The International Journal of Neuropsychopharmacology



Brief Report

Olanzapine excretion in human breast milk: estimation of infant exposure


Simon  Croke  a1 c1, Anne  Buist  a1, L. Peter  Hackett  a2, Kenneth F.  Ilett  a3, Trevor R.  Norman  a1 and Graham D.  Burrows  a1
a1 Department of Psychiatry, University of Melbourne, Austin & Repatriation Medical Centre, Heidelberg, Victoria, Australia
a2 Department of Clinical Pharmacology and Toxicology, The Western Australian Institute for Pathology and Medical Research, Nedlands, Western Australia
a3 Department of Pharmacology, University of Western Australia, Crawley, Western Australia

Abstract

Newer antipsychotic drugs offer significant clinical advantages for the treatment of psychosis. In particular for the treatment of postpartum disorders newer agents may be suited due to their favourable side-effect profiles. Of concern is the passage of the drugs into breast milk and what potential risks this poses for an infant who is breastfed. The excretion of olanzapine into the breast milk of five lactating women with postpartum psychosis was examined in this study. Nine pairs of plasma and breast-milk samples were collected and the concentration of olanzapine determined by high-performance liquid chromatography. Single-point milk-to-plasma ratios were calculated and ranged from 0.2 to 0.84 with a mean of 0.46. The median relative infant dose was 1.6% (range 0–2.5%) of the weight-adjusted maternal dose. During the study period, there were no apparent ill effects on the infant as a consequence of exposure to these doses of olanzapine. As with other antipsychotic drugs this study demonstrates that olanzapine passes into breast milk. The long-term effects of exposure in infants exposed to olanzapine requires further investigation.

(Received November 5 2001)
(Reviewed February 11 2002)
(Revised June 9 2002)
(Accepted June 20 2002)


Key Words: Breast milk; infant; olanzapine.

Correspondence:
c1 Address for correspondence: Dr S. Croke, Department of Psychiatry, University of Melbourne, Austin & Repatriation Medical Centre, Heidelberg, Victoria, Australia Tel.: 61-3-9496 2940 Fax: 61-3-9496 2360 E-mail: simon.croke@armc.org.au