The Body Covers: The XIII International AIDS Conference
More on Salvage Studies
July 11, 2000
Because efavirenz can lower PI blood levels, participants were randomized to the standard dose of lopinavir/ritonavir, 400mg/100mg twice a day, or to a higher dose, 533mg/133mg twice a day. Drug levels of both lopinavir and efavirenz were obtained. Fifty-seven patients with average of three prior PIs had phenotypic resistance testing at entry.
Sixty-eight percent had virus that were cross-resistant to at least three FDA-approved PIs (four-fold decrease in virus susceptibility), and 43% showed significant resistance (ten-fold or more decrease in susceptibility) to lopinavir.
Administration of standard-dose lopinavir with efavirenz resulted in about a 33% decrease in lopinavir levels, but the higher dose of lopinavir given with efavirenz resulted in the same blood levels achieved by lopinavir in the absence of efavirenz. Efavirenz levels were unaffected. As a result, all participants were switched to the higher dose.
Four patients withdrew before week 24 because of side effects and three because of virologic failure. The intent-to-treat analysis demonstrated that 82% of the 533/133 group and 69% of the 400/100 group had viral loads less than 400 copies at week 24. Despite extensive prior treatment with antiretrovirals, CD4 cells increased by an average of 381 and 295 cells for the higher and standard dose arms, respectively. Study therapy was well tolerated, and although cholesterol levels increased somewhat during the study, the increases were not significantly changed from entry. Despite high baseline levels of resistance to lopinavir and other PIs, the majority of patients achieved both viral suppression and significant increases in CD4 cells. Lopinavir plus efavirenz shows considerable promise as the basis of a salvage regimen for patients who have failed multiple PIs.
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