Dopamine is preferred over dobutamine in treatment of shock with oliguria because:-
Dopamine is the drug of choice for cardiogenic shock with oliguric renal failure. It acts on D1 (at a dose of 1-2 mg/kg/ min.), b1 (at 2-10 mg/kg/min.) and a1 (at > 10 mg/kg/min.) receptors. It causes renal vasodilation by acting on D1 receptors and maintains renal perfusion and GFR. Other ionotropic agents like NA cause renal vasoconstriction and thus worsen renal failure.
It has additional renal vasodilatory effect
It increases cardiac output
It causes peripheral vasoconstriction only
It has prolonged action
Sympathetic System