- Use of prescription or non-prescription drugs, vitamins, herbal and dietary supplements within 14 days or 5 half-lives (whichever is longer) prior to study medication administration, or use of St. John's Wort within 28 days prior to the study medication administration Unless in the opinion of the investigator and sponsor the medication will not interfere with study procedures or compromise safety. By exception, the volunteer may take paracetamol (</ 2 grams/day) up to 48 hours prior to the study medication administration.