- use a highly effective method of contraception throughout the entire duration of the study and for 90 days following completion of the last dose of study medication. A highly effective method of contraception is defined as those which result in a low failure rate (that is less than 1 percent per year) when used consistently and correctly such as implants, injectables, combined oral contraceptives, some intrauterine devices, sexual abstinence or vasectomized partner, or