Monday December 3, 2001

Small Study Finds On-And-Off HIV Therapy Effective

By Emma Hitt, PhD

NEW YORK (Reuters Health) - Antiviral HIV drugs may be just as effective, cheaper and less toxic when taken as an on-again, off-again regimen, findings of a small study suggest.

According to researchers, the development of highly active antiretroviral therapy (HAART) means that HIV infection is no longer a death sentence. But to keep virus levels at bay, patients must take the drugs for the rest of their lives.

HAART can increase blood cholesterol and triglyceride levels, boosting the risk of heart disease, and can damage the liver and kidney. These drugs are also expensive, with an annual cost of about $15,000 to $18,000 per patient.

Dr. Mark Dybul of the National Institutes of Health in Bethesda, Maryland, and colleagues wanted to determine if taking the drugs for 7 days, followed by a 7-day drug-free period, would be as effective as taking the drugs every day, which is the standard procedure.

Dybul's team studied 10 patients who had already been taking HAART for an average of more than 13 months and were taking at least three different types of anti-HIV drugs.

The investigators found that the week-on, week-off regimen suppressed patients' blood levels of HIV for 32 to 68 weeks, suggesting that the intermittent regimen could be just as effective as the everyday regimen.

Not only were HIV levels kept down; patients' levels of infection-fighting CD4+ T cells were maintained. The patients' blood cholesterol and triglycerides were reduced, suggesting that the alternating regimen was less toxic.

"Intermittent therapy may be an important strategy to reduce cost and toxicity for HIV-infected individuals,'' Dybul and colleagues note in the Proceedings of the National Academy of Sciences Early Edition, published online December 4.

Although the results are promising, Dybul said, further studies are needed. "This study was done in a small number of patients who had been doing very well on their medications, and we used a specific drug regimen,'' he said.

"Larger studies must be done before this approach can be recommended in a clinical setting,'' he told Reuters Health.

Dybul and his colleagues are investigating whether the drugs can be taken for less than a 7-day cycle. "But it is unlikely that we would be able to do much better than around 50% (i.e. half on, half off) without sacrificing clinical efficacy,'' he said.

According to Dybul, the full dose must be taken for the 7 days, rather than simply cutting the dose in half and taking it every day, or the therapy will not be effective.

The next step, Dybul said, will be to find out if people with lower CD4+ T cell counts, indicating a more progressed HIV infection, can benefit from this regimen; whether other drugs can be taken in the same way; and whether patients who have been on therapy for a shorter period of time could benefit.

In a related editorial, Dr. Diane V. Havlir with the University of California, San Diego, called the observations preliminary but "both fascinating and important.''

SOURCE: Proceedings of the National Academy of Sciences Early Edition