Know Your WHO Functional Class

What are the WHO Functional Classes?

The World Health Organization (WHO) groups people with PAH into 4 classes, called WHO Functional Classes. What class you belong to depends on the seriousness of your symptoms and how much physical activity you are able to do without feeling discomfort.

The PAH treatment your doctor prescribes depends on your WHO Functional Class. Your doctor will decide which class you belong to and determine the appropriate treatment. Only people with WHO Functional Class II or III symptoms should take Letairis.

WHO Functional Classes defined

Class I: Physical activity is not limited. Ordinary physical activity does not cause shortness of breath, feeling tired, chest pain or discomfort, or feeling faint.
Class II: Comfortable at rest, but ordinary physical activity causes shortness of breath, feeling tired, chest pain or discomfort, or feeling faint.
Class III: Comfortable at rest, but less than ordinary physical activity causes shortness of breath, feeling tired, chest pain or discomfort, or feeling faint.
Class IV: Unable to perform any physical activity. Shortness of breath and/or feeling tired may be present at rest, and symptoms increase with almost any physical activity.

Class I: Physical activity is not limited. Ordinary physical activity does not cause shortness of breath, feeling tired, chest pain or discomfort, or feeling faint.

Class II: Comfortable at rest, but ordinary physical activity causes shortness of breath, feeling tired, chest pain or discomfort, or feeling faint.

Class III: Comfortable at rest, but less than ordinary physical activity causes shortness of breath, feeling tired, chest pain or discomfort, or feeling faint.

Class IV: Unable to perform any physical activity. Shortness of breath and/or feeling tired may be present at rest, and symptoms increase with almost any physical activity.

What does this mean for me?

If you don’t know which WHO Functional Class you belong to, talk to your doctor. You and your doctor can use that information to figure out what, if any, exercise is appropriate for you.

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Important Safety Information
and Indication

What is the most important information I should know about Letairis?

Letairis can cause serious birth defects if taken during pregnancy.

Females must not be pregnant when they start taking Letairis or become pregnant while taking Letairis
Females who are able to get pregnant must have a negative pregnancy test before starting Letairis, every month while taking Letairis, and 1 month after stopping Letairis. Your doctor will decide when to do the tests, and order the tests for you depending on your menstrual cycle
- Females who are able to get pregnant are females who have entered puberty (even if they have not started their period), and have a uterus, and have not gone through menopause (menopause means that you have not had a period for at least 12 months for natural reasons, or that you have had your ovaries removed)

Females who are able to get pregnant must use two acceptable forms of birth control while taking Letairis and for 1 month after stopping Letairis because the medicine may still be in the body. See the Letairis Medication Guide for acceptable birth control options.

If you have had a tubal sterilization or have an IUD (intrauterine device) or progesterone implant, these methods can be used alone and no other form of birth control is needed
Talk with your doctor to find out about options for acceptable forms of birth control that you may use to prevent pregnancy during treatment with Letairis
If you decide that you want to change the form of birth control, talk with your doctor to be sure that you choose another acceptable form of birth control
Do not have unprotected sex. Talk to your doctor or pharmacist right away if you have unprotected sex or if you think your birth control has failed. Your doctor may tell you to use emergency birth control
Tell your doctor right away if you miss a menstrual period or think you may be pregnant

If you are the parent or caregiver of a female child who started taking Letairis before reaching puberty, you should check your child regularly to see if she is developing signs of puberty. Tell your doctor right away if you notice that she is developing breast buds or any pubic hair. Your child may reach puberty before having her first menstrual period.

Females can only receive Letairis through a restricted program called the Letairis Risk Evaluation and Mitigation (REMS) program. If you are a female who can get pregnant, you must talk to your doctor, understand the benefits and risks of Letairis, and agree to all of the instructions in the Letairis REMS program.

Who should not take Letairis?

Do not take Letairis if:

You are pregnant, plan to become pregnant, or become pregnant while taking Letairis. Letairis can cause serious birth defects. (See "What is the most important information I should know about Letairis?")
You have Idiopathic Pulmonary Fibrosis (IPF)

What should I avoid while taking Letairis?

Do not get pregnant. If you miss a menstrual period, or think you might be pregnant, call your doctor right away
Do not breastfeed. It is not known if Letairis passes into your breast milk

What are the other possible side effects of Letairis?

Serious side effects of Letairis can include:

Swelling all over the body (fluid retention) can happen within weeks after starting Letairis. Tell your doctor right away if you have any unusual weight gain, tiredness, or trouble breathing while taking Letairis. These may be symptoms of a serious health problem. You may need to be treated with medicine or need to go to the hospital
Decreased sperm counts have happened in some men taking a medicine that is like Letairis, which may affect your ability to father a child. Tell your doctor if being able to have children is important to you
Low red blood cell levels (anemia) can happen during the first weeks after starting Letairis. If this happens, you may need a blood transfusion. Your doctor will do blood tests to check your red blood cells before starting Letairis. Your doctor may also do these tests while you are taking Letairis

The most common side effects of Letairis are swelling of hands, legs, ankles and feet (peripheral edema), stuffy nose (nasal congestion), inflamed nasal passages (sinusitis), hot flashes or getting red in the face (flushing). Tell your doctor if you have any side effect that bothers you or does not go away.

The most common side effects of Letairis when taken with tadalafil are swelling of hands, legs, ankles and feet (peripheral edema), headache, stuffy nose (nasal congestion), cough, low red blood cell levels (anemia), indigestion (dyspepsia) or upper respiratory tract infection (bronchitis).

Some medicines that are like Letairis can cause liver problems. Tell your doctor if you get any of these symptoms while taking Letairis: loss of appetite, nausea or vomiting, fever, achiness, generally do not feel well, pain in the upper right stomach (abdominal) area, yellowing of your skin or the whites of your eyes, dark urine, itching.

What should I tell my doctor before taking Letairis?

All your medical conditions. Be sure to tell your doctor if you have a low red blood cell level (anemia) or liver problems
All the medicines you take, including prescription and over-the-counter medicines, vitamins and herbal supplements. Letairis and other medicines may affect each other, causing side effects. Do not start any new medicines until you check with your doctor
Especially tell your doctor if you take cyclosporine (Gengraf, Neoral, Sandimmune). Your doctor may need to change your dose of Letairis

You are encouraged to report negative side effects of prescription drugs to the FDA. Visit www.fda.gov/medwatch, or call 1-800-FDA-1088.

What is Letairis?

Letairis is a prescription medicine used to treat pulmonary arterial hypertension (PAH), which is high blood pressure in the arteries of the lungs.

Letairis can improve your ability to exercise and it can help slow down the worsening of your physical condition and symptoms
When taken with tadalafil, Letairis is used to reduce the risks of your disease progressing and hospitalization due to worsening PAH, and to improve your ability to exercise

Please see full Prescribing Information, including Medication Guide, with important warnings.