Abstract
Seetal Dodd, Department of Psychiatry, University of Melbourne, Andrew Stocky, The Melbourne Clinic, and Anne Buist, Graham D. Burrows and Trevor R. Norman, Department of Psychiatry, University of Melbourne, Melbourne, Australia:
Sertraline may be prescribed to women for the treatment of postpartum depression. The drug has been favoured because of its efficacy and because it is generally considered to be safe for use in the postpartum period. Nevertheless, it is known that sertraline and its major metabolite desmethylsertraline will be present in the breast milk of mothers treated with the drug [1]. Usually, if the baby is delivered full term and healthy, breastfeeding may be recommended. Levels of sertraline in the plasma of infants exposed through breast-feeding is not generally known. In a study of 11 breast-fed infants of mothers receiving sertraline, the parent drug was detected in the plasma of three babies and desmethylsertraline in the plasma of six of them [2]. We have analysed plasma specimens collected by heel prick from infants exposed to sertraline via their mother's breast milk.
Ten nursing mothers provided a pair of plasma and breast milk specimens while 12 blood specimens were collected from their infants. Data on the excretion of sertraline into the breast milk has been reportedelsewhere [3]. Briefly, the mean milk to plasma ratio was about 1.8 allowing for calculation, using standard assumptions [4] of an infant dose < 2% of the maternal dose. Despite this relatively low potential exposure, it is of interest to attempt to determine actual exposure of infants by examining blood levels. Sertraline and desmethylsertraline were analysed by reverse phase high performance liquid chromatography. The limit of detection of both species by the assay was 2 ng/mL. In none of the 12 blood specimens collected from the infants were we able to detect the presence of sertraline or desmethylsertraline above the limit of detection of the assay. The data would suggest that the systemic exposure of infants to sertraline via breast-feeding is not significant. Nevertheless, the data need to be interpreted cautiously. All of the women in this study received usual therapeutic doses of sertraline (50–150 mg/day) and achieved significant plasma levels CORRESPONDENCE 545 of the parent drug (11–63 ng/mL) and desmethylsertraline (10–110 ng/mL). Similarly, breast milk concentrations of both species were significant (10–87 ng/mL for sertraline, 15–104 ng/mL for desmethylsertraline). Thus low doses in the mothers cannot explain the ‘non-appearance’ of the drug in the infant specimens. Conversely, the volumes of blood available from the infants by heel prick was considerably less than that available by venepuncture (typical volumes of blood were ≤?0.5 mL). The low volumes available for analysis coupled with plasma levels likely to be near the limits of detection of the assay technique test the technical capabilities of the methodology. Clearly a more sensitive drug analytical method would provide greater reassurance that the systemic exposure to sertraline via breast-feeding is little or none. Nevertheless, the present data show that infants do not have excessive exposure. Long-term behavioural consequences of this exposure are not clear, but throughout the period of breast-feeding all infants remained physically well.