A Lancet study from 2003.
“Effects of Chloroquine on Viral Infections: An Old Drug Against Today’s Diseases?”
https://pubmed.ncbi.nlm.nih.gov/14592603/
“Chloroquine is a 9-aminoquinoline known since 1934. Apart from its well-known antimalarial effects, the drug has interesting biochemical properties that might be applied against some viral infections. Chloroquine exerts direct antiviral effects, inhibiting pH-dependent steps of the replication of several viruses including members of the flaviviruses, retroviruses, and coronaviruses.......”
In all the flurry of posts I’d pretty much guess this has been linked before.
"Chloroquine/hydroxychloroquie has a well-studied toxicity profile. The half-century-long use of this drug in the therapy of malaria demonstrates the safety of acute administration of chloroquine to human beings. The use of chloroquine/hydroxychloroquine in rheumatic diseases and for antimalarial prophylaxis showed a low incidence of adverse events during chronic administration of this drug for periods of up to a few years. In these cases, the most serious toxic effect is a macular retinopathy, which depends on the cumulative dose rather than on the daily dose, and permanent damage may be prevented with regular visual monitoring during treatment. A recent study provided encouraging results on the safety of a high dosage of the drug (up to 500 mg of chloroquine base per day) even during pregnancy."
But now it's dangerous poison that needs to be studied to determine just how deadly it is.