d-Norgestrel concentrations in maternal plasma, milk, and child plasma during administration of oral contraceptives to nursing women

Abstract

In order to correlate plasma and milk concentrations of d-norgestrel (d-Ng) in lactating women, three oral contraceptives, containing different amounts of this synthetic gestagen, were given to 15 fully lactating women, starting two months post partum. Plasma and milk samples were collected according to a special schedule. d-Ng concentrations in plasma and milk were measured by radioimmunoassay. When d-Ng was measured in milk, extraction was performed with petroleum ether and in the radioimmunoassay an internal standard was used. This method is evaluated in the present paper. The plasma: milk ratio of d-Ng was found to be about 100:15 and the amounts of d-Ng transferred with 600 ml. of milk per day were calculated to be 0.3 an 0.15 microgram with daily intakes of 250 and 150 microgram of d-Ng, respectively, corresponding to about 0.1 per cent of the given dose. When the women received 30 microgram of d-Ng daily, no d-Ng could be detected in the milk. In three of the breast-fed children the d-Ng concentration in plasma was measured. This concentration was found to be in the same range as would be expected after oral d-Ng medication to adults, allowing for body weight differences, indicating that d-Ng is metabolized and is not accumulated in the baby.

PIP: 3 oral contraceptives containing different amounts of d-norgestrel (d-Ng) were given to 15 lactating women starting 2 months postpartum in order to correlate plasma and milk concentrations of d-Ng in lactating women. Plasma and milk samples were collected according to a schedule. Radioimmunoassay was used to measure d-Ng concentrations in plasma and milk. When d-Ng was measured in milk, extraction was performed with petroleum ether. In the radioimmunoassay an internal standard was used. The plasma: milk ratio of d-Ng was about 100:15, and the amounts of d-Ng transferred with 600 ml of milk/day were .3 an .15 mcg with daily intakes of 250 and 150 mcg of d-Ng, respectively, corresponding to about .1% of the given dose. No d-Ng was detected in the milk when the women received 30 mcg of d-Ng daily. The d-Ng concentration in plasma was measured in 3 of the breast-fed children. The concentration was in the same range as would be expected after oral d-Ng medication to adults, allowing for body weight differences. d-Ng is metabolized and not accumulated in the baby.