Indications
Ambrisentan is indicated for the treatment of pulmonary arterial hypertension (PAH) (WHO Group 1):
- To improve exercise ability and delay clinical worsening.
- In combination with tadalafil to reduce the risks of disease progression and hospitalization for worsening PAH, and to improve exercise ability.
Studies establishing effectiveness included predominantly patients with WHO Functional Class II–III symptoms and etiologies of idiopathic or heritable PAH (60%) or PAH associated with connective tissue diseases (34%).
Therapeutic Class
Pharmacology
Endothelin-1 (ET-1) is a potent autocrine and paracrine peptide. Two receptor subtypes, ETA and ETB, mediate the effects of ET-1 in the vascular smooth muscle and endothelium. The primary actions of ETA are vasoconstriction and cell proliferation, while the predominant actions of ETB are vasodilation, antiproliferation, and ET-1 clearance.
In patients with PAH, plasma ET-1 concentrations are increased as much as 10-fold and correlate with increased mean right atrial pressure and disease severity. ET-1 and ET-1 mRNA concentrations are increased as much as 9-fold in the lung tissue of patients with PAH, primarily in the endothelium of pulmonary arteries. These findings suggest that ET-1 may play a critical role in the pathogenesis and progression of PAH.
Ambrisentan is a high-affinity (Ki=0.011 nM) ETA receptor antagonist with a high selectivity for the ETA versus ETB receptor ( > 4000-fold). The clinical impact of high selectivity for ETA is not known.
Dosage & Administration
Initial treatment is 5 mg once daily, and can be increased to 10 mg once daily if 5 mg is tolerated. Ambrisentan may be administered with or without food.
Interaction
Contraindications
Side Effects
Pregnancy & Lactation
Precautions
Fluid Retention: Peripheral edema is a known class effect of endothelin receptor antagonists, and is also a clinical consequence of PAH and worsening PAH.
Pulmonary Veno-occlusive Disease: If patients develop acute pulmonary edema during initiation of therapy with vasodilating agents such as Ambrisentan, the possibility of pulmonary veno-occlusive disease should be considered, and if con_rmed. Ambrisentan should be discontinued.
Hematological Changes: Decreases in hemoglobin concentration and hematocrit have followed administration of other endothelin receptor antagonists and were observed in clinical studies with Ambrisentan.
Use in Special Population
Pediatric patients: Safety and effectiveness of Ambrisentan in pediatric patients have not been established.
Hepatic impaired patient: Ambrisentan is not recommended in patients with moderate or severe hepatic impairment.
Reviews
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