INTRODUCTION
COVID-19 is an infectious disease caused by the new coronavirus
(SARS-CoV-2), was first reported in Wuhan, China, later reaching
pandemic proportions. Patients may present symptoms (fever, dry cough
and tiredness), severe (dyspnea, hypoxia and/or great pulmonary
involvement) and critical (respiratory failure, systemic shock and/or
multiple organ failure) [1]. Respiratory discomfort syndrome, an
incident complication, affected 15.6% of patients in a study that
collected data from 1,099 patients with COVID-19 in China [2].
Despite the incessant search for effective drugs in their clinical
treatment, no drug has yet been validated [3,4]. Several classes of
drugs and strategies are being evaluated or developed aiming at the
clinical management of COVID-19, such as antibiotics, antiviral,
anti-inflammatory, antibodies, anticoagulants, anti-fibrotic, oxygen
therapy, and immunomodulation, among others. Possibly, different
treatment modalities have different efficiencies according to the stage
of the disease and its manifestation [4]. Thus, it is necessary to
understand the pathophysiology of the disease, as well as the affected
organs and systems, in order to improve the identification of
therapeutic targets and, thus, rigorously define the ideal treatment.
In the context of the search for adequate pharmacotherapy, biguanides,
buformin (BUF), metformin (MET) and phenformin (PHEN) appear as possible
adjuvant therapy for the treatment of COVID-19, due to their
comprehensive pharmacological properties [5]. Only MET is used in
large scale [6], appearing as the first therapeutic line for type 2
diabetes mellitus (DM2) and one of the most prescribed drugs worldwide
[7].
Antihelmintic, antimalarial and antiviral effects of biguanides have
been described, the latter being dependent on the administration of high
doses [8,9]. Considering recent publications of this pharmacological
class, its potential off label use, pharmacological advances that allow
the administration of drugs by alternative routes, as well as the demand
for new therapeutic tools for COVID-19, this study aimed to review the
pharmacological effects of biguanides, as well as its therapeutic
potential in viral infections.