A review on drug repurposing in COVID-19: from antiviral drugs to herbal alternatives

Abstract

Background COVID-19 is an illness caused by severe acute respiratory syndrome coronavirus 2. Due to its rapid spread, in March 2020 the World Health Organization (WHO) declared pandemic. Since the outbreak of pandemic many governments, scientists, and institutions started to work on new vaccines and finding of new and repurposing drugs. Main body of the abstract Drug repurposing is an excellent option for discovery of already used drugs, effective against COVID-19, lowering the cost of production, and shortening the period of delivery, especially when preclinical safety studies have already been performed. There are many approved drugs that showed significant results against COVID-19, like ivermectin and hydrochloroquine, including alternative treatment options against COVID-19, utilizing herbal medicine. Short conclusion This article summarized 11 repurposing drugs, their positive and negative health implications, along with traditional herbal alternatives, that harvest strong potential in efficient treatments options against COVID-19, with small or no significant side effects. Out of 11 repurposing drugs, four drugs are in status of emergency approval, most of them being in phase IV clinical trials. The first repurposing drug approved for clinical usage is remdesivir, whereas chloroquine and hydrochloroquine approval for emergency use was revoked by FDA for COVID-19 treatment in June 2020.

An Overview of Repurposed Drugs for Potential COVID-19 Treatment

“…Chloroquine is an antimalarial drug that displays broad-spectrum antiviral properties [ 24 , 25 ]. Chloroquine is classified as a 4-aminoquinoline compound ( Figure 2 ), and it is employed to treat diseases such as malaria, rheumatoid arthritis and autoimmune diseases such as lupus erythematosus [ 21 , 26 , 27 , 28 ]. It is also a weak base, and the precise mode of action has not been elucidated for all microorganisms.…”

“…Molnupiravir decreases the replication of SARS-CoV-2, thereby impeding COVID-19 [ 21 ]. According to a review conducted by Zarenezhad and Marzi (2022) [ 76 ] and a perspective paper published by Lee et al (2021) [ 77 ], it was indicated that clinical trials resulted in a decreased risk of fatality or hospitalisation in patients displaying mild to moderate COVID-19 symptoms [ 76 , 77 ].…”

“…It should also be noted that some of the side effects of using favipiravir are hyperuricemia and teratogenicity [ 81 ]. Therefore, it is not recommended that pregnant women use the drug, as it can cause birth defects or abnormalities in the embryo [ 21 , 81 , 85 ]. As such, more clinical testing is required to fully understand the pharmacokinetics, advantages, and disadvantages of the drug.…”

“…Due to the long turnaround times for the development of new drugs, a lucrative COVID-19 treatment strategy for decreasing the current burden on healthcare systems is the repurposing of known/existing drugs. Drug repurposing can be implemented as an effective strategy, firstly, in order to shorten delivery times, as well as to lower production costs [ 21 ]. De novo drug development strategies are estimated to cost approximately USD 1 billion [ 22 ].…”

Discovery of Quinacrine as a Potent Topo II and Hsp90 Dual-Target Inhibitor, Repurposing for Cancer Therapy

“…Drug repurposing is an excellent option for the discovery of already used drugs, lowering the cost of production, and shortening the period of delivery [ 29 ]. For example, many approved drugs have shown significant results against COVID−19 [ 30 ]. Otsuka’s team found a new target for S−trityl−L−cysteine−derived compounds distinct from their well−known mitotic kinesin Eg5 inhibition [ 31 ].…”