Does Metformin Satisfy as an Option for Host-Directed Therapy in COVID-19?

Metformin is a dimethyl biguanide known for its anti-hyperglycemic effects since 1922 and, thus, has been used in the treatment of Type 2 Diabetes Mellitus. Apart from this, its function as an anti-inflammatory, anti-oxidant, anti-thrombotic, and anti-microbial agent has also been studied largely. Its effect via inhibition of respiratory complex 1 and glycerol-3-phosphate dehydrogenase (GPD2) in the mitochondria and inhibition of the mammalian target of rapamycin complex 1 (mTORC1) and activation of Adenosine Mono Phosphate dependent kinase (AMPK) in the cytoplasm are its already known mechanisms of action. With the newer proposed effects on endosome/ lysosome regulation via Na+/H+ exchangers and V-ATPase, thereby affecting autophagy, coupled with its use in ARDS owing to its immunomodulatory effects and anti-viral action, the use of metformin against the novel Coronavirus is hypothesized.