Toxicokinetics of hydroxychloroquine following a massive overdose

Am J Emerg Med. 2019 Dec;37(12):2264.e5-2264.e8. doi: 10.1016/j.ajem.2019.158387. Epub 2019 Aug 6.


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 (60 kg) presented 1 h after ingesting 36 g of hydroxychloroquine. Vital signs were: BP, 66 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 5.3 mEq/L decreased to 2.1 mEq/L 1 h later. The presenting electrocardiogram (ECG) showed sinus tachycardia at 119 beats/min with a QRS duration of 146 ms, and a QT interval of 400 ms (Bazett's QTc 563 ms). She had four episodes of ventricular tachydysrhythmias requiring cardioversion, electrolyte repletion, and lidocaine infusion. Her blood hydroxychloroquine concentration peaked at 28,000 ng/mL (therapeutic range 500-2000 ng/mL). Serial concentrations demonstrated apparent first-order elimination with a half-life of 11.6 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 11.6 hour half-life of hydroxychloroquine was shorter than previously described.

Publication types

  • Case Reports

MeSH terms

  • Antimalarials / blood
  • Antimalarials / pharmacokinetics*
  • Antimalarials / poisoning
  • Drug Overdose / therapy*
  • Electrocardiography
  • Female
  • Humans
  • Hydroxychloroquine / blood
  • Hydroxychloroquine / pharmacokinetics*
  • Hydroxychloroquine / poisoning*
  • Toxicokinetics
  • Young Adult


  • Antimalarials
  • Hydroxychloroquine