COVID-19 Therapeutics: Use, Mechanism of Action, and Toxicity (Xenobiotics)

SARS-CoV-2 emerged in 2019 and led to the COVID-19 pandemic. Efforts to develop therapeutics against SARS-Cov-2 led to both new treatments and attempts to repurpose existing medications. Here, we provide a narrative review of the xenobiotics and alternative remedies used or proposed to treat COVID-19. Most repositioned xenobiotics have had neither the feared toxicity nor the anticipated efficacy. Repurposed viral replication inhibitors are not efficacious and frequently associated with nausea, vomiting, and diarrhea. Antiviral medications designed specifically against SARS-CoV-2 may prevent progression to severe disease in at-risk individuals and appear to have a wide therapeutic index. Colloidal silver, zinc, and ivermectin have no demonstrated efficacy. Ivermectin has a wide therapeutic index but is not efficacious and acquiring it from veterinary sources poses additional danger. Chloroquine has a narrow therapeutic index and no efficacy. A companion review covers vaccines, monoclonal antibodies, and immunotherapies. Together, these two reviews form an update to our 2020 review.