- Unable to refrain from the use of prescription or non-prescription drugs, including vitamins, herbal and dietary supplements (including St John's Wort) within 7 days (or 14 days if the drug is a potential enzyme inducer) or 5 half-lives (whichever is longer) before the first dose of study treatment, unless in the opinion of the Investigator, the medication will not interfere with the study procedures or compromise subject safety.