LAUSR

Introduction Urgent action is needed to fight the ongoing COVID-19 pandemic by reducing the number of infected people along with the infection contagiousness and severity. Chlorpromazine (CPZ), the prototype of typical antipsychotics from the phenothiazine group, is known to inhibit clathrin-mediated endocytosis and acts as an antiviral, in particular against SARS-CoV-1 and MERS-CoV. The aim of this in vitro study was to test CPZ against a SARS-CoV-2 isolate in monkey and human cells. Material and methods Monkey VeroE6 cells and human alveolar basal epithelial A549-ACE2 cells were infected with SARS-CoV-2 in presence of different concentrations of CPZ. Supernatants were harvested at day 2 and analysed by RT-qPCR for the presence of SARS-CoV-2 RNA. Cell viability was assessed on non-infected cells. Results We evidenced an antiviral activity of CPZ against SARS-CoV-2 in monkey VeroE6 cells with an IC50 of 8.2 µM, a CC50 of 13.5µM and a SI of 1.65. In human A549-ACE2 cells, CPZ was also associated with an anti-SARS-CoV-2 activity, with an IC50 of 11.3 µM, a CC50 of 23.1 µM and a SI of 2.04. Discussion Even though the measured SI are low, such IC50 measured in vitro may translate to CPZ dosage used in clinical routine because of CPZ high biodistribution in lungs and in saliva. Also, CPZ brain distribution could be of high interest for treating or preventing the neurological and psychiatric forms of COVID-19. Conclusions These preclinical findings support clinical investigation of the repurposing of CPZ, a largely used drug with mild side effects, in COVID-19 treatment.