Summary:
What is already known
Drugs that block hERG potassium channels in the heart have potential
to cause cardiac arrhythmias
Hydroxychloroquine, chloroquine and azithromycin can block hERG
potassium channels
What this study adds
Disease associated metabolic changes such as febrile temperature,
acidosis and electrolyte imbalance modify hERG potency and hence
proarrhythmic risk
Chronic exposure to hydroxychloroquine and azithromycin causes
additional prolongation pf repolarisation compared to their acute
effects
Clinical significance
There is significant proarrhythmic risk for hydroxychloroquine and
chloroquine at doses being proposed to treat COVID-19
Clinicians should implement long term QT interval monitoring in
trials, particularly in patients with electrolyte imbalances