title: Long-term contraception with norethindrone subcutaneous capsules.
abstract: Norethindrone (NET) contained in silicone rubber, for slow release, was implanted subcutaneously. The rate of release of NET was 10-12 mug/day/10 mm length of the silicone rubber. The total length of the implants used varied from 100 mm to 200 mm. During the whole observation time 562 women months, 14 a-cidental pregnancies occurred. The pregnancy rate decreased with increasing length of implants. The implants produced a transient ovulation suppression, which subsided in four to five cycles. The plasma levels of NET stabilized at a level which was less than that reached by daily oral administration of 350 mug of NET. The high pregnancy rate and the great number of implants required render the method impractical for contraception. However, the active life-span of implants is three years and because there were few minor side-effects, the method was well accepted.
mesh_terms: D003267:Contraception; D003692:Delayed-Action Preparations; D004343:Drug Implants; D005260:Female; D006801:Humans; D009640:Norethindrone / Q000378:metabolism / Q000627:therapeutic use*; D011247:Pregnancy; D011372:Progestins / Q000097:blood; D013997:Time Factors
chemical_list: D003692:Delayed-Action Preparations; D004343:Drug Implants; D011372:Progestins; D009640:Norethindrone