- Participant is unable to refrain from or anticipates the use of any medication, including prescription and non-prescription drugs or herbal remedies (such as St. John's Wort [hypericum perforatum]) beginning approximately 2 weeks (or 5 half-lives) prior to administration of the initial dose of study drug, throughout the study (including washout intervals between treatment periods), until the telephone follow-up. There may be certain medications that are permitted. Participants must be explicitly warned of the potential risk of taking erythromycin, clarithromycin, nefazodone, ketoconazole, itraconazole, cyclosporine, and human immunodeficiency virus (HIV)protease inhibitors during the study.