Concentrations of thiopentone in mature breast milk and colostrum following an induction dose.

In two groups of eight patients, concentrations of thiopentone in mature breast milk and colostrum following anaesthesia induction with 5.4 and 5.0 mg kg-1 b.w. (mean), respectively, were measured in the first 36 h postoperatively. Blood concentrations were measured simultaneously. The maximal concentrations were: in mature breast milk, 3.4 +/- 0.68 mumol l-1 (mean +/- s.e. mean) (0.090 mg 100 ml-1), and in colostrum, 1.3 +/- 0.5 mumol l-1 (0.034 mg 100 ml-1). The milk/plasma ratio was less than 1.0 in both groups. The above concentrations may be regarded as negligible and therefore non-toxic for the nursing infant.