Fosamprenavir slows the progress of HIV infection. It is one of a number of medicines that you will need to take regularly.
Take fosamprenavir twice a day.
Tablets can be taken either with or without food.
Fosamprenavir has been associated with some side-effects. Your doctor will discuss these with you before you start treatment.
|Type of medicine
|A protease inhibitor (PI) antiretroviral medicine
|Human immunodeficiency virus (HIV) infection in adults and in children over 6 years of age
Fosamprenavir is an antiretroviral medicine. It is prescribed for human immunodeficiency virus (HIV) infection. It slows the progress of HIV infection, but it is not a cure. HIV destroys cells in the body, called CD4 T cells. These cells are a type of white blood cell and are important because they are involved in protecting your body from infection. If left untreated, the HIV infection weakens your immune system so that your body cannot defend itself against bacteria, viruses and other germs. Fosamprenavir slows down the progress of HIV infection by reducing the amount of virus in your body. It does this by stopping the production of a protein that the virus needs to copy (replicate) itself.
Fosamprenavir will be prescribed for you by a doctor who is a specialist. It belongs to a group of antiretroviral medicines known as protease inhibitors (PIs). It is given alongside a number of other antiretroviral medicines, as part of a combination therapy. Taking three or more antiretroviral medicines at the same time is more effective than taking one alone. Taking a combination of different medicines also reduces the risk that the virus will become resistant to any individual medicine.
It is vital to take your antiretroviral medicines exactly as prescribed to maintain success and to help to prevent the virus from becoming resistant to the medicines. These medicines are usually taken for life.
Before taking fosamprenavir
Some medicines are not suitable for people with certain conditions, and sometimes a medicine can only be used if extra care is taken. For these reasons, before you start taking fosamprenavir it is important that your doctor knows:
- If you are pregnant, trying for a baby or breastfeeding.
- If you have diabetes (diabetes mellitus).
- If you have liver inflammation (called hepatitis), or any other liver problem.
- If you have either haemophilia or porphyria, which are both rare inherited blood disorders.
- If you are taking any other medicines. This includes any medicines which are available to buy without a prescription, as well as herbal and complementary medicines.
- If you have ever had an allergic reaction to a medicine.
How to take fosamprenavir
- Before you start the treatment, read the manufacturer's printed information leaflet from inside your pack. It will give you more information about fosamprenavir, and it will also provide you with a full list of the side-effects which you could experience from taking it.
- Take fosamprenavir exactly as your doctor tells you to. It is usual to take two doses each day at the same time as a medicine called ritonavir - take the doses 12 hours apart. The directions for taking the medicine will be printed on the label of the pack to remind you about what the doctor said to you.
- Swallow the tablet whole with a drink of water. Do not crush or break the tablet. You can take fosamprenavir tablets either with or without food.
- Try to take fosamprenavir at the same times of day each day, as this will help you to remember to take it regularly.
- If you forget to take a dose, take it as soon as you remember (unless it is nearly time for your next dose, in which case do not take the forgotten dose but take the next dose when it is due). Do not take two doses together to make up for a missed dose.
Getting the most from your treatment
- Keep your regular appointments with your doctor so that your progress can be monitored. You will need to have regular blood tests to check how well your medicines are working.
- It is important that you continue to take fosamprenavir and your other antiretroviral treatment regularly. This will help to prevent the HIV from becoming resistant to the medicines you are taking. Even if you miss only a small number of doses, the virus can become resistant to treatment.
- If you develop any infection soon after you start this treatment, let your doctor know. As a result of taking fosamprenavir, your immune system may start fighting an infection which was present before you started the treatment, but which you may not have been aware of.
- Follow carefully any advice your doctor gives to you about making lifestyle changes to reduce any risk of damage to your heart and blood vessels. These can include stopping smoking, eating healthily and taking regular exercise.
- Some people taking antiretroviral medicines develop changes to the way body fat is distributed in the body. This can result in changes to body image. Your doctor will discuss the possibility of this with you.
- Although treatment with antiretroviral medicines may reduce the risk of you passing HIV to others through sexual contact, it does not stop it. It is important that you use condoms.
- It is not uncommon for people with HIV to feel low or even depressed, especially soon after the diagnosis has been made and treatment has been started. If you have any feelings of depression, or any distressing thoughts about harming yourself then you should speak with your doctor straightaway.
- Some people who have taken antiretroviral medicines (particularly over a long time) have developed a condition called osteonecrosis. This is a bone disease where bone tissue dies because there is a reduced blood supply to it. It leads to joint pains and stiffness, and can cause difficulties in movement. If you notice any of these symptoms, speak with your doctor.
- If you buy any medicines, check with a pharmacist that they are suitable to take with fosamprenavir and your other medicines. This is because some remedies interfere with fosamprenavir and stop it from working properly. In particular, do not take the herbal remedy St John's wort.
- If you have diabetes you may need to check your blood sugar (glucose) more frequently, as this medicine can affect the levels of sugar in your blood. Your doctor will advise you about this.
- If you are having an operation or dental treatment, tell the person carrying out the treatment which medicines you are taking.
- Treatment for HIV is usually lifelong. Continue to take fosamprenavir regularly for as long as your doctor tells you to, even if you feel well. This is to keep your immune system healthy.
Can fosamprenavir cause problems?
Along with their useful effects, most medicines can cause unwanted side-effects although not everyone experiences them. The table below contains some of the most common ones associated with fosamprenavir. You will find a full list in the manufacturer's information leaflet supplied with your medicine. The unwanted effects often improve as your body adjusts to the new medicine, but speak with your doctor or pharmacist if any of the following continue or become troublesome.
|Very common fosamprenavir side-effects (these affect more than 1 in 10 people)
|What can I do if I experience this?
|Drink plenty of water to replace lost fluids
|Common fosamprenavir side-effects (these affect fewer than 1 in 10 people)
|What can I do if I experience this?
|Feeling sick (nausea) or being sick (vomiting), tummy (abdominal) pain
|Stick to simple meals - avoid fatty or spicy food
|Drink plenty of water and ask a pharmacist to recommend a suitable painkiller. If the headaches continue, let your doctor know
|Feeling tired or dizzy
|Do not drive and do not use tools or machines while affected
|Tingling feelings in your mouth
|Speak with your doctor if troublesome
|Itchy skin rash
|Speak with your doctor about this (see below)
|Changes to some blood tests
|Your doctor will check for this
Important: although it is common for people taking fosamprenavir to develop a skin rash during the first few weeks of treatment, a severe rash with blisters may be a sign of a more serious allergic-type reaction. Let your doctor know straightaway if you develop the following:
- Severe blistering rash, high temperature, muscle and joint aches or pains, feeling generally unwell, and mouth ulcers.
If you experience any other symptoms which you think may be due to the medicine, speak with your doctor or pharmacist for further advice.
How to store fosamprenavir
- Keep all medicines out of the reach and sight of children.
- Store in a cool, dry place, away from direct heat and light.
Important information about all medicines
Never take more than the prescribed dose. If you suspect that you or someone else might have taken an overdose of this medicine, go to the accident and emergency department of your local hospital at once. Take the container with you, even if it is empty.
This medicine is for you. Never give it to other people even if their condition appears to be the same as yours.
Do not keep out-of-date or unwanted medicines. Take them to your local pharmacy which will dispose of them for you.
If you have any questions about this medicine ask your pharmacist.
Further reading and references
Manufacturer's PIL, Telzir® 700 mg film-coated tablets; ViiV Healthcare UK Ltd, The electronic Medicines Compendium. Dated June 2021.
Medicines Complete BNF 86th Edition; British Medical Association and Royal Pharmaceutical Society of Great Britain, London.