Conventional and synchronous spectrofluorometric determination of the recently administered drugs for treatment of COVID-19 favipiravir and apixaban

COVID-19 is a fast-spreading pandemic that is caused by SARS-CoV-2 viral pathogen. Combination therapy of the antiviral favipiravir and the anticoagulant apixaban is one of the efficient treatment regimens. Therefore, development of novel and sensitive methods for simultaneous analysis of such combination is highly advantageous. Herein, two eco-friendly, simple, rapid, and cost-effective spectrofluorometric methods were evolved for the estimation of favipiravir and apixaban in pharmaceutical and biological matrices. Method I was based on analysis of favipiravir and apixaban by the first-order derivative of the conventional fluorescence spectra obtained after excitation at 300 nm, where favipiravir and apixaban were detected at 468.8 and 432.0 nm, respectively. Method II relied on dual scan synchronous spectrofluorometry, in which favipiravir was determined at 364 nm using Δλ = 60 nm while apixaban was analyzed at 274 nm using Δλ = 200 nm. Method optimization was performed for selecting the optimum conditions at which maximum sensitivity and selectivity were obtained. This report is the first one that describes simultaneous analysis of favipiravir and apixaban by synchronous spectrofluorometry. The developed methods were successfully applied to evaluate favipiravir and apixaban in spiked human plasma and in pharmaceutical dosages with high %recoveries and low RSD.