Long-term contraception by a single silastic implant-D containing norethindrone acetate in women: a clinical evaluation.

PIP: 876 women were followed over a 3975-woman-month period after implantation of a single silastic capsule containing 40 mg of norethindrone acetate. Data were analyzed by a life-table method with 3 cut-off dates. Net cumulative pregnancy rate until 7 months was 2.3/100, whereas it rose to 3.9/100 after 8 months of implantation. Net cumulative termination rates rose from .7-10.9 at the end of 7 months and reached 13.6 after 8 months. Removal rates for planned pregnancy, personal, and medical reasons after 8 months were .6, 1.2, and 5.7, respectively. 1.4/100 requested implant removals in preparation for sterilization procedures. Expulsion occurred at a rate of .8/100 at the end of 8 months. The continuation rate was 86.4/100 after 8 months. Menstrual pattern abnormalities showed a reduction with time. This implant seems an acceptable long-term contraception alternative.^ieng

Long-term contraception by steroid-releasing implants. II. A preliminary report on long-term contraception by a single silastic implant containing norethindrone acetate (ENTA) in women.

PIP: A preliminary report on the long-term contraceptive effectiveness and acceptability of a single subdermal silastic implant containing norethindrone acetate (ENTA) is presented. The 4 types of implants used varied in length, wall thickness, and amount of ENTA; implant A contained 20-25 mg ENTA, implant B contained 30-35 mg ENTA, implant C contained 45-50 mg ENTA as was longer than all the other implants, and implant D contained 40 mg ENTA and had a greater wall thickness than all the other implants. 213 women volunteers received a single implant and were followed for a total of 909 cycles. 2 of 13 women receiving implant A, 2 of 39 women receiving implant B, 3 of 76 women receiving implant C, and none of the 85 women receiving implant D became pregnant. Implant D had the longest expected life-span (10 months). Menstrual irregularities were fewest with implants A (23%) and D (20%), and greatest with implant C (42%). there were no complaints of nausea, insomnia, tender breasts, or loss of libido. 4 patients with implant B and 6 patients with implant C had the capsules removed for medical reasons. More detailed studies of implant D are in progress.^ieng