A contraceptive subdermal implant releasing the progestin ST-1435: ovarian function, bleeding patterns, and side effects

To study ovarian function, bleeding patterns, and side effects during the 1-year use of a new modified contraceptive subdermal implant releasing the progestin ST-1435 with a lifetime of 2 years.The effect on ovarian function and bleeding patterns of one contraceptive implant releasing the progestin ST-1435 was studied in 26 healthy women who volunteered. Side effects were recorded.The outpatient clinic of the City Maternity Hospital, Helsinki, Finland.One ST-1435 contraceptive implant was inserted subcutaneously into the ventral aspect of left upper arm.The women attended the clinic at half-year intervals. Records of bleeding were kept. Blood samples were collected from 5 women before insertion of an implant, from 12 women during the first 5 to 6 weeks of use, and from 10 women during the 6th and 12th month of use. Serum concentrations of ST-1435, progesterone, and estradiol were determined. Side effects were reported.The study covered 302 woman-months. The implant gave serum concentrations of ST-1435 high enough to inhibit ovulation in all of the 37 analyzed cycles. No pregnancies occurred. Irregular bleeding or spotting was the main event observed, especially during the 1st year of use. One half of the users had irregular cycles. None of the women's implants was removed during 1 year of use because of irregular bleeding. The implant was well accepted and tolerated by the women; no hormonal side effects were reported.One single 4-cm subdermal ST-1435 implant with a lifetime of 2 years showed good contraceptive efficacy and led to suppression of ovulation. No hormonal side effects were reported. Irregular bleeding patterns were common but well-tolerated, and the implant had a high continuation rate.Physicians inserted a new 4-cm subdermal implant releasing the progestin ST-1435 (78 mg) into the ventral area of the left upper arm in 26 healthy 20-36 year old women at the outpatient clinic at the City Maternity Hospital in Helsinki, Finland, and followed them for 12 months (total of 302 woman months) to examine its side effects, ovarian function, and bleeding patterns. (This implant has a lifetime of 2 years.) The implant released ST-1435 at serum levels high enough to suppress ovulation in all 37 analyzed menstrual cycles. None of the women became pregnant. Irregular bleeding occurred in 11 women. Even though a high proportion of women experienced irregular bleeding, it did not lead any women to request removal of the implant. The total spotting days decreased significantly between the first 6 months and the last 6 months (24-16 days; p .05). None of the women experience hormonally induced side effects, other than irregular bleeding. After 1 year of use, the continuation rate stood at 89%. 2 women wanted the implant removed so they could become pregnant. 1 woman wanted it removed for personal reasons. In conclusion, the women tolerated this implant well. Moreover, it was effective in preventing pregnancy.