Raltegravir (MK-0518, brand name Isentress) is an antiretroviral drug produced by Merck & Co., used to treat HIV infection. It received approval by the U.S. Food and Drug Administration (FDA) in October 2007, the first of a new class of HIV drugs, the integrase inhibitors, to receive such approval.

Mechanism

Raltegravir targets integrase, an HIV enzyme that integrates the viral genetic material into human chromosomes, a critical step in the pathogenesis of HIV. The drug is metabolized away via glucuronidation.

Research

Raltegravir significantly alters HIV viral dynamics and decay and further research in this area is ongoing. In clinical trials patients taking raltegravir achieved viral loads less than 50 copies per millitre sooner than those taking similarly potent Non-nucleoside Reverse Transcriptase Inhibitors or Protease Inhibitors. This statistically significant difference in viral load reduction has caused some HIV researchers to begin questioning long held paradigms about HIV viral dynamics and decay.[7] Research into raltegravir's ability to affect latent viral reservoirs and possibly aid in the eradication of HIV is currently ongoing.

Research results were published in the New England Journal of Medicine on July 24, 2008. The authors concluded that "raltegravir plus optimized background therapy provided better viral suppression than optimized background therapy alone for at least 48 weeks."

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How does it work?

Isentress tablets contain the active ingredient raltegravir, which is medicine used to treat infection with HIV (human immunodeficiency virus). Raltegravir is a new type of anti-HIV medicine known as an integrase strand transfer inhibitor.

AIDS (acquired immune deficiency syndrome) is caused by infection with HIV. This virus cannot replicate and increase in numbers on its own, so it invades human cells to use their metabolism. The virus invades cells of the immune system, particularly the white blood cells known as CD4 T-helper lymphocytes. These cells normally work to activate other cells in the immune system to fight infection. The HIV virus kills the CD4 T-helper cells in the process of its replication, and because of this, over time the body becomes less able to fight the virus or subsequent infections.

Once the virus is inside the CD4 T-cell it multiplies. Part of the process of viral multiplication involves the integration of the viral genetic material, DNA, into the CD4 T-cell’s DNA. This is achieved by a compound essential to the virus, called HIV-1 integrase. HIV-1 integrase is known as an enzyme. Raltegravir works by blocking the action of this enzyme, thereby interfering with the integration of viral DNA into the CD4 T-cell DNA. This stops the virus from multiplying.

This mechanism of action is different from all the other currently available anti-HIV drugs, which means that raltegravir is active against strains of HIV that have become resistant to other anti-HIV medicines.

There is no cure for HIV, but raltegravir is one of a number of medications that lowers the amount of virus in the body (viral load) and slows the progression of the disease from HIV to AIDS. Raltegravir is used in conjunction with other anti-HIV drugs that attack the HIV virus in different ways. This helps prevent the virus becoming resistant to the medicine.