18. Subject does not agree to use an acceptable method of effective contraception: intrauterine device, intrauterine system, established use of oral/injectable/implantable/transdermal hormonal methods, barrier methods of contraception (condoms, occlusive caps) with spermicidal foam/gel/film/suppository, vasectomised partner or true abstinence (periodic abstinence and withdrawal are not effective methods) from screening until the end of the safety follow-up period