Sustiva (efavirenz), which is one of the most commonly prescribed antiretrovirals, is both safe and just as effective at fighting HIV when the standard dose is reduced by a third, MedPage Today reports. Investigators conducted a randomized controlled trial of 630 treatment-naive HIV-positive participants in 13 countries around the globe, who were given either the standard 600-milligram daily dose of Sustiva or 400 mg per day, along with a standard background regimen of Truvada (tenofovir and emtricitabine). (Together, these three drugs are the components of the single-pill, once-a-day triple combination first-line therapy Atripla.) Researchers reported their findings at the 7th International AIDS Society Conference on HIV Pathogenesis, Treatment and Prevention (IAS 2013) in Kuala Lumpur.

After 48 weeks, there was no significant difference between the two arms of the study in terms of the proportion that reached a viral load of less than 200: 94 percent of those taking the smaller dose and 92 percent of those taking the larger dose reached this endpoint. (While in the United States the standard cut-off for defining a viral load as undetectable is 50, in some sites where the study was conducted they only had the capacity to test for as low as 200, so that was established as the standard in this study.)

Reducing the dose of Sustiva also did not change the number of adverse events or improve tolerability. But fewer people stopped treatment because of central nervous system reactions in the lower-dose arm.

In theory, this new finding may lead to a reduction both in the standard dosing of the drug and the cost.

Also at the IAS conference, the World Health Organization recommended Sustiva as a component of the preferred first-line HIV therapy in its new guidelines stipulating that anyone with 500 or fewer CD4 cells should begin treatment.

To read the MedPage Today story, click here.

To read the conference abstract, click here.