A HIV Study Of A Fixed-Dose Combination Tablet In Antiretroviral Experienced Patients

Inclusion Criteria: * Currently receiving an initial antiretroviral therapy (ART) regimen composed of the drug abacavir (ABC) 300mg twice a day, plus the drug 3TC (lamivudine) 150mg twice a day in combination with either a protease inhibitor or non-nucleoside reductase inhibitor (NNRTI) for at least 24 weeks. * NOTE: Subjects who have required a change in initial protease inhibitor (PI) or NNRTI therapy due to intolerance (not treatment failure) are eligible. Subject must be on a stable regimen of the second PI or NNRTI therapy for at least 6 months before enrollment in this study. * Plasma HIV-1 RNA less than 400 copies/mL for at least 3 months immediately preceding the screening visit, and at screening. * CD4+ cell count of at least 50 cells/mm3 at screening. * Written informed consent to participate in the study before participation. * Male or female (Females of child-bearing potential must have a negative serum pregnancy test at screening and agree to an acceptable method of contraception.) Exclusion Criteria: * History of a CDC Clinical Category C event requiring treatment (not including cutaneous Kaposi's sarcoma) within 45 days of the screening visit. Treatment for the acute event must have been completed at least 30 days before screening. * Subject is enrolled in one or more investigational drug studies which may impact HIV RNA suppression. * Subject is unable to complete the 48-week dosing period, evaluations and assessments. * Subject is pregnant or breastfeeding. * History of clinically relevant inflammation of the pancreas or hepatitis within 6 months prior to screening. * Subject suffers from a serious medical condition, such as diabetes or heart problem. * Pre-existing mental, physical, or substance abuse disorder. * History of inflammatory bowel disease or malignancy, intestinal ischemia, malabsorption, or other gastrointestinal dysfunction. * Abnormal laboratory results within 28 days before the first dose of study medication. * Required treatment with radiation therapy or cytotoxic chemotherapeutic agents within 28 days before screening, or will need these during the study. * Subject requires treatment with immunomodulating drugs such as systemic corticosteroids, interleukins, vaccines, or interferons within 28 days prior to screening, or subject has received an HIV-1 immunotherapeutic vaccine within 90 days prior to screening. * Asthmatic subjects using inhaled corticosteroids are eligible for enrollment. * Subject requires treatment with foscarnet, hydroxyurea or other agents with documented activity against HIV-1 in vitro within 28 days of screening. * Subject has a history of allergy to any of the study drugs.