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An inotropic agent is a medicine or substance that changes the strength of heart-muscle contraction. A positive inotrope increases contractility, while a negative inotrope decreases it. In clinical emergency and critical-care settings, the term inotrope commonly refers to a drug used to increase cardiac output. The medicine's effects on heart rate, blood vessels, and blood pressure can differ from its inotropic effect.
read more about inotropic agent ...Positive inotropic agents can support circulation when the heart cannot pump enough blood to the organs. They are used in selected cases of cardiogenic shock, severe acute heart failure, low-output states after cardiac surgery, and other critical conditions. Some agents also have longer-term or specialized roles, such as digoxin in selected patients. The underlying cause of poor cardiac output must be treated alongside temporary inotropic support.
Positive inotropes increase the availability or effect of calcium within heart-muscle cells. Adrenergic drugs such as dobutamine stimulate receptors that raise cyclic adenosine monophosphate, while milrinone slows its breakdown by inhibiting phosphodiesterase 3. Digoxin indirectly increases intracellular calcium by inhibiting the sodium-potassium pump. Different mechanisms produce different effects on heart rate, vascular resistance, oxygen demand, and rhythm.
Common positive inotropes include dobutamine, dopamine, milrinone, epinephrine, and digoxin. Some drugs have both inotropic and vasopressor or vasodilator effects. Negative inotropes include beta blockers and nondihydropyridine calcium-channel blockers, which reduce contraction strength in appropriate clinical settings. Drug selection depends on blood pressure, heart rhythm, ventricular function, organ perfusion, and the cause of circulatory failure.
Positive inotropes can cause abnormal heart rhythms, faster heart rate, increased myocardial oxygen demand, chest pain, and blood-pressure changes. Some can worsen ischemia or increase mortality when used unnecessarily or for prolonged periods. Treatment commonly requires continuous heart-rhythm and blood-pressure monitoring, along with assessment of urine output, perfusion, electrolytes, and organ function. Doses are adjusted frequently according to hemodynamic response and adverse effects.
No. An inotrope primarily changes cardiac contractility, while a vasopressor mainly raises vascular tone and blood pressure. Some medicines, including epinephrine and dopamine, can produce both effects.
No. Some commonly raise heart rate, but the degree varies by drug and dose. Digoxin can increase contractility while slowing conduction through the atrioventricular node.
Continuous positive inotropic therapy is generally reserved for selected advanced or palliative situations because long-term use can increase risks. Other heart-failure medicines are preferred for routine long-term management.
They can rapidly change heart rhythm, blood pressure, cardiac output, and oxygen demand. Continuous assessment helps clinicians find the lowest effective dose and respond quickly to complications.
Inotropes and Vasopressors. StatPearls (NCBI Bookshelf). https://www.ncbi.nlm.nih.gov/books/NBK482411/. Date Accessed August 5, 2026.
Cardiogenic Shock. StatPearls (NCBI Bookshelf). https://www.ncbi.nlm.nih.gov/books/NBK482255/. Date Accessed August 5, 2026.
Dobutamine. StatPearls (NCBI Bookshelf). https://www.ncbi.nlm.nih.gov/books/NBK470431/. Date Accessed August 5, 2026.
Milrinone. StatPearls (NCBI Bookshelf). https://www.ncbi.nlm.nih.gov/books/NBK532943/. Date Accessed August 5, 2026.
Digoxin. StatPearls (NCBI Bookshelf). https://www.ncbi.nlm.nih.gov/books/NBK556025/. Date Accessed August 5, 2026.