Anti-COVID-19 activity and simple HPLC method for concurrent detection of repurposed drugs in novel binary mixtures

The discovery of a new antiviral drug specifically targeting SARS-CoV-2 would require considerable time and effort. Repositioning drugs that are already used for other viral infections is a valuable approach. Remdesivir is the first antiviral treatment approved by the Food and Drug Administration (FDA) for COVID-19. Nitazoxanide is a broad-spectrum anti-infective agent that has been suggested for repurposing in COVID-19 treatment. Recent research has demonstrated the synergistic anti-SARS-CoV-2 antiviral activity of Remdesivir when combined with Nitazoxanide. Moreover, Daclatasvir is an FDA-approved antiviral for managing chronic HCV infection, and its potential use in treating COVID-19 has been reported. Piroxicam is an FDA-approved anti-inflammatory with some clinical evidence supporting its application for COVID-19. There is no evidence for exploiting the anti-SARS-CoV-2 activity of Daclatasvir when combined with Piroxicam. We were able to demonstrate the enhanced anti-SARS-CoV-2 activity of the Remdesivir-Nitazoxanide and Daclatasvir-Piroxicam binary mixtures in Vero-E6 cells. In addition, we were able to develop a simple HPLC methodology for the concurrent determination of the two analytes of each binary mixture (Remdesivir-Nitazoxanide mixture and Daclatasvir-Piroxicam mixture) in both pure form and in human plasma using non-complicated, widely available analytical instruments. The proposed method is simple, accurate, quick, and sensitive. No drug interactions were observed in the tested binary mixtures.