How does it work?

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

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

Once the virus is inside the CD4 T-cell it multiplies, producingnumerous copies of itself. An enzyme produced by the HIV virus, calledprotease, plays an important role in this process. Protease breaks up newprotein produced by the virus, so that new copies of the virus can be assembledfrom the pieces. If this enzyme is stopped from working, any new virus that isproduced is faulty and unable to infect more CD4 cells. Protease inhibitorssuch as amprenavir work by stopping the protease enzyme fromworking.

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

Low-doses of the protease inhibitor ritonavir must be used incombination with this medicine. The ritonavir increases the blood level ofamprenavir, which boosts its effect and therefore reduces the dose of Telzirthat is needed.

What is it used for?

• HIV infection.

Warning!

• In adults, Telzir oral suspension should be taken without food and on an empty stomach. In children, the suspension should be taken with food to make it more palatable. 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 make sure that you take all your doses at the correct time, and that you visit your doctor for repeat prescriptions before you run out of medicine.
• 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.
• 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.
• If you have advanced HIV and a history of opportunistic infections such as pneumocystis carinii pneumonia (PCP) or cytomegalovirus (CMV), you may experience signs and symptoms of inflammation from previous infections soon after you start combination anti-HIV treatment. It is believed that these symptoms are due to an improvement in the body’s immune response, which allows the body to fight infections that may have been present with no obvious symptoms. You should tell your doctor immediately if you experience any signs or symptoms of infection, such as inflammation or high temperature, after starting treatment with this medicine, so that this can be investigated and treated if necessary.
• 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.

Use with caution in

• 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.
• People who are allergic to sulphonamide medicines, eg the antibiotic sulfamethoxazole.

Not to be used in

• People who are allergic to amprenavir or ritonavir.
• 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 orany of its ingredients. Please inform your doctor or pharmacist if you havepreviously experienced such anallergy.If you feel you haveexperienced an allergic reaction, stop using this medicine and inform yourdoctor or pharmacist immediately.

Pregnancy and breastfeeding

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

• The safety of this medicine for use in pregnancy has not been established. It should only be used in women who are pregnant if the potential benefits to the mother outweigh any potential risks to the developing baby. Seek medical advice from your doctor.
• It is not known if this medicine passes into breast milk. However, it is recommended that women infected with the HIV virus must not breastfeed their infants under any circumstances, and regardless of their treatment, in order to avoid passing the virus to the baby in the breast milk. Seek medical advice from your doctor.

Side effects

Medicines and their possible side effects can affect individualpeople in different ways. The following are some of the side effects that areknown to be associated with this medicine. Just because a side effect is statedhere does not mean that all people using this medicine will experience that orany side effect. See also the warning section above.

Very common (affect more than 1 in 10 people)

• Diarrhoea.
• Increased levels of fats called triglycerides in the blood.

Common (affect between 1 in 10 and 1 in 100 people)

• Headache.
• Dizziness.
• Pins and needles or tingling sensations in the mouth.
• Disturbances of the gut such as nausea, vomiting or abdominal pain.
• Rash, with or without itching (see warning section above).
• Fatigue.

Uncommon (affect between 1 in 100 and 1 in 1000 people)

• Swelling of the face, throat and tongue (angioedema).

Rare (affect between 1 in 1000 and 1 in 10,000 people)

• 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 sideeffects reported by the medicine'smanufacturer. See also the warning section above.For moreinformation about any other possible risks associated with this medicine,please read the information provided with the medicine or consult your doctoror pharmacist.

How can this medicine affect other medicines?

You should tell your doctor or pharmacist what medicines you areusing, particularly those listed below, before you start treatment with thismedicine. This includes those bought without a prescription and herbalmedicines. Likewise, check with your doctor or pharmacist before taking anynew medicines while you are taking this medicine, so they can check that thecombination is safe.

As Telzir is used in combination with ritonavir, your doctor orpharmacist will also check whether any of your medicines interact withritonavir(Norvir).

Telzir should not be taken in combination with any othermedicines that contain amprenavir, eg Agenerase.

Telzir must not be taken in combination with any of the following medicines,because it may decrease the breakdown of these medicines in the body, leading to a risk of serious orlife threatening side effects:

• amiodarone
• astemizole
• bepridil
• cilostazol
• cisapride
• dihydroergotamine
• ergotamine
• flecainide
• methysergide
• midazolam taken by mouth
• pimozide
• propafenone
• quinidine
• terfenadine
• triazolam taken by mouth.

The following medicinesmust not be taken while you are taking Telzir because they may increase the breakdown of amprenavir in your body, thus making it lesseffective against HIV:

• rifampicin
• the herbal remedy St John's wort (Hypericum perforatum).

Kaletra (lopinavir with ritonavir) is not recommended for use in combination with Telzir.

Amprenavir decreases the breakdown of the antibiotic rifabutin in the body. If youneed treatment with rifabutin, a lower than normal dose of this antibiotic should beprescribed.

Amprenavir with ritonavir may also decrease the breakdown ofthe following medicines in the body, and you may need increased monitoring by your doctorif you are taking any of these with Telzir:

• alprazolam
• aripiprazole
• ciclosporin
• cimetidine
• clarithromycin
• clonazepam
• clozapine
• dapsone
• darifenacin (not recommended for people taking Telzir)
• diazepam
• erythromycin
• flurazepam
• halofantrine (not recommended for people taking Telzir)
• itraconazole (high doses of more than 200mg per day are not recommended in combination with Telzir)
• ketoconazole (high doses of more than 200mg per day are not recommended in combination with Telzir)
• lidocaine by injection (not recommended for people taking Telzir)
• loratadine
• midazolam given by injection
• sildenafil (not recommended for people taking Telzir)
• sirolimus
• tacrolimus
• tadalafil (not recommended for people taking Telzir)
• telithromycin
• tolterodine (not recommended for people taking Telzir)
• the calcium channel blockers diltiazem, nicardipine, nifedipine or nimodipine
• tricyclic antidepressants, eg amitriptyline, nortriptyline
• vardenafil (not recommended for people taking Telzir)
• warfarin (your blood clotting time, INR, should be monitored more frequently if you are taking warfarin with Telzir).

Amprenavir may also decrease the breakdown ofcholesterol-lowering medicines known as statins in the body. Simvastatin, lovastatin and rosuvastatin arenot recommended for use in combination with Telzir, as the increased bloodlevels may lead to side effects on the muscles. If cholesterol-loweringtreatment is needed, fluvastatin or pravastatin are recommended.

Amprenavir and ritonavir may decrease the breakdown of thecorticosteroids fluticasone or budesonide taken by inhaler or nasal spray. Thiscould increase the risk of systemic side effects of these steroids, such asCushing's syndrome, or decreased production of natural steroids by the adrenalglands. For this reason, the use of these corticosteroids in combination withamprenavir and ritonavir is not recommended, unless the benefits are thought tooutweigh the potential risks.

Amprenavir may reduce the effect of hormonal contraceptives such as the pill andfor this reason, a barrier method of contraception, such as condoms, should beused to prevent pregnancy, as well as to prevent transmission of the HIVvirus.

Amprenavir may increase the breakdown of methadone, which could cause withdrawal effects in people taking methadone as treatment for opioid addiction.

Amprenavir may increase the breakdown of the antidepressant paroxetine. If you are taking this antidepressant and think it has become less effective after starting treatment with Telzir you should tell your doctor, as your dose of paroxetine may need to be increased.

The antiepileptics phenobarbital or carbamazepinemay increase the breakdown of amprenavir in the body, which could make it less effective against HIV. These antiepileptic medicines should be used with caution incombination with Telzir.

The antiepileptic medicine phenytoin may increase the amount of amprenavir in the blood, while amprenavir may decrease the amount of phenytoin in the blood. This combination should be used with caution, and phenytoin blood levels should be monitored.

Other medicines containing the same active ingredient

There are currently no other medicines available in the UK thatcontain fosamprenavir as the active ingredient.