Comparison of HPLC and UV Spectrophotometric Methods for Quantification of Favipiravir in Pharmaceutical Formulations

There is no currently successful method to treat Covid-19 infection. Nevertheless, previously licensed pharmaceuticals to treat other virus infections are used on an off-label basis either alone or in combination. One of them is favipiravir. Favipiravir, also known as favilavir, is an antiviral drug that is active against many viruses. Spectrophotometric and liquid chromatographic methods have been developed and validated for the quantitative determination of favipiravir in pharmaceutical formulations. Chromatographic method has been performed using reverse-phase technique on a C-18 column with a mobile phase consisting of sodium acetate solution (pH adjusted to 3.0 with glacial acetic acid) and acetonitrile (85:15, v/v) at 30 oC. The mobile phase flow rate was 1.0 mL min-1. For the determination of favipiravir, UV spectrum has been recorded between 200 and 800 nm using deionized water as solvent and the wavelength of 227 nm has been selected. Both methods have been validated in terms of their specificity, linearity, limits of detection and quantification, precision, accuracy, and robustness. Both methods have demonstrated good linearity, precision and recovery. No spectral and chromatographic interferences from the tablet excipients were found in spectrophotometric and liquid chromatographic methods. In both methods, correlation coefficients were greater than 0.999 within a concentration range of 10–60 mg mL-1 using spectrophotometry and chromatography. Intra-day and inter-day precision were observed with low relative standard deviation values. The accuracy of the methods were within the range 99.57-100.10% for LC and from 99.83–100.45% for UV. Therefore, both methods gave the most reliable outcomes for the determination of favipiravir in pharmaceutical formulation.