Pharmacology. Dopamine is an endogenous catecholamine and the immediate metabolic precursor of norepinephrine. It stimulates alpha- and beta-adrenergic receptors directly and indirectly. In addition, it acts on specific dopaminergic receptors. Its relative activity at these various receptors is dose-related. At low infusion rates (1–5 mcg/kg/min), dopamine stimulates beta1 activity (increased heart rate and contractility) and increases renal and mesenteric blood flow through dopaminergic agonist activity. At high infusion rates (10–20 mcg/kg/min), alpha-adrenergic stimulation predominates, resulting in increased peripheral vascular resistance. Dopamine is not effective orally. After IV administration, its onset of action occurs within 5 minutes, and the duration of effect is less than 10 minutes. The plasma half-life is about 2 minutes.

Indications

1. 
   

   Dopamine is used to increase blood pressure, cardiac output, and urine flow in patients with shock who have not responded to intravenous fluid challenge, correction of hypothermia, or reversal of acidosis.

   
   
2. 
   

   Low-dose infusion is most effective for hypotension caused by venodilation or reduced cardiac contractility; high-dose dopamine is indicated for shock resulting from decreased peripheral arterial resistance.

Contraindications

1. 
   

   Tachyarrhythmias or ventricular fibrillation and uncorrected hypovolemia.

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