Postmortem hydroxychloroquine concentrations in nontoxic cases

Hydroxychloroquine (HCQ) is a 4-aminoquinoline compound used to treat malaria and chronic autoimmune disorders and is not uncommonly found in the medical examiner setting. Studies have shown HCQ to have a long half-life (32-56 days in blood), high volume of distribution (580-815 L/kg), and therapeutic concentrations ranging from 0.03 to 15 mg/L, depending on the chronicity of treatment. Previous reports have shown that the toxic concentration of HCQ ranges from 3 to 26 mg/L, whereas the lethal concentration ranges from 20 to 104 mg/L. A report addressing nontoxic postmortem concentrations of HCQ in individuals known to be taking the medication, and in whom there is no evidence of toxicity, has not been previously undertaken. This study found that postmortem concentrations in nontoxic cases can range from 0.3 to 39 mg/L, which is well within the reported range of both lethal and toxic concentrations. It is recommended that all investigative and autopsy data be considered and that the cause of death not be certified based purely on blood HCQ concentrations.