Abstract
In this report, we describe a case of late-onset respiratory depression and seizure caused by carbamazepine (CBZ) overdose. A 15-year-old female was admitted unconscious with suspicion of drug overdose. The drugs found at the scene were CBZ and mirtazapine. A urine drug screen was positive for tricyclic antidepressant. She suffered respiratory depression, seizure, mydriasis and oliguria after admission, which required mechanical ventilation and intravenous administration of anticonvulsant and lipid emulsion. The concentration of CBZ in her blood was high enough to diagnose intoxication. These symptoms improved in accordance with the decrease of CBZ concentration, and she was discharged without complications on hospital day 8. Approximately 100 tablets of CBZ (200 mg) and 50 of mirtazapine (15 mg) were ascertained to have been ingested 11 hours before arrival. The latency of respiratory depression and seizure after ingestion were 12 hours and 15 hours, respectively. The maximum blood concentration of CBZ was 104.5 µg/mL 20 hours after ingestion, and a concentration below the toxic level was confirmed 67 hours after ingestion. It should be emphasized that because of the considerable latency, a CBZ overdose might cause serious symptoms later. Therefore, close observation is required even if the initial symptoms seem minor.
