A randomized multicenter study comparing the efficacy and bleeding pattern of a single-rod (Implanon) and a six-capsule (Norplant) hormonal contraceptive implant.
To compare the contraceptive efficacy, tolerability, and bleeding patterns, 200 healthy female volunteers received, in an open, comparative, randomized, multicenter study in China, either a single-rod (Implanon) or a six-capsule (Norplant) contraceptive implant for 2 years with an optional extension of up to 4 years. Women were exposed to Implanon for 341.6 woman-years and Norplant for 329.1 woman-years. There were no pregnancies during the study. Per 90-day reference period, the median number of bleeding/spotting days with Implanon decreased from 33.5 in the first period to 19.0-21.5 days in the last year. Similarly, with Norplant, the median number of bleeding/spotting days decreased from 34.5 to 18.0-23.0 days, respectively. The number of bleeding/spotting episodes during year 1 was 2.0 per 90-day reference period with Implanon and 3.0 per period with Norplant (p < 0.05 for periods 1-4). For the remaining 90-day periods, there was no statistical difference between the two groups. In general, there was less frequent bleeding with Implanon compared with Norplant, whereas the incidences of amenorrhea and infrequent bleeding were higher with Implanon than with Norplant. The mean overall incidence of prolonged bleeding fell markedly during the study, from 66.0% in reference period 1 to 27.3% in period 16 with Implanon and from 69.0% to 21.7% with Norplant, respectively. The most common adverse events were related to disturbed bleeding patterns, which were also the major reasons for discontinuation (Implanon n = 8; Norplant n = 14). Normal menses returned in almost all subjects within 3 months after removal of the implants. Implanon was inserted in a mean time of 0.61 min and Norplant in 3.90 min (p < 0.001). Similarly, the mean time required to remove the implant was significantly shorter for Implanon than for Norplant (2.18 min vs 11.25 min, p < 0.001). The maximum time required for removal of the implant was 10 min for the Implanon group and 60 min for the Norplant group. In both groups, blood pressure and hemoglobin were not affected, whereas body weight tended to increase. It can be concluded that both contraceptive systems demonstrated excellent contraceptive efficacy and were well tolerated. Compared with Norplant, there was less frequent bleeding with Implanon, whereas the incidence of infrequent bleeding and amenorrhea was higher. Implanon was significantly quicker to insert and to remove than was the multiple capsule system.