Opsumit (Macitentan)
Complete patient guide for uses, dosage, side effects, and safety information
Prescription RequiredQuick Facts
What Is Opsumit Used For?
Opsumit contains macitentan and belongs to a group of medicines called endothelin receptor antagonists. It is specifically designed to treat pulmonary arterial hypertension (PAH).
Primary Uses
Opsumit treats pulmonary arterial hypertension (PAH), which is high blood pressure in the blood vessels that carry blood from the heart to the lungs. It can be used alone or combined with other PAH medications.
How It Works
In PAH, the pulmonary arteries become narrower, forcing the heart to work harder to pump blood through them. This causes tiredness, dizziness, and shortness of breath. Opsumit widens these arteries, making it easier for the heart to pump blood, which lowers blood pressure and relieves symptoms.
How to Take Opsumit
Opsumit is taken as a tablet once daily and can be taken with or without food. It’s best to take it at the same time each day.
Dosage Instructions
Adults: Take one 10 mg film-coated tablet once daily. Swallow the whole tablet with water – do not chew or break it. Children over 2 years: The dose is based on body weight using dispersible tablets. Children weighing 40 kg or more may use the 10 mg film-coated tablet. For dispersible tablets, they must be mixed with liquid to form a suspension before taking.
What If You Miss a Dose?
If you forget a dose and it’s almost time for your next dose, skip the missed dose and take the next dose at the regular time. Never take a double dose to make up for a missed one.
Important: Never take a double dose to make up for a missed dose. Continue taking Opsumit until your doctor tells you to stop.
Available Tablet Strengths
Side Effects
Like all medications, this medicine can cause side effects. Most are mild and temporary, but some require medical attention.
Common Side Effects
These side effects occur relatively frequently and usually don’t require emergency care:
- Anemia (low red blood cell count)
- Swelling of ankles, feet, or hands
- Nose, sinus, or throat infections
- Headache or migraine
- Diarrhea and stomach pain
- Fever
- Flushing
- Low blood pressure
- Joint and muscle pain
- Difficulty sleeping
- Skin rash or itching
- Urinary tract infections
- Heavy menstrual periods
Seek immediate medical attention if you experience:
- Severe allergic reaction with swollen face, lips, mouth, tongue, or throat
- Difficulty swallowing or breathing
- Signs of liver problems: nausea, vomiting, fever, stomach pain, yellowing of skin or eyes, dark urine, itching, unusual tiredness
- Pulmonary edema: sudden increase in breathlessness and low oxygen
Important Warnings
Opsumit has several important warnings, especially regarding pregnancy and certain medical conditions.
Who Should Not Take Opsumit
Do not take Opsumit if you are allergic to macitentan, soya, or any ingredients; if you are pregnant, planning to become pregnant, or could become pregnant without reliable birth control; or if you have serious liver disease or very high liver enzyme levels.
Medical Conditions to Discuss
Tell your doctor if you have lactose intolerance, anemia, liver or kidney problems, pulmonary veno-occlusive disease, low blood pressure, or if you are 75 years or older. Your doctor will order blood tests before and during treatment to monitor for anemia and liver function.
Pregnancy and Breastfeeding
Opsumit may cause birth defects and must not be taken during pregnancy or while planning pregnancy. Women of childbearing age must use at least two reliable forms of birth control during treatment and for 3 months after stopping. Do not breastfeed while taking Opsumit. Men should use appropriate contraception to avoid exposing partners to semen, as Opsumit may lower sperm count.
Birth Defects Warning: Opsumit may cause birth defects. Do not take if you are pregnant or plan to become pregnant.
Drug Interactions
Several medications can interfere with Opsumit and affect how it works. Always tell your doctor about all medicines you’re taking.
- Antibiotics: rifampicin, clarithromycin, ciprofloxacin, erythromycin
- HIV medicines: ritonavir
- Antifungal medicines: ketoconazole, itraconazole, voriconazole, fluconazole, miconazole
- Seizure medicines: phenytoin, carbamazepine
- Heart rhythm medicines: amiodarone
- Transplant medicines: ciclosporin
- Blood pressure medicines: diltiazem, verapamil
- Herbal medicines: St. John’s Wort, piperine
Alcohol & Driving
Opsumit may cause headaches in some people, so be careful when driving or operating machinery until you know how it affects you.
Alcohol
No specific alcohol warnings are mentioned in the prescribing information.
Driving and Operating Machinery
Be careful before driving or using machines or tools until you know how Opsumit affects you, as it may cause headaches in some people.
Storage
Store Opsumit tablets below 30°C in the original pack. Keep in a cool, dry place away from moisture, heat, and sunlight. Do not store in the bathroom, near a sink, in the car, or on window sills. Keep out of reach of children.
Overdose Information
If you think you have taken too much Opsumit, seek urgent medical attention immediately. Contact the Poisons Information Centre (Australia: 13 11 26, New Zealand: 0800 764 766), your doctor, or go to the nearest hospital emergency department, even if you feel fine.
Frequently Asked Questions
The source doesn’t specify how long Opsumit takes to work. Your doctor will monitor your response to treatment and may order regular blood tests to check how well the medication is working for you.
Yes, Opsumit can be taken with or without food. It’s best to take it at the same time each day for consistency.
If you forget a dose and it’s almost time for your next dose, skip the missed dose and take the next dose at the regular time. Never take a double dose to make up for a missed one.
No, do not stop taking Opsumit without talking to your doctor. Opsumit is a treatment that you will need to keep taking to control your pulmonary arterial hypertension.
Your doctor will order blood tests before you start treatment and during treatment to check for anemia (low red blood cell count) and to make sure your liver is working properly.
Signs include nausea, vomiting, fever, stomach pain, yellowing of skin or eyes, dark urine, itching, unusual tiredness, or flu-like symptoms with joint and muscle pain. Tell your doctor immediately if you notice any of these signs.
Patients who are 75 years or older should discuss this with their doctor, as age is mentioned as a condition to check with your doctor about before taking Opsumit.
Important Disclaimer
This information is intended for general educational purposes only and should not be considered medical advice. Always consult your healthcare provider or pharmacist before starting, stopping, or changing any medication.
If you think you may have a medical emergency, call your doctor or emergency services immediately.