Benzonatate overdose associated with seizures and arrhythmias

Background: Benzonatate is an antitussive with a unique chemical structure. It contain as many as 8 structural analogs. Therefore, laboratory analysis of benzonatate is difficult. We report 2 cases of benzonatate poisoning wi th seizures and cardiac arrest and an analytical method to identify and qua ntify benzonatate in human plasma. Case Reports: Case 1: A 12-month-old mal e presented to the emergency department of a rural hospital following inges tion of an unknown amount of benzonatate. Upon arrival, the child was seizi ng and in full cardiac arrest. Resuscitative measures were unsuccessful and the child died shortly after arriving at the emergency department. Case 2: A 39-year-old male ingested 36 benzonatate capsules in a suicide attempt. Enroute to the health care facility, the patient experienced a seizure, had a cardiac arrest, and was cardioverted. Upon arrival at the emergency depa rtment, the patient was acidotic with a pH of 6.8. Gastric lavage was perfo rmed followed by the administration of activated charcoal. Six hours after arrival at the emergency department, the patient was alert, oriented, and h emodynamically stable. The patient was observed for 24 hours and subsequent ly discharged. Laboratory confirmation of benzonatate in the plasma of the patient was performed using high-pressure liquid chromatography with tandem mass spectrometry (MS/MS). The benzonatate concentration was estimated to be 2.5 mu g/mL. Conclusion: Seizures and cardiac arrest are possible follow ing an acute ingestion. Quantitative analysis of benzonatate is possible us ing high-pressure liquid chromatography with tandem mass spectrometry. Rout ine analysis for benzonatate is not common.