Excretion of paracetamol in human breast milk.

Breast milk and plasma levels of paracetamol were monitored in 3 lactating women after ingestion of a single 500 mg dose of paracetamol. The paracetamol concentrations were consistently lower in milk, with a mean milk/plasma AUC ratio of 0.76. This value was in close agreement with the milk/plasma partition ratio of 0.81 found in vitro, and could be related to quantitative binding differences between the two fluids. The half-lives of paracetamol in plasma and breast milk were almost identical, with an overall mean of 2.7 h. As less than 0.1% of the maternal dose would be present in 100 ml milk, breast feeding need not be discontinued due to paracetamol treatment in conventional dosage.