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LETAIRIS
(ambrisentan)

WARNING

CONTRAINDICATED IN PREGNANCY

Do not administer LETAIRIS to a pregnant woman because it may cause fetal harm. LETAIRIS is very likely to produce serious birth defects if used by pregnant women, as this effect has been seen consistently when it is administered to animals [see CONTRAINDICATIONS].

Pregnancy must therefore be excluded before the initiation of treatment with LETAIRIS and prevented during treatment and for one month after stopping treatment by the use of two acceptable methods of contraception unless the patient has had a tubal sterilization or chooses to use a Copper T 380A IUD or LNg 20 IUS, in which case no additional contraception is needed. Obtain monthly pregnancy tests [see WARNINGS AND PRECAUTIONS].

Because of the risk of birth defects, LETAIRIS is available only through a restricted program under a Risk Evaluation and Mitigation Strategy (REMS) called the LETAIRIS Education and Access Program (LEAP). As a component of the LETAIRIS REMS, prescribers, patients, and pharmacies must enroll in the program [see WARNINGS AND PRECAUTIONS].

DRUG DESCRIPTION

LETAIRIS is the brand name for ambrisentan, an endothelin receptor antagonist that is selective for the endothelin type-A (ETA) receptor. The chemical name of ambrisentan is (+)-(2S)-2-[(4,6-dimethylpyrimidin-2-yl)oxy]-3-methoxy-3,3-diphenylpropanoic acid. It has a molecular formula of C22H22N2O4 and a molecular weight of 378.42. It contains a single chiral center determined to be the (S) configuration and has the following structural formula:

Figure 1 : Ambrisentan Structural Formula

LETAIRIS (ambrisentan) Structural Formula Illustration

Ambrisentan is a white to off-white, crystalline solid. It is a carboxylic acid with a pKa of 4.0. Ambrisentan is practically insoluble in water and in aqueous solutions at low pH. Solubility increases in aqueous solutions at higher pH. In the solid state ambrisentan is very stable, is not hygroscopic, and is not light sensitive.

LETAIRIS is available as 5 mg and 10 mg film-coated tablets for once daily oral administration. The tablets include the following inactive ingredients: croscarmellose sodium, lactose monohydrate, magnesium stearate and microcrystalline cellulose. The tablets are film-coated with a coating material containing FD&C Red #40 aluminum lake, lecithin, polyethylene glycol, polyvinyl alcohol, talc, and titanium dioxide. Each square, pale pink LETAIRIS tablet contains 5 mg of ambrisentan. Each oval, deep pink LETAIRIS tablet contains 10 mg of ambrisentan. LETAIRIS tablets are unscored.

What are the possible side effects of ambrisentan (Letairis)?

Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Call your doctor at once if you have a serious side effect such as:

  • anxiety, sweating, pale skin, severe shortness of breath, wheezing, gasping for breath, cough with foamy mucus, chest pain, fast or uneven heart rate;
  • swelling of the feet, ankles, or legs;
  • pounding heartbeats or fluttering in your chest; or
  • nausea, upper stomach pain, itching, loss of appetite, dark urine, clay-colored...

Read All Potential Side Effects and See Pictures of Letairis »

What are the precautions when taking ambrisentan tablets (Letairis)?

Before taking ambrisentan, tell your doctor or pharmacist if you are allergic to it; or to other endothelin receptor blockers (e.g., bosentan); or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

Before using this medication, tell your doctor or pharmacist your medical history, especially of: liver disease, anemia.

Older adults may be at greater risk for swelling ankles/feet while using this drug.

This medication must not be used during pregnancy. It may harm an unborn baby. If you are planning pregnancy, become pregnant, or think you may be pregnant, tell your doctor immediately. Women who may become pregnant must have a negative pregnancy...

Read All Potential Precautions of Letairis »

Last reviewed on RxList: 2/24/2012
This monograph has been modified to include the generic and brand name in many instances.