Letairis: An Overview of Uses, Dosage, Demographics, Side Effects, Interactions, and Generic Options Letairis is a prescription medication used in the treatment of pulmonary arterial hypertension (PAH). This chronic and progressive condition is characterized by high blood pressure in the pulmonary arteries, which supply the lungs with oxygenated blood. Letairis is classified as an endothelin receptor antagonist, which means it works by blocking the effects of a hormone called endothelin, which is involved in the narrowing of blood vessels. Uses Letairis is indicated for the treatment of PAH to improve exercise capacity and delay disease progression. It is often prescribed as a monotherapy, but it can also be used in combination with other medications such as phosphodiesterase type 5 inhibitors (e.g. sildenafil) and prostanoids (e.g. epoprostenol). Letairis is not recommended for the treatment of pulmonary hypertension caused by left heart disease or chronic obstructive pulmonary disease (COPD). Dosage Letairis is available in tablet form and is typically taken once daily with or without food. The initial dose is usually 5 mg, but it can be increased to 10 mg after 4 weeks based on the patient's response and tolerability. Patients with severe liver impairment should start with a lower dose of 2.5 mg, and the maximum daily dose is 10 mg. The tablets should not be crushed, chewed, or broken, and they should be swallowed whole. Demographics PAH is a rare disease, with an estimated prevalence of 15-50 cases per million adults. It affects women more often than men and typically occurs in people between the ages of 30 and 60. PAH is often associated with connective tissue diseases such as scleroderma, lupus, and rheumatoid arthritis, but it can also occur idiopathically (without a known cause) or as a result of exposure to certain drugs or toxins. Side Effects Like all medications, Letairis can cause side effects, although not everyone experiences them. The most common side effects of Letairis include: - Headache - Nasal congestion - Flushing - Fluid retention - Anemia - Abdominal pain - Diarrhea - Nausea and vomiting - Decreased appetite - Fatigue Less common but potentially serious side effects include liver injury, pulmonary edema (fluid in the lungs), and decreased sperm count in men. Patients should report any new or worsening symptoms to their healthcare provider. Interactions Letairis can interact with several other medications, including: - Cyclosporine: Can increase Letairis levels in the blood, increasing the risk of side effects. - Rifampin: Can decrease Letairis levels in the blood, reducing its effectiveness. - Phosphodiesterase type 5 inhibitors (PDE5 inhibitors): Can cause dangerously low blood pressure when taken with Letairis. - Warfarin: Can increase the risk of bleeding when taken with Letairis. Patients should inform their healthcare provider of all medications they are taking, including prescription, over-the-counter, and herbal products. Generic Options At the time of writing, there are no generic versions of Letairis available in the United States. However, its active ingredient, ambrisentan, is available in generic form in other countries. Patients who have difficulty affording their medication should talk to their healthcare provider about financial assistance programs. In conclusion, Letairis is a medication used in the treatment of pulmonary arterial hypertension to improve exercise capacity and delay disease progression. Its active ingredient, ambrisentan, is an endothelin receptor antagonist that works by blocking the effects of a hormone called endothelin. Letairis can cause side effects and interact with other medications, so patients should inform their healthcare provider of all medications they are taking. While there are currently no generic versions of Letairis available in the United States, patients who have difficulty affording their medication should explore financial assistance programs.