 During the study, participants was asked to return to the clinic at Weeks 4, 8, 16, 24, 36, and 48 and then every 16 weeks until the end of the study. They were also contacted by telephone during Week 2 to check on their status. Visits were last about 1 hour. At most visits, participants had a physical exam and answered questions about any medications they were taken. Additionally, participants completed questionnaires addressing their smoking and alcohol habits, had blood drawn, and were asked to give urine samples. At some visits, participants had to come to the clinic without having eaten for 8 hours. If the participant was female and able to become pregnant, a pregnancy test might be given at any visit if pregnancy was suspected. 