‘There are very limited data to support its use.’

5 highlights from NPS MedicineWise’s new comprehensive update for health professionals on the use hydroxychloroquine for COVID-19

NPS MedicineWise has added a new article that reviews the latest evidence on the use of hydroxychloroquine for the prevention or treatment of COVID-19.

The article complements an earlier article written for consumers which reminded them that currently there is no evidence to support the use of hydroxychloroquine as a treatment for COVID-19 outside of the hospital setting.

An editorial published in Australian Prescriber last week also looked at principles of ethical prescribing for self and others relating to hydroxychloroquine.

Here are 5 important things to know from NPS MedicineWise’s most recent article:

  1. Hydroxychloroquine can have serious adverse effects, especially as daily doses increase (> 5 mg/kg actual weight) or accumulate over the long term (> 5 years). Common (> 1%) adverse effects of hydroxychloroquine include nausea, vomiting, anorexia, abdominal cramps, rash, itch, alopecia and headache. Hydroxychloroquine reduces HbA1c and there are rare reports of severe hypoglycaemia. The main toxicological adverse effects from prolonged exposure to hydroxychloroquine include: retinopathy; cardiac toxicity; neuromyopathy as evidenced by abnormal nerve conduction and sensory changes (infrequent).
  2. Hydroxychloroquine is thought to be incompatible with monoamine oxidase inhibitors; other medicines known to prolong the QT interval e.g., Class IA and III antiarrhythmics, tricyclic antidepressants, antipsychotics and some anti-infectives; antidiabetic agents, other antimalarial agents known to lower convulsion threshold (e.g., mefloquine), digoxin and some antiepileptic medicines; and tamoxifen due to its own retinal toxicity.
  3. Currently there are very limited data to support the use of hydroxychloroquine for the treatment or prevention of COVID-19. Multiple international clinical trials are underway to further explore the efficacy of chloroquine or hydroxychloroquine in treating patients diagnosed with COVID-19. Clinical evidence is emerging, but results are inconclusive. For example:

    A small pilot study conducted in China randomised 30 patients with a confirmed diagnosis of COVID-19 to receive either standard treatment or standard treatment plus hydroxychloroquine (400 mg for 5 days). Results were similar in both groups. By day 7, more patients on standard treatment alone (93.3%) had a negative throat swab compared to those taking the hydroxychloroquine (86.7%). The rate of progression to pneumonia (on CT scan) was slightly reduced in the patients treated with hydroxychloroquine. One patient in the hydroxychloroquine group progressed to severe disease. The limitations of this study included small sample size, and a negative throat swab as the primary endpoint, which is not a clinical indication of whether the patient is at risk of more severe disease or death.

    Another small study from France reported that hydroxychloroquine alone or in combination with azithromycin reduced detection of SARS-CoV-2 in upper respiratory tract specimens compared with a non-randomised control group. The study did not assess clinical benefit and results were unreliable due to study limitations. These included that the trial was open label and not randomised. The accuracy of the testing was inconsistent, the number of patients needed to give statistical confidence to the results was not reached, patients were lost to follow-up and there was no opportunity to gather medium- or long-term data.

    As recently as 21 April 2020, a relatively large US study of veterans hospitalised with COVID-19 (n=368) found no evidence that use of hydroxychloroquine, either with or without azithromycin, reduced the risk of mechanical ventilation in patients hospitalised with COVID-19. An association of increased overall mortality was identified in patients treated with hydroxychloroquine alone. However limitations include that the study was a non-randomised, retrospective analysis, and there was a narrow demographic: males, predominantly African-American, aged over 65 years.

  4. Risks and unknowns highlight the importance of waiting for results of ongoing prospective, randomised, controlled studies before widespread adoption of hydroxychloroquine in COVID-19. Australians recommendations state that for patients with COVID-19 illness, antiviral medications or other disease-modifying treatments should only be administered in the context of clinical trials with appropriate ethical approval. There are significant concerns about the potential harms of unproven treatments, including the possibility of adverse effects and toxicity.
  5. Due to new rules passed in Australia, medical practitioners who do not work in one of the following specialist areas cannot initiate treatment with hydroxychloroquine: dermatology; emergency medicine; intensive care medicine; paediatrics and child health; physician; oral medicine. GPs and doctors in training can only prescribe hydroxychloroquine for continued treatment of patients where initial treatment has been authorised by one of the listed specialists.

Please read the full resource from NPS MedicineWise here.

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