Background: Atazanavir is a once daily protease inhibitor (PI) that rapidly and durably suppresses HIV RNA and durably increases CD4 cell count. Current PIs cause prompt, marked, and sustained elevations in lipids. No elevations in lipids have been observed with atazanavir treatment through week 48.

Methods: In addition to evaluating safety and efficacy, clinical trials AI424-007 and AI424-008 carried out in treatment-naïve subjects, have evaluated changes in lipid profiles of atazanavir administered once daily and nelfinavir administered 2 or 3 times daily, both with 2 nucleoside reverse transcriptase inhibitors (NRTIs).

Results: Changes in lipid profile from baseline at week 48 are shown in the table. The atazanavir dose of 400 mg once daily is the dose currently used in phase III clinical trials. Available lipid results beyond  week 48 will be presented.

                                                                                         Mean Change, % (n) from Baseline

                                                                Total Cholesterol    Fasting LDL            Fasting Triglycerides

Trial AI424-007 at week 48 (n)

   Atazanavir 400 mg qd (101)                  7* (81)                       -7* (35)                          2* (44)

   Nelfinavir 750 mg tid (100)                 28   (82)                         31 (39)                          42 (46)

Trial AI424-008 at week 48 (n)

   Atazanavir 400 mg qd (178)                  5* (153)                       5* (87)                         7* (85) 

   Nelfinavir 1,250 mg bid (91)                25     (76)                      23  (41)                       50   (50)

*p<0.05, atazanavir vs nelfinavir

Conclusion: Results of these 2 studies in treatment-naïve subjects at week 48 confirm that the prompt, marked, and sustained elevations in lipids seen with current PIs are not seen with atazanavir. This suggests that atazanavir may reduce the risk of cardiovascular events in this population.