Posters IV - The American Academy of Clinical Toxicology

elative to usual rise seen with hepatic injury and led to premature discontinuation of IV NAC therapy.
Conclusion: Onset of rise of AST/ALT beyond 24 hours post ingestion may occur in large acetaminophen
overdose.
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Profound Hydroxychloroquine Toxicity with Resistance to Sedation with High Dose Diazepam
Melissa Halliday 1 , Kris Nanagas 1 , Zack Worley 1 , David Burns 2
1 Indiana University School of Medicine, Indianapolis IN USA
2 Indiana Poison Information Center, Indianapoliis IN USA
Background: Hydroxychloroquine is a synthetic 4-aminoquinoline derivative used as an
antirheumatologic agent. Hydroxychloroquine ingestions are rarely seen, but result in rapid toxicity and
high rates of mortality. Case Report: A 32 year-old female attempted suicide by ingesting 18g of
hydroxychloroquine. On initial presentation her blood pressure was 66/47 with a heart rate of 90, however
quickly fell to 31/16 despite 2 liters of crystalloid replacement. She was intubated, placed on an
epinephrine drip and given a 2mg/kg diazepam bolus, followed by continuous diazepam infusion at
5mg/hr. Her initial ECG revealed QRS at 148ms and QTc of 642ms, which was treated with sodium
bicarbonate and magnesium sulfate. Her initial potassium level was 3.9 mmol/L, however reached a nadir
of 1.6mmol/L four hours later. This hypokalemia ultimately required treatment with a total of 199 mEq IV
potassium. Initial serum phosphorus was 1.0mg/dL, which stabilized after treatment with 21 mmol of
potassium phosphate. Most notably, following a 140mg bolus of intravenous diazepam and 5mg/hr
diazepam infusion, the patient remained awake and was attempting to mouth words around her
endotracheal tube. She was later discharged neurologically intact. Case Discussion: Hydroxychloroquine
is a rarely described but serious and rapidly fatal cause of overdose. One case series of 6 moderate to
severe overdoses estimated the lethal dose to be 4g. Our patient ingested 18g of hydroxychloroquine and
exhibited severe hypotension, ECG abnormalities and severe electrolyte derangement within 1 hour of
ingestion. While decreased mortality has been noted with high dose diazepam treatment in chloroquine
overdose, its efficacy in hydroxychloroquine ingestion has not been well explored. Our patient had clinical
improvement in her blood pressure and ECG after administration; however she remained awake and alert
despite large doses of this sedating medication. It has been suggested previously that chloroquine has an
antagonistic effect on benzodiazepine sedation. Chloroquine's chemical structure is similar to compounds
that inhibit benzodiazepine binding at certain receptors, possibly attributing to the diminished sedation
noted in overdose. Conclusion: This case is remarkable for the degree of toxicity and the diminished
sedation response to high dose diazepam. This is one of the most severe toxicities with patient survival
documented in the literature. Clinical improvement was noted after administration of high dose diazepam
but sedation was not achieved. This warrants further study of the mechanism of toxicity in
hydroxychloroquine overdose.
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Intractable seizure following dalfampridine ingestion: Case Report
Jeffrey L Bargeon, Cynthia K Aaron
Background: Dalfampridine (4-aminopyridine or 4-AP) is a broad-spectrum potassium channel blocker
believed to enhance action potential transduction in demyelinated neurons via potassium channel
inhibition. Daily dose is 10mg; doses greater than 10 mg may cause seizures. We report an overdose
leading to prolonged status epilepticus and death. Case Report: A 45-year-old male presented to the ED