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Do not administer Letairis to a pregnant female because it may cause fetal harm. Letairis is very likely to produce serious birth defects if used by pregnant females, as this effect has been seen consistently when it is administered to animals [see CONTRAINDICATIONS, Use in Specific Populations].
Exclude pregnancy before the initiation of treatment with Letairis. Females of reproductive potential must use acceptable methods of contraception during treatment with Letairis and for one month after treatment. Obtain monthly pregnancy tests during treatment and 1 month after discontinuation of treatment [see Use in Specific Populations].
Because of the risk of embryo-fetal toxicity, females can only receive Letairis through a restricted program called the Letairis REMS program [see WARNINGS AND PRECAUTIONS].
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
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...
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...
Last reviewed on RxList: 2/13/2014
This monograph has been modified to include the generic and brand name in many instances.
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