Psychiatric Effects of the Chloroquines: During the coronavirus outbreak, prescriptions for chloroquine and hydroxychloroquine have climbed 5-fold to 10-fold as as people turn to these experimental therapies for COVID-19. Their psychiatric properties are worth knowing. The chloroquines readily cross the blood-brain barrier, where they create a number of undesirable effects, increasing serotonin, acetylcholine, and glutamatergic transmission and causing toxic metabolites to accumulate. The drugs have known associations with suicide, psychosis, mania, and depression (Mascolo A et al, Inflammopharmacology 2018;26(5):1141–1149).

Drug interactions are another problem. As moderate CYP2D6 inhibitors, the chloroquines can raise levels of many psychiatric medications. They also prolong QTc and increase the risk of neutropenia on clozapine. These effects can linger, as the chloroquines have unusually long half-lives of 20–40 days.

Lithium and the Coronavirus: Lithium has also been proposed as a potential therapy for COVID-19. Lithium improves immune function, increasing neutrophils, lymphocytes, leukocytes, and natural killer cells. It also has direct antiviral activity. It has been used to treat herpes and impedes the replication of over a dozen viruses, including four coronavirus strands. Lithium has never been tested against the current novel coronavirus (Nowalk JK and Walkowiak J, F1000Research 2020;9(93)).

While lithium’s properties may be welcome news for patients who are taking it, they should be warned that viral illnesses raise the risk of lithium toxicity, mainly through dehydration, diarrhea, and the use of nonsteroidal anti-inflammatories (NSAIDs), which raise lithium levels by unpredictable degrees.