 7. Use of prescription especially cytochrome P450 3A4 CYP3A4 inhibitors or inducers or non-prescription drugs except paracetamol at doses of up to 2 gramsday, including vitamins especially vitamin C, herbal and dietary supplements including St. Johns Wort within 7 days or 14 days if the drug is a potential enzyme inducer or 5 times the drug half-life whichever is longer prior to the first dose of study medication until the completion of the follow-up procedure, unless in the opinion of investigator, the medication will not interfere with the study procedures or compromise subject safety; the investigator will take advice from the manufacturer representative as necessary. 