What is Isentress (Raltegravir) Used For? Side Effects and Dosage

What is Isentress (Raltegravir) Used For? Side Effects and Dosage

What is Isentress (Raltegravir)?

Isentress, the trade name of the drug raltegravir, is a medication used in the treatment of human immunodeficiency virus (HIV), the virus responsible for the development of acquired immunodeficiency syndrome (AIDS) in the human body. Isentress is an integrase strand transfer inhibitor (INSTI), a class of medications designed to prevent the incorporation of the viral genomes into a patient’s DNA chains through the activity of the enzyme integrase. Developed, produced, and marketed by U.S. pharmaceutical company Merck & Co., it was introduced to the market in 2007 as the world’s first approved integrase inhibitor HIV medication. Its success in treating HIV in combination with other antiretroviral medications has led to its inclusion on the World Health Organization’s list of essential medicines.

What is It Used For?

Isentress, when combined with other classes of antiretroviral medications, is used in the treatment of HIV Type 1 and Type 2. The class of medications to which it belongs, integrase strand transfer inhibitors, are named for their ability to inhibit the activity of retroviral integrase, a form of the enzyme integrase that the virus uses to integrate its genetic material into infected DNA chains. By blocking this process, Raltegravir halts the spread of the viral infection in an infected individual. To decrease the likelihood of viral mutations adapting to the treatment, Isentress is best used in conjunction with other antiretroviral medications that target different parts of the virus’ reproduction cycle, such as protease inhibitors and reverse-transcriptase inhibitors.

How to Take Raltegravir

Isentress is available in the form of chewable tablets, hard tablets, or an oral suspension powder to be mixed with water. All forms are intended for oral ingestion. The hard tablets should not be chewed, crushed, or broken prior to ingestion, while the chewable and oral suspension forms are intended for dosing in children. Raltegravir may be taken with or without food. The oral suspension powder is intended to be mixed thoroughly with 5 mL (1 teaspoon) of water and swallowed within 30 minutes of preparation. Unlike other classes of antiretroviral medications, integrase inhibitors such as Raltegravir are metabolized through different pathways in the body and are not currently thought to be affected by the consumption of grapefruit or grapefruit juice. Isentress has been evaluated as being safe for pregnant women to take.

Isentress Side Effects

Various side effects have been observed in patients taking Isentress. To reduce the risk of side effects, prospective patients should consult with their health care provider regarding any other medications being taken, as these may interact with Isentress and increase the likelihood and severity of side effects.

The following side effects are common and often manageable:

  • nausea
  • diarrhea
  • insomnia
  • fatigue
  • changes in body fat shape and location
  • drowsiness
  • dizziness
  • headache

The following side effects occur less frequently but may require immediate medical attention:

  • rash
  • skin peeling
  • pale skin
  • psychiatric symptoms such as depression, anxiety, or thoughts of self-harm
  • allergic reaction symptoms such as hives, itchiness or face swelling
  • weakness
  • fever
  • discoloring of urine or stool
  • wheezing, coughing, or shortness of breath
  • stomach pain
  • yellowing of skin, nails, or eyes


The standard dosage of Isentress in adults is 800 mg per day, in the form of one 400 mg tablet each morning and evening. A newer version, named Isentress HD and containing the same active ingredient (raltegravir), is available in 600 mg tablets. When prescribed to adults, these are to be taken two at a time (1200 mg), once per day.

Isentress is not intended to be taken by children weighing less than 2 kg, while Isentress HD is not intended for any patients weighing less than 40 kg. In pediatric patients, dosage is to be determined by the prescribing doctor based on patient weight. Patients weighing between 3 and 25 kg are typically prescribed chewable or oral suspension forms, taken twice daily, while patients between 2 and 3 kg are normally only prescribed a 100 mg oral suspension, taken once or twice daily. There are variances in the above dosage depending on whether a patient has undergone prior treatment for HIV (treatment experienced or treatment naïve).

Disclaimer: Please note that the contents of this article are for informational purposes only and should not be considered medical advice. This article, and other AIDS and HIV Information articles on AIDS Drugs Online, are not written by AIDS Drugs Online or reviewed by its staff for medical validity. All views and opinions expressed by the third-party authors are not endorsed by AIDS Drugs Online or its staff. Always consult a medical professional for medical advice.


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