A liquid chromatography-tandem mass spectrometry method development for the quantification of favipiravir drug and its related impurities in rat plasma and its application to pharmacokinetic studies.

Favipiravir is an antiviral drug used for the treatment of virus-based diseases such as influenza. In this context, the development of a reliable liquid chromatography-tandem mass spectrometry method for the quantification of the drug and its impurities is necessary, particularly following the COVID-19 pandemic. Chromatographic separation was achieved on an inertial ODS column using gradient elution with a buffer containing triethylamine in high-performance liquid chromatography water and adjusting its pH with formic acid. The mixture of buffer and acetonitrile was used as a mobile phase with a flow rate of 1 ml/min at ambient temperature. The separation of favipiravir and its related impurities from remdesivir as an internal standard was achieved. The results indicated that all the variables, like precision, accuracy, linearity, matrix effect and stability, were successfully achieved within the limits of US Food and Drug Administration guidelines. This study could provide a new protocol for the development of new analytical methods for the detection of favipiravir and its impurities.