Major exclusion criteria were: current DSM-IV axis I psychiatric
diagnosis other than schizophrenia; significant risk of suicidal or violent
behavior; history of mental retardation, major depressive episodes,
neuroleptic malignant syndrome, tardive dyskinesia, any neurologic
disorder, severe head trauma, or any unstable medical condition; history
of substance dependence or participation in a drug clinical trial within
3 months before screening; standard treatment with aripiprazole or
risperidone within 4 weeks before screening; allergy, hypersensitivity,
or history of lack of response to aripiprazole or risperidone; prohibited
medications including mood stabilizers, antidepressants, and other psychotropics,
within 2 weeks, or drug depot preparation within 4 weeks,
or clozapine within 3 months before screening; refractory schizophrenia
(treatment resistance to antipsychotics according to prior trials of two different
antipsychotics of adequate dose and duration); or clinically significant
abnormal vital signs or laboratory values.