A Simple and Rapid LC-MS/MS Method for the Quantification of Nirmatrelvir/Ritonavir in Plasma of Patients with COVID-19.

The combined prescriptions of nirmatrelvir/ritonavir and other drugs are limited due to potential drug-drug interactions, so therapeutic drug monitoring (TDM) becomes particularly important. In this study, a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was established for determination of the nirmatrelvir/ritonavir in plasma of patients with COVID-19, providing technical and theoretical support for the TDM. Plasma samples were processed by protein precipitation using acetonitrile, and analytes were separated on an Agilent Poroshell 120 SB-C18 (2.

Separation and quantification of Azvudine in plasma of patients with COVID-19 using LC-MS/MS.

Azvudine (FNC) is a new drug conditionally approved in 2022 for the treatment of coronavirus disease 2019 (COVID-19) in China. However, the exposure level of FNC in COVID-19 patients in clinical practice is still obscure, and there is no liquid chromatography-tandem mass spectrometry (LC-MS/MS) or LC method reported for quantifying the FNC. In this study, a simple, fast, and reliable LC-MS/MS method using L-phenylalanine-D5 (Phe-D5) as the internal standard (IS) was developed for the quantification of FNC in plasma from COVID-19 patients.