Prolactin (PRL) data from adolescents treated with olanzapine are presented.

Data from 454 adolescents (13-18, mean=15.9 yrs) with schizophrenia or bipolar mania were pooled from 4 olanzapine (2.5-20.0mg/day) studies (4-32 weeks; 2 double-blind, placebo-controlled studies [combined for acute phase endpoint PRL levels] with open-label extensions; 2 open-label studies). Age- and sex-specific Covance reference ranges defined normal PRL; categorical increases were based on multiples of the upper limit of normal (ULN). Baseline-to-endpoint PRL changes in adolescents were compared with data pooled from 84 olanzapine clinical trials in adults with schizophrenia or bipolar disorder.

Olanzapine-treated adolescents had mean PRL increases at both the acute (11.4μg/L) and open-label endpoints (4.7μg/L). Of those patients with normal PRL levels at baseline (N=311), high PRL occurred in 54.7% at anytime; 32.2% at endpoint. The percentage of patients in which PRL levels shifted from normal-to-abnormal was smaller at endpoint than at anytime during treatment; 26.7% shifted to a higher category. Among patients with normal baseline PRL, 32.7% remained <=1X ULN; 32.3% increased to 1¬<=2X; 6.0%, >2-<=3X; and 1.2%, >3X at anytime; 4.6% had at >=1 potentially PRL-related adverse event. Adolescents had significantly higher mean changes at endpoint (p=.004), and a greater incidence of high PRL levels at anytime during olanzapine treatment (p<.001) versus adults.

Incidence of high PRL was significantly higher, and mean increases in PRL were significantly greater in adolescents versus adults. Mean increases and high PRL incidence were lower at the open-label compared with the acute phase endpoint.