Why might hydroxychloroquine and azithromycin be effective against the novel Coronavirus SARS-CoV-2/Covid-19?

Repurposing of older drugs such as chloroquine or hydroxychloroquine (HC) and more recently, azithromycin (AZ), has received much attention recently in the treatment of Covid-19. Both HC and AZ have immune modulating and antiviral activity that may potentially be effective in our fight against Covid-19.

 
Chloroquine/HC: Chloroquine is an old drug used for its antimalarial activity as well as for its immune modulation and anti-inflammatory properties. It is active in mice against a variety of viruses, including some enteroviruses, Zika virus, and influenza A H5N1 (1). Both chloroquine and HC are active in vitro against Covid-19, though HC appears to be more active (2).

 
Azithromycin: A macrolide often used for treatment of bacterial respiratory tract infections but also with anti-inflammatory and antiviral activity. Azithromycin has been shown to augment interferon response in rhinovirus-infected bronchial epithelial cells as well as in an experimental mouse model of asthma exacerbation (3,4). It also has activity against Zika virus (5). As recently as 2016, some authors opined that macrolides may be useful in pandemic influenza characterized by excessive inflammatory cytokine production because of their anti-inflammatory and interferon-boosting potential (6).

 
March 2020 French clinical trial: A small non-randomized clinical trial involving 36 confirmed Covid-19 patients (mean age 45 y) reported that HC (200 mg 3x/day x 10 days) was associated with rapid viral clearance from nasopharynx, often within 3-6 days (7). The effect was even more pronounced when AZ (500 mg 1st day, followed by 250 mg daily x 4 days) was added in 6 patients.

It’s worth emphasizing that most subjects in this study were either asymptomatic (17%) or had mild disease with upper respiratory tract infection symptoms only (61%). Pneumonia was diagnosed in only 6 patients.  A significant number of patients in the treatment arm also dropped out of the study, some due to ICU transfer.

 
Although such preliminary reports appear promising, the proof of the efficacy and safety of HC and/or AZ in the treatment of Covid-19 awaits larger properly designed clinical studies. Stay tuned!

 

 

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References
1. Touret F, de Lamballerie X. Of chloroquine and COVID-19. Antiviral Research 2020;177. 104762. https://www.ncbi.nlm.nih.gov/pubmed/32147496
2. Yao X, Ye F, Zhang M, et al. In vitro antiviral activity and projection of optimized dosing design of hydroxychloroquine for the treatment of severe acute respirartory syndrome coronavirus 2 (SARS-CoV-2). Clin Infect Dis 2020, March 9. https://www.ncbi.nlm.nih.gov/pubmed/32150618
3. Menzel M, Akbarshai H, Bjermer L, et al. Azithromycin induces anti-viral effects in cultured bronchial epithelial cells from COPD patients. Scientific Reports 2016;6:28698. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4923851/
4. Menzel M, Akbarshai H, Uller L. Azithromycin exhibits interferon-inducing properties in an experimental mouse model of asthma exacerbation. Eur Resp J 2015;46:PA5095. https://erj.ersjournas.com/content/46/suppl_59/PA5095
5. Retallack H, Di Lullo E, Knopp AC, et al. Zika virus cell tropism in the developing human brain and inhibition by azithromycin. Proc Nat Acad Sci USA 2016;113:14408-13. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5167169/
6. Porter JD, Watson J, Roberts LR, et al. Identification of novel macrolides with antibacterial, anti-inflammatory and type I and III-IFN-augmenting activity in airway epithelium. J Antimicrob Chemother 2016;71:2767-81. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5031920/
7. Gautret P, Lagier JC, Parola P, et al. Hydroxychloroquine and azithromycin as a treatment of COVID-19:results of an open-label non-randomized clinical trial. International Journal of Antimicrobial Agents—In Press 17 March 2020-DOI: 10.1016/j.ijantimicag.2020.105949 . https://www.sciencedirect.com/science/article/pii/S0924857920300996

 

Disclosures: The listed questions and answers are solely the responsibility of the author and do not necessarily represent the official views of Massachusetts General Hospital, Harvard Catalyst, Harvard University, its affiliate academic healthcare centers, or its contributors. Although every effort has been made to provide accurate information, the author is far from being perfect. The reader is urged to verify the content of the material with other sources as deemed appropriate and exercise clinical judgment in the interpretation and application of the information provided herein. No responsibility for an adverse outcome or guarantees for a favorable clinical result is assumed by the author. Thank you!

Why might hydroxychloroquine and azithromycin be effective against the novel Coronavirus SARS-CoV-2/Covid-19?

What existing drugs are currently being evaluated or repurposed for treatment of Coronavirus (Covid-19) infection?

There are currently no drugs specifically approved for treatment of Covid-19 infections. However, there are legions of therapies that are being considered, tried, and/or evaluated in clinical trials. Many experts believe a combination of drugs may be necessary for optimal therapy. Here is my select list of potentially promising drugs from gleaning the literature and online resources to date.1-16

  • Remdisivir: A broad spectrum investigational nucleoside analogue, originally developed to treat a variety of viruses, including Ebola, SARS and MERS. Active in vitro against Covid-19. Favorable results have been reported in some cases, including the first reported patient in the U.S.
  • Chloroquine: An old drug used for its antimalarial activity as well as for its immune modulation and anti-inflammatory properties. Has also been found to be active in mice against a variety of viruses, including certain enteroviruses, Zika virus, influenza A H5N1.  Active in vitro against Covid-19, though hydroxychloroquine may be more effective. Evidence for its efficacy in treating acute viral infections in humans is currently lacking.
  • Lopinavir/ritonavir: Protease inhibitor combo used in HIV infection with possibly some benefit in the treatment of SARS. Recent study showed no significant efficacy in severe Covid-19 disease. 
  • Interferon-alpha: An antiviral cytokine used against hepatitis B and C viruses. May be more effective for prophylaxis than post-exposure, based on experimental animal studies involving SARS.
  • Ribavirin: Another nucleoside analogue approved for hepatitis C (in combination with other drugs) and respiratory syncytial virus (RSV) infections but also evaluated in SARS and MERS. Has been reported to be active in vitro against Covid-19.
  • Sofosbuvir: Inhibits RNA-dependent RNA polymerase. Approved for treatment of hepatitis C, but also with in vitro activity against Covid-19.
  • Tocilizumab: Anti-interleukin-6 monoclonal antibody used in rheumatoid and giant cell arthritis. Theoretically, may mitigate cytokine storm observed in some patients during the later stages of Covid-19 disease.

Of course, there are many more drugs some of which would not be expected to be effective against Covid-19, based on what we so far know this virus. These include darunavir/cobicistat, oseltamivir, immunoglobulins, arbidol (an antiviral used in Russia and China vs influenza), angiotensin receptor blockers, stem cell therapy, convalescent plasma, and traditional Chinese medicine.

Remember corticosteroids are currently not recommended in the absence of other indications for their use (see related PEARL).

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References

  1. US National Library of Medicine. https://clinicaltrials.gov/ct2/results?cond=2019nCoV&term=&cntry=&state=&city=&dist
  2. Li Guangdi, De Clercq E. Therapeutic options for the 2019 novel coronavirus (2019-nCoV). Nature Reviews Drug Discovery 2020; Feb 19, 2010. https://www.nature.com/articles/d41573-020-00016-0
  3. Harrison C. Coronavirus puts drug repurposing on the fast track. Nature Biotechnology 020, Feb 27. https://www.nature.com/articles/d41587-020-00003-1
  4. Velavan TP, Meyer CG. The COVID-19 epidemic. Tropical Medicine and International Health 2020;25:278-280. https://onlinelibrary.wiley.com/doi/full/10.1111/tmi.13383
  5. Elfiky AA. Anti-HCV, nucleotide inhibitors, repurposing against COVID-19. Life Sciences 2020;248. 11747. https://www.sciencedirect.com/science/article/pii/S0024320520302253
  6. Wang Y, Wang Y, Chen Y, et al. Unique epidemiological and clinical features of the emerging 2019 novel coronavirus pneumonia (COVID-19) implicate special control measures. J Med Virol 2020;March 5. https://www.ncbi.nlm.nih.gov/pubmed/32134116
  7. Huang C, Wang Y, Li X, et al. Clinical features of patients infected with 2029 novel coronavirus in Wuhan, China. Lancet 2020;395:497-506. https://www.ncbi.nlm.nih.gov/pubmed/31986264
  8. Paules CI, Marston HD, Fauci AS. Coronavirus infections—More than just the common cold. JAMA 2020;323:707-78. https://jamanetwork.com/journals/jama/fullarticle/2759815
  9. Touret F, de Lamballerie X. Of chloroquine and COVID-19. Antiviral Research 2020;177. 104762. https://www.sciencedirect.com/science/article/pii/S0166354220301145
  10. Gurwitz D. Angiotensin receptor blockers as tentavie SARS-CoV-2 therapeutics. https://www.ncbi.nlm.nih.gov/pubmed/32129518/
  11. Wang M, Cao R, Zhang L, et al. Remdesivir and chlorquine effectively inhibit the recently emerged novel coronavirus (2019-nCoV) in vitro. Cell Research 2020;30:269-71. https://www.nature.com/articles/s41422-020-0282-0
  12. Roques P, Thiberville SD, Dupuis-Maguirara L, et al. Paradoxical effect of chloroquine treatment in enhancing Chikungunya virus infection. Viruses 2018;10, 268. https://www.ncbi.nlm.nih.gov/pubmed/29772762
  13. Young BE, Ong SWX, Kalimuddin S, et al. Epidemiologic features and clinical course of patients infected with SARS-CoV-2 in Singapore. JAMA 2020;March 3. https://jamanetwork.com/journals/jama/fullarticle/2762688
  14. Holshue ML, DeBolt C, Lindquist S, et al. First case of 2019 novel coronavirus in the United States. N Engl J Med 2020; March 5. https://www.nejm.org/doi/full/10.1056/NEJMoa2001191
  15. Yao X, Ye F, Zhang M, et al. 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). Clin Infect Dis 2020. March 9. https://www.ncbi.nlm.nih.gov/pubmed?term=32150618
  16. Cao B, Wang Y, Wen D, et al. A trial of lopinavir-ritonavir in adults hospitalized with severe Covid-19. N Engl M Med 2020, March18. DOI:10.1056/NEJMoa2001282. https://www.nejm.org/doi/full/10.1056/NEJMoa2001282

 

Disclosures: The listed questions and answers are solely the responsibility of the author and do not necessarily represent the official views of Massachusetts General Hospital, Harvard Catalyst, Harvard University, its affiliate academic healthcare centers, or its contributors. Although every effort has been made to provide accurate information, the author is far from being perfect. The reader is urged to verify the content of the material with other sources as deemed appropriate and exercise clinical judgment in the interpretation and application of the information provided herein. No responsibility for an adverse outcome or guarantees for a favorable clinical result is assumed by the author. Thank you!

What existing drugs are currently being evaluated or repurposed for treatment of Coronavirus (Covid-19) infection?