Saturday, December 1, 2007

Canada Approves AIDS Drug Isentress

Health Canada has granted license approval for a new HIV-AIDS drug, the first in a promising new class of medications.

Drug maker Merck Frosst says it has been given permission to bring Isentress to the Canadian market for treatment of HIV-positive people whose viruses are resistant to multiple other HIV drugs.

AIDS expert Dr. Mark Wainberg says there is tremendous optimism about the drug in the community of HIV patients, doctors and researchers.

The drug's generic name is raltegravir.

It is the first in a new class of drugs known as integrase inhibitors to hit the global AIDS drug market; another drug, eltegravir, is in development by Gilead Sciences Inc. of Foster City, CA.

New classes of AIDS drugs are critical because viruses can develop resistance to existing classes of drugs over time.

Raltegravir works by blocking an enzyme called integrase that the virus needs in order to be able to insert its DNA into the host cell's chromosome.

"The amount of virus in the blood stream goes down much faster with this drug than with other drugs,'' says Wainberg, a professor at McGill University who practices at Montreal's Jewish General Hospital.

"I think it is a drug that has the potential to do so much good. You know, there are even things we hope we can do with it that we don't want to talk about (yet).''

Health Canada licensed the drug for use in combination with other antiretroviral medications for the treatment of HIV-1 infection in ``treatment-experienced'' adult patients who show evidence of viral replication and drug resistance.

The release from the company says the marketing authorization comes with conditions, pending the results of studies to verify the drug's clinical benefit.

Merck Frosst says a notice of compliance - essentially a license to market - with conditions signals ``the promising nature of the clinical evidence in patients with this serious disease and the need for further follow up to verify the clinical benefits.''

Clinical trials have shown that raltegravir, in combination with other antiretroviral drugs, was effective at reducing viral load and increasing CD4 cell counts, the two most widely accepted measures of efficacy against HIV/AIDS.

The drug was given a priority review by the Food and Drug Administration, which announced on Oct. 16 that it had approved the drug for use in the U.S.

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