Hydroxychloroquine is a 4-aminoquinoline derivative that has both anti-inflammatory and antimalarial activities. According to 21^stWHO Model List of Essential Medicines (2019), it is a disease-modifying agent used in rheumatoid disorders (DMARDs)¹. It can be used as an immunosuppressive agent also².

On 11^th March 2020, WHO declared Novel Coronavirus Disease (COVID-19) is a global pandemic disease³. COVID-19 is caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). Nowadays, there is no specific treatment for COVID-19. Some clinical studies has been going on for combating this global pandemic diseases. Among those, Hydroxychloroquine or combination withHydroxychloroquine has been studied to fight the COVID-19.  In in vitro study, Hydroxychloroquine is better than chloroquineto resist SARS-CoV-2 but, there is no enough proof to support the use of Hydroxychloroquine in SARS-CoV-2 infection⁴.The treatment of Hydroxychloroquine significantly reduces the viral load to resist COVID-19. At the same time, the effect of Hydroxychloroquineis enhanced by theincorporation of Azithromycin⁵.The spike (S) viral protein uses sialic acids and gangliosides for attachment to the surface of respiratory cells for replication. Some molecular modelling approach shows that chloroquine and its more active derivatives Hydroxychloroquine bind with sialic acids and gangliosides with high affinity so that the viral S protein is unable to bind with gangliosides⁶.In the meantime, Indian Council of Medical Research (ICMR) has recommended the use of Hydroxychloroquine for health workers who engaged in the treatment of COVID 19 patients for prophylactic purpose with the consultation of the doctors due to some undesirable side effects.

But, some precautions should be taken while using Hydroxychloroquine, such as regulating of haematological parameters (RBC, WBC and platelet counts), serum electrolytes, blood glucose (due to hypoglycemic effect of Hydroxychloroquine), hepatic and renal functions. It may cause QTc prolongation also⁷.

So, Hydroxychloroquine is not widely accepted drug to treat this disease, based on little evidences till date.But, some of the institutions and organizations have already recognized the utility of chloroquine and Hydroxychloroquine⁸.Itis preferably safe, low cost, and easily available in the countries where malaria is endemic⁹. The research on Hydroxychloroquine is going on rapidly. Therefore, it may be effective treatment to control COVID-19 in near future.

References

1. World Health Organization model list of essential medicines: 21st list 2019. Geneva: World Health Organization.

2.Liang N, Zhong Y, Zhou J, Liu B, Lu R, Guan Y, Wang Q, Liang C, He Y, Zhou Y, Song J, Hou J, (2018) Immunosuppressive effects of Hydroxychloroquine and artemisinin combination therapy via the nuclear factor‑κBsignaling pathway in lupus nephritis mice, Experimental and therapeutic medicine 15: 2436-2442.

3. https://www.who.int/india/emergencies/novel-coronavirus-2019.
4. Yao X, Fei Ye F., et al., (2020)In Vitro Antiviral Activity and Projection of Optimized Dosing Design of Hydroxychloroquine for the Treatment of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), Clinical Infectious Diseases, ciaa237, https://doi.org/10.1093/cid/ciaa237.
5. Gautret P., Lagier JC., et al., (2020) Hydroxychloroquine and azithromycin as a treatment of COVID-19: results of an open-label non-randomized clinical trial, International Journal of Antimicrobial Agents, https://doi.org/10.1016/j.ijantimicag.2020.105949.
6. Fantini J., Di ScalaC. et al.,(2020) Structural and molecular modelling studies reveal a new mechanism of action of chloroquine and hydroxychloroquine against SARS-CoV-2 infection,International Journal of Antimicrobial Agents, https://doi.org/10.1016/j.ijantimicag.2020.105960.
7. Liu D, Li X, Zhang Y, Kwong JSW, Li L, Zhang Y, et al.(2018) Chloroquine and hydroxychloroquine are associated with reduced cardiovascular risk: a systematic review and meta-analysis. Drug Des DevTher, 12:1685-95.
8. Touret F, de Lamballerie X. (2020) Of chloroquine and COVID-19. Antivir Res, Mar 5;177:104762. https://doi.org/10.1016/j.antiviral.2020.104762.
9. Singh AK., Singh A., Shaikh A., Singh R., Misra A., (2020)Chloroquine and hydroxychloroquine in the treatment of COVID-19 with or without diabetes: A systematic search and a narrative review with a special reference to India and other developing countries, Diabetes & Metabolic Syndrome: Clinical Research & Reviews, 14: 241-246.