New data, presented this week at a scientific meeting in San Francisco, California, suggest that an HIV treatment regimen based on a once-daily dose of Abbott Laboratories' protease inhibitor (PI) Kaletra (lopinavir/ritonavir) had comparable viral suppression when compared to a twice-daily dose through one year (48 weeks) in patients new to treatment. Currently, the adult recommended dosage of Kaletra is 400/100 mg (three capsules or five milliliters) twice daily with food.

"Patients taking a once-daily Kaletra-based regimen showed comparable results to the twice-daily regimen in terms of virologic suppression," said Joseph Gathe, Jr., lead investigator and clinical instructor at Baylor College of Medicine. "These results suggest future potential for use in HIV treatment-naïve patients for whom once-daily dosing is optimal."

This is the first study of an entirely once-daily Kaletra-based regimen and represents the first clinical study in which emtricitabine and tenofovir are co-administered. In this open-label, randomized 96-week study, 190 patients new to therapy received either Kaletra once daily or Kaletra twice daily. Patients in both arms received once-daily emtricitabine and tenofovir.

At 48 weeks, 90 per cent of patients in the once-daily arm and 85 per cent in the twice-daily arm had an undetectable viral load. Additionally, an intent-to-treat analysis, which includes any patient who does not complete the study as treatment failure, showed 70 per cent of patients in the once-daily group and 64 percent of patients in the twice-daily group achieved HIV RNA less than 50 copies per milliliter. Mean increases in CD4 cell count from baseline to the one-year visit were 185 and 188 cells per cubic millimeter in the once-daily and twice-daily arms, respectively.

Results of genotypic resistance testing were available for five patients in each arm with HIV RNA greater than 500 copies per milliliter occurring at any time between weeks 12 through 24. No mutations associated with HIV resistance were detected to lopinavir or tenofovir and only one patient in each group demonstrated emtricitabine resistance.