Vicriviroc in HIV-Treatment Experienced Subjects (Study P04889AM8)(COMPLETED)

Vicriviroc (vye-kri-VYE-rock) is an investigational drug (not yet approved by Government Regulatory Authorities for commercial use) that belongs to a new class of drugs, called CCR5 receptor blockers. This group of drugs blocks one of the ways HIV enters T-cells (the cells that fight infection). Previous smaller studies in HIV treatment-experienced patients, have shown that vicriviroc is safe and effective. The purpose of this study is to confirm the previous findings in a larger phase 3 study over a 48-week period, and show that when taken in combination with other appropriate HIV drugs, vicriviroc can decrease the level of HIV (viral load) in the blood and that it is well tolerated.