Abstract
BACKGROUND Dextromethorphan is a widely used over-the-counter antitussive medication. Generally safe within the recommended dosages, its misuse can lead to severe adverse effects, particularly in large amounts. However, comprehensive descriptions of severe overdose cases - including pharmacokinetic data of dextromethorphan and its active metabolite (dextrorphan) - are scarce. CASE REPORT A 21-year-old woman with schizophrenia ingested 20 280 mg of dextromethorphan along with other prescribed medications during a suicide attempt. She was discovered semiconscious and experienced a generalized seizure en route to the hospital. Despite intensive treatments - including endotracheal intubation and administration of propofol and midazolam - she continued to experience refractory status epilepticus. Subsequent neurological examination revealed cranial nerve reflex loss. The serum concentration of dextromethorphan was 5.8 mg/L on admission and decreased to 2.2 mg/L by day 1 and 1.1 mg/L by day 2, contrasting with that of dextrorphan, which remained within the therapeutic limits. By day 4, her condition stabilized; she became alert, responsive to commands, and was successfully extubated. She was discharged on day 9 without any sequelae. CONCLUSIONS This report describes the case of a patient who survived a massive dextromethorphan overdose, who presented with refractory status epilepticus followed by reversible suppression of cranial nerve reflexes. The pharmacokinetic profiles suggested that dextromethorphan, rather than dextrorphan, was responsible for the symptoms. High-dose dextromethorphan ingestion can lead to varied and potentially fatal outcomes, especially when compounded by metabolism-altering factors such as CYP2D6 inhibition, genetic variability, or co-ingested medications. This case underscores the importance of prompt, intensive supportive care in managing severe dextromethorphan toxicity.