- Use of prescription or nonprescription drugs and dietary supplements within 7 days or 5 half-lives (whichever is longer) before the first dose of study medication. Phytotherapic medicine and phytotherapic supplements should be discontinued 28 days before the first dose of study medication. With one exception, acetaminophen/paracetamol can be used at doses of 1 g/day. The limited use of nonprescription medications not considered as affecting the patient's safety or the general study results may be allowed on a case by case basis after sponsor's approval.