Development and validation of LC–MS/MS methods for the simultaneous quantification of sofosbuvir and its major metabolite (GS‐331007) in blood plasma and cerebrospinal and seminal fluid: Application to a pilot clinical trial with a focus on Zika

Zika still poses a threat to global health owing to its association with serious neurological conditions and the absence of a vaccine and treatment. Sofosbuvir, an anti‐hepatitis C drug, has shown anti‐Zika effects in animal and cell models. Thus, this study aimed to develop and validate novel LC–MS/MS methods for the quantification of sofosbuvir and its major metabolite (GS‐331007) in human plasma and cerebrospinal (CSF) and seminal fluid (SF), and apply the methods to a pilot clinical trial. The samples were prepared by liquid–liquid extraction and separated using isocratic mode on Gemini C18 columns. Analytical detection was performed using a triple quadrupole mass spectrometer equipped with an electrospray ionization source. The validated ranges for sofosbuvir were 0.5–2,000 ng/mL (plasma) and 0.5–100 ng/mL (CSF and SF), while for the metabolite they were 2.0–2,000 ng/mL (plasma), 5.0–200 ng/mL (CSF) and 10–1,500 ng/mL (SF). The intra‐day and inter‐day accuracies (90.8–113.8%) and precisions (1.4–14.8%) were within the acceptance range. The developed methods fulfilled all validation parameters concerning selectivity, matrix effect, carryover, linearity, dilution integrity, precision, accuracy and stability, confirming the suitability of the method for the analysis of clinical samples.