Patient leaflet - Opsumit 2.5 mg dispersible tablets
1. What Opsumit is and what it is used for
Opsumit contains the active substance macitentan, which belongs to the class of medicines called “endothelin receptor antagonists”.
Opsumit is used for the long-term treatment of pulmonary arterial hypertension (PAH) in children aged 2 years to less than 18 years with WHO Functional Class (FC) II to III.
It can be used on its own or with other medicines for PAH. PAH is high blood pressure in the blood vessels that carry blood from the heart to the lungs (the pulmonary arteries). In people with PAH, these arteries get narrower, so the heart has to work harder to pump blood through them. This causes people to feel tired, dizzy, and short of breath.
Opsumit widens the pulmonary arteries, making it easier for the heart to pump blood through them. This lowers the blood pressure, relieves the symptoms and improves the course of the disease.
2. What you need to know before you take or give Opsumit
Do not take or give Opsumit
if you are allergic to macitentan or any of the other ingredients of this medicine (listed in
if you are pregnant, if you are planning to become pregnant, or if you could become
pregnant because you are not using reliable birth control (contraception). See section ‘Pregnancy and breastfeeding’.
- if you are breastfeeding. See section ‘Pregnancy and breastfeeding’.
if you have liver disease or if you have very high levels of liver enzymes in your blood.
Talk to your doctor, who will decide whether this medicine is suitable for you.
If any of these apply to you, please tell your doctor.
Warnings and precautions
Talk to your doctor or pharmacist before taking or giving Opsumit.
You will need blood tests, as indicated by your doctor:
Your doctor will take blood before and during treatment with Opsumit to test:
- whether you have anaemia (a reduced number of red blood cells)
- whether your liver is working properly
If you have anaemia (a reduced number of red blood cells), you may have the following signs:
- dizziness
- fatigue/malaise/weakness
- fast heart rate, palpitations
- pallor
If you notice any of these signs, tell your doctor.
Signs that your liver may not be working properly include:
- feeling sick (nausea)
- vomiting
- fever
- pain in your stomach (abdomen)
- yellowing of your skin or the whites of your eyes (jaundice)
- dark-coloured urine
- itching of your skin
- unusual tiredness or exhaustion (lethargy or fatigue)
flu-like syndrome (joint and muscle pain with fever)
If you notice any of these signs, tell your doctor immediately.
If you have kidney problems, talk to your doctor before using Opsumit. Macitentan may lead to more reduction of blood pressure and decrease in haemoglobin in patients with kidney problems.
In patients with pulmonary veno-occlusive disease (obstruction of the lung veins), the use of medicines for treatment of PAH, including Opsumit, may lead to pulmonary oedema. If you have signs of pulmonary oedema when using Opsumit, such as a sudden, important increase in breathlessness and low oxygen, tell your doctor immediately. Your doctor may perform additional tests, and will determine what treatment regimen is most suitable for you.
Children and adolescents
Do not give this medicine to children below 2 years of age because efficacy and safety have not been established.
Other medicines and Opsumit
Tell your doctor or pharmacist if you or the child are taking, have recently taken or might take any other medicine.
Opsumit can affect other medicines.
If you take or give Opsumit together with other medicines including those listed below, the effects of Opsumit or the other medicines might be altered. Please talk to your doctor or pharmacist if you are taking any of the following medicines:
rifampicin, clarithromycin, telithromycin, ciprofloxacin, erythromycin (antibiotics used
to treat infections),
- phenytoin (a medicine used to treat seizures),
- carbamazepine (used to treat depression and epilepsy),
- St. John’s Wort (an herbal preparation used to treat depression),
- ritonavir, saquinavir (used to treat HIV infections),
- nefazodone (used to treat depression),
ketoconazole (except shampoo), fluconazole, itraconazole, miconazole, voriconazole
(medicines used against fungal infections),
- amiodarone (to control the heartbeat),
- ciclosporine (used to prevent organ rejection after transplant),
- diltiazem, verapamil (to treat high blood pressure or specific heart problems)
Opsumit with food
If you are taking piperine as a dietary supplement, this may alter how the body responds to some medicinal products, including Opsumit. Please talk to your doctor or pharmacist should this be the case.
Pregnancy and breastfeeding
If you are pregnant or breastfeeding, think you may be pregnant or are planning to have a baby, ask your doctor for advice before taking this medicine.
Opsumit may harm unborn babies conceived before, during or soon after treatment.
If it is possible you could become pregnant, use a reliable form of birth control
(contraception) while you are taking Opsumit. Talk to your doctor about this.
- Do not take Opsumit if you are pregnant or planning to become pregnant.
If you become pregnant or think that you may be pregnant while you are taking Opsumit,
or shortly after stopping Opsumit (up to 1 month), see your doctor immediately.
If you are a woman who could become pregnant, your doctor will ask you to take a pregnancy test before you start taking Opsumit and regularly (once a month) while you are taking Opsumit.
It is not known if Opsumit is transferred to breast milk. Do not breastfeed while you are taking Opsumit. Talk to your doctor about this.
Fertility
If you are a man taking Opsumit, it is possible that this medicine may lower your sperm count. Talk to your doctor if you have any questions or concerns about this.
Driving and using machines
Opsumit can cause side effects such as headaches and hypotension (listed in section 4), and the symptoms of your condition can also make you less fit to cycle, drive or use machines.
Opsumit contains isomalt and sodium
Opsumit contains a sugar substitute called isomalt. If you have been told by your doctor that you have an intolerance to some sugars, contact your doctor before taking this medicine.
This medicine contains less than 1 mmol sodium (23 mg) per tablet, that is to say essentially ‘sodium-free’.
3. How to take or give Opsumit
Opsumit should only be prescribed by a doctor experienced in the treatment of pulmonary arterial hypertension.
Always take or give this medicine exactly as your doctor has told you. Check with your doctor if you are not sure.
Recommended dose
Your doctor will determine the number of tablets of Opsumit depending on the body weight of the child.
How to take or give this medicine
- Take or give Opsumit dispersible tablets once a day.
- Take or give them at about the same time every day.
- They can be taken or given with or without food.
Take or give Opsumit dispersible tablets as an oral suspension only
Opsumit dispersible tablets must be dispersed in liquids to form an oral suspension before they can be given to patients. The oral suspension should be prepared in a small glass. Take care that the entire dose is swallowed. Hands must be thoroughly washed and dried before and after preparation of the medicine.
How to prepare and take or give the oral suspension using a small glass
- 1.
Prepare the oral suspension by adding the prescribed number of dispersible tablets to
a small amount (from 10 mL (approximately 2 teaspoonfuls) up to maximum 100 mL) of room temperature drinking water in a small glass.
- 2.
Gently stir with a spoon for 1 to 2 minutes. Have the child drink the resulting white
cloudy liquid right away.
- 3.
Add a little more water (minimum 5 mL (approximately 1 teaspoonful)) to the small glass
and stir with the same spoon and have the child drink the entire contents of the glass to make sure all the medicine has been taken.
- 4. If not taken within 2 hours, discard the medicine and prepare a new dose.
In case of difficulties in using only water for administration, alternative suitable soft foods or beverages may be used, as detailed below.
How to prepare and take or give the oral suspension using a small glass for mixing with soft foods
- 1.
Prepare the oral suspension by adding the prescribed number of dispersible tablets to
a small amount (5 mL (approximately 1 teaspoonful)) of room temperature drinking water in a small glass.
- 2. Gently stir with a spoon for 1 to 2 minutes.
- 3.
Mix it further with a small amount of apple sauce or youghurt to facilitate immediate
consumption right away.
- 4.
Add a little more water (minimum 5 mL (approximately 1 teaspoonful)) to the small glass
and stir with the same spoon and have the child drink the entire contents of the glass to make sure all the medicine has been taken.
- 5. If not taken within 2 hours, discard the medicine and prepare a new dose.
How to prepare and take or give the oral suspension using a small glass for mixing with beverages
- 1.
Prepare the oral suspension by adding the prescribed number of dispersible tablets to
a small amount (5 mL (approximately 1 teaspoonful)) of room temperature orange juice, apple juice, or skimmed milk in a small glass.
- 2.
Gently stir with a spoon for 1 to 2 minutes and have the child drink the entire contents of
the glass.
- 3.
Add a little more of the chosen liquid (minimum 5 mL (approximately 1 teaspoonful))
to the small glass and stir with the same spoon and have the child drink the entire contents of the glass to make sure all the medicine has been taken.
- 4. If not taken within 2 hours, discard the medicine and prepare a new dose.
Special information for caregivers
Caregivers are advised to avoid contact with suspensions of Opsumit dispersible tablets. Wash hands thoroughly before and after preparation of the suspension.
If you take or give more Opsumit than you should
If you have taken or given more tablets than you have been told to take, you may experience headache, nausea, or vomiting. Ask your doctor for advice.
If you forget to take or give Opsumit
If you forget to take or give Opsumit, take or give a dose as soon as you remember, then continue to take or give the tablets at the usual times. Do not take or give a double dose to make up for a forgotten tablets.
If you stop taking or giving Opsumit
Opsumit is a treatment that you will need to keep on taking to control your PAH. Do not stop taking or giving Opsumit unless you have agreed this with your doctor.
If you have any further questions on the use of this medicine, ask your doctor or pharmacist.
4. Possible side effects
Like all medicines, this medicine can cause side effects, although not everybody gets them.
Uncommon serious side effects (may affect up to 1 in 100 people)
- Allergic reactions (swelling around the eyes, face, lips, tongue or throat, itching and/or rash) If you notice any of these signs, tell your doctor immediately.
Very common side effects (may affect more than 1 in 10 people)
Anaemia (low number of red blood cells) or reduced haemoglobin
- Headache
- Bronchitis (inflammation of the airways)
- Nasopharyngitis (inflammation of the throat and nasal passages)
- Oedema (swelling), especially of the ankles and feet
Common side effects (may affect up to 1 in 10 people)
- Pharyngitis (inflammation of the throat)
- Influenza (flu)
- Urinary tract infection (bladder infection)
- Hypotension (low blood pressure)
- Nasal congestion (blocked nose)
- Elevated liver tests
- Leukopenia (decreased white blood cell counts)
- Thrombocytopenia (decreased blood platelet counts)
- Flushing (redness of the skin)
- Increased uterine bleeding
Side effects in children and adolescents
The side effects listed above may also be seen in children. Additional side effects very commonly seen in children include upper respiratory tract infection (infected nose sinuses, or throat) and gastroenteritis (inflamed stomach and gut). Rhinitis (itchy, runny, or blocked nose) was seen commonly in children.
Reporting of side effects
If you get any side effects, talk to your doctor or pharmacist. This includes any possible side effects not listed in this leaflet. You can also report side effects directly via the Yellow Card Scheme at: www.mhra.gov.uk/yellowcard or search for MHRA Yellow Card in the Google Play or Apple App Store. By reporting side effects you can help provide more information on the safety of this medicine.
5. How to store Opsumit
Keep this medicine out of the sight and reach of children.
Do not use Opsumit after the expiry date which is stated on the carton and blister after “EXP”. The expiry date refers to the last day of that month.
Store in the original blister to protect from moisture.
This medicinal product does not require any special temperature storage conditions.
Do not throw away any medicines via wastewater or household waste. Ask your pharmacist how to throw away medicines you no longer require. These measures will help to protect the environment.
6. Contents of the pack and other information
What Opsumit contains
- The active substance is macitentan. Each dispersible tablet contains 2.5 mg macitentan.
- The other ingredients are mannitol, isomalt (E953), croscarmellose sodium, magnesium stearate.
What Opsumit looks like and contents of the pack
Opsumit 2.5 mg tablets are white to almost white, round, immediate-release dispersible tablets with a “2.5” on one side and with “Mn” on the other side.
Opsumit is supplied as 2.5 mg dispersible tablets in an aluminium cold form film blister with integrated desiccant and an aluminium push-through lidding foil in packs of 30 tablets.
Marketing Authorisation Holder
Janssen-Cilag Limited
50-100 Holmers Farm Way
High Wycombe
Buckinghamshire
HP12 4EG
UK
Manufacturer
Janssen Pharmaceutica NV
Turnhoutseweg 30
B-2340 Beerse
Belgium
For information in large print, tape, CD or Braille, telephone 0800 7318450.
This leaflet was last revised in October 2025.
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