The Use of Milrinone in Infants and Children

Marcia L. Buck, Pharm.D.

Pediatr Pharm. 2003;9(2) 

In This Article


Traditionally, catecholamines such as dopamine, dobutamine, epinephrine, and norepinephrine have been used for their positive inotropic effect in children with low cardiac output. These agents, however, produce several undesirable effects, including an increase in heart rate and myocardial oxygen consumption, down-regulation of beta-adrenergic receptors, and an increase in systemic vascular resistance. Unlike the catecholamines, milrinone produces a positive inotropic effect with concurrent vasodilation and little chronotropic effect. As a result of these differences, milrinone has become a valuable tool in the treatment of children following cardiac surgery and in the management of shock.

Milrinone, like its predecessor inamrinone (formerly called amrinone), is a bipyridine inotrope/vasodilator. It is a selective inhibitor of peak III cyclic adenosine monophosphate (cAMP) phosphodiesterase in cardiac and vascular muscle. Inhibition of this enzyme results in an accumulation of cAMP, producing an increase in intracellular ionized calcium in cardiac muscle which increases contractile force. Increasing cAMP also produces relaxation of vascular smooth muscle. Milrinone exhibits a concentration-dependent response, with optimal effects occurring between 100 and 300 ng/ml.[1,2,3]


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