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
Drugs in this class
- DopamineA 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)
- EpinephrineAdrenaline: the first medicine for anaphylaxis, given into the thigh muscle. By infusion it also supports blood…Alpha and beta adrenergic receptors (beta-2 shown)
- DobutamineAn intravenous inotrope that strengthens the heartbeat in cardiogenic shock and decompensated heart failure, with…Beta-1 adrenergic receptor
- NorepinephrineNoradrenaline: the usual first vasopressor in septic shock. It tightens blood vessels to restore blood pressure and is…Alpha-1 adrenergic receptor (also beta-1)
- EphedrineA 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
- IsoprenalineA 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
- MilrinoneAn intravenous inodilator that blocks phosphodiesterase 3: it strengthens the heartbeat and widens vessels in acute…Phosphodiesterase 3 (PDE3)
- PhenylephrineA pure alpha-1 agonist that tightens vessels. Given intravenously for low blood pressure during anaesthesia; it…Alpha-1 adrenergic receptor
- LevosimendanA calcium sensitiser given intravenously in acute decompensated heart failure. It strengthens contraction without…Cardiac troponin C (calcium sensitiser); also ATP-sensitive potassium channels
- MidodrineAn 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)
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.
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 (DailyMed (U.S. National Library of Medicine), 2022); DailyMed - DOBUTAMINE injection, solution, concentrate (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.