Category:Vasodilators: Difference between revisions

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The pulmonary arterial hypertension pharmacopoeia is a distinct sub-set of the vasodilators. The endothelin receptor antagonists [[wikipedia:Bosentan|bosentan]], [[wikipedia:Ambrisentan|ambrisentan]], and [[wikipedia:Macitentan|macitentan]] block the endothelin-1 ET-A and ET-B receptors that drive pulmonary-vascular constriction and remodelling in pulmonary arterial hypertension; the soluble guanylate cyclase stimulator [[wikipedia:Riociguat|riociguat]] acts on the same pathway as the nitrates but is direct rather than nitric-oxide-dependent and is approved for both pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension. The prostacyclin analogues [[wikipedia:Epoprostenol|epoprostenol]] (intravenous continuous infusion), [[wikipedia:Iloprost|iloprost]] (inhaled), [[wikipedia:Treprostinil|treprostinil]] (subcutaneous, intravenous, inhaled, oral), and the IP-receptor agonist selexipag (oral) target the prostacyclin pathway in pulmonary vascular smooth muscle.

The clinical use of a vasodilator is constrained by the limitations of the chosen mechanism. Reflex tachycardia, common with the short-acting dihydropyridines, hydralazine, and minoxidil, is moderated by concurrent beta-blockade in chronic use. Postural hypotension, common with alpha blockers (the well-known "first-dose phenomenon" of prazosin) and with the nitrates, requires patient education and careful titration. Tachyphylaxis (the development of pharmacological tolerance on continuous exposure) limits the chronic use of the organic nitrates and is managed by a nitrate-free interval each day. The ~~drug-drug~~ interaction between PDE5 inhibitors and any nitrate produces severe and prolonged hypotension and is an absolute contraindication; the same caution applies to the soluble guanylate cyclase stimulator riociguat with nitrates and with PDE5 inhibitors. Cyanide accumulation on prolonged or high-dose sodium nitroprusside infusion is monitored by serum thiocyanate level in extended ICU use.

The clinical use of a vasodilator is constrained by the limitations of the chosen mechanism. Reflex tachycardia, common with the short-acting dihydropyridines, hydralazine, and minoxidil, is moderated by concurrent beta-blockade in chronic use. Postural hypotension, common with alpha blockers (the well-known "first-dose phenomenon" of prazosin) and with the nitrates, requires patient education and careful titration. Tachyphylaxis (the development of pharmacological tolerance on continuous exposure) limits the chronic use of the organic nitrates and is managed by a nitrate-free interval each day. The interaction between PDE5 inhibitors and any nitrate produces severe and prolonged hypotension and is an absolute contraindication; the same caution applies to the soluble guanylate cyclase stimulator riociguat with nitrates and with PDE5 inhibitors. Cyanide accumulation on prolonged or high-dose sodium nitroprusside infusion is monitored by serum thiocyanate level in extended ICU use.

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