A multicentred phase III comparative study between single-implant containing 3-ketodesogestrel (Implanon®) and implants containing levonorgestrel (Norplant®) I. efficacy, acceptability and safety (three-year results)

With the objective to evaluate the efficacy, acceptability and safety of subdermal-single-rod ethylene vinyl acetate (EVA) implant contraceptive containing 68 mg 3-ketodesogestrel (Implanon9), a multicentred comparative study has been conducted between Implanon® and Norplant® (subdermal implant contraceptive consisting of six silastic capsules, each capsule containing 36 mg levonorgestrel). A total of 898 women were recruited into an eight centre, randomized clinical trial. One subject was excluded from the study because she had been already pregnant when the implant inserted. Follow up scheduled for 3 years. The mean insertion time was 0.8 minute for Implanon® and 4.4 minutes for Norplant®. The mean removal time was 4.9 minutes for Implanon® and 30.2 minutes for Norplant. These differences are statiscally significant (p<0.01). In three- year follow up, the study showed none of the subjects became pregnant in both groups. One-year continuation rates were 97.3 per hundred women for Implanon® and 97.6 per hundred women for Norplant®. After three years the continuation rates were 90.6 and 92.0 respectively. In Implanon® group there were 42 subjects discontinued the method use. The reasons were: bleeding irregularities (4 subject), amenorrhoea (1 subject), other medical reasons (4 subjects) non-medical reasons (24 subjects) and lost to follow- up (9 subjects). While in Norplant® group there were 36 subjects discontinued the method use. The reasons were bleeding irregularities (4 subjects), other medical reason (5 subjects), non-medical reasons (11 subjects), and lost to-follow up (16 subject). There are no statistically significant differences between the groups. None of the subjects in both groups suffered from serious side-effects.