RETRACTED: The effects of Implanon on lipid metabolism in comparison with Norplant

This open, randomized study was intended to assess the effects of the new single-rod contraceptive implant (Implanon) containing etonogestrel on lipid metabolism in Indonesian women, in comparison with the six-rod implant Norplant, containing levonorgestrel. The effects of both products were compared with a control group using an intrauterine device (IUD) over a 3-year period. A total of 135 healthy volunteers of childbearing potential, aged 22 to 41 years, were enrolled in Jakarta, Indonesia. Ninety volunteers were randomized to use Implanon (n = 45) or Norplant (n = 45), and a nonrandomized group of 45 Multiload Cu 250 IUD users served as a control. Serum concentrations of total cholesterol, triglycerides, HDL cholesterol, LDL cholesterol, apolipoprotein AI, apolipoprotein AII, and apolipoprotein B were measured. The ratios of HDL cholesterol to total cholesterol, of HDL to LDL cholesterol, and of apolipoprotein AI to apolipoprotein B were determined. Lipid and lipoprotein determinations were done at screening and after 3, 6, 12, 18, 24 and 36 months. Contraceptive efficacy and insertion and removal times were also recorded. Mean changes from baseline in the lipid and apolipoprotein parameters, although occasionally statistically significant, were small in all groups (less than 1 standard deviation of the mean concentration at baseline) and clinically not significant. Statistically significant differences between the Implanon and Norplant groups were only occasionally observed. In both implant groups, total mean cholesterol, LDL cholesterol, and apolipoprotein AI concentrations tended to decrease during the study, but statistically significant changes from baseline were only occasionally observed, suggesting that drug-related factors are not involved. The mean ratios of HDL/total cholesterol and the HDL/LDL cholesterol showed very little change over time in both implant groups; slight and statistically nonsignificant increases were noted at most time points. Similar changes were seen in the group of IUD users. It can be concluded that changes from baseline in the lipid and apolipoprotein parameters tested were generally small and did not differ between Implanon and Norplant.