- 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) prior to the first dose of study treatment until completion of the post-study medical, unless in the opinion of the investigator and GlaxoSmithKline (GSK) Medical Monitor, the medication will not interfere with the study procedures or compromise subject safety; examples are anti-hypertensive medication for at least 3 months prior to the screening visit and lipid-lowering medications (statins or fibrates) for at least 3 months prior to the screening visit.