Pharmacokinetic Study of Two HIV Protease Inhibitors in Patients

The Pharmacokinetics of Lopinavir/Ritonavir in Combination With Atazanavir in HIV-Infected Subjects

The objective of this study is to determine the pharmacokinetics of lopinavir, ritonavir, and atazanavir when lopinavir/ritonavir and atazanavir are used in combination.

Thirty patients with HIV infection will be enrolled in this open-label, parallel arm pharmacokinetic study. Subjects receiving either lopinavir/ritonavir or atazanavir/ritonavir as part of their antiretroviral therapy will have a pharmacokinetic study performed over 12-20 days to examine whether coadministration of lopinavir and atazanavir alters the pharmacokinetics of either agent. The safety of these agents in combination will also be explored.

Inclusion Criteria:

• HIV-seropositive
• Currently receiving atazanavir/ritonavir or lopinavir/ritonavir in combination with 2-3 nucleoside RT inhibitors or are antiretroviral treatment-naïve
• If female, is not of childbearing potential or is of childbearing potential and agrees to use a barrier method of contraception throughout the study

Exclusion Criteria:

• HIV-1 RNA > 400 copies/mL if currently receiving antiretroviral therapy

• Concurrent use of CYP450 inhibitors or inducers

• Concurrent use of P-glycoprotein substrates, inhibitors, or inducers

• Concurrent use of medications known to interact with ritonavir or atazanavir

• Presence of a chronic health condition deemed by the investigators to potentially impair lopinavir, ritonavir, or atazanavir pharmacokinetics

• Presence of conduction abnormalities on electrocardiogram

• Women who are pregnant or breastfeeding

• Laboratory Abnormalities at baseline:

  • Aminotransferases > 3x ULN
  • Serum bilirubin > 5x ULN
  • Serum creatinine > 1.5x ULN
  • Hemoglobin concentration < 8.0 g/dL
  • Absolute neutrophil count < 800 cells/μL
  • Platelet count < 50,000 cells/μL