"While this is just a small study that requires confirmation before it can be recommended, it would allow patients some relief in side effects and costs," said Susan Swindells, professor of internal medicine at the University of Nebraska Medical Center in Omaha.

Swindells reported her study as part of a special news briefing conducted by the Journal of the American Medical Association (JAMA) during this week's 16th International AIDS Conference in Toronto, Canada.

For the study, Swindells recruited 34 patients to test whether treatment with a single drug -- actually the combination of two protease inhibitors, ritonavir (Norvir) and atazanavir (Reyataz) -- would be sufficient to keep the virus which causes AIDS in check.

The patients were required to have logged at least one year of being able to keep the virus at undetectable levels. They were then switched to a single pill of atazanavir/ritonavir in place of their former protease inhibitor medication. After six weeks of treatment to make sure the new regimen was tolerated, the nucleoside analogs were discontinued. The patients were followed for the next six months, undergoing testing to determine if the virus had rebounded at least three times.

"After 24 weeks, 91 percent of our patients had virus levels that remained undetectable," Swindells told United Press International.

"In this pilot study, the data suggest that simplified maintenance therapy with atazanavir-ritonavir alone in patients who have never experienced treatment failure may be efficacious in maintaining HIV suppression below 200 copies per milliliter for 24 weeks after discontinuing nucleoside reverse transcriptase inhibitors," she said.

Swindells added, "Maintenance therapy with a single boosted protease inhibitor offers a treatment strategy with potentially less complexity, pill burden, long-term complications and cost."

She told UPI that cost-effectiveness studies are under way to determine how much could be saved using the one-drug therapy.

"This is an interesting treatment option, but it is too early to recommend it except as part of a well-controlled clinical trial," Scott Hammer, professor of infectious diseases at Columbia University, told UPI. "We did not include this type of drug holiday in our recommendations or guidelines for HIV treatment."

The guidelines were also printed in the AIDS-theme issue of JAMA, to be published Thursday.

Swindells said blood levels of atazanavir in two of the patients who experienced virological failure -- there was a viral rebound -- indicated no presence of the drug, a suspicion that the patients didn't take the medication. The third person experienced a blip in viral load, but according to the rules of the study, he was counted as a failure. In fact, the patient remains on Reyataz monotherapy.

The researchers chose Reyataz for study, Swindells said, because it is taken once daily, it is known to cause fewer lipid abnormalities than other protease inhibitors, and it has a unique resistance profile, so that if resistance developed it would not rule out other treatment options.

The patients have completed 48 weeks of follow-up, but data on that extension of the trial are not available.

The study was funded by several NIH grants and by industry support from Bristol-Myers Squibb, maker of Reyataz, and Abbott Laboratories, maker of Norvir, in the form of supplying study drugs and participation on the protocol team.

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