ATC Group: C02KX Antihypertensives for pulmonary arterial hypertension

Ambrisentan is an orally active, propanoic acid-class, ERA selective for the endothelin A (ETA) receptor. Endothelin plays a significant role in the pathophysiology of PAH.

Bosentan is a dual endothelin receptor antagonist (ERA) with affinity for both endothelin A and B (ET_A and ET_B) receptors. Bosentan decreases both pulmonary and systemic vascular resistance resulting in increased cardiac output without increasing heart rate.

Macitentan is an orally active potent endothelin receptor antagonist, active on both ET_A and ET_B receptors. Endothelin (ET)-1 and its receptors (ET_A and ET_B) mediate a variety of effects such as vasoconstriction, fibrosis, proliferation, hypertrophy, and inflammation. In disease conditions such as PAH, the local ET system is upregulated and is involved in vascular hypertrophy and in organ damage.

Riociguat is a stimulator of soluble guanylate cyclase (sGC), an enzyme in the cardiopulmonary system and the receptor for nitric oxide (NO). Riociguat restores the NO-sGC-cGMP pathway and leads to increased generation of cGMP.

Sitaxentan is a potent (Ki 0.43 nM) and highly selective ETA antagonist (approximately 6,500-fold more selective for ETA as compared to ETB). Endothelin-1 (ET-1) is a potent vascular paracrine and autocrine peptide in the lung, and can also promote fibrosis, cell proliferation, cardiac hypertrophy, and remodelling and is pro-inflammatory. ET-1 actions are mediated through endothelin A (ETA) and endothelin B receptors (ETB). ET-1 concentrations are elevated in plasma and lung tissue of patients with pulmonary arterial hypertension (PAH), as well as other cardiovascular disorders and connective tissue diseases.