- Planned use during the study, from study entry through the last PK blood draw, of any of the following: prescription medication(s) [excluding IUDs that elute locally active hormonal contraceptives], herbal supplement(s), nutritional supplement(s), or over-the-counter medication(s). Note: Multivitamins, acetaminophen (up to 650 mg every 6 hours as an analgesic), ibuprofen (up to 600 mg twice daily), naproxen (up to 500 mg twice daily for pain or headache), and diphenhydramine (up to 25 mg daily for insomnia or seasonal allergies) are permitted.