Macitentan for pulmonary arterial hypertension Opsumit

Authored by , Reviewed by Sid Dajani | Last edited | Meets Patient’s editorial guidelines

Macitentan will be prescribed for you by a specialist doctor.

Take one 10 mg tablet each day. Swallow the tablet whole with a drink of water.

Common side-effects include respiratory infections and feeling tired or dizzy.

Type of medicineA vasodilator antihypertensive medicine
Used forPulmonary hypertension
Also calledOpsumit®
Available asTablets

Pulmonary arterial hypertension (PAH) is a condition where there is too high a blood pressure in the arteries which supply blood to your lungs from your heart. The arteries become narrowed so your heart has to work harder to pump blood to your lungs.

Macitentan relaxes the muscles in the walls of the arteries, allowing the blood vessels to become wider. This reduces the pressure in the arteries and allows blood to flow more easily through them. In turn, this increases the supply of blood to your lungs and improves your ability to do physical activities. Macitentan will be prescribed for you by a doctor who is a specialist.

Some medicines are not suitable for people with certain conditions, and sometimes a medicine may only be used if extra care is taken. For these reasons, before you start taking macitentan it is important that your doctor knows:

  • If you have any problems with the way your liver works, or if you have any problems with the way your kidneys work.
  • If you have been told you have a reduced number of red blood cells (anaemia).
  • If you are pregnant, trying for a baby, or breastfeeding.
  • If you have ever had an allergic reaction to a medicine, or if you are allergic to soya.
  • If you are taking any other medicines. This includes any medicines you are taking which are available to buy without a prescription, as well as herbal and complementary medicines.
  • Before you start the treatment, read the manufacturer's printed information leaflet from inside the pack, along with any information you have been given by your hospital. The manufacturer's leaflet will give you more information about macitentan and a full list of side-effects which you may experience from taking it.
  • Take macitentan exactly as your doctor tells you to. The usual dose is one 10 mg tablet daily. Try to take your doses at the same time of day each day, as this will help you to remember to take the tablets regularly.
  • Swallow the tablet whole with a drink of water. You can take macitentan either before or after food.
  • If you forget to take a dose at your usual time, take it as soon as you remember. If you do not remember until the following day, skip the forgotten dose. Do not take two doses at the same time to make up for a missed dose.
  • Try to keep your regular appointments with your doctor so your progress can be checked. Your doctor will want you to have some blood tests both before and during your treatment. The tests will check that your liver is staying healthy.
  • Treatment with macitentan is usually long-term. Continue to take the tablets unless you are advised otherwise.
  • If you buy any medicines 'over the counter', always check with a pharmacist that they are suitable for you to take. The herbal medicine called St John's wort can interfere with macitentan so you should not take preparations containing this ingredient.
  • If you are due to have an operation or some other medical treatment, it is important that you tell the person carrying out the treatment that you are on macitentan.
  • Women with pulmonary hypertension should avoid becoming pregnant as pregnancy can lead to serious worsening of your condition. Women of childbearing potential must use effective contraception during treatment with macitentan. Speak with your doctor about which contraceptive methods are suitable for you.

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 macitentan. 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 macitentan side-effects (these affect more than 1 in 10 people)What can I do if I experience this?
Mouth, throat and chest infectionsIf troublesome, speak with your doctor for advice
HeadacheDrink plenty of water and ask your doctor or pharmacist to recommend a suitable painkiller. If the headaches continue, let your doctor know
Feeling tired (due to anaemia)If troublesome, speak with your doctor for advice. Do not drive and do not use tools or machines while affected
Fluid retention and swelling of ankles or feetTry raising your feet when sitting down and avoid wearing tight socks or stockings. If troublesome, speak with your doctor for advice
Common macitentan side-effects (these affect fewer than 1 in 10 people)What can I do if I experience this?
Feeling dizzyThis could be a symptom of your condition or a side-effect of using macitentan. If you begin to feel dizzy, sit or lie down for a few minutes so you do not faint, and then get up more slowly. Do not drive and do not use tools or machines while affected
Flu-like symptoms and urine infectionsIf troublesome, speak with your doctor for advice
Blocked nose (nasal congestion)Try a steam inhalant such as menthol crystals or eucalyptus oil or ask a pharmacist for advice. Avoid taking decongestant medicines, such as pseudoephedrine, as these may affect your medical condition

Important: macitentan can affect the way your liver works. Your doctor will discuss this with you before you start the treatment but it is important that you tell your doctor if you develop any of the following signs that your liver is being affected:

  • Dark-coloured urine
  • Feeling sick (nausea) or unusually tired
  • Tummy (abdominal) pain
  • Itching
  • Yellowing of your skin or of the whites of your eyes

If you experience any other symptoms which you think may be due to the tablets, please speak with your doctor or pharmacist for further advice.

  • Keep all medicines out of the reach and sight of children.
  • Store in a cool, dry place, away from direct heat and light. 

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. 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.

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