multiple reaction monitoring mode using the m/z 450.1/289.1 for bictegravir and 420.1/277.1 for IS. The dynamic range of the method was 1-10,000 ng/mL with a correlation coefficient of ≥0.9991. The precision results of calibration standards were in the range of 0.05-4.57% and accuracies were 95.07-104.70%. The mean extraction recovery was 98.64% with a precision of 2.91%. The method was validated as per US Food and Drug Administration guidelines and was found to be accurate and precise. The method was successfully applied to in vitro cellular uptake study.