INTRODUCTION
Coronavirus disease 2019 (COVID-19), an infectious viral disease caused
by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was
first reported in Wuhan in the Hubei province of China in December 2019
(Lu et al., 2020). It was declared a public health emergency of
international concern and subsequently a global pandemic by World Health
Organisation on 20th January 2020 and 11th March 2020
respectively (WHOa, 2020). As at 17th May 2020, there
were about 4.5 million confirmed cases of COVID-19 and well over 300 000
deaths resulting from the pandemic globally (WHOb, 2020).
Most of the cases of COVID-19 (about 80%) are asymptomatic (Crosby et
al., 2020). In the initial symptomatic phase of the disease, there could
be flu-like clinical features like sore throat, dry cough, rhinorrhea,
fever and fatigue. Myalgia, shortness of breath, haemoptysis, chest
pain, diarrhea, nausea and vomiting, headache and confusion may set in
subsequently. In the later phase, complications like acute respiratory
distress syndrome (ARDS), pneumonia, arrhythmia and septic shock may set
in (Chen et al., 2020; Yan et al., 2020; Huang et al., 2020; Wang, D. et
al, 2020). It has also been observed that the symptoms are
usually more severe in elderly patients with co-morbidities, in patients
with allergic conditions like asthma, and patients with chronic
obstructive pulmonary disease (Yang et al., 2020).
As at date, neither drug nor vaccine has been approved for the treatment
or prevention of this dreaded pandemic that has plunged the entire world
into confusion and fear as well as socio-economic straits.However, a combination of oxygen therapy, mechanical ventilation, drugs
like antivirals, antibiotics and other supportive therapies appear to
give promising clinical outcomes in the management of COVID-19 patients
(Yan et al., 2020). These therapeutic agents are being used on
“off-label” basis as they have not been approved for use in COVID-19
patients. This “off-label” use is a way of drug repurposing (drug
repositioning) in the bid to find fast-tracked remedy for the disease.
Drug repurposing can be said to be the process of identifying and
developing new uses for existing drugs (Ashburn & Thor, 2004).
A recent study shows that as at 20th March 2020, about
344 interventional studies had been registered on clinical trials
registries including ClinicalTrials.gov, WHO ICTRP, EU Clinical Trials
Register, and Cochrane Central Register of Controlled Trials (Lythgoe &
Middleton, 2020). Also, WHO had on 18th March 2020
launched a clinical trial called SOLIDARITY to trial the four
most promising drug candidates for COVID-19 treatment, namely:
chloroquine/hydroxychloroquine, remdesvir, lopinavir/ritonavir and
lopinavir/ritonavir/interferon beta-1a. This mega clinical trial is
involving participants across over 90 countries (WHOc, 2020). Also, as
at 14th April 2020, over 600 clinical trials on this
subject matter had been registered with the WHO with about 133 of them
being for therapeutic purposes.12 Putting the
therapeutic drug candidates together, they fall into about four major
therapeutic groups: antivirals, antimalarials,
immunosuppressants/immunomodulators and antibiotics. The antiviral
candidates include remdesvir, favipiravir, lopinavir/ritonavir,
ostelmavir, ganciclovir, peniclovir, umifenovir, triazavirin, baloxavir
marboxil, danoprevir/ritonavir, azvudine, sofosbuvir/ledipasvir,
sofosbuvir/daclatasvir, darunavir/cobicistat, emtricitabine/tenofovir
and ribavarin. The antibiotics include azithromycin, pirfenidone,
carimycin and teicoplanin. The antimalarials are the chloroquine/
hydroxychloroquine whereas the immunosuppressants/immunomodulators
include glucocorticoids (corticosteroids, methylprednisolone,
dexamethasone), anti-cytokines (tocilizumab, adalimumab, eculizumab,
sarilumab, ixekizumab) pegylated interferon with ribavarin,
lopinavir/ritonavir/interferon beta-1a (Lythgoe & Middleton, 2020;
WHOc, 2020). This list is not exhaustive but enough to show that the
race to find effective therapeutics for COVID-19 is certainly on and
hopefully, some of these drug candidates will make it through the
clinical trials and get formal approval.