[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Pharmacology](https://durgical.com/en/pharmacology/) › Vasopressors and inotropes [Pharmacology](https://durgical.com/en/pharmacology/) · Class # Vasopressors and inotropes Intravenous medicines that raise blood pressure or make the heart pump harder in shock. They are high-alert drugs, given by infusion with close monitoring. Updated 2026-11-01 ## What they are Catecholamines and related drugs used in intensive care, the emergency room and theatre to support a failing circulation: norepinephrine, epinephrine, dopamine and phenylephrine mainly tighten vessels (vasopressors); dobutamine, milrinone and levosimendan mainly strengthen contraction (inotropes). Oral midodrine treats orthostatic hypotension. ## Mechanism of action Most act on adrenergic receptors: alpha-1 receptors on vascular smooth muscle constrict arterioles and veins; beta-1 receptors in the heart raise contractility and heart rate; beta-2 receptors dilate vessels and bronchi. Milrinone raises cAMP by blocking phosphodiesterase 3, and levosimendan makes troponin C more sensitive to calcium. Target: Alpha and beta adrenergic receptors, dopamine receptors, phosphodiesterase 3, cardiac troponin C ## Key points - High-alert medicines: infusion pump, a large or central vein, continuous blood pressure and ECG monitoring. - Extravasation of a vasoconstrictor can cause tissue necrosis; local phentolamine infiltration is the antidote. - Correct hypovolaemia first: vasopressors in an empty circulation cause severe ischaemia of the gut, kidneys and limbs. - Norepinephrine is the usual first-line vasopressor in septic shock; epinephrine is the drug of anaphylaxis. - MAO inhibitors and tricyclic antidepressants can make the pressor response severe and prolonged. ## Drugs in this class - [**Dopamine** A natural catecholamine given by intravenous infusion in shock. Its effects change with the dose: dopamine receptors… Dopamine D1 receptor (also beta-1 and alpha-1 adrenergic receptors)](https://durgical.com/en/pharmacology/dopamine/) - [**Epinephrine** Adrenaline: the first medicine for anaphylaxis, given into the thigh muscle. By infusion it also supports blood… Alpha and beta adrenergic receptors (beta-2 shown)](https://durgical.com/en/pharmacology/epinephrine/) - [**Dobutamine** An intravenous inotrope that strengthens the heartbeat in cardiogenic shock and decompensated heart failure, with… Beta-1 adrenergic receptor](https://durgical.com/en/pharmacology/dobutamine/) - [**Norepinephrine** Noradrenaline: the usual first vasopressor in septic shock. It tightens blood vessels to restore blood pressure and is… Alpha-1 adrenergic receptor (also beta-1)](https://durgical.com/en/pharmacology/norepinephrine/) - [**Ephedrine** A mixed-acting sympathomimetic given intravenously to treat low blood pressure during anaesthesia. Repeated doses lose… Alpha and beta adrenergic receptors, plus release of stored norepinephrine](https://durgical.com/en/pharmacology/ephedrine/) - [**Isoprenaline** A pure beta agonist given intravenously. It speeds and strengthens the heart and relaxes the bronchi; it can bridge… Beta-1 and beta-2 adrenergic receptors](https://durgical.com/en/pharmacology/isoprenaline/) - [**Milrinone** An intravenous inodilator that blocks phosphodiesterase 3: it strengthens the heartbeat and widens vessels in acute… Phosphodiesterase 3 (PDE3)](https://durgical.com/en/pharmacology/milrinone/) - [**Phenylephrine** A pure alpha-1 agonist that tightens vessels. Given intravenously for low blood pressure during anaesthesia; it… Alpha-1 adrenergic receptor](https://durgical.com/en/pharmacology/phenylephrine/) - [**Levosimendan** A calcium sensitiser given intravenously in acute decompensated heart failure. It strengthens contraction without… Cardiac troponin C (calcium sensitiser); also ATP-sensitive potassium channels](https://durgical.com/en/pharmacology/levosimendan/) - [**Midodrine** An oral prodrug of an alpha-1 agonist for disabling orthostatic hypotension. Its main risk is high blood pressure when… Alpha-1 adrenergic receptors (through desglymidodrine)](https://durgical.com/en/pharmacology/midodrine/) ## Others in the class - Vasopressin - Metaraminol - Droxidopa ## Test yourself Think of the answer, then tap the question to see it. ## Which receptor explains the vasoconstriction caused by norepinephrine and phenylephrine? The alpha-1 adrenergic receptor on vascular smooth muscle (Gq, rise in intracellular calcium). ## What is the antidote when a norepinephrine infusion extravasates? Phentolamine, an alpha blocker, infiltrated into the affected area as early as possible to reverse the local vasoconstriction. ## Why should hypovolaemia be corrected before starting a vasopressor? Constricting the vessels of an under-filled circulation reduces flow to the kidneys, gut and limbs and can cause lactic acidosis and gangrene despite a 'normal' pressure. ## How do milrinone and dobutamine differ in how they raise cAMP in the heart? Dobutamine stimulates beta-1 receptors, so more cAMP is made; milrinone blocks phosphodiesterase 3, so less cAMP is broken down. [Add to my cards (4)](https://durgical.app/estudiar/?add=/en/pharmacology/classes/vasopressors-and-inotropes/) [← All of pharmacology](https://durgical.com/en/pharmacology/) Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given. Sources: [DailyMed - NOREPINEPHRINE BITARTRATE injection, solution, concentrate](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=728734e7-1684-4b37-980c-f1dfd408b436) (DailyMed (U.S. National Library of Medicine), 2022); [DailyMed - DOBUTAMINE injection, solution, concentrate](https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=89becb0c-da60-4f43-0a98-29ff7a9eca58) (DailyMed (U.S. National Library of Medicine), 2026); Farmacología básica y clínica (Katzung), cap. 9 (McGraw Hill, 2025). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/pharmacology/classes/vasopressors-and-inotropes/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/pharmacology/classes/vasopressors-and-inotropes/