- Use of prescription or non-prescription drugs, vitamins, herbal and dietary supplements within 7 days or 5 half-lives (whichever is longer) prior to the first dose of study medication, or use of St. John's Wort within 28 days prior to the first dose of study medication. Unless in the opinion of the investigator and sponsor the medication will not interfere with study procedures or compromise safety. By exception, the subject may take paracetamol or acetaminophen (≤2 grams/day) up to 48 hours prior to the first dose of study medication.