Dobutamine

Dobutamine, a synthetic catecholamine bearing chemical structural resemblance to dopamine, is a beta-adrenoceptor agonist. It has remained the drug of choice in management of acute heart failure patients with systolic dysfunction.
Mechanism of action:
Clinically available preparations of dobutamine are a racemic mixture of (+) and (–) isomers and have complex pharmacological effects. While both isomers are full agonists at β1 and β2 receptors their effects on alpha receptors are contrasting. The (–) isomer, a potent agonist at α1 receptors is capable of causing significant pressor effects. However, (+) isomer is a potent α1 receptor antagonist, which can block the effects of (–) isomer. In the myocardium, β1 adrenergic stimulation by dobutamine
Optimal infusion rates are usually between 2 to 20 mcg/kg/min and should not exceed 40 mcg/kg/min., which may cause undesirable α1 receptor overstimulation leading to increased peripheral vascular resistance and increased afterload. Patients with history of recent use of beta blockers may respond variably and require higher doses of dobutamine.

Adverse effects:
The principal adverse effects of dobutamine are tachycardia, hypertension and supraventricular or ventricular arrhythmias. Patients demonstrating significant increases in blood pressure and heart rate in response to dobutamine infusions may require reduction of infusion rates. Angina, dyspnea, eosinophilic myocarditis and injection site reactions have also been reported in treated patients. Development of tolerance can limit the efficacy of dobutamine infusions beyond few days and can further necessitate supplementation or substitution with type III phosphodiesterase