Determination of Favipiravir in Human Plasma by Using Liquid Chromatography-Tandem Mass Spectrometry: Application to Pharmacokinetic Studies

Abstract

The outbreak of Covid-19 infection has become a pandemic affecting millions of people throughout the world. No specific antiviral drugs have been approved for the treatment of Covid-19. The antiretroviral drug favipiravir (FAV) has been experimentally used for COVID-19 treatment since March 2020 in Japan. China's Science and Technology Ministry official announced that Japan-based anti-flu drug FAV has been observed to help Covid-19 patients recover. Because of that, a simple LC-MS/MS method for the quantification of FAV in human plasma was developed and validated. Sample preparation was carried out using protein precipitation. The FAV and internal standard ([ 13 C 15 N] Favipiravir, (IS)) were chromatographed under a liquid chromatography tandem mass spectrometry (LC-MS/MS) system on a Shiseido Capcell PAK C18, (250 × 4.6 mm, 5 µm) with mobile phase consisting of water and acetonitrile (15/85, v/v). FAV was analyzed by LC-MS/MS with electrospray ionization in the negative ion mode and the multiple reaction monitoring (MRM) mode. MRM transitions were m/z 156.1 ˃ 113.1 for FAV and m/z 158.1 ˃ 113 for IS. The lower limit of quantitation (LLOQ) for this method is 80 ng/mL. The linear calibration range is 80-30000 ng/mL for FAV. The results of the intra-and inter-day precision and accuracy studies were well within the acceptable limits. The method is precise and sensitive enough for its intended purpose. This validated method was applied to pharmacokinetic studies of favipiravir.

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“…Stability studies were performed as bench top study and freeze-thaw stability studies and the coefficient of variation was found to be within 3%. The validated method was found to be precise and sensitive and can be applied to pharmacokinetic studies of Favipiravir-marketed formulations 35 . Paul Curley et al developed a highly sensitive bioanalytical assay to quantify Favipiravir using liquid chromatography-tandem mass spectrometry.…”