Multicentred, Phase III Clinical Trial of Norethisterone Enanthate 50 mg plus estradiol valerate 5 mg as a monthly injectable contraceptive; Final three-year report

Abstract

Norethisterone enanthate (NET-EN) 50 mg combined with estradiol valerate (EV) 5 mg was studied as a once-a-month injectable contraceptive with regard to effectiveness, cycle control, adverse events and acceptability. In eight Family Planning Centres from five Latin American countries, 931 fertile women were followed-up for a period of 36 months, providing a total of 15,787 woman-months of experience. Only one pregnancy occurred: in the first treated month a few days before the second injection (failure rate 0.08 per 100 woman-years). Under treatment, the first cycle was drastically shortened in most cases, but thereafter cycles tended to recover to pre-treatment patterns. There was a significant decrease of hypermenorrhoea and dysmenorrheic cycles. Intracyclic bleeding and spotting appeared in 1.8% and 2.2%, respectively, and amenorrhea in 2.8% of cycles. The incidence of other adverse events was very low with the exception of weight gain of more than 2 kg (36.8%). The continuation rate at 12 months was 64.7%, at 24 months 31.0% and at 36 months 20.4%. The cumulative discontinuation rate due to bleeding problems was 6.1% and 7.2% due to adverse events at 36 months. The treatment was shown to be a highly effective contraceptive method that offers fairly good cycle control, good tolerance and a continuation rate that makes it suitable for use in family planning programmes in the Latin American area.