Negative serum pregnancy test within 14 days. All females of childbearing potential must agree to practice active birth control measures (barrier methods such as condoms, diaphragms, cervical cap, etc. or an intrauterine device such as a coil) to avoid pregnancy while receiving the study drugs and for 30 days after the last dose of the study drugs. Additionally, men enrolled in the study should practice active birth control for the same period of time with their female partners of childbearing potential.