Development and validation of an LC-MS/MS method for simultaneous determination of remdesivir and its hydrolyzed metabolite and nucleoside, and its application in a pharmacokinetic study of normal and diabetic nephropathy mice.

ABSTRACT

Remdesivir (RDV), a phosphoramidate prodrug, has broad-spectrum antiviral activity. It is the first antiviral drug approved by the US Food and Drug Administration (FDA) for the treatment of COVID-19. Remdesivir is rapidly metabolized in the body to produce derivatives alanine metabolite (RM-442) and RDV C-nucleoside (RN). Here, the phosphatase inhibitor PhosSTOP and carboxylesterase inhibitor 5,5'-dithiobis-2-nitrobenzoic acid were used to improve stability of RDV in mouse blood. We developed a rapid and sensitive LC-MS/MS method to simultaneously quantify RDV, RM-442 and RN in mouse blood. Chromatographic separation was achieved by gradient elution on an Acquity HSS T3 column. The run time was 3.2 min. The linearity ranges of the analytes were 0.5-1,000 ng/ml for RDV and 5-10,000 ng/ml for both RM-442 and RN. The method had an acceptable precision (RSD < 8.4% for RDV, RSD < 10.7% for RM-442 and RSD < 7.2% for RN) and accuracy (91.0-106.3% for RDV, 92.5-98.6% for RM-442 and 87.5-98.4% for RN). This method was successfully applied to analyze RDV, RM-442 and RN in the blood of normal and diabetic nephropathy DBA/2 J mice after intravenous injection of RDV at 20 mg/kg. The area under the concentration-time curve of RN between the normal and diabetic nephropathy mice showed a significant difference (P < 0.01).