Determination of favipiravir in human plasma using homogeneous liquid–liquid microextraction followed by HPLC/UV

Favipiravir is an antiviral drug that was recently approved for the management of COVID-19 infection. This work aimed to develop a new method, using sugaring-out induced homogeneous liquid–liquid microextraction followed by HPLC/UV for the determination of favipiravir in human plasma. The optimum extraction conditions were attained using 500 μl of tetrahydrofuran as an extractant and 1400 mg of fructose as a phase-separating agent. The developed method was validated according to the US FDA bioanalytical guidelines and was found linear in the range of 25-80,000 ng/ml with a correlation coefficient of 0.999. These results showed that the developed method was simple, easy, valid and adequately sensitive for determination of favipiravir in plasma for bioequivalence studies.