A CFTR corrector (combined with ivacaftor)
Tezacaftor
A CFTR corrector used with ivacaftor, often better tolerated than lumacaftor, for suitable cystic fibrosis gene changes.
What is Tezacaftor?
Tezacaftor is a cystic fibrosis medicine known as a corrector, which helps the faulty CFTR protein form properly and reach the cell surface. It is given together with ivacaftor (sold as Symkevi) for people with certain gene changes, decided by a genetic test. It is often better tolerated than the older corrector lumacaftor, with fewer breathing-related effects when starting. It can affect the liver, so blood tests are done. It is a specialist medicine taken with fatty food and overseen by a cystic fibrosis team.
Education and reference only. This is a plain-language guide to Tezacaftor — it deliberately contains no doses. Doses depend on the person, the brand and the reason for treatment, and belong with your prescriber. Always check the BNF, the product labelling (SmPC) and follow medical advice.
What it is
Tezacaftor is a CFTR modulator used to treat cystic fibrosis, a lifelong inherited condition causing thick, sticky mucus because of a faulty protein called CFTR. Like lumacaftor it is a corrector, helping the misshapen CFTR protein fold properly and move to the cell surface. It is always combined with ivacaftor (a potentiator) in a product called Symkevi, and it suits people with particular gene changes confirmed by genetic testing. It is taken by mouth with fatty food and started by a specialist cystic fibrosis team.
How it works
In many people with cystic fibrosis the CFTR protein is made in the wrong shape and is broken down before it reaches the cell surface. Tezacaftor is a corrector that helps more of this protein fold correctly and travel to the surface, while the ivacaftor it is combined with helps the protein open so salt and water can move. Together they can thin the mucus, improve lung function and reduce flare-ups. Tezacaftor tends to cause fewer breathing-related effects when starting than the older corrector lumacaftor, which is why it is often better tolerated.
Company & origin
Originated / developed by: Vertex Pharmaceuticals.
A cystic fibrosis medicine used in the UK, combined with ivacaftor (as Symkevi), for people with suitable CFTR gene changes.
Practical use
How to take Tezacaftor
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- Take it by mouth with food that contains fat, such as a meal or snack with butter, cheese, eggs or full-fat milk, to help absorption.
- Take the morning and evening doses as directed (the combination usually includes a separate evening ivacaftor dose), keeping a regular routine.
- Avoid grapefruit and grapefruit juice, and do not take St John's wort.
- Check with your cystic fibrosis team or pharmacist before starting any new medicine or supplement.
- Tell your team about any new or worsening symptoms, including changes in mood or wellbeing.
- Continue your other cystic fibrosis treatments, such as physiotherapy and inhaled medicines, alongside it.
Weighing it up
Advantages & disadvantages of Tezacaftor
Advantages
- Targets the underlying protein problem for people with suitable gene changes.
- Often better tolerated than lumacaftor, with fewer breathing-related effects when starting.
- Combined with ivacaftor, it can improve lung function and reduce flare-ups in those it suits.
Disadvantages
- Only suitable for people with particular gene changes, confirmed by genetic testing.
- Can affect the liver, so regular blood tests are needed.
- Interacts with some medicines, grapefruit and St John's wort, so combinations must be checked.
Practical use
Good to know
Tezacaftor is a gene-change-specific medicine, so a genetic test decides whether it is suitable for you. It is often better tolerated than lumacaftor, with less chest tightness or breathlessness on starting, though it can still cause headache or tummy upset. It is taken with fatty food to help your body absorb it. The liver can be affected, so blood tests are done before and during treatment. It interacts with some other medicines, so always tell your team and pharmacist what you take, and avoid grapefruit and St John's wort. It is started and supervised by a specialist team and does not replace the rest of your cystic fibrosis care.
Who should not take it / use with caution
- People whose cystic fibrosis is not caused by a gene change that tezacaftor with ivacaftor can act on.
- Anyone who has had a serious allergic reaction to tezacaftor or ivacaftor.
- It is used with extra care and closer monitoring in people with significant liver problems, under specialist guidance.
Monitoring
- Liver blood tests before starting and regularly during treatment.
- Reviewing lung function, weight and flare-ups with the cystic fibrosis team.
- Checking tolerability, including any mood or breathing changes.
- Eye (cataract) checks in children and young people, as the combination contains ivacaftor.
Side effects
- Headache, dizziness and tummy upset are among the more common effects.
- A blocked or runny nose and breathing-related symptoms can occur, though usually less than with lumacaftor.
- Changes in liver blood tests, which is why the liver is monitored.
Key interactions
- Medicines and foods that affect the liver enzymes that break it down (such as some antibiotics, antifungals, grapefruit and St John's wort) can change its levels.
- It can affect the levels of some other medicines, so your team may adjust treatment.
- Tell your cystic fibrosis team and pharmacist about all medicines, supplements and herbal products you take.
Available as: Tablets (combined with ivacaftor) taken by mouth with fatty food.
Answers
Tezacaftor: frequently asked questions
How is tezacaftor different from lumacaftor?
Both are correctors used with ivacaftor, but tezacaftor is often better tolerated, with fewer breathing-related effects when starting.
Who can take it?
It is for people with particular CFTR gene changes, confirmed by a genetic test, and is always combined with ivacaftor as Symkevi.
Why must I take it with fatty food?
Fat helps your body absorb the medicine, so it should be taken with a meal or snack containing fat.
Do I need blood tests?
Yes, the liver is checked before and during treatment, as the medicine can affect liver blood tests.
Does it replace my other treatments?
No, you should continue your usual cystic fibrosis care, such as physiotherapy and inhaled medicines, alongside it.
Authoritative sources
- BNF
- NICE CKS
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