Simultaneous spectrofluorimetic determination of remdesivir and simeprevir in human plasma

As new infectious mutations of SARS-CoV-2 emerged throughout the world, innovative therapies to counter the virus-altered drug sensitivities were urgently needed. Several antiviral options have been in clinical trials or in compassionate use for the treatment of SARS-CoV-2 infections in an attempt to minimize both clinical severity and viral shedding. Recent research indicated that simeprevir acts synergistically with remdesivir, allowing for a multiple-fold decrease in its effective dose when used at physiologically acceptable concentrations. The goal of this work is to develop a sensitive synchronous spectrofluorimetric approach to simultaneously quantify the two drugs in biological fluids. Using this method, remdesivir and simeprevir could be measured spectrofluorimetrically at 283 and 341 nm, respectively, without interference from each other using Δλ of 90 nm. The effect of various experimental parameters on the fluorescence intensity of the two drugs was extensively explored and optimized. For each of remdesivir and simeprevir, the method exhibited a linearity range of 0.10-1.10 μg/mL, with lower detection limits of 0.01 and 0.02 μg/mL and quantification limits of 0.03 and 0.05 μg/mL, respectively. The high sensitivity of the developed method permitted the simultaneous determination of both drugs in spiked plasma samples with % recoveries ranging from 95.0 to 103.25 with acceptable standard deviation values of 1.92 and 3.04 for remdesivir and simeprevir, respectively. The validation of the approach was approved by the International Council of Harmonization (ICH) guidelines.