Hypokalaemia related to acute chloroquine ingestion

Large doses of chloroquine can cause poisoning. Our aim was to determine the possible relation between the plasma potassium concentration on admission with the severity of acute chloroquine poisoning and to assess the mechanism of chloroquine-induced hypokalaemia. We conducted a retrospective study of 191 consecutive cases. The main data included the occurrence of vomiting before admission, plasma, and urinary potassium concentration at admission, whole blood chloroquine concentration on admission, haemodynamic parameters and ECG, administration of catecholamines and outcome. Mean blood chloroquine level was 20·1 μmol/L (SD 14·3) (therapeutic level ≤6 μmol/L). Mean plasma potassium concentration was 3·0 mmol/L (0·8) and was lower in the subjects who died than in those who survived (p=0·0003). Plasma potassium varied directly with the systolic blood pressure and inversely with the QRS and QT. Plasma potassium varied inversely with the blood chloroquine (p=0·0001; τ=-0·42). Acute chloroquine intoxication is responsible for a hypokalaemia which correlates with the gravity of the intoxication and may be due to a transport-dependent mechanism. Plasma potassium concentrations should be carefully observed, particularly among patients who also receive catecholamine infusions. We should keep in mind, however, that overzealous repletion invokes the risk of subsequent hyperkalaemia and thus should be avoided.