Telzir (fosamprenavir)

How does it work?

Telzir tablets and oral suspension contain fosamprenavir calcium. Fosamprenavir is a known as a pro-drug, which means it is converted into the active medicine once it is inside the body. Fosamprenavir is converted into amprenavir, which is a type of medicine called a protease inhibitor. It is used in the treatment of HIV (human immunodeficiency virus) infection.

AIDS (acquired immune deficiency syndrome) is caused by infection with HIV (human immunodeficiency virus). This virus invades cells of the immune system, particularly the white blood cells known as CD4 T-helper lymphocytes. These cells normally activate other cells in the immune system to fight infection. Since HIV kills CD4 T-helper cells, the body cannot fight the virus or subsequent infections.

Once the virus is inside the CD4 T-cell it multiplies, producing numerous copies of itself. An enzyme produced by the HIV virus, called protease, plays an important role in this process. Protease breaks up new protein produced by the virus, so that new copies of the virus can be assembled from the pieces. If this enzyme is stopped from working, any new virus that is produced is faulty and unable to infect more CD4 cells. Protease inhibitors, such as amprenavir, work by stopping the protease enzyme from working.

There is no cure for HIV, but amprenavir is one of a number of medicines that slows the progression of the disease from HIV to AIDS. Amprenavir is used in conjunction with other anti-HIV medicines that attack the virus in different ways. This minimises the chance of the virus becoming resistant to any one medicine.

Low-doses of the protease inhibitor ritonavir must be used in combination with this medicine. The ritonavir increases the blood level of amprenavir, which boosts its effect and therefore reduces the dose of Telzir that is needed.

What is it used for?

HIV infection.

Warning!

Telzir oral suspension should be taken without food and on an empty stomach. Telzir tablets may be taken with or without food.

The HIV virus is very good at becoming resistant to anti-HIV medicines. For this reason it is very important that you carefully follow your doctor's instructions for taking your anti-HIV medicines, in order to maintain effective levels of the medicines in your blood. If the blood levels drop, the virus will be given more chance to replicate and develop resistance to the drugs. Skipping even a few doses increases the risk of treatment failure, so you should try to ensure that you take all your doses at the correct time, and that you visit your doctor for repeat prescriptions before you run out.

Treatment of HIV infection with anti-HIV medicines such as this one does not reduce the risk of transmitting the virus to other people through sexual contact or blood contamination. You should continue to use condoms to prevent transmitting the virus to your sexual partner.

Combination antiretroviral therapy has been associated with a redistribution of body fat (lipodystrophy) in people with HIV. The long-term consequences of this are currently unknown, however your doctor may wish to monitor your body fat, and the levels of lipids (eg cholesterol) and sugar (glucose) in your blood, and may prescribe additional medicines for any lipid disorders that occur during treatment with this medicine. Contact your doctor if you notice any changes in your body fat during treatment with your HIV medicines.

Some people being treated with combination antiretroviral therapy may develop a bone condition called osteonecrosis. This condition is caused by loss of blood supply to a bone, causing death of the bone tissue. The risk of the condition is thought to be increased by corticosteroid use, alcohol consumption, severe immunosuppression, higher body mass index, advanced HIV disease and long-term use of antiretroviral medicines. If you notice any joint stiffness, aches and pains (especially of the hip, knee and shoulder) or difficulty in movement while using this medicine, you should tell your doctor so this can be investigated.

You should have regular blood tests to monitor your liver function while you are taking this medicine. This is especially important if you already have any problems with your liver, in particular chronic hepatitis B or C. Symptoms that may suggest a liver problem include persistent nausea and vomiting, abdominal pain, or the development of jaundice (a yellow colouring to the skin and the whites of the eyes). Consult your doctor if you experience any of these symptoms.

You may get a rash while taking this medicine. If the rash is mild you can continue taking the medicine and it should normally get better within a couple of weeks. Taking an antihistamine such as cetirizine may help reduce any itching and help it clear up quicker. Ask your pharmacist for advice. If your rash is more severe or you also have other symptoms you should consult your doctor, as you may need to stop treatment with this medicine.

Use with caution in

Mild to moderately decreased liver function.

Hepatitis, especially chronic hepatitis B or C.

The blood clotting disorder haemophilia (this medicine may increase the risk of bleeding in haemophilia).

Diabetes.

Allergy to sulphonamides.

Not to be used in

Allergy to amprenavir or ritonavir.

Severely decreased liver function.

The safety and efficacy of Telzir in combination with low dose ritonavir have not been studied in children under six years of age. This medicine is not recommended for this age group.

This medicine should not be used if you are allergic to one or any of its ingredients. Please inform your doctor or pharmacist if you have previously experienced such an allergy. If you feel you have experienced an allergic reaction, stop using this medicine and inform your doctor or pharmacist immediately.

Pregnancy and breastfeeding

Certain medicines should not be used during pregnancy or breastfeeding. However, other medicines may be safely used in pregnancy or breastfeeding providing the benefits to the mother outweigh the risks to the unborn baby. Always inform your doctor if you are pregnant or planning a pregnancy, before using any medicine.

The safety of this medicine in pregnancy has not been established. It should therefore be used with caution during pregnancy, and only if the benefits to the mother outweigh any risks to the foetus. Seek medical advice from your doctor.

It is recommended that women infected with the HIV virus must not breastfeed their infants under any circumstances, in order to avoid transmission of the virus to the baby. Seek medical advice from your doctor.

Side effects

Medicines and their possible side effects can affect individual people in different ways. The following are some of the side effects that are known to be associated with this medicine. Just because a side effect is stated here does not mean that all people using this medicine will experience that or any side effect.

Disturbances of the gut such as diarrhoea, flatulence, nausea, vomiting or abdominal pain.

Rash.

Fatigue.

Headache.

Dizziness.

Redistribution of body fat, eg decreased fat under the skin, increased fat on the abdomen, 'buffalo humps' and breast enlargement.

Increase in the level of fats such as triglycerides and cholesterol in the blood.

High blood glucose level (hyperglycaemia).

Pain in the muscles (myalgia).

Severe blistering skin reaction affecting the tissues of the eyes, mouth, throat and genitals (Stevens-Johnson Syndrome).

Muscle breakdown (rhabdomyolysis).

The side effects listed above may not include all of the side effects reported by the drug's manufacturer. For more information about any other possible risks associated with this medicine, please read the information provided with the medicine or consult your doctor or pharmacist.

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