[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Pharmacology](https://durgical.com/en/pharmacology/) › [Pulmonary arterial hypertension drugs (endothelin receptor antagonists and prostacyclins)](https://durgical.com/en/pharmacology/classes/pulmonary-arterial-hypertension-drugs/) › Ambrisentan # Ambrisentan ## Pulmonary arterial hypertension drugs (endothelin receptor antagonists and prostacyclins)? Pulmonary arterial hypertension drugs (endothelin receptor antagonists and prostacyclins) ## Pregnancy: contraindicated? Contraindicated: animal studies show birth defects and fetal death; pregnancy is excluded before treatment and effective contraception continues until a month after stopping. An oral endothelin receptor blocker selective for ETA, used in pulmonary arterial hypertension; it must never be used in pregnancy. Updated Nov 1, 2026 ## Quick facts **Group** [Pulmonary arterial hypertension drugs (endothelin receptor antagonists and prostacyclins)](https://durgical.com/en/pharmacology/classes/pulmonary-arterial-hypertension-drugs/) **Target** Endothelin receptor type A **Used for** Pulmonary arterial hypertension **Key effects** Peripheral oedema · Nasal congestion and sinusitis **Monitor** Pregnancy test before starting · Weight **ATC** C02KX02 No doses: the clinician sets them by the current guideline. On this page - The basics Mechanism of action - Indications - Adverse effects - Pharmacokinetics - Memory aid - Clinical What the labels mean - Safety Contraindications - Key interactions - What is monitored - Administration and safety - Pregnancy and breastfeeding - Nursing care - Study Test yourself - Connections Connections ## Mechanism of action ◎**Endothelin receptor type A**Ambrisentan ⓘ The figure shows ambrisentan bound to the human endothelin receptor type A (cryo-EM). **Target in 3D:** Endothelin receptor type A. PDB structure 8XVK (RCSB PDB, public domain). [View the structure at RCSB PDB](https://www.rcsb.org/structure/8XVK) · Drag to rotate · pinch to zoom Ambrisentan is a high-affinity antagonist that is highly selective for the ETA receptor over ETB. ETA mediates the vasoconstriction and smooth-muscle growth caused by endothelin-1, which is raised in pulmonary arterial hypertension; ETB, which it largely spares, mediates vasodilation and endothelin clearance. Blocking ETA relaxes and remodels the pulmonary arteries, improving exercise capacity and delaying clinical worsening. - Endothelin-1 is raised in the lungs in PAH - Ambrisentan blocks the ETA receptor and largely spares ETB - Pulmonary arteries constrict and proliferate less - Exercise capacity improves and worsening is delayed ## Indications - Pulmonary arterial hypertension (WHO group 1), to improve exercise ability and delay clinical worsening [Pulmonary hypertension and cor pulmonale →](https://durgical.com/en/conditions/pulmonary-hypertension-and-cor-pulmonale/) ## Adverse effects ### Common - Peripheral oedema - Nasal congestion and sinusitis - Flushing - Headache - Falling haemoglobin ### Serious (rare, important) - Birth defects and fetal death if used in pregnancy - Clinically important fluid retention - Acute pulmonary oedema in pulmonary veno-occlusive disease - Lower sperm counts ## Contraindications - Pregnancy - Idiopathic pulmonary fibrosis - Not recommended in moderate or severe liver impairment ## Key interactions **Ciclosporin** Raises ambrisentan exposure; the regimen is limited **Phosphodiesterase-5 inhibitors (tadalafil, sildenafil)** Often combined on purpose; additive blood pressure lowering ## What is monitored - Pregnancy test before starting in females who could become pregnant, and as clinically indicated - Haemoglobin at the start, after a month and periodically - Weight, oedema and breathlessness - Liver tests if symptoms of liver injury appear ## Administration and safety - Oral tablet, swallowed whole: not split, crushed or chewed - Effective contraception before, during and for a month after treatment in females who could become pregnant ## Pregnancy and breastfeeding Contraindicated: animal studies show birth defects and fetal death; pregnancy is excluded before treatment and effective contraception continues until a month after stopping. ## Nursing care - Confirm the pregnancy test and contraception counselling - Weigh the patient and check for ankle swelling and new breathlessness - Watch for acute breathlessness at the start of treatment, a sign of pulmonary oedema - Teach that breastfeeding is not recommended during treatment ## Pharmacokinetics **Absorption** Oral; food does not change bioavailability **Distribution** Very highly bound to plasma proteins **Metabolism** Liver, by CYP3A, CYP2C19 and glucuronidation; substrate of P-glycoprotein **Elimination** Mainly non-renal **Half-life** Terminal half-life about 15 hours; effective half-life about 9 hours **Onset and duration** Peak levels about two hours after a dose ## Memory aid AmbrisentAn = selective for A: blocks ETA, spares ETB; and A for «Avoid pregnancy». ## Test yourself Think of the answer, then tap the question to see it. ## How does ambrisentan differ from bosentan at the receptor level? Ambrisentan is highly selective for ETA; bosentan blocks both ETA and ETB. ## In which lung disease is ambrisentan contraindicated? Idiopathic pulmonary fibrosis. ## Which common side effect of ambrisentan requires checking weight and ankles? Fluid retention with peripheral oedema. [Add to my cards (3)](https://durgical.app/estudiar/?add=/en/pharmacology/ambrisentan/) [More Pharmacology questions →](https://durgical.com/en/practice/?f=pharmacology) ## What the labels mean **Pregnancy: contraindicated** Contraindicated: animal studies show birth defects and fetal death; pregnancy is excluded before treatment and effective contraception continues until a month after stopping. ## Connections ## Related drugs 3 - [Bosentan](https://durgical.com/en/pharmacology/bosentan/) - [Tadalafil](https://durgical.com/en/pharmacology/tadalafil/) - [Ciclosporin](https://durgical.com/en/pharmacology/ciclosporin/) ## Related conditions 1 - [Pulmonary hypertension and cor pulmonale](https://durgical.com/en/conditions/pulmonary-hypertension-and-cor-pulmonale/) [← Back to the class: Pulmonary arterial hypertension drugs (endothelin receptor antagonists and prostacyclins)](https://durgical.com/en/pharmacology/classes/pulmonary-arterial-hypertension-drugs/) Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given. Sources: [DailyMed - AMBRISENTAN tablet, film coated](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=291a782a-77e1-8a8e-e1c8-2626f305c2b7) (DailyMed (U.S. National Library of Medicine), 2025); [Ambrisentan: MedlinePlus Drug Information](https://medlineplus.gov/druginfo/meds/a612023.html) (MedlinePlus (U.S. National Library of Medicine), 2026); [RCSB PDB - 8XVK: Cryo-EM structure of ETAR bound with Ambrisentan](https://www.rcsb.org/structure/8XVK) (RCSB Protein Data Bank, 2024). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/pharmacology/ambrisentan/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/pharmacology/ambrisentan/