The endothelin (ET) system has emerged as a novel target for hypertension treatment where a medical need persists despite availability of several pharmacological classes, including renin angiotensin system (RAS) blockers. ET receptor antagonism has demonstrated efficacy in preclinical models of hypertension, especially under low-renin conditions and in hypertensive patients. We investigated the pharmacology of aprocitentan (N-[5-(4bromophenyl)-6-[2-[(5-bromo-2-pyrimidinyl)oxy]ethoxy]-4pyrimidinyl]-sulfamide), a potent dual ET A /ET B receptor antagonist, on blood pressure (BP) in two models of experimental hypertension: deoxycorticosterone acetate (DOCA)-salt rats (lowrenin model) and spontaneously hypertensive rats [(SHR), normal renin model]. We also compared the effect of its combination with RAS blockers (valsartan and enalapril) with that of the combination of the mineraloreceptor antagonist spironolactone with the same RAS blockers on BP and renal function in hypertensive rats. Aprocitentan was more potent and efficacious in lowering BP in conscious DOCA-salt rats than in SHRs. In DOCA-salt rats, single oral doses of aprocitentan induced a dose-dependent and long-lasting BP decrease and 4-week administration of aprocitentan dose dependently decreased BP (statistically significant) and renal vascular resistance, and reduced left ventricle hypertrophy (nonsignificant). Aprocitentan was synergistic with valsartan and enalapril in decreasing BP in DOCA-salt rats and SHRs while spironolactone demonstrated additive effects with these RAS blockers. In hypertensive rats under sodium restriction and enalapril, addition of aprocitentan further decreased BP without causing renal impairment, in contrast to spironolactone. In conclusion, ET A /ET B receptor antagonism represents a promising therapeutic approach to hypertension, especially with low-renin characteristics, and could be used in combination with RAS blockers, without increasing the risk of renal impairment.

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The add-on effect of macitentan on top of bosentan in two pathological models confirms that this novel compound can achieve a superior blockade of ET receptors and provides evidence for greater maximal efficacy.