- 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) prior to the first dose of study medication, unless in the opinion of the Investigator and GSK Medical Monitor the medication will not interfere with the study procedures or compromise subject safety. However, in elderly cohorts of Part C and Part D, use of concomitant medications may be considered on a case by case basis by the PI in consultation with the GSK Medical monitor.