Chloroquine:
Chloroquine is an anti-malarial drug. It is used to treat chronic inflammatory diseases, including rheumatoid arthritis and systemic lupus erythematosus. Recently, It’s broad-spectrum antiviral activity is identified. Chloroquine interferes with the biosynthesis of nucleic acids and caused accumulation of toxic heme metabolite within the parasite, thus killing them. Chloroquine inhibits the production of interleukin-1 and the release of enzymes in the treatment of rheumatoid arthritis. Its anti-viral mechanism of action involves inhibition of glycosylation of SARS-CoV-2 cell receptors blocking viral entering and increasing the pH of endosomes. Chloroquine showed in vitro inhibition of SARS-CoV-2 (EC50 = 1.13 μM). Reports have so far shown that chloroquine phosphate is preferred in managing of pneumonia. It encourages virus-negative transformation and reduces illness duration[41]. 500mg dose of Chloroquine orally once or twice daily proved very effective[20]. Clinical trials of chloroquine phosphate should be designed in such a way to monitor the possible side effects used by oral use.
Hydroxychloroquine:
Hydroxychloroquine has a similar mechanism of action as chloroquine. Furthermore, Hydroxychloroquine prevents the activation of pro-inflammatory genes. It also reduced the cytokine syndrome via inhibition of T-cell receptors. Anti-inflammatory, as well as the anti-viral role of hydroxychloroquine, proved very potent in combating COVID-19. Hydroxychloroquine is safer than that of chloroquine. EC50 of hydroxychloroquine = 6.14 μM and that of chloroquine is 23.90 μM[20]. The dose of hydroxychloroquine in COVID-19 treatment is 400 mg of loading dose twice for one day, followed by 200 mg twice daily. Dosing needed further studies. Side effects of hydroxychloroquine include hypoglycemia, retinopathy, QTc prolongation, and neuropsychiatric effects. However, no infant ocular toxicity is reported in a review of 12 studies, including 588 pregnant patients[20]. Hydroxychloroquine proved less toxic than chloroquine, but prolonged use is still associated with severe side effects. Considering that most patients are asymptomatic or present with less severe symptoms, the use of dangerous drug Chloroquine and hydroxychloroquine cannot be recommended unless they are proven effective in treatment. Social distancing remains the top priority measure for the prevention of COVID-19.[18]