PRESS RELEASE: FDA Approves of Isentress

FDA Approves of Isentress

ROCKVILLE, Md., Oct. 12, 2007--The Food and Drug Administration (FDA) today, October 12, 2007, granted accelerated approval for raltegravir tablets (400 mg) for treatment of Human Immunodeficiency Virus (HIV)-1 infection in combination with other antiretroviral agents. Raltegravir, sold under the trade name Isentress, is the first agent of the pharmacological class of antiretroviral agents known as HIV integrase strand transfer inhibitors, commonly referred to as integrase inhibitors. They are designed to slow the advancement of HIV-1 infection by blocking the HIV integrase enzyme that the virus needs in order to multiply. 

When used with other anti-HIV medicines, raltegravir may reduce the amount of HIV in the blood and may increase white blood cells, called CD4+ (T) cells, that help fight other infections.

Raltegravir received a priority review by the FDA. The review and approval of the New Drug Application was completed in within six months.

FDA's approval of raltegravir is based on efficacy and safety data from two double-blind, placebo-controlled studies (BENCHMRK 1 and BENCHMRK 2) in 699 highly antiretroviral treatment-experienced HIV-1 infected adult patients (16 years or older, with documented resistance to at least 1 drug in each of 3 Classes (NNRTIs, NRTIs, PIs) of antiretroviral therapies). 462 patients used the recommended 400 mg dose twice daily in combination with other currently available HIV medications; 237 patients received a placebo in combination with other currently available HIV medications. The mean changes in plasma HIV-1 RNA from baseline were -1.85 log10 copies/mL in the ISENTRESS 400 mg twice daily arm and -0.84 log10 copies/mL for the control arm. The mean increase from baseline in CD4+ cell counts was higher in the arm receiving ISENTRESS 400 mg twice daily (89 cells/mm3) than in the control arm (35 cells/mm3).

The most common adverse events reported with raltegravir were diarrhea, nausea, and headache. Blood tests showed abnormal elevated levels of a muscle enzyme in some patients receiving raltegravir. Caution is advised when using raltegravir in patients at increased risk for certain types of muscle problems, such as patients taking other medications that can cause muscle problems.

Raltegravir has not been studied in pregnant women. Women who are taking HIV medications when they get pregnant are advised to ask their physician about registering with the Antiretroviral Pregnancy Registry <> .

As with other treatments for HIV, patients taking raltegravir may still develop infections, including opportunistic infections or other conditions that may develop in patients living with HIV-1 infection, and can still pass the virus on to others through sexual contact, sharing needles, or being exposed to blood.

The long-term effects of raltegravir are not known at this time, and its safety and effectiveness in children less than 16 years of age has not been studied.

Raltegravir is distributed by New Jersey-based Merck & Co., Inc.

Please refer to the attached product labeling and patient information sheet for additional information about raltegravir. <> <> Richard Klein Office of Special Health Issues Food and Drug Administration

Kimberly Struble Division of Antiviral Drug Products Food and Drug Administration An archive of past list serve announcements is available on the FDA web site at