The U.S. Food and Drug Administration has authorized hydroxychloroquine for emergency use for the treatment of patients with COVID-19 infection. Efficacy of the drug for COVID-19 is supported by anecdotal evidence and Donald Trump, but the approval is considered controversial. Novartis/Sandoz has donated 30 million doses and Bayer has donated 1 million tablets of chloroquine phosphate.
Hydroxychloroquine is approved for the treatment of malaria, lupus and rheumatoid arthritis. An unpublished observational study in France by Gautret and colleagues reported on a combination of hydroxychloroquine and azithromycin in 80 inpatients with COVID-19 infection. Treatment was associated with a rapid fall in nasopharyngeal viral load as evaluated by PCR; 83% of samples were negative at Day 7 and 93% at Day 8. A total of 97.5% of virus cultures from respiratory samples were negative at Day 5. All but two patients were discharged from hospital after a mean stay of 5 days. One patient died and one patient remained in ICU.
The group has also reported an open-label study (42% male, mean age 45 years) of 20 patients who received hydroxychloroquine and 16 controls (Gautret et al. Int J Antimicrob Agents 2020 ; epublished March 20, 2020 ; free full text at https://www.sciencedirect.com/science/article/pii/S0924857920300996/pdfft?md5=332491a1ab112f0e0058fb400a5ea8ca&pid=1-s2.0-S0924857920300996-main.pdf). There was a significant difference in nasopharyngeal viral load beginning on Day 3 and continuing to Day 6. At Day 6, the virological cure rate was 100% with hydroxychloroquine/azithromycin, 57% with hydroxychloroquine monotherapy and 12.5% for controls. For a review of hydroxychloroquine and coronaviruses see www.sciencedirect.com/science/article/pii/S0924857920300881/pdfft?md5=9642973db7b44aad39f38aeb755c95e8&pid=1-s2.0-S0924857920300881-main.pdf.
A rapid review of the literature found two small studies that reported conflicting results on whether chloroquines had antiviral activity against SARS CoV-2 (Gbinigie & Frie. BJGP Open 2020; epublished April 7, 2020; free full text at https://bjgpopen.org/content/bjgpoa/early/2020/04/07/bjgpopen20X101069.full-text.pdf).
Quebec’s Institut national d’excellence en santé et services sociaux (INESSS) has urged caution, stated that the widespread use of hydroxychloroquine or chloroquine is not justified due to concerns about treatment efficacy and safety (for the press release in French see www.inesss.qc.ca/en/covid-19/traitements/chloroquine.html). Dr Emily McDonald, Assistant Professor, McGill University, is one of the principal investigators of a hydroxychloroquine study that has started to enroll Canadian patients (sign-up at www.covid-19research.ca/).
A recent editorial in JAMA also warned that unproven COVID-19 therapies, such as hydroxychloroquine/chloroquine, have the potential for serious harm. Adverse events associated with hydroxychloroquine include QT interval prolongation, hepatotoxicity and hypoglycemia, which may be especially problematic in elderly patients with COVID-19 and comorbidities (https://jamanetwork.com/journals/jama/fullarticle/2763802?resultClick=1).