1. Aschenbrenner, Diane S. MS, APRN, BC

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With the recent approval of raltegravir (Isentress), the first integrase strand transfer inhibitor, a new class of drugs is available for the treatment of HIV infection. Integrase is an HIV-1-encoded enzyme that facilitates the insertion of the HIV-1 virus into the host cell, allowing viral replication. Raltegravir inhibits the enzyme, thereby preventing the propagation of the virus. The drug has been approved for use in combination antiretroviral therapy in adult patients who have already been treated for HIV-1 infection with other antiretroviral agents and have developed resistant strains.


In clinical studies, greater proportions of patients treated with raltegravir in combination with other HIV drugs achieved reduction in HIV viral loads, compared with those who received a placebo in combination with other HIV drugs. The safety and effectiveness of raltegravir in pregnant women or in children under age 16 have not been established.


During initial treatment, the drug can cause immune reconstitution syndrome, an inflammatory response to latent or residual opportunistic infections such as Mycobacterium avium, cytomegalovirus, Pneumocystis jiroveci pneumonia, Mycobacterium tuberculosis, or varicella zoster virus. If the patient develops any signs or symptoms of infection, she or he should be evaluated and treated. The most common adverse effects have been diarrhea, nausea, headache, and fever, which were also observed in patients receiving a placebo in clinical trials. In addition, the creatine kinase level might rise with the use of raltegravir, and the development of myopathy or rhabdomyolysis is possible. Nurses should monitor the patient's creatine kinase levels and ask patients about muscle pain and weakness. The risk of elevations in creatine kinase level, myopathy, and rhabdomyolysis is greater if the patient is taking other drugs that cause those conditions, such as the statins used in the treatment of hyperlipidemia. Additional monitoring is necessary in such a patient.


Raltegravir is not metabolized by the cytochrome P-450 isoenzyme system but rather by the enzyme uridine diphosphate glucuronosyltransferase 1A1. When it's taken with a drug that induces that enzyme, such as the tuberculosis medication rifampin (Rifadin and others), plasma concentrations of raltegravir can be reduced significantly. If such a drug combination is necessary, the patient should be assessed to determine whether the therapeutic effect is being achieved; adjustments of the dosage may be indicated.


Merck and Company. [Label information]: Isentress (raltegravir) tablets. 2007.; FDA approves new HIV drug: Raltegravir tablets used in combination with other antiretroviral agents. FDA News 2007 Oct 16.