- Either commit to true abstinence from heterosexual contact (which must be reviewed on a monthly basis), or agree to use, and be able to comply with, effective contraception (</=1% failure rate annually) without interruption, 28 days prior to starting therapy (including dose interruptions), and while on study medication or for a period of 90 days following treatment completion. [Periodic abstinence (eg, calendar, ovulation, symptothermal, post-ovulation methods) and withdrawal are not acceptable methods of contraception].