Response surface experimental design for simultaneous chromatographic determination of two antiviral agents “Favipiravir and Remdesivir” in pharmaceuticals and spiked plasma samples

Abstract The antiviral agents, Favipiravir (FAV) and Remdesivir (REM), were introduced in the last few years alone or as combination regimen for successful management of the rapidly spreading CORONA virus pandemic. A newly developed rapid and sensitive high performance liquid chromatographic method (HPLC) has been developed for the simultaneous determination of their mixture. Firstly, one factor at a time optimization (OFAT) has been applied. Afterwards, quality by design approach (QbD) has been utilized using Box Behnken experimental design (BBD) for the development of an experimental design of four independent and nine dependent variables for much better refining of the optimized parameters. The established model has given an optimum resolution at; acetonitrile percentage of 52.66, mobile phase of pH 2.91, percentage of triethylamine of 0.15 and 1.30 mL/min flow rate. The proposed method has been validated according to the USP 31 NF 26 guidelines. Good linearity ranges have been obtained from 5.00 up to 50.00 μg/mL for FAV and from 2.00 up to 60.00 μg/mL for FAV and REM, respectively. Excellent relative standard deviation values (not more than 1.40) were obtained upon investigation of accuracy, precision and robustness. The developed method has succeeded in analysis of investigated drugs in their pharmaceutical formulations and spiked plasma samples with good recoveries of 99.00 and up to 106.00%. The proposed method is considered eligible for the quality control laboratories as well as in‐vivo determinations of both analytes.