Amoxapine is marketed as an
antidepressant. However, its in-vitro profile, receptor occupancy and preclinical effects are very similar to atypical
antipsychotics.
Amoxapine has also shown efficacy as an atypical
antipsychotic in open trials. The objective of this study was to compare the
antipsychotic and side effect profile of
amoxapine and
risperidone in a randomised assignment, standardized dosing, double-blind trial of acutely psychotic patients with
schizophrenia. A total of 48 schizophrenic patients were enrolled and randomized in a double-blind 6-week trial to receive either
risperidone (up to 5 mg/day) or
amoxapine (up to 250 mg/day). Positive, negative, affective symptoms and motor side effects were measured using standardized weekly assessments.
Prolactin levels were also determined at baseline and at the end of the study. A total of 39 patients (
amoxapine, n=22;
risperidone, n=21) completed the trial. Both pharmacological treatments,
amoxapine 228.0 mg/day (SD=34.6) and
risperidone 4.5 mg/day (SD=0.7), showed equivalent improvement in positive, negative, and depressive symptoms.
Amoxapine was associated with less EPS and less
prolactin elevation than
risperidone. These data support previous reports about the efficacy of
amoxapine as an atypical
antipsychotic. Since
amoxapine is off-patent, it may be a valuable low-cost alternative to new atypical
antipsychotics, particularly in low-income countries where the majority of the patients are still treated with typical
antipsychotics.