ATC Group: C02K Other antihypertensives

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.

Aprocitentan is an ERA that inhibits the binding of endothelin (ET)-1 to ET_A and ET_B receptors. ET-1, via its receptors (ET_A and ET_B), mediates a variety of deleterious effects such as vasoconstriction, fibrosis, cell proliferation, and inflammation. In hypertension, ET-1 can cause endothelial dysfunction, vascular hypertrophy and remodeling, sympathetic activation, and increased aldosterone synthesis.

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.

Metirosine inhibits tyrosine hydroxylase, which catalyzes the first transformation in catecholamine biosynthesis, i.e., the conversion of tyrosine to dihydroxyphenylalanine (DOPA). Because the first step is also the rate-limiting step, blockade of tyrosine hydroxylase activity results in decreased endogenous levels of catecholamines, usually measured as decreased urinary excretion of catecholamines and their metabolites.

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.