- For patients with low or moderate HIV loads, the nucleoside analog abacavir is as effective as the protease inhibitor indinavir as part of an antiretroviral cocktail, researchers in Germany report.
"Abacavir ... has demonstrated suppression of human immunodeficiency virus (HIV) replication alone and in combination therapy," explained S. Staszewski and colleagues at the University of Frankfurt. "However, the role of abacavir in a triple nucleoside combination regimen has not been evaluated against a standard protease inhibitor-containing regimen for initial antiretroviral treatment."
After conducting a Phase III trial comparing the two drugs in combination with lamivudine and zidovudine, Staszewski et al. found that both have almost identical efficacy for therapy-naive patients with viral loads of less than 100,000 copies per milliliter.
Just over half of patients (51%) treated with either regimen for 48 weeks achieved viral load reductions to less than 400 copies/mL, they said. All patients enrolled in their study had baseline plasma HIV RNA levels of at least 10,000 copies/mL.
However, in patients with viral loads of more than 100,000 copies/mL, the researchers found a large discrepancy in the effectiveness of abacavir and indinavir. While 45% of indinavir-treated patients achieved undetectable levels of HIV RNA (less than 50 copies/mL), only 31% of patients on an abacavir-based regimen realized this level of viral suppression, study data showed.
Both treatments had similar effects on CD4 cell counts, as well as comparable side effect profiles ("Abacavir-lamivudine-zidovudine vs. indinavir-lamivudine-zidovudine in antiretroviral-naive HIV-infected adults - A randomized equivalence trial," JAMA 2001 Mar 7;285(9):1155-63.
"In this study of antiretroviral-naive HIV infected adults, the triple nucleoside regimen of abacavir-lamivudine-zidovudine was equivalent to the regimen of indinavir-lamivudine-zidovudine in achieving a plasma HIV RNA level of less than 400 copies/mL at 48 weeks," Staszewski and colleagues concluded.
The corresponding author for this report is S. Staszewski, Universitat Frankfurt Klinikum, Zentrum Inneren Medizin, Haus 68, Theodor Stern Kai 7, D-60596 Frankfurt, Germany.
Key points reported in this study include:
- Abacavir is as effective as indinavir in combination therapy for patients with moderate plasma HIV RNA levels
- For these patients, either drug in combination with lamivudine and zidovudine produced viral suppression in almost identical proportions of patients
- However, for patients with viral loads of more than 100,000 copies/mL, indinavir was significantly more effective
This article was prepared by AIDS Weekly editors from staff and other reports.