Spectrofluorimetric Protocol for Estimation of Commonly Used Antispasmodic Drotaverine. Fluorescence Quenching Study.

A fast, simple, accurate, precise, and cheap fluorimetric protocol has been proposed for analysis of a phosphodiesterase-IV inhibitor, namely drotaverine hydrochloride. Fluorimetric protocol is based on estimating the decrease in the eosin Y fluorescence intensity by quantitative addition of drotaverine at pH 3.1 (acetate buffer). An ion pair complex is formed, which leads to quenching in the fluorescence intensity of the dye without need of prior extraction at 534 nm (λex. 339 nm). Different reaction perimeters which influence the production of complex (ion pair between drotaverine and eosin) were deeply investigated and optimized. The developed fluorimetric protocol is capable for quantitative estimation of drotaverine in linear range of 0.4 to 2.5 µg mL-1. After method validation in respect to ICH guidelines, it was applied to determine drotaverine in its commercial preparation. By comparing with other reported method, the developed and validated fluorimetric protocol is capable for estimation of drotaverine in commercial preparation with good accuracy and excellent precision.

Spectrofluorimetric determination of the anti-Covid 19 agent, remdesivir, in vials and spiked human plasma.

Following the sudden widespread of the novel coronavirus (COVID-19) which first appeared in Wuhan city. Remdesivir (REM) was the first medicine licensed by the US Food and Drug Administration (FDA) for COVID-19 infected hospitalized patients. Hence, there was an urgent demand for the optimization of efficient selective and sensitive methods to be developed for the determination of REM in pharmaceuticals as well as biological samples. A sensitive and simple green spectrofluorimetric method has been developed to determine REM in pharmaceutical formulation, in addition to, spiked human plasma. The technique involves measuring the native fluorescence of REM in distilled water at 410 nm followed by excitation at 241 nm, giving a linear relationship over the range 50.00-500.00 ng/mL, and then improving the sensitivity of REM through micellar formation using 2.00% w/v sodium dodecyl sulfate (SDS). A linear relationship has been obtained over the range 10.00-350.00 ng/mL having detection and quantitation limits of 2.34 and 7.10 ng/mL, respectively. Different analytical parameters have been carefully studied. A validation study has been conducted successfully in accordance with the FDA and the International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use (ICH) guidelines. The developed methods' greenness was assessed utilizing a greenness profile and analytical eco-scale standards. Both methods were discovered to be environmentally friendly and could be successfully used for the determination of the studied drugs in pharmaceutical formulation and human plasma with good accuracy and high precision. As a result, the developed spectrofluorimetric methods could be ideally suited for determination of REM in quality control and medicinal laboratories.

Novel environment friendly TLC-densitometric method for the determination of anti-coronavirus drugs "Remdesivir and Favipiravir": Green assessment with application to pharmaceutical formulations and human plasma.

A great demand for discovering new therapeutic solutions has been considered all over the world for managing the rapidly progressing COVID-19 pandemic. Remdesivir (REM) and Favipiravir (FAV) are introduced as promising newly developed antiviral agents against the corona virus as evidenced by the clinical findings. Hence, the optimization of an analytical method for their simultaneous determination acquires potential importance in quality control labs and further confirmatory investigations. Herein, a green, sensitive, and selective densitometric method has been proposed and validated for determination of REM and FAV in pharmaceutical formulations and spiked human plasma on normal phase TLC plates. A solvent mixture of ethyl acetate-methanol-ammonia (8:2:0.2 by volume) has been chosen as developing mobile phase system. Well resolved spots have been detected at 235 nm with retardation factors (Rf) of 0.18 and 0.98 for REM and FAV, respectively. A validation study has been carried out in the light of ICH guidelines. Remdesivir and FAV have shown excellent sensitivities with quantitation limits down to 0.12 and 0.07 µg/band, respectively. The developed method has been successfully applied to tablet formulations and spiked plasma with excellent recoveries ranged from 97.21 to 101.31%. The greenness of the method has been evaluated using the standards of greenness profile and Eco-Scale. It has passed the four greenness profile quadrants and achieved 80 score in Eco-Scale.