What is OPSUMIT? OPSUMIT® (macitentan) is a prescription medicine used to treat pulmonary arterial hypertension (PAH, WHO... Read more Group 1). PAH is high blood pressure in the arteries of your lungs. OPSUMIT can:

bullet imageImprove your ability to exercise as measured by the 6-minute walk distance (6MWD). In a clinical study of mainly WHO FC II-III patients, those taking OPSUMIT walked, on average, 22 meters farther at Month 6 than patients not taking it

bullet imageImprove some of your symptoms

bullet imageHelp slow down the progression of your disease. Disease progression included the need for injectable PAH medication or other worsening of PAH (decreased 6MWD, PAH symptoms getting worse, and the need for new PAH treatment)

bullet imageLower your chance of being hospitalized for PAH

It is not known if OPSUMIT is safe and effective in children. Read less

How PAH Can Affect You

PAH is a lifelong condition

PAH is a chronic and progressive disease. Progressive means that the symptoms of PAH will get worse over time and may limit your physical activities.2,3 You play an important role in your treatment. Start by keeping track of your symptoms and how they affect you. Then partner with your healthcare team and set treatment goals. With treatment, some symptoms may improve.1 Learn how OPSUMIT has been proven to help patients walk farther.

Functional classes of PAH

Functional class is a common way to measure how patients are affected by PAH. The World Health Organization (WHO) has defined 4 functional classes.11 The higher the class, the more serious the condition. Make a note of your functional class each time it’s measured. You can also talk with your healthcare team about your functional class and ask them what you can do that may maintain or improve it.

Functional Class I for PAH Patients

Physical activity is not limited.

Can do regular activity without feeling dizzy or faint, being short of breath, feeling tired, or having chest pain.

Functional Class II for PAH Patients

Physical activity is slightly limited.

Comfortable at rest, but regular activity causes patients to feel dizzy or faint, be short of breath, feel tired, or have chest pain.

Functional Class III for PAH Patients

Greater limitation of physical activity.

Comfortable at rest, but activity is very limited. Less than regular activity causes patients to feel dizzy or faint, be short of breath, feel tired, or have chest pain.

Functional Class IV for PAH Patients

Unable to do any physical activity without discomfort.

May be short of breath, feel tired even at rest. Any physical activity increases discomfort.

I have to listen to
my body.

Cheryl, living with PAH
Watch now 0:36

Setting PAH Treatment Goals

According to PAH experts, maintaining or improving functional class is an important goal of pulmonary arterial hypertension treatment.7 Talk to your healthcare team to discuss your own treatment goals.

The most important information about OPSUMIT® (macitentan)

Do not take OPSUMIT if you are pregnant or trying to get pregnant. OPSUMIT can cause serious birth defects if taken while pregnant.

Women who are able to get pregnant must have negative pregnancy tests:

  • Before starting OPSUMIT
  • Each month while taking OPSUMIT
  • For 1 month after stopping OPSUMIT

Your doctor will decide when you should take pregnancy tests.

You are medically able to get pregnant if you are a woman who fits all of the following guidelines:

  • has started puberty, even if you have not had a menstrual period yet
  • has a uterus
  • has not gone through menopause (menopause means you have not had a menstrual period for at least 12 months for natural reasons, or have had your ovaries removed)

You are not medically able to get pregnant if you are a woman who fits at least 1 of the following guidelines:

  • has not started puberty
  • does not have a uterus
  • has gone through menopause (you have not had a menstrual period for at least 12 months for natural reasons, or have had your ovaries removed)
  • is infertile for other medical reasons and this infertility is permanent and cannot be reversed

While taking OPSUMIT, and for 1 month after stopping OPSUMIT, women who are able to get pregnant must use 2 acceptable forms of birth control. Women who have had a tubal sterilization, a progesterone implant, or have an IUD (intrauterine device) do not need a second form of birth control. Talk to your doctor about which birth control to use while on OPSUMIT. If you decide to change your form of birth control, talk with your doctor or gynecologist. This way you can be sure to choose another acceptable form of birth control. Also review the Medication Guide for birth control options.

It’s important not to have unprotected sex while taking OPSUMIT. Tell your doctor right away if you have unprotected sex, think your birth control has failed, miss a menstrual period, or think you may be pregnant. He or she may recommend using a form of emergency birth control.

If you are the parent or caregiver of a female child who started taking OPSUMIT before reaching puberty, check with your child regularly for any signs of puberty. Your child may reach puberty before having her first menstrual period. Talk to your doctor if you think your child is showing signs of puberty or if you have any questions about the signs of puberty.

Before starting OPSUMIT, women must enroll in a program called the OPSUMIT Risk Evaluation and Mitigation Strategy (REMS). If you are a woman who is able to get pregnant, you must talk to your doctor to learn the benefits and risks of OPSUMIT. You must also agree to all of the instructions in the program. Men who are prescribed OPSUMIT do not need to enroll in this program.

Who should not take OPSUMIT?

Do not take OPSUMIT if you are pregnant, plan to become pregnant, or become pregnant during treatment with OPSUMIT. OPSUMIT can cause serious birth defects. See "The most important information about OPSUMIT."

Talk to your doctor about all your medical conditions, as well as all the medicines, vitamins, and supplements you take. OPSUMIT and other medicines may affect each other causing side effects. Tell your doctor right away if you take an HIV medicine. Do not start any new medicine until you check with your doctor.

What should I avoid while taking OPSUMIT?

  • Do not get pregnant. OPSUMIT can cause serious birth defects. See "The most important information about OPSUMIT." If you miss a menstrual period or think you may be pregnant, call your doctor right away
  • You should not breast-feed if you take OPSUMIT. It is not known if OPSUMIT passes into your breast milk. Talk to your doctor about the best way to feed your baby

What are the possible side effects of OPSUMIT?

OPSUMIT can cause serious side effects, including:

  • Serious birth defects. See "The most important information about OPSUMIT"
  • Some medicines that are like OPSUMIT can cause liver problems. Your doctor should do blood tests to check your liver before you start OPSUMIT. Tell your doctor if you have any of these symptoms, which could be a sign of liver problems while on OPSUMIT:
    • Nausea or vomiting
    • Pain in the upper right stomach
    • Feeling tired
    • Loss of appetite
    • Your skin or the whites of your eyes turn yellow
    • Dark urine
    • Fever
    • Itching
  • Fluid retention could happen during the first weeks after starting OPSUMIT. Tell your doctor right away if you notice unusual weight gain or swelling in your ankles or legs. Your doctor will look for the cause
  • Low red blood cell levels (anemia) can happen while taking OPSUMIT, usually during the first weeks after starting OPSUMIT. In some cases a blood transfusion may be needed, but this is not common. Your doctor will do blood tests to check for anemia before you start OPSUMIT. You may also need to do these blood tests while taking OPSUMIT
  • Reduced sperm counts. This has been seen in some men taking a medicine similar to OPSUMIT. If fathering a child is important to you, tell your doctor

The most common side effects are:

  • Stuffy nose or sore throat
  • Irritation of the airways (bronchitis)
  • Headache
  • Flu
  • Urinary tract infection

Talk to your doctor if you have a side effect that bothers you or does not go away. These are not all the possible side effects of OPSUMIT. For more information, ask your doctor or pharmacist.

You may report side effects to FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.

Please see accompanying full Prescribing Information and Medication Guide, including an Important Warning about Serious Birth Defects.