Further studies on long-term contraception by subcutaneous silastic R capsules containing megestrol acetate

One year contraception with a single subdermal implant containing nomegestrol acetate (Uniplant)

One single silastic capsule containing nomegestrol acetate, Uniplant, was inserted subcutaneously in 100 women of reproductive age who desired to avoid conception. Insertions and removals of the capsules were made in the gluteal region following intracutaneous local anesthesia with 2% procaine. Eighty women completed one year of use. Eleven women bore the implant for 6-11 months. A total of 1,085 women-months were recorded. One pregnancy occurred, resulting in a Pearl Index of 1.1. Bleeding episodes similar to menstruation occurred in all women but the degree of regularity varied from subject to subject. Amenorrhea developed in the range of 14-18% during the first six months of use but declined to less than 10% during the last six months. Menorrhagia likewise was higher in the first six months (18% in the first month) but fell to less than 10% during the last six months. Spotting was 5% or less. Of the twenty women who did not complete one year of use, nine discontinued because they found other methods were either more practical or less revealing. Three discontinued because of bleeding irregularities, three desired to become pregnant, one became pregnant. Other complaints included dizziness, headache, increased blood pressure, loss of libido, painful breasts and nausea. Over half of the women indicated their desire to continue using the single implant as a contraceptive.

Clinical evaluation of the Capronor contraceptive implant: preliminary report

Capronor, a single-capsule, biodegradable, subdermal contraceptive that releases levonorgestrel over a 12- to 18-month period, has been evaluated in 48 healthy women, ages 18 to 40 years. Sixteen participants received a 2.5 cm capsule (12 mg of levonorgestrel), and 32 received a 4.0 cm capsule (21.6 mg of levonorgestrel). Serum levonorgestrel levels were significantly lower in the 2.5 cm group. Ovulation occurred in all cycles in the 2.5 cm group and in 26.3% of cycles in the 4.0 cm group. Levonorgestrel levels with the shorter capsule were too low for reliable contraception in all users, and 4 cm may be a minimal functional length. Bleeding patterns were regular in most women who ovulated and irregular in most remaining subjects. It is assumed that changes in cervical mucus and the endometrium contributed to effective contraception despite the frequency of ovulation.

Anovulation, inadequate luteal phase and poor sperm penetration in cervical mucus during prolonged use of Norplant implants

Blood samples for progesterone assay were collected for a total of 49 cycles, from 27 volunteers using the NORPLANT system. Levonorgestrel determinations were carried out in the same samples. A group of 12 women with normal cycles were studied in the same manner to serve as controls. Of the 49 cycles studied, 20 (41%) were ovulatory. The mean levonorgestrel level in ovulatory patients was 0.34 +/- 0.11 ng/ml (S.D.) compared to 0.42 +/- 0.14 ng/ml (S.D.) in anovulatory cycles. Compared to the control group, progesterone levels were significantly lower for users of NORPLANT implants during days -12 to -10 (p less than 0.025), -9 to -7 (p less than 0.05), -6 to -4 (p less than 0.0005) and days -3 to -1 (p less than 0.01). Cervical mucus evaluations and post-coital tests were done around mid-cycle in 29 of the cycles studied. All samples of cervical mucus were of poor quality, viscous and scarce, with a mean SPK of 4.1 +/- 2.3 cm. Most had absent or atypical ferning. Twenty-one subjects (73%) had a post-coital score of 1, and 4 (14%) of zero. Thus, anovulation, inadequate luteal phase and the direct effect of the continuous administration of levonorgestrel over cervical function, all seem to contribute to the effectiveness of NORPLANT implants.