- Chronic use of any systemic medications (with the exception of vitamins taken at standard supplement doses); use of a drug therapy (including herbal preparations, e.g., St. John's wort) known to induce or inhibit hepatic drug metabolism within 30 days before the first dose of study medication; use of prescription medication within 14 days before administration of study medication or over-the-counter products (including natural products) within 7 days before administration of study medication, except for topical products without systemic absorption, unless approved by the Sponsor