Earlier quoted context omitted.
Because it's a highly effective and widespread malaria (and RA/lupus) treatment?
The dose for malaria is 200mg. It's the higher doses that are associated with heart arythmia in covid patients. According to a trial reported in https://bmcmedicine.biomedcentral.com/track/pdf/10.1186/s129... "No serious cardiac adverse effects were recorded in malaria clinical trials of 35,548 participants who received quinoline and structurally related antimalarials with close follow-up including 18,436 individuals…
They are often conflated in the media and colloquial reporting.