Use of a single implant of elcometrine (ST-1435), a nonorally active progestin, as a long acting contraceptive for postpartum nursing women

Because of its unique features, the contraceptive effectiveness and toleran ce during breast-feeding of 16-methylene-17 alpha-acetoxy-19-nor-4-pregnene -3,20-dione (elcometrine), delivered within a single subdermal capsule of m edical grade polydimethylsiloxane, was investigated. Unlike other progestat ional steroids, elcometrine has no affinity for androgen and estrogen recep tors and is inactive by the oral route. A total of 66 breast-feeding women receiving elcometrine by the subdermal r oute were enrolled in the study, and 69 women who elected to use Copper-T38 0 intrauterine devices (IUD) served as control subjects. The women and thei r infants were observed until the end of the first postpartum year. There were no significant differences in growth and development measurement s among the infants in the elcometrine and control groups. The percentage o f infants continuing to breast-feed at 3 and 6 months was significantly hig her in the elcometrine group. There were no significant differences between the concentration of elcometrine in the mother's blood and milk. At 75 day s, blood levels of elcometrine in the infants were near the undetectable an d were significantly lower than the levels in maternal blood or milk (p <0. 01). In 15 of 25 infants, blood levels of elcometrine were at the limit of assay sensitivity or undetectable. Two pregnancies occurred in women using IUD, whereas none occurred in those using implants. There were menstrual bl eeding irregularities in both groups. A single elcometrine capsule placed subcutaneously at G-monthly intervals a ppears to be an effective method of contraception for lactating women and r esults in blood concentrations of nursing infants at or near undetectable l evels. (C) 1999 Elsevier Science Inc. All rights reserved.