Acute toxic reaction to carbamazepine: clinical effects and serum concentrations.

The clinical spectrum of toxic effects and serum concentrations after ingestion of carbamazepine were studied in 82 pediatric patients. Serum carbamazepine level was related to the depth of coma (p less than 0.001), convulsions (p = 0.002), hypotension (p less than 0.001), and the requirement for mechanical ventilation (p less than 0.001). In 10 patients in deep coma with a Glasgow Coma Scale (GCS) of 3-4, the mean serum level was 213 mumol/L (range 143 to 343); seizures, ventilatory failure, or hypotension caused by myocardial failure and conduction defects were observed. In four of these, large doses of inotropic agents were required, one patient was treated with plasmapheresis, and two died--one of cardiac failure and one of aspiration pneumonitis. In 27 patients with moderate coma (GCS 5-8), the mean serum level of carbamazepine was 112 mumol/L (range 63 to 176); convulsions were observed in two patients in this group. In 45 patients whose conscious state was mildly depressed or normal (GCS 9-15), the mean serum level was 73 mumol/L (range 37 to 128); additional effects were drowsiness (80%), ataxia (53%), nystagmus (38%), vomiting (17%), and dystonia (7%). I conclude that patients with serum carbamazepine levels of approximately 100 mumol/L require close observation, whereas those with levels greater than 150 mumol/L may require intensive life support.