and Dopaminergic Receptor Agonists
Dopamine [dope' a meen]
[doe bue' ta meen]
Dopamine and dobutamine are used for
short-term inotropic support of the failing
Dobutamine is less arrhythmogenic and
produces less tachycardia compared to endogenous
catecholamines or isoproterenol.
Dobutamine is a racemate that binds to
and activates beta-1 and beta-2 adrenoceptor
subtypes. The (-) enantiomer stimulates alpha 1
and alpha 2 receptors, but this effect in humans
appear negated by binding of the inactive (+)
enantiomer. Therefore the positive inotropic
action mediated by beta receptor activation
Dobutamine does not activate dopamine
receptors and therefore does not increase renal
Because of its vasodilator properties,
dobutamine's positive inotropism is accompanied
by a decrease in afterload. For this reason
dobutamine is favored over dopamine for most
advanced heart failure patients who have not
improved with digoxin, diuretics, and vasodilator
Dopamine has limited
utility in patents with left ventricular
dysfunction. It often produces tachycardia which
may increase left ventricular work.
vasodilation is mediated by direct stimulation of
D1 and D2 post-synaptic dopamine receptors.
Vasodilation of renal vasculature is noteworthy
and may benefit patients with marginal GFR due to
poor renal perfusion.