Dobutamine

    

Dobutamine, a synthetic analog of dopamine, has predominantly β 1-adrenergic effects. 

    When compared with isoproterenol, inotropy is more affected than chronotropy. It exerts less of a β2 -type effect than isoproterenol does and less of an α 1 -type effect than does norepinephrine. Unlike dopamine, endogenous norepinephrine is not released, and dobutamine does not act at dopaminergic receptors. 

    Dobutamine is potentially useful in patients with congestive heart failure (CHF) or myocardial infarction complicated by low cardiac output. Doses smaller than 20 μg/kg/min usually do not produce tachycardia. Because dobutamine directly stimulates β 1 -receptors, it does not rely on endogenous norepinephrine stores for its effects and may still be useful in catecholamine-depleted states such as chronic CHF. 

    However, prolonged treatment with dobutamine causes downregulation of β-adrenergic receptors. If given more than 3 days, tolerance and even tachyphylaxis may occur and can be avoided by intermittent infusions of dobutamine. However, there are no controlled trials demonstrating improved survival.

Dosage in adults:

According to experience, the majority of patients respond to doses of 2.5-10 µg dobutamine/kg/min. In individual cases, doses up to 40 µg dobutamine/kg/min have been administered.

Dosage in paediatric patients:

For all paediatric age groups (neonates to 18 years) an initial dose of 5 micrograms/kg/minute, adjusted according to clinical response to 2– 20 micrograms/kg/minute is recommended. Occasionally, a dose as low as 0.5-1.0 micrograms/kg/minute will produce a response.

Contraindications

Dobutamine must not be used in the case of:

- known hypersensitivity to dobutamine or to any of the excipients,

- mechanical obstruction of ventricular filling and/or of outflow, such as pericardial tamponade, constrictive pericarditis, hypertrophic obstructive cardiomyopathy, severe aortic stenosis,

- hypovolaemic conditions.

Dobutamine stress echocardiography

Dobutamine must not be used for detection of myocardial ischaemia and of viable myocardium in case of:

- recent myocardial infarction (within the last 30 days),

- unstable angina pectoris,

- stenosis of the main left coronary artery,

- haemodynamically significant outflow obstruction of the left ventricle including hypertrophic obstructive cardiomyopathy,

- haemodynamically significant cardiac valvular defect,

- severe heart failure (NYHA III or IV),

- predisposition for or documented medical history of clinically significant or chronic arrhythmia, particularly recurrent persistent ventricular tachycardia,

- significant disturbance in conduction,

- acute pericarditis, myocarditis or endocarditis,

- aortic dissection,

- aortic aneurysm,

- poor sonographic imaging conditions,

- inadequately treated / controlled arterial hypertension,

- obstruction of ventricular filling (constrictive pericarditis, pericardial tamponade),

- hypovolaemia,

- previous experience of hypersensitivity to dobutamine.