Correlation of antipsychotic and prolactin concentrations in children and adolescents acutely treated with haloperidol, clozapine, or olanzapine

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.