Open-Label, multiple-dose, drug interaction study to assess the effect of nevirapine on the pharmacokinetics of atazanavir in HIV-infected individuals.

Inclusion Criteria:

• signed informed consent form
• For Cohort 1, HIV-infected subjects receiving nevirapine 200 mg twice-daily and 2 to 3 NRTIs for at least 6 weeks
• For Cohort 2, HIV-infected subjects receiving atazanavir 300 mg and ritonavir 100 mg once-daily and 2 to 3 NRTIs for at least 6 weeks
• Have had 2 measurements of plasma HIV RNA of <400 copies/mL. The first test being 6 to 16 weeks prior and the second being within 3 weeks prior to Day 1
• Have CD4 cell count >=200 cells/mm3
• Body Mass Index of 18 to 35 kg/m2.
• Men and women, ages 18 to 55.

Exclusion Criteria:

• Women who are pregnant or breastfeeding
• Presence of a newly diagnosed HIV-related opportunistic infection or CD4 cell count <200 cell/mm3 within the previous 6 months.
• Any significant acute or chronic medical illness, unless stable or controlled by a non-prohibited medication.
• History of virologic failure on an antiretroviral regimen.