Pharmacopsychiatry 2005; 38 - 20
DOI: 10.1055/s-2005-862633

Plasma Prolactin Levels During Treatment with Olanzapine

D Degner 1, P Niedmann 2, E Rüther 1, S Kropp 3
  • 1Department of Psychiatry, University of Göttingen, Germany
  • 2Department of Clinical Chemistry, University of Göttingen, Germany
  • 3Department of Clinical Psychiatry, Medical School Hannover, Germany

The elevation in plasma prolactin concentration is a side-effect of typical and (some) atypical antipsychotics. This endocrine complication seems to be rare (1,2), but varied among different atypicals (3). The onset begins shortly after drug administration.

In a naturalistic study patients with mainly schizophrenia were included,which were treated with olanzapine in the Department of Psychiatry, Göttingen (group A). Olanzapine serum concentrations were determined in the Department of Clinical Chemistry (Therapeutic Drug Monitoring).

In subgroup B, prolactin concentrations were investigated in 16 patients, before and after starting 14 to 21 days of olanzapine administration (stable dosage) in clinical routine treatment. These patients had regular pretreatment prolactin levels. The aim of the study was to investigate potential relationships between prolactin levels and dose/serum concentrations of olanzapine.

In total, 73 patients were investigated (A). The medium observation time was 73.8 days, medium daily dose 17.8mg/d,medium serum concentration 33.1 ng/dl. There was a significant correlation between dosage and blood levels: r=0.69 (p<0.001). In all patients no prolactin-related adverse drug reactions like galactorrhea or gynecomastia were seen.

In group B (n=16) 10 patients recieved olanzapine as monotherapy (medium daily dose 21.9mg/d). Hyperprolactinaemia was detected in 4 patients (medium prolactin level 52.4 ng/ml), 3 patients received olanzapine in combination treatments. No correlation between prolactin and olanzapine levels was observed.

Dose and blood concentrations were not associated with a potential risk of hyperprolactinaemia, but combination treatments and gender may be risk factors.

References: 1) David S et al. The effects of olanzapine,risperidone,and haloperidol on plasma prolactin levels in patients with schizophrenia. Clin Ther 2000;22:1085–1096; 2) Turrone P et al. Elevation of prolactin levels by atypical antipsychotics Am J Psychiatry 2002;159:133–135; 3) Kropp S et al. Galactorrhea due to psychotropic drugs. Pharmacopsychiatry 2004;37/S1 84–88