Drug repurposing: new strategies for addressing COVID-19 outbreak.

Introduction: COVID-19 outbreak has infected 34.20 million people with 1019 thousand deaths in more than 125 countries till 30 September 2020. Due to the unavailability of vaccine or targeted novel drug therapy against Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), screening of existential medical treatments facilitates identification of promising drugs for the treatment and management of COVID-19.Areas covered: The review article highlights repurposing of antiviral, antimalarial, antineoplastic, antidiabetic, analgesic, and immunomodulatory drugs. Furthermore, clinical trials, in-vitro studies, benefits, adverse effects, toxicities, mechanisms of action, and regulatory status of drugs are covered in this article.Expert opinion: Lack of conclusive results from randomized clinical trials indicates absence of specific drugs for treatment of COVID-19. Unavailability of complete data regarding safety, efficacy, and adverse reactions of drugs restricts the recommendation of clinical advice on dose and duration of the drug therapy. Remdesivir and favipiravir show promising outcomes but more clinical evidence is required for use in large populations. Experimental and repurposed drug therapies targeting spike and envelope proteins, Mpro, 3CLpro and PLpro enzymes, and RdRp and TMPRSS2 genes show capability to produce effective anti-SARS-CoV-2 action. Development of vaccine against SARS-CoV-2 will offer long-term solution to terminate spread of this global pandemic.