A phase II study with a single implant contraceptive containing 3-ketodesogestrel (Implanon®): Efficacy and safety

Abstract

With the objective to find out the efficacy and safety of a single ethylene-vinyl-acetate (EVA) implant containing 3-ketodesogestrel, a phase II study was conducted in 200 women. The study planned for a two-year use with the possibility to extend the use to 3 or 4 years; 193 subjects completed 2 years, 150 subjects entered the third year and 131 subjects completed, 124 subjects entered the fourth year and 96 subjects completed. There was no pregnancy occurred in four years of use, a total exposure of 658.4 woman-years. One subject discontinued due to amenorrhoea (0.5%). None of the subjects discontinued for bleeding irregularities. A total of 4 subjects (2.0%) reported at least one side-effect. No serious side-effects were reported. Three (1.5%) subjects discontinued due to side-effects as primary reason. Side-effects that were considered drug-related were headache and dyspnoea (reported by two and one subjects, respectively). Six subjects once had a clinically significant low value for haemoglobin and for one subject this occurred twice during treatment. Except for “headache” and “dyspnoea” (reported twice and once, respectively), no clinically relevant shifts from normal to abnormal were reported with respect to physical examinations and gynecological evaluations. At implant removal, Pap smear class I was reported for all subjects but one (Pap II). No clinically significant values of systolic and diastolic blood pressure were observed. An effect on body mass index was indicated by a slight mean increase (about 2-7%) from the month 12 assessment onwards: an increase of 10% or more at any time-point was reported by 41 subjects (20.5%). It is concluded that the single implant contraceptive containing 3-ketodesogestrel is a highly effective contraceptive method with minimal side-effects.