Ziagen is a medicine that contains the active substance abacavir. It is available as yellow capsule-shaped tablets (300 mg) and as an oral solution (20 mg/ml).
|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?|
Ziagen is used in combination with other antiviral medicines to treat patients who are infected with human immunodeficiency virus (HIV), the virus that causes acquired immune deficiency syndrome (AIDS).
The medicine can only be obtained with a prescription.
Ziagen should be prescribed by a doctor who has experience in the management of HIV infection.
Before starting treatment with Ziagen, all patients should have a test to find out if they have a gene called ?HLA-B (type 5701)?. Patients with this gene are at an increased risk of having an allergic reaction to abacavir, so they should only take Ziagen if there are no other treatment options. This test is also recommended in patients who have tolerated abacavir in the past and are about to start taking it again.
The recommended dose of Ziagen for patients over 12 years of age is 600 mg daily, either as 600 mg once a day or 300 mg twice a day. In children (aged below 12 years), the dose depends on body weight. Children taking Ziagen tablets should be closely monitored for side effects.
Ziagen tablets should ideally be swallowed without crushing. Patients who cannot swallow tablets should use the oral solution, or alternatively they may crush the tablets and add them to a small amount of food or drink immediately before swallowing it. For more information, see the Package Leaflet.
Patients who take Ziagen must be given the special alert card that summarises the key safety information about the medicine.
The active substance in Ziagen, abacavir, is a nucleoside reverse transcriptase inhibitor (NRTI). It blocks the activity of reverse transcriptase, an enzyme produced by HIV that allows it to infect cells in the body and make more viruses. By blocking this enzyme, Ziagen, taken in combination with other antiviral medicines, reduces the amount of HIV in the blood and keeps it at a low level. Ziagen 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.
Ziagen has been studied in six main studies including 1,843 HIV-infected adults (aged 18 years and over). Ziagen was taken alone, or added to the combination of lamivudine and zidovudine (other antiviral medicines) or the patients? existing HIV treatment. One study compared the effects of Ziagen taken once and twice a day, in combination with lamivudine and efavirenz (other antiviral medicines) in 784 patients.
Ziagen has also been studied in three studies including 489 HIV-infected patients aged between three months and 18 years.
Ziagen?s effects were compared with other antiviral medicines, placebo (a dummy treatment) or no treatment.
The main measures of effectiveness were the levels of HIV in the blood (viral load) and the number of CD4 T-cells in the blood (CD4 cell count). CD4 T-cells are white blood cells that are important in helping to fight infections, but which are killed by HIV.
In all of the studies, Ziagen caused a decrease in viral loads, particularly when taken with other antiviral medicines. It was more effective than placebo, and was as effective as other antiviral medicines in reducing viral loads in all age groups. In one of the studies in adults, 77% of the patients taking Ziagen with lamivudine and zidovudine had viral loads below 400 copies/ml after 16 weeks (67 out of 87), compared with 38% of the adults taking lamivudine and zidovudine without Ziagen (33 out of 86). Once- and twice-daily Ziagen had similar effects on viral load. Patients receiving Ziagen also had increases in their CD4 cell counts.
The most common side effects with Ziagen (seen in between 1 and 10 patients in 100) are loss of appetite, headache, nausea (feeling sick), vomiting, diarrhoea, rash, fever, lethargy (lack of energy) and fatigue (tiredness). For the full list of all side effects reported with Ziagen, see the Package Leaflet.
Hypersensitivity reactions (allergic reactions) occur in about 3% of patients taking Ziagen, usually within the first six weeks of treatment, and can be life-threatening. The risk of hypersensitivity is higher in patients who have the HLA-B (type 5701) gene. Symptoms almost always include fever or rash, but also very commonly include nausea, vomiting, diarrhoea, abdominal pain (stomach ache), dyspnoea (difficulty breathing), cough, fever, lethargy, malaise (feeling unwell), headache, signs of liver damage in the blood and myalgia (muscle pain). Patients treated with Ziagen receive a card detailing these symptoms so that they are aware of them, and must contact their doctor immediately if they develop a reaction. For more information, see the Package Leaflet.
Ziagen should not be used in people who may be hypersensitive (allergic) to abacavir or any of the other ingredients. It must not be used in patients with severe liver problems.
As with other anti-HIV medicines, patients taking Ziagen may be at risk of lipodystrophy (changes in the distribution of body fat), osteonecrosis (death of bone tissue) or immune reactivation syndrome (symptoms of infection caused by the recovering immune system). Patients who have problems with their liver (including hepatitis B or C infection) may be at an elevated risk of liver damage when taking Ziagen. As with all other NRTIs, Ziagen may also cause lactic acidosis (a build-up of lactic acid in the body) and, in the babies of mothers taking Ziagen during pregnancy, mitochondrial dysfunction (damage to the energy-producing components within cells that can cause problems in the blood).
The CHMP noted that the demonstration of the benefit of Ziagen was based on the results of studies mainly carried out with the medicine taken twice a day in combination with other medicines in adults who had not taken HIV treatment before. The Committee decided that Ziagen?s benefits are greater than its risks and recommended that it be given marketing authorisation.