ENG is eliminated with a mean half-life of approximately 30 hours, with no difference between single and multiple dosing. Steady-state levels in plasma are reached after 4-5 days. The serum clearance after . administration of ENG is approximately 10 l per hour. Excretion of ENG and its metabolites either as free steroid or as conjugates, is with urine and faeces (ratio :1). In lactating women, ENG is excreted in breast milk with a milk/serum ratio of -. Based on these data and an estimated milk intake of 150 ml/kg/day, - microgram etonogestrel maybe ingested by the infant.