Clozapine (Clozaril, Denzapine, FazaClo, and Zaponex) was the first atypical antipsychotic to be released in the US. Studies in children, adolescents, and adults with autism suggest good tolerability and effective management of severe aggression and irritability. It is used to decrease aggression, and often leads to a reduction in the number of psychotropic drugs.
Doses range from 200 to 475 mg/day and adverse effects are minimal. Side effects included constipation and weight gain.
[Note: This drug carries the increased risk of agranulocytosis (lowers the white blood cell count) and has the potential to lower the seizure threshold, making its use limited in ASDs.]