Charcoal hemoperfusion in the therapy for methsuximide and phenytoin overdose.

Two patients suffered overdoses of anticonvulsant drugs. The first patient took methsuximide and the second, phenytoin. Because of profound CNS depression, both patients underwent hemoperfusion with a cellulose-activated charcoal hemoperfusion column. The primary metabolite of methsuximide, N-desmethylmethsuximide, primarily was responsible for the CNS depression in the first patient. The clearance of N-desmethylmethsuximide by the charcoal column was high, and clinical improvement became apparent during the hemoperfusion period. The clearance of phenytoin, on the other hand, was much lower than that of N-desmethylmethsuximide, and there was no apparent clinical improvement in that patient's condition.