December 17, 2001
Atazanavir (BMS-232632) is an investigational protease inhibitor (PI) that has several potential advantages over the currently FDA-approved protease inhibitor, including its once-daily dosing schedule, low pill burden (two pills once daily) and the lack of adverse impact upon lipid profiles. Currently, atazanavir is in phase III trials.
BMS-008 compared atazanavir (400mg or 600mg) versus nelfinavir (Viracept) twice daily in combination with stavudine (Zerit) and lamivudine (Epivir). At baseline, the enrolled patients were antiretroviral-naive and the demographics between the two arms were similar, with baseline viral loads of approximately 4.77 log10 copies/mL.
Using an intent-to-treat analysis, 74 percent, 75 percent and 53 percent, achieved a viral load <400 copies/mL at 48 weeks. Under an on-treatment analysis, the viral load decline was similar in the three arms -- approximately 2.5 log10 copies/mL at 48 weeks -- and 74% of the patients on 400mg a day of atazanavir and 60% of the patients on viracept achieved a viral load <400 copies/mL. The three arms were equal in their suppression to <50 copies/mL and their rise in CD4+ T cell counts. Total cholesterol, LDL and triglycerides changed little in the atazanavir arms, while they rose significantly in the Viracept arm at 48 weeks. In addition, diarrhea was relatively common in the viracept arm (56 percent) and uncommon in the atazanavir arm (15-20 percent). Unconjugated hyperbilirubinemia occurred in <5 percent of patients and four patients required dose reduction.
This study indicates that atazanavir is at least comparable to nelfinavir in efficacy. Further, atazanavir's favorable lipid profile, ease of dosing and lower rate of diarrhea will provide an advantage over nelfinavir for many patients. Further studies of atazanavir are underway, comparing it to efavirenz (sustiva/stocrin) and kaletra (lopinavir/ritonavir), and additional data should be forthcoming regarding the effectiveness and tolerability of atazanavir HAART regimens.
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