FRIDAY, Aug. 1 (HealthDay News) -- Once-daily treatment with atazanavir/ritonavir (A/R) is as effective as twice-daily treatment with lopinavir/ritonavir (L/R) in HIV patients who are starting antiretroviral treatment for the first time, a European study shows.

Based on their findings, the researchers recommended once-daily A/R as a first-line treatment option for treatment-naive HIV patients since it has a number of advantages over the currently recommended twice-daily L/R.

The study included 883 treatment-naive HIV patients who were randomly assigned to receive A/R 300/100 milligrams once daily (440 patients) or L/R 400/100 milligrams twice daily (443 patients). Both regimens were in combination with tenofovir/emtricitabine 300/200 once daily, as is standard.

After 48 weeks of treatment, 78 percent of patients receiving A/R and 76 percent of those receiving L/R had a viral load of less than 50 copies per milliliters in their blood, and both groups showed similar increases in the numbers of immune system CD4 cells. Six percent of patients in both groups failed on the treatments, and two patients in the A/R group developed resistance mutations to treatment, compared with none in the L/R group.

Serious side effects were reported in 12 percent of the A/R patients and 10 percent of the L/R patients, but fewer A/R patients experienced treatment-related diarrhea (2 percent vs. 11 percent) and nausea (4 percent vs. 8 percent). None of the L/R patients developed jaundice, which occurred in 4 percent of A/R patients.

"In treatment-naive patients, atazanavir/ritonavir once-daily demonstrated similar antiviral efficacy to lopinavir/ritonavir twice daily, with less gastrointestinal toxicity but with a higher rate of hyperbilirubinaemia...the results of this study support the use of once-daily atazanavir/ritonavir as a recommended first-line treatment option, with a number of patient benefits over the currently recommended ritonavir-boosted twice-daily lopinavir for the treatment of HIV-infected antiretroviral-naive patients," the researchers concluded.

The study appears online in The Lancet, and was expected to be published in an upcoming print edition of the journal.

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