Estudo da degradação forçada em meio alcalino do molnupiravir por cromatografia eletrocinética micelar capilar

Abstract

COVID-19 is an infectious disease caused by the SARS-CoV-2 coronavirus, which was declared a pandemic by the World Health Organization (WHO) in March 2021, and still represents a threat to public health. Currently, some drugs are recommended by the WHO as a therapeutic approach to tackling the health crisis. Among them, molnupiravir is the first oral anti-SARS-CoV-2 antiviral to be approved by the health agencies of several countries, including Brazil. Given the recent nature of antiviral therapies to combat COVID-19, ensuring appropriate safety and efficacy in the production of these drugs depends on guaranteeing the quality control of raw materials. Molnupiravir is a prodrug of β-D-N 4 -hydroxycytidine (NHC), a strategy for increasing bioavailability. In addition, NHC is reported as a by-product in several total synthetic routes and a metabolite of molnupiravir, considerations that highlight the need for simultaneous monitoring of both substances in the context of pharmaceutical products. The aim of this work was to develop and optimize an analytical method for the analysis of molnupiravir in raw materials, and to apply this methodology in an investigative approach to the forced degradation study (FDS). In its development, the separation of molnupiravir and NHC was evaluated by zone capillary electrophoresis techniques: in free solution and in micellar phase, using diode array detection at 236 nm. The electrolyte was optimized using a 3 2 factorial design, in which the influence of the pH value and the micellar concentration on the separation efficiency of the drugs was evaluated. The optimized method consisted of the analysis of molnupiravir by micellar electrokinetic capillary chromatography using a fused silica capillary externally coated with polyamide with a total length of 48.5 cm (40.0 cm effective), 75 μm internal diameter; cartridge temperature maintained at 25.0 ºC; positive voltage of 20 kV; hydrodynamic injection of 25 mbar for 4s; electrolyte consisting of carbonate buffer solution (NaHCO3/Na2CO3) at a concentration of 20 mmol L-1 , pH 10.4, and SDS at a concentration of 60 mmol L-1 ; with a total analysis time of 12 minutes. Some analytical performance parameters were evaluated, so that selectivity was certified, and the accuracy of the method, whose values range from 91 to 113%, was established by recovery tests at three concentration levels. No impurities were found in the raw material analyzed. Assessing the chemical stability of pharmaceutical formulations is a public health issue since instability can reduce the therapeutic effect or expose users to potentially toxic degradation products (DPs). Therefore, the FDS was carried out by exposing the raw material to stress conditions in an alkaline environment. Based on the analytical methodology implemented, up to five degradation products were detected. One of these DPs is estimated to be NHC, considering the characterization by UV-VIS spectroscopy, demonstrating the potential of the method as an indicator of stability in the experimental setting investigated, assisting in other FDS under other stress conditions, and in the development of future formulations.