ABSTRACT
BACKGROUND: We report a patient with a massive hydroxychloroquine overdose manifested by profound hypokalemia and ventricular dysrhythmias and describe hydroxychloroquine toxicokinetics. CASE REPORT: A 20-year-old woman (60â¯kg) presented 1â¯h after ingesting 36â¯g of hydroxychloroquine. Vital signs were: BP, 66â¯mmHg/palpation; heart rate, 115/min; respirations 18/min; oxygen saturation, 100% on room air. She was immediately given intravenous fluids and intubated. Infusions of diazepam and epinephrine were started. Activated charcoal was administered. Her initial serum potassium of 5.3â¯mEq/L decreased to 2.1â¯mEq/L 1â¯h later. The presenting electrocardiogram (ECG) showed sinus tachycardia at 119 beats/min with a QRS duration of 146â¯ms, and a QT interval of 400â¯ms (Bazett's QTc 563â¯ms). She had four episodes of ventricular tachydysrhythmias requiring cardioversion, electrolyte repletion, and lidocaine infusion. Her blood hydroxychloroquine concentration peaked at 28,000â¯ng/mL (therapeutic range 500-2000â¯ng/mL). Serial concentrations demonstrated apparent first-order elimination with a half-life of 11.6â¯h. She was extubated on hospital day three and had a full recovery. CONCLUSION: We present a massive hydroxychloroquine overdose treated with early intubation, activated charcoal, epinephrine, high dose diazepam, aggressive electrolyte repletion, and lidocaine. The apparent 11.6â¯hour half-life of hydroxychloroquine was shorter than previously described.