Similar antiviral efficacy and tolerability between efavirenz and lopinavir/ritonavir, administered with abacavir/lamivudine (Kivexa), in antiretroviral-naïve patients: a 48-week, multicentre, randomized study (Lake Study).

Background: Although efavirenz and lopinavir/ritonavir(r) are both recommended antiretroviral agents in antiretroviral-naïve HIV-infected patients, there are few randomized comparisons of their efficacy and tolerability.

Methods: A multicenter and randomized study was performed including 126 antiretroviral-naïve patients, randomly assigned to efavirenz+Kivexa (n=63) or lopinavir/r+Kivexa (n=63). Efficacy endpoints were the percentage of patients with HIV-RNA < or =50 copies/mL at week 48 and CD4 recovery. Safety was assessed by comparing toxicity and discontinuations. Statistical analyses were performed on an intention-to-treat (ITT) basis (Missing=Failure).

Results: At week 48, 56.7% of patients in the efavirenz and 63.2% in the lopinavir/r groups showed HIV-1 RNA <50 copies/mL (P=0.770) (intention-to-treat analysis; Missing=Failure). Only 1 (1.53%) patient from each group experienced virological failure. CD4 values increased in both groups (298 cells in the efavirenz group, P=0.001; 249 cells in the lopinavir/r group, P=0.002; P=0.126 between groups). HDL-cholesterol only increased in the efavirenz group (from 39+/-12 mg/dL to 49+/-11; P=0.001). Discontinuations were more frequent in the lopinavir/r group (36.5% versus 28.5%; P=0.193), but more patients with efavirenz interrupted due to toxicity (11.1% versus 6.3%); most of them were attributed to hypersensitivity reaction.

Conclusions: Similar virological efficacy was observed for efavirenz and lopinavir/r, when administered with Kivexa in antiretroviral-naïve patients, while immunological improvement was slightly superior for efavirenz. The higher rate of discontinuation due to toxicity in the efavirenz group was related to a higher incidence of hypersensitivity reaction. Nowadays, the use of the new formulation of lopinavir/r and the HLA-B*5701 genotype test before starting abacavir should improve the safety profiles of these regimens.