Background: Recommended antiretroviral regimens include a nucleoside reverse transcriptase inhibitor (NRTI) component. Class cross-resistance and mitochondrial toxicity are recognized as problems with this class of antiretrovirals.
Methods: In a pilot open-label study, 65 antiretroviral-naive and 21 experienced but nonnucleoside reverse transcriptase inhibitor-naive HIV-1-infected adults were given a combination of lopinavir/ritonavir (533.3/133.3 mg twice daily) and efavirenz (600 mg once daily) for 48 weeks.
Results: At baseline, the mean viral load was 4.84 log10 copies/mL and the mean CD4 count was 311 cells/mm3. At week 24, the proportions of patients with a viral load <400 copies/mL were 78% and 93% using an intent-to-treat and on-treatment analysis, respectively. At week 48, proportions were 73% and 97%, respectively. Treatment discontinuation occurred in 21 patients during the 48-week period, with 33% of those attributable to drug-related adverse effects. A viral load >400 copies/mL at week 24 or 48 was associated with nonadherence in 3 patients and virologic failure in 1 patient. After an increase during the first 8 weeks, fasting lipid levels remained stable up to 48 weeks.
Conclusion: The lopinavir/ritonavir-efavirenz combination is associated with a high rate of virologic response and should be compared with more classic NRTI-containing regimens in randomized and controlled clinical trials.