Drugs known to interact with posaconazole and that may lead to life-threatening side effects (terfenadine, cisapride, and ebastine at entry or within 24 hours before entry, or astemizole at entry or within 10 days before entry); b. Drugs known to lower the serum concentration/efficacy of posaconazole: cimetidine, rifampin, carbamazepine, phenytoin, rifabutin, barbiturates, and isoniazid at entry or within 24 hours before entry; c. Subjects who are planned to receive > 2mg flat dose of vinca alkaloids.