Symptoms of cinchonism are well described and consist of headaches, tinnitus, nausea, abdominal pain, and hypotension. Acute intoxication has been associated with blindness, arrhythmias, acute renal failure, and death. Symptoms are likely in any single dose greater than 4 g and death has been reported with as little as 8 g.1 Quinine is almost completely absorbed from the gut and peak plasma concentrations are reached at about 1 to 3 hours.2 It is 70% protein bound and metabolism occurs in the liver.23

In a study of 48 cases, the mean time from ingestion to onset of minor symptoms was 3.5 hours, blindness developed somewhat later, after a mean of 9 hours. Visual loss occurred in every patient with a plasma quinine concentration above 10 mg/l.4 A level above 15 mg/l is associated with increasing risk of permanent ocular damage.5

The mechanism by …