- Female volunteers of child-bearing potential who are sexually active must use a highly effective method of contraception throughout the study and for 30 days after completion of the study. Acceptable highly effective methods include: established use of oral, injected or implanted hormonal methods of contraception (resulting in a failure rate of less than 1% per year); placement of an intrauterine device or intrauterine system; true abstinence where this is already established as the volunteer's preferred and usual lifestyle; a male partner who has undergone sterilisation (provided that they are the sole sexual partner and that the vasectomised partner has received medical assessment of the surgical success).