Macitentan (Oral)

Macitentan is a medication approved in 2013 for the treatment of PAH or pulmonary arterial hypertension and sold under the name Opsumit.


Pulmonary arterial hypertension is a disease that is diagnosed in patients with elevated blood pressure in the arteries located within the lungs and pulmonary system. Patients with PAH often have chest pains, swollen legs, rapid heart rhythms and difficulty breathing. There is no cure for this condition and there are an estimated 1,000 new diagnoses per year in the US alone.

Macitentan controls the symptoms of the disease by acting to open up the blood vessels in the lungs, easing the blood flow and lowering the pressure. The medicine works by blocking nerve receptors in the blood vessels known as endothelin receptors. By binding with these receptors, Macitentan prevents them from stimulating other receptors that constrict the blood flow and increase the pressure. This relaxes the vessels, which increases the blood supply to the lungs and lowers the pressure at which the heart is under to perform.

Conditions Treated

  • Pulmonary arterial hypertension

Type Of Medicine

  • Antihypertensive agent
  • Antihypertensive PAH agent
  • Endothelin receptor antagonist
  • Vasodilating agent

Side Effects

Macitentan directly affects blood flow and the cardiopulmonary system. In working to ease hypertensive symptoms, it may cause other symptoms that can be dangerous. Alert your physician if you begin to have the following symptoms as a result of taking this medication:

  • Difficulty breathing when exerting oneself
  • Bruising or bleeding that is unexpected
  • Fatigue
  • Skin paleness
  • Muscle weakness
  • Stomach or abdominal tenderness or pain
  • Stools are clay in color
  • Urine is dark in color
  • Trouble urinating or pain and burning during urination
  • Increased frequency to urinate
  • Pain in side or lower back
  • Pains or aches in muscles
  • Difficulty breathing
  • Chest tightness
  • Skin or eyes appear yellow in color

Other symptoms may occur that are not cause for alarm but usually disappear over time with the use of the medication. It is best to let your doctor know about these symptoms in case there are ways to alleviate them easily:

  • Fever
  • Chills
  • Coughing
  • Throat soreness
  • Runny or stuffed nose

Report any changes to your health or mental state after you begin to take Macitentan to your doctor for your own safety.


Take your prescribed dosage exactly as it has been written for you by your physician. Do not increase or decrease the amount of Macitentan you are prescribed to take, keeping to the dosage schedule and duration as written.

You will be provided with a patient information leaflet that you should read and comprehend prior to taking your first dose of Macitentan. Ask your physician or pharmacist if you have any questions about how to take your dosage or the medication in general.

Included in the patient information leaflet are the rules of a program called Opsumit REMS. This program is the Risk Evaluation and Mitigation Strategy required by the FDA in assisting with managing serious drug risks. If you are a female patient, you will be asked to consent to this program, which has the goal of minimizing the risk of fetal exposure to this medication, known in the market as Opsumit. This agreement basically states that you have been informed of the danger of serious birth defects if you take this medication while pregnant and that you will let your physician know if you are pregnant before or during your medical treatment with this drug.

Macitentan tablets are meant to be swallowed whole without chewing, breaking or crushing them in any way. Adult patients will typically be prescribed a 10-milligram dose of Macitentan to be taken once daily.

Missing a dose should not prompt you to double your dosage to make up for it. If you remember far enough away from the time of your next dosage, you should make up the missing dose. If it is close to your next scheduled dosage, skip the missing dose rather than double dose yourself. Consult your physician if you have any questions about an accidentally missed dose of Macitentan.


Hypersensitive reactions you have experienced in the past to this or any other medication should be explained to your doctor, along with any sensitivity to food, animals, perfumes, dyes, preservatives or colorings. Protect your health and mention any allergies to your physician prior to taking this or any new medication.

Pediatric patients have not been studied to provide data that definitively proves that this age group is safe to take Macitentan. Use in this age group is not recommended.

Macitentan has not been determined to have any age-related effectiveness or safety issues with use in the geriatric population. This age group should experience the same effectiveness and risks that adult patients have.

Women who are pregnant or who may become pregnant are advised that this drug has been proven to cause serious birth defects if taken while pregnant. Female patients will be asked to agree to a program known as Opsumit REMS. This program is the Risk Evaluation and Mitigation Strategy required by the FDA in assisting with managing serious drug risks. This program has the goal of minimizing the risk of fetal exposure to this medication, known in the market as Opsumit. This agreement basically states that you have been informed of the danger of serious birth defects if you take this medication while pregnant and that you will let your physician know if you are pregnant before or during your medical treatment with this drug.

Women who are breastfeeding are advised that they are placing their children at risk if they do so while taking Macitentan. It is advised that you discontinue breastfeeding while you are taking this medication and for at least one month after you stop the medicine as well.

There are often multiple medications prescribed to patients to provide an overall treatment of their symptoms. Combination therapies are a good way for patients to lead normal lives with a lower impact of their condition on their daily tasks. Other medications, however, are dangerous when combined and should be avoided completely. For your own wellbeing, it is best to avoid taking any other medications during your Macitentan dosage but if you cannot avoid it, be sure to list your current medications for your prescribing physician including any vitamins or herbal supplements, over-the-counter remedies and other substances you use regularly.

Alert your physician of all prescription drugs you are taking, especially if they are on the following list of medications, which need to have a dosage adjustment when taken with Macitentan:

  • Atazanavir
  • Carbamazepine
  • Boceprevir
  • Cobicistat
  • Clarithromycin
  • Enzalutamide
  • Conivaptan
  • Fosphenytoin
  • Fluconazole
  • Indinavir
  • Idelalisib
  • Ketoconazole
  • Itraconazole
  • Nefazodone
  • Lopinavir
  • Phenytoin
  • Nelfinavir
  • Primidone
  • Posaconazole
  • Rifampin
  • Rifabutin
  • Ritonavir
  • Rifapentine
  • St John's Wort
  • Saquinavir
  • Telithromycin
  • Telaprevir
  • Voriconazole
  • Tipranavir

Discuss your diet with your physician and if you should take Macitentan with or without food or if you should avoid certain foods. Let your doctor know if you consume alcoholic beverages or use tobacco products, as these substances may interfere with the way Macitentan affects your condition.

The following medical issues can cause Macitentan to affect you differently than expected and may become worse themselves due to the action of the drug. Let your doctor know your full medical history, especially if you have been diagnosed with:

  • Low red blood cells, known as anaemic condition
  • Liver problems or diseases


Macitentan has been proven to cause birth defects if taken when you are pregnant or trying to get pregnant. Women who are candidates for treatment with Macitentan will be required to have a negative pregnancy test prior to the start of their dosage. Testing will be continued each month throughout their treatment and for one month after they discontinue use of the drug.

Female patients will be required to enrol in the Opsumit REMS program, a program that educates them on preventing pregnancy due to the risks associated with taking Macitentan, known as Opsumit in the market. This program, instituted by the FDA, educates women on the risks associated with this drug and why monthly pregnancy testing is required.

It is advised that women use two forms of birth control known to be effective for them while they are using Macitentan. The most effective forms of birth control may include hormone pills, vaginal rings, shots, patches, implants or vasectomy. In combination with one of those forms, choose a condom, cervical cap or diaphragm to prevent against pregnancy as well. Women who have had an IUD implant or tubal ligation are exempt from being required to use a second birth control format.

All patients, male or female, will be required to plan regular visits to their doctor's office for monitoring their condition and if Macitentan has improved their symptoms. Blood testing may be performed during these visits, which will help determine if the medication is causing harm to your system.

Be alert for signs of a liver condition that has been reported in some patients who are taking Macitentan. Symptoms include yellow skin or eyes, painful stomach or abdomen, little to no appetite, vomiting, nausea, elevated body temperature and pale stool or dark urine. Report these symptoms to your physician immediately should they occur.

A serious lung condition called pulmonary edema has been reported in some patients taking Macitentan. This condition is a back-up of blood in the veins of the lungs as the heart cannot efficiently pump it through as normal. Symptoms include blue lips, wheezing or loud breathing, pain in chest area, difficulty breathing, and excessive sweat production, coughing up pink foam and having pale skin. Report any of these symptoms to your doctor immediately.

Men who are taking Macitentan will produce less sperm while on this medication, affecting their ability to father children. If you are planning to have children while on this medication, discuss this with your physician to determine the best treatment for you.

Avoid taking other medications while you are taking Macitentan unless you have specifically approved them with your physician. This includes any over-the-counter medications you take and any health supplements like herbs, vitamins or minerals.


Maintain storage of Macitentan in its original packaging, out of sight and reach of children and at room temperature. Avoid exposing the medication package to excessive light, moisture, heat or cold conditions and never allow it to freeze. Dispose of this medication safely according to the instructions given to you by your physician or pharmacist.


Macitentan is a prescription hypertensive medication that works on the specific condition known as PAH, pulmonary arterial hypertension. This is a condition in which the arteries of the lungs are constricted, leading to high blood pressure within the arteries themselves. Macitentan works by stopping a nerve receptor in the central nervous system from constricting the vessels, opening them up for easier blood flow and lowering the pressure. Patients with this condition often experience difficulty breathing, fatigue, pains in chest, swollen legs and rapid heart rhythms. Patients are typically prescribed a 10-milligram tablet swallowed whole once per day.

Macitentan is known in the market as Opsumit and is proven to cause fetal harm when taken by women who are pregnant. An FDA program known as Opsumit REMS is in place to warn women to avoid pregnancy during their drug treatment with Macitentan and inform them about the risks to their unborn children. Women taking this drug will be required to have a negative pregnancy test prior to their prescription and to undergo regular monthly testing during their drug treatment. Women are advised to use two forms of birth control including hormonal and barrier methods in combination unless they have had a tubal ligation or an IUD implant.

Commonly reported symptoms by patients taking Macitentan include flu-like symptoms with nasal congestion, cough and elevated body temperature. Dangerous health symptoms include difficulty breathing, pale or blue skin and bruising or bleeding unexpectedly. These symptoms should be reported to your physician immediately, as should any symptoms that indicate you have begun to experience damage to you liver, such as yellow skin or eyes, light-colored stool or dark-colored urine and abdominal pain.