Macitentan

pronounced as (ma'' si ten' tan)

Brand Name(s): Opsumit®

Why is this medicine prescribed?

Macitentan is used to manage the symptoms of pulmonary arterial hypertension (PAH; high blood pressure in the vessels that carry blood to the lungs). Macitentan is in a class of medications called endothelin receptor antagonists. It works by stopping the action of endothelin, a natural substance that causes blood vessels to narrow and prevents normal blood flow in people who have PAH.

Are there other uses for this medicine?

This medication may be prescribed for other uses; ask your doctor or pharmacist for more information.

How should this medicine be used?

Macitentan comes as a tablet to take by mouth. It is usually taken with or without food once a day. Take macitentan at around the same time every day. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take macitentan exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.

Swallow the tablets whole; do not split, chew, or crush them.

What special precautions should I follow?

Before taking macitentan,

  • tell your doctor and pharmacist if you are allergic to macitentan, any other medications, or any of the ingredients in macitentan tablets. Ask your pharmacist or check the Medication Guide for a list of the ingredients.
  • tell your doctor and pharmacist what prescription and nonprescription medications, vitamins, and nutritional supplements you are taking or plan to take. Be sure to mention any of the following: carbamazepine (Carbatrol, Epitol, Equetro, Tegretol), clarithromycin (Biaxin, in Prevpac); efavirenz (Sustiva); certain HIV protease inhibitors such as nelfinavir (Viracept), indinavir (Crixivan), and ritonavir (Norvir, in Kaletra); itraconazole (Onmel, Sporanox); ketoconazole; nefazodone; nevirapine Viramune); phenobarbital; phenytoin (Dilantin, Phenytek); rifabutin (Mycobutin); and rifampin (Rifadin, Rifamate, Rifater, Rimactane). Your doctor may need to change the doses of your medications or monitor you carefully for side effects. Many other medications may also interact with macitentan, so be sure to tell your doctor about all the medications you are taking, even those that do not appear on this list.
  • tell your doctor what herbal products you are taking, especially St. John's wort.
  • tell your doctor if you have or have ever had anemia (condition in which red blood cells do not bring enough oxygen to the organs) or liver disease.
  • you should know that this medication may decrease fertility in men. Talk to your doctor about the risks of taking macitentan.
  • do not breastfeed while taking this medication.

What special dietary instructions should I follow?

Unless your doctor tells you otherwise, continue your normal diet.

What should I do if I forget to take a dose?

Take the missed dose as soon as you remember it. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.

What should I do in case of overdose?

In case of overdose, call the poison control helpline at 1-800-222-1222. Information is also available online at https://www.poisonhelp.org/help . If the victim has collapsed, had a seizure, has trouble breathing, or can't be awakened, immediately call emergency services at 911.

Symptoms of overdose may include:

  • headache
  • nausea
  • vomiting

What side effects can this medicine cause?

Macitentan may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

  • stuffy nose
  • sore throat
  • cough
  • flu like symptoms
  • headache
  • urgent, frequent, or painful urination
  • rash

Some side effects can be serious. If you experience any of these symptoms, stop taking macitentan and call your doctor immediately or get emergency medical treatment:

  • itchy skin
  • dark urine
  • yellowing of your skin or eyes
  • pain in the upper right part of your stomach
  • unexplained nausea or vomiting
  • loss of appetite
  • extreme tiredness
  • fever
  • swelling of the face, throat, tongue, lips, and eyes
  • difficulty swallowing or breathing
  • hoarseness
  • shortness of breath, especially when lying down
  • coughing up pink, frothy sputum or blood
  • unusual weight increase
  • swelling of the ankles or legs

Macitentan may cause other side effects. Call your doctor if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your doctor may send a report to the Food and Drug Administration's (FDA) MedWatch Adverse Event Reporting program online ( http://www.fda.gov/Safety/MedWatch ) or by phone (1-800-332-1088).

What should I know about storage and disposal of this medication?

Keep this medication in the container it came in, tightly closed, and out of reach of children. Store it at room temperature and away from excess heat and moisture (not in the bathroom).

It is important to keep all medication out of sight and reach of children as many containers (such as weekly pill minders and those for eye drops, creams, patches, and inhalers) are not child-resistant and young children can open them easily. To protect young children from poisoning, always lock safety caps and immediately place the medication in a safe location – one that is up and away and out of their sight and reach. http://www.upandaway.org

Unneeded medications should be disposed of in special ways to ensure that pets, children, and other people cannot consume them. However, you should not flush this medication down the toilet. Instead, the best way to dispose of your medication is through a medicine take-back program. Talk to your pharmacist or contact your local garbage/recycling department to learn about take-back programs in your community. See the FDA's Safe Disposal of Medicines website ( http://goo.gl/c4Rm4p ) for more information if you do not have access to a take-back program.

What other information should I know?

Keep all appointments with your doctor and the laboratory. Your doctor may order tests to see how well your liver is working, and to check for anemia before starting treatment and from time to time during your treatment with macitentan.

Do not let anyone else take your medication. Ask your pharmacist any questions you have about refilling your prescription.

It is important for you to keep a written list of all of the prescription and nonprescription (over-the-counter) medicines you are taking, as well as any products such as vitamins, minerals, or other dietary supplements. You should bring this list with you each time you visit a doctor or if you are admitted to a hospital. It is also important information to carry with you in case of emergencies.

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