Drug Repurposing: A Strategy for Discovering Inhibitors against Emerging Viral Infections
Authors: dos Santos Nascimento Igor José , de Aquino Thiago Mendonça , da Silva-Júnior Edeildo Ferreira 
Published: August 2020

Background:
Viral diseases are responsible for several deaths around the world. Over the
past few years, the world has seen several outbreaks caused by viral diseases that, for a long time,
seemed to possess no risk. These are diseases that have been forgotten for a long time and, until
nowadays, there are no approved drugs or vaccines, leading the pharmaceutical industry and several
research groups to run out of time in the search for new pharmacological treatments or prevention
methods. In this context, drug repurposing proves to be a fast and economically viable technique,
considering the fact that it uses drugs that have a well-established safety profile. Thus, in this review,
we present the main advances in drug repurposing and their benefit for searching new treatments
against emerging viral diseases.

Methods:
We conducted a search in the bibliographic databases (Science Direct, Bentham Science,
PubMed, Springer, ACS Publisher, Wiley, and NIH’s COVID-19 Portfolio) using the keywords
"drug repurposing", "emerging viral infections" and each of the diseases reported here (CoV; ZIKV;
DENV; CHIKV; EBOV and MARV) as an inclusion/exclusion criterion. A subjective analysis was
performed regarding the quality of the works for inclusion in this manuscript. Thus, the selected
works were those that presented drugs repositioned against the emerging viral diseases presented
here by means of computational, high-throughput screening or phenotype-based strategies, with no
time limit and of relevant scientific value.

Results:
291 papers were selected, 24 of which were CHIKV; 52 for ZIKV; 43 for DENV; 35 for
EBOV; 10 for MARV; and 56 for CoV and the rest (72 papers) related to the drugs repurposing and
emerging viral diseases. Among CoV-related articles, most were published in 2020 (31 papers), updating
the current topic. Besides, between the years 2003 - 2005, 10 articles were created, and from
2011 – 2015, there were 7 articles, portraying the outbreaks that occurred at that time. For ZIKV,
similar to CoV, most publications were during the period of outbreaks between the years 2016 -
2017 (23 articles). Similarly, most CHIKV (13 papers) and DENV (14 papers) publications occur at
the same time interval. For EBOV (13 papers) and MARV (4 papers), they were between the years
2015 - 2016. Through this review, several drugs were highlighted that can be evolved in vivo and
clinical trials as possible used against these pathogens showed that remdesivir represent potential
treatments against CoV. Furthermore, ribavirin may also be a potential treatment against CHIKV;
sofosbuvir against ZIKV; celgosivir against DENV, and favipiravir against EBOV and MARV, representing
new hopes against these pathogens.

Conclusions:
The conclusions of this review manuscript show the potential of the drug repurposing
strategy in the discovery of new pharmaceutical products, as from this approach, drugs could be
used against emerging viral diseases. Thus, this strategy deserves more attention among research
groups and is a promising approach to the discovery of new drugs against emerging viral diseases
and also other diseases.