Tetrandrine as a Therapeutic Agent for COVID-19

More than one million patients worldwide have been diagnosed with coronavirus disease 19 (COVID-19) to date (WHO situation report, 8th April 2020). There is neither a vaccine to prevent infection with the causative organism, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), nor a cure. In the struggle to devise potentially useful therapeutics in record time, the repurposing of existing drugs is a key route of action. In this review we argue that the bisbenzylisoquinoline and calcium channel blocker tetrandrine, originally extracted from the plant Stephania tetrandra and utilised in traditional Chinese medicine, could be repurposed to treat COVID-19. We collate and review evidence for tetrandrine’s putative mechanism of action in viral infection, specifically its recently discovered antagonism of the two-pore channel 2 (TPC2). Consideration of its pharmacodynamics and pharmacokinetics suggests that oral tetrandrine at doses currently used in clinical practice could be an effective agent for the treatment of SARS-CoV-2 infection in humans.