Patients with a Diagnostic and Statistical Manual of Mental Disorders (third edition, revised) diagnosis of
schizophrenia or
psychotic disorder not otherwise specified with onset of
psychosis before the age of 13 participated in 6- to 8-week open or double-blind trials of
haloperidol (n = 15, mean dose 15.4 +/- 8.1 mg/day [0.27 +/- 0.15 mg/kg/day]),
clozapine (
n = 30, mean dose 269.9 +/- 173.3 mg/day [4.4 +/- 2.6 mg/kg/day]), or
olanzapine (n = 12, mean dose 17.5 +/- 2.8 mg/day [0.30 +/- 0.13 mg/kg/day]). Blood samples were obtained at 6 weeks for evaluation of
haloperidol,
reduced haloperidol,
clozapine,
desmethylclozapine, and
olanzapine plasma concentrations and serum
prolactin concentrations. No gender differences were noted for
antipsychotic dose or concentration within each treatment group. Correlations between
antipsychotic plasma concentration and serum
prolactin concentration were significant only for the
olanzapine treatment group (r = 0.80, p = 0.002). Separate correlations for gender were significant only for females receiving
olanzapine (r = 0.91, p = 0.03); the patient with the highest serum
prolactin experienced
galactorrhea. Further studies evaluating the
prolactin-elevating properties of
antipsychotics are warranted in this population.