Acute confusion and blindness from quinine toxicity

Abstract

Quinine is widely used for nocturnal leg cramps, despite limited evidence of its clinical efficacy in this condition. Accidental overdose is associated with serious ocular complications and can potentially be fatal. We report the case of a 57-year-old man who presented with acute confusion and bilateral blindness after consuming approximately 7.2 g quinine sulphate along with an unknown quantity of alcohol. He was treated with general supportive measures and nitrates, with an apparent initial recovery, but visual field defects persisted. This case highlights the potential toxic effects of quinine, the dangers of its bulk prescription, and the lack of strict guidelines with regard to its prescription. We suggest that restricted prescribing for leg cramps, better patient education about the toxic nature of the drug, and clear labelling of this hazard on the dispensing bottles might lead to a reduction in the cases of quinine poisoning.

Muscle cramps

“…Symptoms include temporary visual and hearing disturbances, dizziness, fever, nausea, vomiting, and diarrhea. Blindness may be permanent in some cases when the levels exceed 10 mg/L 12, 67. One of the most concerning side‐effects unrelated to blood levels is drug‐induced thrombocytopenia, a potentially serious problem whose link to quinine sulfate use may be challenging to recognize 70.…”

Psychiatric effects of malaria and anti-malarial drugs: historical and modern perspectives

“…The earliest human experience with the quinolines dates to discovery of the naturally-occurring drug quinine, a 4-quinolinemethanol alkaloid first isolated from the bark of the Cinchona tree in the seventeenth century, together with the related cinchona alkaloid quinidine [ 109 ]. Although reports from the early twentieth century noted that quinine could have significant psychiatric effects [ 11 ], including causing depression, mania, irritability and personality change [ 110 ], and that these might not be distinguished from those attributed to disease [ 7 ], only relatively recently has it become clear that quinine, independent of malaria infection, may cause a serious toxic state marked by symptoms including delirium and confusion [ 111 , 112 ].…”

Ocular quinine toxicity in a sleepwalker

“…Furthermore, a case of an overdose of quinine with alcohol was reported 10 years ago in which the authors highlighted the toxic effects and dangers of routine prescribing 4. The publication of cases of quinine toxicity over a wide time period, suggests that lessons are not being learned from adverse outcomes of routine prescription.…”