Neonatal Exposure to Tramadol through Mother's Breast Milk

Tramadol is an opioid used in the treatment of moderate to moderately severe pain. Tramadol's use during pregnancy is generally avoided and may cause some reversible withdrawal effects in neonates, and its use during lactation is not licensed by the manufacturer. A small clinical trial reported infants were exposed to <3% of a mother's tramadol dose through breast milk with no evidence of harmful effects. Presented is a case study of breast milk, neonatal urine, and neonatal oral fluid for the analysis of tramadol and its metabolites, along with the validation of a method for the analysis of tramadol, O-desmethyltramadol, and N-desmethyltramadol in breast milk. Tramadol and its metabolites were extracted by solid-phase extraction after saponification of breast milk to remove lipids. Samples were analyzed by ultra-pressure liquid chromatography-tandem mass spectrometry. To the author's knowledge, this is the first report of tramadol and its metabolites in neonatal oral fluid. The breast milk concentrations were 63, 22, and 76 ng/mL for the analysis of tramadol, O-desmethyltramadol, and N-desmethyltramadol, respectively, on day of life 12. On day of life 20, the breast milk concentrations were 1,254, 388, and 937 ng/mL for the analysis of tramadol, O-desmethyltramadol, and N-desmethyltramadol, respectively. Oral fluid concentrations were 1,011, 1,499, and 406 ng/mL for the analysis of tramadol, O-desmethyltramadol, and N-desmethyltramadol, respectively, on day of life 20. Oral fluid concentrations were similar to breast milk for tramadol, almost four times higher for O-desmethyltramadol, and less than half for N-desmethyltramadol. The absolute infant dose was calculated to be 10 μg/kg/day and 294 μg/kg/day for tramadol on day of life 12 and 20, respectively.