New HIV Drug May Be More Effective

Drug, Called Prezista, May Help When Other HIV Medications Fail

By Miranda Hitti
WebMD Health News

Reviewed By Louise Chang, MD

April 4, 2007 -- A new HIV drug called Prezista helps curb HIV in patients who don't respond to other HIV drugs, a new study shows.

Prezista belongs to a class of drugs called protease inhibitors, which block HIV (the virus that causes AIDS) from multiplying.

The FDA approved Prezista in June 2006 for use with a protease inhibitor called Norvir and other anti-HIV drugs in adults whose HIV infection hasn't responded to other treatments.

Now, an international study shows that Prezista may give such patients a new treatment option.

"For now, all of us treating HIV-infected individuals in clinical practice will probably rejoice in the availability of [Prezista], since it seems to be a safe, well-tolerated, and a truly effective agent against multidrug-resistant HIV," states an editorial accompanying the study.

The study and editorial appear online in The Lancet.

Prezista Study

The study included 230 adults with HIV who had already tried other HIV drugs. The patients lived in the U.S., Europe, Brazil, Canada, Australia, or Argentina.

The researchers included Bonaventura Clotet, MD, who works in Barcelona, Spain at the Hospital Universitari Germans Trias i Pujol and irsiCaixa Foundation.

First, the patients provided blood samples. Using those blood samples, Clotet's team measured levels of HIV (viral load) and certain immune system cells (CD4 cells) in the patients' blood.

Next, the researchers split the patients into two groups.

For 48 weeks, patients in one group took Prezista and Norvir every day. Patients in the other group took another protease inhibitor HIV drug, but not Prezista, for the same amount of time.

All patients in both groups also took other classes of  HIV drugs throughout the study.

Patients periodically provided more blood samples so that the researchers could see how well the drugs lowered HIV levels and improved immune response as demonstrated by CD4 cell count.

Study's Results

Treatment with Prezista and Norvir was more successful than treatment with other HIV drugs, the study shows.

Among patients taking Prezista and Norvir, 61% reached the researchers' goal for a substantial drop in HIV viral load in their blood, compared with 15% of those not taking Prezista.

Patients taking Prezista and Novir also had a bigger increase in their CD4 cell count, compared with those not taking Prezista.

In short, the Prezista-and-Norvir plan appeared to have a greater impact in fighting HIV and in boosting the patients' immune systems.

The researchers note "favorable safety and tolerability" with Prezista-Norvir treatment, with no new safety concerns, compared with other protease inhibitors.

The study was sponsored by Tibotec, the drug company that makes Prezista. Several of the researchers note financial ties to various drug companies including Tibotec; two of the researchers work for Tibotec.

Ideally, a trial would last two to three years, notes editorialist Rodger MacArthur, MD, of Wayne State University in Detroit.

MacArthur calls for more Prezista studies. Meanwhile, he states that there is reason to "rejoice" in Prezista's availability.

SOURCES: Clotet, B. The Lancet, April 5, 2007; online edition. WebMD Medical Reference from Healthwise: "Protease Inhibitors (PIs) for HIV." MacArthur, R. The Lancet, April 5, 2007; online edition. FDA: "Patient Information Sheet: Darunavir (marketed as Prezista)." News release, FDA. News release, The Lancet.

© 2007 WebMD Inc. All rights reserved.


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