What is fostemsavir?
Fostemsavir is a medication used to treat HIV, marketed under the brand name Rukobia. It is taken in combination with other antiretroviral drugs.
The usual adult dose of fostemsavir is one 600mg tablet, taken twice a day.
How does fostemsavir work?
Fostemsavir is from a class of drugs known as attachment inhibitors. Your doctor will prescribe fostemsavir as part of your HIV treatment, along with antiretrovirals from at least one other class of drugs. The other drugs you take will be chosen after your HIV has been tested for resistance so that the combination you take will be as effective as possible.
It is important to take all the drugs as prescribed, every day. Each drug class works against HIV in a different way.
The aim of HIV treatment is to reduce the level of HIV in your body (viral load). Ideally, your viral load should become so low that it is undetectable – usually less than 50 copies of virus per ml of blood. Taking HIV treatment and having an undetectable viral load protects your immune system and stops HIV being passed on to someone else during sex.
How do I take fostemsavir?
Fostemsavir (Rukobia) is taken as one 600mg tablet, twice day with or without food.
HIV treatment works best if you take it every day. When would be a good time for you to plan to take your treatment? Think about your daily routine and when you will find it easiest to take your treatment.
If you forget to take a dose of fostemsavir, take it as soon as you remember. If your next dose is due within four hours, then don’t take a double dose, just skip the dose you’ve forgotten and carry on.
If you regularly forget to take your treatment, or you aren’t taking it for another reason, it’s important to talk to your doctor about this.
What are the possible side effects of fostemsavir?
All drugs have possible side effects. It’s a good idea to talk to your doctor about possible side effects before you start taking a drug. If you experience something that might be a side effect, talk to your doctor about what can be done. A full list of side effects, including less common side effects, should be included in the leaflet that comes in the packaging with fostemsavir.
We generally divide side effects into two types:
Common – a side effect that occurs in at least one in a hundred people (more than 1%) who take this drug.
Rare – a side effect that occurs in fewer than one in a hundred people (less than 1%) who take this drug.
Common side effects of fostemsavir include:
- Nausea, vomiting, diarrhoea, abdominal pain, indigestion
- Headache, sleep disturbance and fatigue
Does fostemsavir interact with other drugs?
You should always tell your doctor and pharmacist about any other drugs or medication you are taking. That includes anything prescribed by another doctor, medicines you have bought from a high-street chemist, herbal and alternative treatments, and recreational or party drugs (‘chems’).
Some medicines or drugs are not safe if taken together – the interaction could cause increased, dangerous levels, or it could stop one or both of the drugs from working. Other drug interactions are less dangerous but still need to be taken seriously. If levels of one drug are affected, you may need to change the dose you take. This must only be done on the advice of your HIV doctor.
A list of drugs, known to have interactions with fostemsavir, should be included in the leaflet that comes in the packaging with fostemsavir. Tell your doctor if you are taking any of these drugs, and other drugs that are not on the list.
If you are taking fostemsavir, it is particularly important to check with your HIV doctor or pharmacist before taking any of the following medicines:
- St John’s wort.
Can I take fostemsavir in pregnancy?
If you are considering having a baby, or think you might be pregnant, talk to your doctor as soon as possible about which combination of anti-HIV medications would be right for you. It is important to take antiretroviral treatment during pregnancy to prevent passing HIV from mother to baby.
It is not recommended to take fostemsavir at the time of becoming pregnant or during pregnancy, as not enough is known about its use during pregnancy.
If you become pregnant while taking fostemsavir, see your doctor as soon as possible to review your treatment.
Can children take fostemsavir?
Fostemsavir is not approved for use in children.
Talking to your doctor
If you have any concerns about your treatment or other aspects of your health, it’s important to talk to your doctor about them.
For example, if you have a symptom or side-effect or if you are having problems taking your treatment every day, it’s important that your doctor knows about this. If you are taking any other medication or recreational drugs, or if you have another medical condition, this is also important for your doctor to know about.
Building a relationship with a doctor may take time. You may feel very comfortable talking to your doctor, but some people find it more difficult, particularly when talking about sex, mental health, or symptoms they find embarrassing. It’s also easy to forget things you wanted to talk about.
Preparing for an appointment can be very helpful. Take some time to think about what you are going to say. You might find it helpful to talk to someone else first, or to make some notes and bring them to your appointment.
For detailed information on this drug, visit the fostemsavir page in the A to Z of antiretroviral drugs.