A medicine for high blood pressure in the lung arteries
Macitentan
A once-daily oral medicine that widens the lung arteries for pulmonary arterial hypertension, with anaemia and fluid retention as key effects.
What is Macitentan?
Macitentan is a once-a-day tablet used to treat pulmonary arterial hypertension, which is high blood pressure in the arteries of the lungs. Like bosentan and ambrisentan, it is an endothelin receptor antagonist that relaxes and widens the lung arteries, easing breathlessness and helping you do more. Its main effects to watch for are a fall in the blood count (anaemia) and fluid retention. It can harm an unborn baby, so reliable contraception is essential. It is started and supervised by a specialist pulmonary hypertension centre.
Education and reference only. This is a plain-language guide to Macitentan — 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
Macitentan is an oral medicine for pulmonary arterial hypertension, a serious condition where the pressure in the arteries between the heart and lungs is too high, straining the right side of the heart and causing breathlessness and tiredness. Macitentan is one of the endothelin receptor antagonists, taken once a day, and is prescribed only through specialist pulmonary hypertension services in the UK.
How it works
In pulmonary arterial hypertension a natural substance called endothelin makes the lung arteries tighten. Macitentan blocks the receptors endothelin acts on, so the lung arteries relax and widen. This lowers the pressure the heart pumps against and can improve breathlessness and the ability to be active. It is designed to act steadily over the day and controls rather than cures the condition, often used with other pulmonary hypertension treatments.
Company & origin
Originated / developed by: Janssen (originator).
An endothelin receptor antagonist used in the UK by specialist centres to treat pulmonary arterial hypertension.
Practical use
How to take Macitentan
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- Take one dose by mouth once a day, as directed by your pulmonary hypertension specialist, swallowed whole with water.
- Attend the blood tests your team arranges, especially blood-count checks for anaemia.
- Use reliable contraception throughout treatment, as it can harm an unborn baby.
- Do not stop the medicine suddenly without specialist advice, and keep taking it even when you feel well.
- Report increasing tiredness, breathlessness, swelling of the ankles or signs of anaemia to your team.
Weighing it up
Advantages & disadvantages of Macitentan
Advantages
- Taken just once a day by mouth, which is simple and convenient.
- Can ease breathlessness and help you stay more active in pulmonary arterial hypertension.
- Acts steadily over the day and fits into combination treatment plans.
Disadvantages
- Can lower the blood count, causing anaemia and tiredness.
- Can cause fluid retention with swollen ankles or legs.
- Can harm an unborn baby, so reliable contraception is essential throughout treatment.
Practical use
Good to know
Macitentan is a specialist medicine, always started and monitored by a pulmonary hypertension centre. It is taken once a day, which many people find convenient. The main practical points are that it can lower the blood count, causing anaemia, and can cause fluid retention, so blood counts, weight and ankle swelling are checked at clinic visits. Like others in its group it can harm a developing baby, so it must not be used in pregnancy and effective contraception is essential throughout treatment and for a time afterwards. As with all these medicines, it works best as part of a wider plan and should not be stopped suddenly without specialist advice.
Who should not take it / use with caution
- Women who are pregnant, or who could become pregnant without reliable contraception, must not take it because it can harm the baby.
- People with significant liver disease or certain abnormal liver blood tests are usually not started on it.
- It is used with caution, under specialist guidance, in people with significant anaemia.
Monitoring
- Blood-count checks to watch for anaemia, and liver blood tests as the team advises.
- Review of fluid retention, weight and ankle swelling.
- Regular specialist review of breathlessness, walking distance and overall response.
Side effects
- A fall in the blood count (anaemia) with tiredness is a common effect.
- Fluid retention with swollen ankles, headache and flushing.
- Nasal congestion and, less often, low blood pressure.
Key interactions
- Can harm an unborn baby, so it is part of a careful contraception plan.
- Levels can be affected by some antifungal, antibiotic and HIV medicines, so the specialist team coordinates these.
- Used alongside other pulmonary hypertension medicines under specialist supervision.
Available as: Tablets taken by mouth.
Answers
Macitentan: frequently asked questions
How is macitentan taken?
It is taken by mouth once a day, swallowed whole with water, as directed by your pulmonary hypertension specialist.
Can I take it if I might become pregnant?
No. It can harm an unborn baby, so it must not be used in pregnancy and reliable contraception is essential throughout treatment.
Why do I feel more tired on it?
Macitentan can lower the blood count, causing anaemia, which can make you tired; your team checks your blood count to pick this up.
Why are my ankles swollen?
It can cause fluid retention, leading to swollen ankles or legs; tell your specialist team so it can be assessed and managed.
Does it cure pulmonary hypertension?
No, it controls the condition by relaxing and widening the lung arteries, which can ease breathlessness and help you stay more active.
Authoritative sources
- BNF
- NICE CKS
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