Cardiotonic agent

In medicine and pharmacology, cardiotonic agents are "agents that have a strengthening effect on the heart or that can increase cardiac output. They may be cardiac glycosides; sympathomimetics; or other drugs. They are used after myocardial infarct; cardiac surgical procedures; in shock; or in congestive heart failure (heart failure)."

Examples of sympathomimetic cardiotonic agents include:

• Dobutamine [r]: A beta-2 agonist catecholamine that has cardiac stimulant action without evoking vasoconstriction or tachycardia; it is proposed as a cardiotonic after myocardial infarction or open heart surgery, and used as a pharmacological stressor in cardiac stress testing. ^[e]
• Dopamine [r]: A monoamine neurotransmitter formed in the brain by the decarboxylation of dopa and essential to the normal functioning of the central nervous system. ^[e]
• Epinephrine [r]: A hormone (adrenalin) adrenergic systems-stimulator used in asthma and cardiac failure. ^[e]
• Isoproterenol [r]: Isopropyl analog of epinephrine; beta-sympathomimetic that acts on the heart, bronchi, skeletal muscle, alimentary tract, etc. It is used mainly as bronchodilator and heart stimulant. ^[e]
• Norepinephrine [r]: Precursor of epinephrine that is secreted by the adrenal medulla and is a widespread central and autonomic neurotransmitter. Norepinephrine is the principal transmitter of most postganglionic sympathetic fibers and of the diffuse projection system in the brain arising from the locus ceruleus. It is also found in plants and is used pharmacologically as a sympathomimetic. ^[e]

Examples of cardiac glycosides cardiotonic agents include:

• Digoxin [r]: The most commonly used synthetic derivative of digitalis glycosides, used clinically to improve the pumping action of the heart ^[e]

Examples of phosphodiesterase inhibitors cardiotonic agents include:

• Milrinone [r]: A positive inotropic cardiotonic agent with vasodilator properties; inhibits cAMP phosphodiesterase activity in myocardium and vascular smooth muscle; is a derivative of amrinone and has 20-30 times the ionotropic potency of amrinone. ^[e]