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A liquid chromatography with triple quadrupole mass spectrometry method was developed and validated for the determination of tenofovir and tenofovir alafenamide concentrations in human plasma and cerebrospinal fluid. Tenofovir and tenofovir alafenamide were extracted from matrix by solid phase extraction. The dried extraction eluents were dissolved in water for LC-MS/MS analysis. Separation was achieved with a Phenomenex Synergi 4 μm Polar-RP 80A column (50 × 2 mm) with a gradient elution of 0.1% formic acid in water and acetonitrile. The total run time was 5 min. Detection of analytes was achieved using electrospray ionization (positive mode) and triple quadrupole selected reaction monitoring. Standard curve concentrations ranged from 0.5 to 500 ng/mL for the plasma assay and 0.1-50 ng/mL for the cerebrospinal fluid assay. The intra- and inter-day accuracy and precision were less than 12% in low, medium, and high quality control samples for both matrices. The validated methods were applied to the analysis of plasma and cerebrospinal fluid samples of a patient undergoing tenofovir therapy which involved the switch from Stribild (elvitegravir 150 mg/cobicistat 150 mg/emtricitabine 200 mg/tenofovir disoproxil fumarate 300 mg) to Genvoya (elvitegravir 150 mg/cobicistat 150 mg/emtricitabine 200 mg/tenofovir alafenamide 10 mg).

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An ultra-performance liquid chromatography with triple quadrupole mass spectrometry method was developed and validated for the determination of direct acting antiviral drug concentrations in human liver fine needle aspirates. Liver fine needle aspirate (FNA) biopsy samples were homogenized in acetonitrile to stabilize the analytes and precipitate protein. The acetonitrile supernatants were diluted with internal standards and mobile phase. Separation was achieved with a Waters Acquity BEH C18 column (50 X 2.1 mm, 1.7 um) with a gradient elution of 0.1% formic acid in water and acetonitrile. The total run time was 4.25 minutes. Detection of analytes was achieved using electrospray ionization (positive mode) and triple quadrupole selected reaction monitoring. Standard curve concentrations ranged from 12.5 to 5000 ng/mL for dasabuvir and the m1 metabolite of dasabuvir, 1.25 to 2500 ng/mL for ombitasvir and ritonavir, and 5.00 to 5000 ng/mL for paritaprevir. The intra- and inter-day accuracy and precision were less than 13.7% in low, medium, and high quality control samples. The validated method was applied to the analysis of a liver fine needle aspirate of a patient undergoing direct acting antiviral therapy for hepatitis C virus.

Aim: Determination of paritaprevir and ritonavir in rat liver tissue samples. Results: We successfully validated a UPLC-MS/MS method to measure paritaprevir and ritonavir in rat liver using deuterated internal standards (d8-paritapervir and d6-ritonavir). The method is linear from 20 to 20,000 and 5 to 10,000 pg on column for paritaprevir and ritonavir, respectively, and is normalized per milligram tissue. Interday and intraday variability ranged from 0.591 to 5.33% and accuracy ranged from -6.68 to 10.1% for quality control samples. The method was then applied to the measurement of paritaprevir and ritonavir in rat liver tissue samples from a pilot study. Conclusion: The validated method is suitable for measurement of paritaprevir and ritonavir within rat liver tissue samples for PK studies.