Innovative, rapid, high-throughput method for drug repurposing in a pandemic—A case study of SARS-CoV-2 and COVID-19

Abstract

Several efforts to repurpose drugs for COVID-19 treatment have largely either failed to identify a suitable agent or agents identified did not translate to clinical use. Reasons that have been suggested to explain the failures include use of inappropriate doses, that are not clinically achievable, in the screening experiments, and the use of inappropriate pre-clinical laboratory surrogates to predict efficacy. In this study, we used an innovative algorithm, that incorporates dissemination and implementation considerations, to identify potential drugs for COVID-19 using iterative computational and wet laboratory methods. The drugs were screened at doses that are known to be achievable in humans. Furthermore, inhibition of viral induced cytopathic effect (CPE) was used as the laboratory surrogate to predict efficacy. Erythromycin, pyridoxine, folic acid and retapamulin were found to inhibit SARS-CoV-2 induced CPE in Vero cells at concentrations that are clinically achievable. Additional studies may be required to further characterize the inhibitions of CPE and the possible mechanisms.

Erythromycin, retapamulin, pyridoxine, folic acid, and ivermectin inhibit cytopathic effect, papain-like protease, and MPRO enzymes of SARS-CoV-2

“…Vero cell preparation, passaging, SARS-CoV-2 virus, and sources of experimental drugs were as previously described ( Bello et al., 2023 ). Three different doses of each drug were tested for antiviral activity: erythromycin, retapamulin, folic acid, and ivermectin were tested at 5 µM, 7.5 µM, and 10 µM, while pyridoxine was tested at 10 µM, 15 µM, and 20 µM, all in three independent replicates.…”

“…Neutral red (NR) assay ( Bello et al., 2023 ) was used to quantify cell viability and the inhibition of CPE. The NR uptake assay provides a quantitative estimation of the number of viable cells in the culture.…”

“…The NR uptake assay provides a quantitative estimation of the number of viable cells in the culture. It is based on the ability of viable cells to incorporate and bind the neutral red dye in the lysosomes, which are then extracted using glacial acid for measurement of optical densities using a spectrophotometer ( Bello et al., 2023 ).…”

“…Our team previously developed and validated an algorithm that involves deliberate consideration of multiple targets, cost, toxicity, and availability in selecting drugs for rapid repurposing efforts with an off-label application as the immediate goal ( Bello et al., 2023 ).…”

“…SARS-CoV-2-induced cytopathic effect (CPE) has previously been validated as a surrogate for SARS-CoV-2 infectivity, and it is non-inferior to PCR ( Basile et al., 2021 ). Therefore, in our previous study ( Bello et al., 2023 ), the demonstration of inhibition of CPE was considered more cost-effective and a surrogate of clinical efficacy than the demonstration of inhibition of viral multiplication alone due to the possibility of a threshold effect in viral-induced CPE ( Shahsavandi et al., 2013 ). We also identified erythromycin, pyridoxine, folic acid, and ivermectin as potential drugs to repurpose for COVID-19; with saw a wet laboratory demonstration of inhibition (qualitative assay) of SARS-COV-2-induced CPE in Vero cells and in silico prediction of inhibition of multiple critical SARS-CoV-2 enzymes ( Bello et al., 2023 ).…”