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Study Finds Reduced Intake of Anti-AIDS Drugs May Be Possible

New studies show that people who periodically stop taking anti-AIDS drugs may get the same health benefit and experience fewer side effects.

There's still no cure for AIDS. But the lives of those infected with HIV have been extended and dramatically improved by treating them with anti-retroviral drugs that keep the deadly virus at bay. The drug cocktails are also known as "highly active anti-retroviral therapy," or HAART.

But there are problems with HAART. Mark Dybul is an AIDS researcher at the National Institute of Allergy and Infectious Diseases near Washington.

"Although HAART therapy is very effective, it is now clear that it will not cure the virus [HIV]. And so we're talking about lifelong therapy. And lifelong therapy has some definite downsides," he says.

Including very unpleasant side effects, such as chronic upset stomach and diarrhea. Then there's the enormous expense of anti-retroviral drugs to treat HIV.

"Ninety five percent of the people in the world don't have access to the therapies, in large part because of the cost of the therapies. There are other factors including cost of monitoring and things like that. But the cost of the drugs is a primary problem," he says.

In an effort to overcome these problems, researchers have been examining if they could reduce the quantity of drugs given to patients.

"People can't take drugs everyday or twice a day for the rest of their lives. We know that from a lot of chronic disease types, says researcher Mark Dybul. "So the hope is that by giving people less drug they might be able to keep up with the drugs better."

Because of the drawbacks with HAART, researchers started looking at studies of AIDS patients who had been on anti-retroviral therapy for long periods and then stopped. Investigators found virtually no increase in the amount of HIV in the blood or lymph glands of infected individuals within the first seven days.

So Mark Dybul and colleagues designed a study in which they placed 10 HIV patients on HAAT for seven days and then took them off for seven days. The on again-off again cycle, known as "structured intermittent therapy," was repeated for up to 68 weeks.

"If you looked at the results we have in terms of the viral load and in terms of virus levels in the reservoir sites and the CD4 cell count, they look exactly like individuals who are on continuous therapy. You wouldn't be able to tell the difference if you showed them to a clinician," Mr. Dybul says.

HIV attacks and depletes immune system cells known as CD4T cells. The results of the study were published in "Proceedings of the National Academy of Sciences."

AIDS expert Helene Gayle of the Bill and Melinda Gates Foundation is optimistic but cautious about the benefits of structured intermittent therapy. "If you could figure out a way that people only had to take the drugs intermittently the potential benefit is great. We're just too early in our knowledge of the actual application of it to translate that into practice," she says.

For that reason, researchers are telling people on HAART not to cut their drug therapy in half.