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Author: Merck Sharp & Dohme Ltd.


Long information

What is it?

Isentress is a medicine that contains the active substance raltegravir. It is available as pink, oval tablets (400 mg).

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Table of Contents
What is it used for?
How is it used?
How does it work?
How has it been studied?
What benefits has it shown during the studies?
What is the risk associated?
Why has it been approved?

What is it used for?

Isentress is used in combination with other antiviral medicines to treat adults infected with human immunodeficiency virus (HIV-1), a virus that causes acquired immune deficiency syndrome (AIDS).

The medicine can only be obtained with a prescription.

How is it used?

Treatment with Isentress should be started by a doctor who has experience in the management of HIV infection.

It is taken as one tablet twice a day.

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How does it work?

The active substance in Isentress, raltegravir, is an integrase inhibitor. It blocks an enzyme called integrase, which is involved in a step in the reproduction of HIV. When the enzyme is blocked, the virus cannot reproduce normally, slowing down the spread of infection. Isentress, taken in combination with other antiviral medicines, reduces the amount of HIV in the blood and keeps it at a low level. Isentress does not cure HIV infection or AIDS, but it may delay the damage to the immune system and the development of infections and diseases associated with AIDS.

How has it been studied?

Isentress has been studied in three main studies:

  • two studies involved a total of 699 ?treatment-experienced? patients who were already receiving treatment for HIV infection that was not working. The studies compared Isentress with placebo (a dummy treatment), which were added to ?optimised background therapy? (a combination of other antiviral medicines chosen for each patient as it had the best chances of reducing the levels of HIV in the blood). The main measure of effectiveness was the reduction in the levels of HIV in the blood (viral load) after 16 weeks;
  • the third study involved 566 adults who had not taken HIV treatment before and compared Isentress with efavirenz (another antiviral medicine). All of the patients also took tenofovir and emtricitabine (other antiviral medicines). The main measure of effectiveness was the number of patients who had ?undetectable? viral loads (below 50 copies per millilitre of blood) after 48 weeks.

What benefits has it shown during the studies?

In treatment-experienced patients, Isentress was more effective than placebo: 77% of the patients who took Isentress had viral loads below 400 copies/ml after 16 weeks, compared with 42% of those who took placebo. The response was sustained for at least 48 weeks.

In patients who had not taken HIV treatment before, Isentress was as effective as efavirenz. After 48 weeks, 86% of the patients taking Isentress had viral loads below 50 copies/ml (241 out of 281), compared with 82% of those taking efavirenz (230 out of 282).

What is the risk associated?

The most common side effects with Isentress (seen in between 1 and 10 patients in 100) are abnormal dreams, insomnia (difficulty sleeping), dizziness, headache, vertigo (a spinning sensation), abdominal distension (swollen tummy), abdominal pain (stomach ache), diarrhoea, flatulence (gas), nausea (feeling sick), vomiting, rash, asthenia (weakness), fatigue (tiredness), pyrexia (fever), atypical lymphocytes (abnormal white blood cells), and increased blood levels of some enzymes (alanine aminotransferase, aspartate aminotransferase and lipase) and triglycerides (a type of fat). For the full list of all side effects reported with Isentress, see the Package Leaflet.

Isentress should not be used in people who may be hypersensitive (allergic) to raltegravir or to any of the other ingredients.

As with other anti-HIV medicines, patients taking Isentress may be at risk of osteonecrosis (death of bone tissue) or immune reactivation syndrome (symptoms of infection caused by the recovering immune system).

Why has it been approved?

The CHMP decided that Isentress?s benefits are greater than its risks and recommended that it be given marketing authorisation.

Isentress was originally given ?conditional approval? because there was more evidence to come about the medicine. As the company has supplied the additional information necessary, the authorisation has been switched from conditional to full approval.

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