The transfer of glyburide into breast milk

Abstract

Purpose To determine the extent of transfer of glyburide into breast milk in women with type 2 diabetes. Presently women are advised not to breastfeed while on oral hypoglycemics. Methods Six women were studied following a single 5 mg oral dose of glyburide. Glyburide concentrations in plasma and milk were measured by high performance liquid chromatography with fluorescence detection following liquid-liquid extraction with chloroform and derivatization with NBD-Chloride. Results The subjects had a mean age of 38 years (range 33-42 years) and a mean body weight of 91 kg (range 69–123 kg). When normalized to body weight, the median dose of glyburide was 0.06 mg•kg−1•day−1 (range 0.04-0.07 mg•kg−1•day−1). There was no detectable glyburide in any of the milk samples (limit of detection (LOD) 5ng/ml) over an 8 hour period. In contrast, plasma concentrations were within the normal range for patients taking 5 mg per day of the drug. Conclusions The concentrations of glyburide in breast milk are not detectable above the 5ng/ml LOD. Thus the maximum relative infant exposure is negligible for breastfeeding. We conclude that glyburide use by breastfeeding mothers is safe. Nevertheless, it is still prudent to follow the baby for potential signs of hypoglycemia. Clinical Pharmacology & Therapeutics (2004) 75, P24–P24; doi: 10.1016/j.clpt.2003.11.089