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Source: Ohman R, et al. J Clin Psychiatry 1999;60:519-523.
Depression affects 13% of women after childbirth, a period with a four-fold higher risk for depression. Although appropriate treatment of depression in the post-partum period is important to both the mother and infant, many women and physicians shy away from medication because of concern about adverse events to infants who are exposed to antidepressant medications in breast milk.
The current article describes seven patients with depression or panic disorder, who received a constant 20 mg morning dose of paroxetine for eight days. In six subjects, trough and peak serum and breast milk levels were determined. The seventh subject had samples drawn at steady-state, 0, 1, 2, 3, 4, 6, 8, and 24 hours after paroxetine intake, on two occasions (at 20 mg/d and 40 mg/d) with an interval of seven weeks. A total of 58 milk/serum samples were analyzed. Concentrations varied in milk from 5.3-145 ng/mL and serum from 11-188 ng/mL. There was a mean increase of 61% in the paroxetine concentration from the time of the daily dose to six hours after the dose. The estimated individual mean relative dose to the infants was 1.4% (0.7%-2.9%) of the weight-adjusted maternal dose. Single milk/serum ratios varied from 0.31 to 2.00, with a mean of 0.69. Ten pairs of foremilk and hindmilk samples were collected; the concentration of paroxetine was 78% higher in hindmilk compared to foremilk. In summary, the study demonstrated a considerable time-dependent, dose-dependent, and interindividual variability in the excretion of paroxetine in breast milk. Data on other antidepressants reveal that the relative dose to the infant is 1.2%-6.5% for fluoxetine, 0.7%-9% for citalopram, 0.5% for fluvoxamine, and 0.45%-1.04% for sertraline, compared to 1.4% for paroxetine in this study.
The small sample size of the current study limits definitive conclusion and precludes the ability to detect adverse events in the infants. In addition, the validity of the data is limited because serum levels were not measured in the infants.
This preliminary study sets the stage for larger studies that may help us determine the safety of SSRIs for infants during breastfeeding. It is premature to conclude that one SSRI may be more safely used than another, given small sample sizes and the lack of head-to-head comparison. However, data regarding fluoxetine indicate that children followed for up to seven years following intrauterine exposure had no evidence of alteration in development or cognition. If a SSRI is clinically indicated in a mother who is breastfeeding, the overall risk of exposure to the infant may be reduced by not breastfeeding during the period of time in which peak levels of medication will be in the milk, or if possible, by maximizing the use of foremilk rather than hindmilk.
The Therapeutics & Drugs Briefs in this issue were written by Alan Z. Segal, MD, Assistant Professor, Department of Neurology, Weill-Cornell Medical College, Attending Neurologist, New York Hospital; and Donald M. Hilty, MD, Assistant Professor of Clinical Psychiatry, University of California—Davis, Sacramento, CA.