1 What is Opsumit?

Brand: Opsumit

Generic: Macitentan

Opsumit is used to treat high blood pressure in lungs (pulmonary arterial hypertension). It is an endothelin receptor blocker.

It blocks certain substances in lungs and thus helps in relaxing the vessels in the lungs and brings back the pressure to normal range. Opsumit is available in tablet form and only with your doctor’s prescription.

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2 What to Know Before Using

If you are about to start Opsumit, speak with your doctor about what you need to know.


Inform your doctor if you are allergic to any food, preservatives, dyes, or had an allergic reaction when you used this drug before.


It does not cause any different side effects from adults. However, safety and efficacy have not been established.


This medicine does not cause any different side effects or problem than it does in younger adults.


It is a category X drug. It is not safe to use in pregnancy. It causes harm to an unborn baby and can result in the loss of an unborn baby.

Breast Feeding

There are no adequate studies which prove that Macitentan passes into breast milk. It is not safe to use it while breastfeeding. If you are using Macitentan while nursing, discuss it with your doctor for possible risk factors.

Drug Interactions

Macitentan may interact with other drugs. Your doctor should be informed of any other medicines which you are taking. He may want to change the dosage or drug. Some of them are listed below:

  • Atazanavir
  • Boceprevir
  • Carbamazepine
  • Clarithromycin
  • Cobicistat
  • Conivaptan
  • Enzalutamide
  • Fluconazole
  • Fosphenytoin
  • Idelalisib
  • Indinavir
  • Itraconazole
  • Ketoconazole
  • Lopinavir

This is not a complete list of drugs.

Other Medical Problems

Several other conditions may reduce its effectiveness.

Make sure you inform your doctor of conditions such as:

  • Anemia (low level of red blood cells)
  • History of heart failure
  • Fluid retention (unusual swelling of feet, legs, arm, and hands).
  • Liver diseases

3 Proper Usage

Proper usage of Opsumit requires strict adherence to your doctor’s orders. Read the medication guide carefully. Ask your pharmacist if you have any queries.


It is different for different patients. Dosage mentioned below is an average dose. It is best to take each dose at equally spaced times, day and night. You must follow your doctor’s command.


10 milligram (mg) once a day.

Missed dose

If you miss a dose, take it as soon as you remember it. If it is almost time for your next dose, skip the missed dose and continue your daily schedule. Do not double the dose.


Store it at room temperature. Keep it away from children

4 Precautions to Take

In using Opsumit, you must be careful and take some precautions as advised by your doctor. Your doctor should check your daily progress at regular visits.

While using Macitentan, use a very effective form of birth control pill during and after 1 month of treatment. Your doctor will do a pregnancy test before starting the treatment.

If the pregnancy test is positive, he/she may change the treatment. If you miss a period during the treatment, inform your doctor right away. It can cause damage to the liver.

Go to your doctor if you experience:

  • headache
  • stomach pain
  • vomiting
  • dark-colored urine
  • loss of appetite
  • weight loss
  • the general feeling of tiredness or weakness
  • light-colored stools
  • upper right stomach pain
  • yellow eyes or skin

It may cause serious lung diseases.

Inform your doctor if you experience:

  • any chest pain or difficulty in breathing
  • blue lips and fingernails
  • fast and noisy breathing
  • increased sweating and coughing

These could be a sign of pulmonary edema. It can cause infertility in men because it decreases the production of sperms. If you want to have children, discuss it with your doctor.

Tell your doctor or dentist that you take Macitentan before you receive any medical, dental or surgery care.

5 Potential Side Effects

As with many medications, there are several potential side effects associated with Opsumit. Some people may experience none or minor side effects.

Consult with your doctor if they become problematic or frequent:

Most common are:

  • Pale skin
  • Troubled breathing with exertion
  • Unusual bleeding or bruising
  • Unusual tiredness or weakness
  • Headache
  • Sore throat
  • Stuffy nose

Less common are:

  • Abdominal or stomach pain or tenderness
  • Clay-colored stools
  • Dark urine
  • Difficult, burning, or painful urination
  • Frequent urge to urinate
  • Lower back or side pain
  • Muscle aches and pains
  • Difficulty with breathing
  • Tightness in the chest
  • Yellow eyes or skin

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

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