SHOULD CONTRACEPTIVE STEROIDS BE TAKEN BY LACTATING WOMEN?

... How Much Reaches Breast Milk? Although many breast-feeding women have taken hormonal contraceptives, secretion of these drugs into breast milk has not been adequately studied. Radioimmunoassay methods were used to estimate hormone levels in breast milk and plasma in lactating women using hormonal contraception [1].

• In all 7 women given a ISOmg medroxyprogesterone acetate ('Depo-Provera'; Upjohn)injection I week after delivery, this hormone was detectable in milk and plasma throughout the study period (up to 87 days). The ratio of milk level:plasma level was almost I : I.

• In 5 women on oral contraceptives-3S0j.lg norethisterone('Micronor'; Ortho)-:--levels of this hormone in breast milk and plasma were similar, with peaks around 2-4 hours after taking the pills, followed by a gradual decline. The concentration of norethisterone in breast milk was about I / 10th of the amount in plasma.

• Another 2 women took a combination pill containing 150j.lg d-norgestrel plus 30].lgethinyloestradiol ('Nordette'; Wyeth). d-Norgestrel was detectable in milk 10-12 hours after the pill intake, but at concentrations less than 1/ I Oth those in plasma.

'Further studies are necessary to determine the various metabolites and biological activities of the contraceptive drugs in the breast milk as well as metabolism of these drugs in suckling infants. Such studies are ,a pre-requisite before one can routinely recommend the use of hormonal drugs for post-partum contraception:

In another study megestrol acetate levels in plasma and breast milk were estimated by radioimmunoassay in 5 nursing mothers who started taking an OC containing 4mg megestrol acetate plus 50j.lg ethinyloestradiol ('Neo-Delpregmin'; Novo) 2 months post partum [2].

• The mean plasma: milk ratio of megestrol acetate was about 100:80. An estimated 2j.lg of this hormone was transferred with 600ml of milk per day - about I % of the mother's dose. Two women, however, had a higher concentration in milk than in plasma 3 hours after tablet intake.

[I] Saxena, B.N. etal.: Contraception 16: 605 (Dec 1977) [2] Nilsson. S. et aI.: Ibid \ 6: 615 (Dec 1977)

INPHARMA 25th March, 1978 p14