Characterization of 4-aminopyridine in overdose.

We report three cases of 4-aminopyridine overdose resulting in seizure activity. All patients were on therapeutic regimens for the treatment of multiple sclerosis. All patients were responsive to intensive supportive care, although the length of toxicity was prolonged more than 24 hours in one patient. Seizure activity was responsive to benzodiazepine and phenytoin therapy.