New Drug Surprises AIDS Experts With Its Effectiveness

The new protease inhibitor darunavir is significantly better than other medications in attacking drug-resistant HIV, according to a new study. Darunavir, whose trade name is Prezista, last year received an accelerated federal approval that required its developer, Tibotec Pharmaceuticals, to continue safety and efficacy testing.

Participating in the new study were 230 patients who had failed to respond to at least three kinds of AIDS drugs. All were given a standard drug regimen prescribed by their doctors. In addition, 110 patients received twice-daily doses of darunavir (600 mg) boosted with the protease inhibitor ritonavir (100 mg).

At 48 weeks, 61 percent of the darunavir group had achieved a 10-fold reduction in viral levels. In the control group, about 15 percent achieved such a reduction. Forty-five percent of the darunavir patients achieved an undetectable viral load, compared to 10 percent of the control patients.

Dr. Charles Farthing, a study author and the chief of medicine at the AIDS Healthcare Foundation, said he was "almost staggered" by the results from a subgroup of patients who had failed on all previous treatment. Twenty percent of these patients achieved an undetectable viral load on darunavir.

The authors noted no significant differences in side effects for the darunavir patients, other than slightly more herpes infections. The researchers plan to study whether darunavir should be administered to patients newly infected with HIV.

The study, "Efficacy and Safety of Darunavir-Ritonavir at Week 48 in Treatment-Experienced Patients with HIV-1 Infection in POWER 1 and 2: A Pooled Subgroup Analysis of Data in Two Randomised Trials," was published in The Lancet (2007;369(9568):1169-1178).

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