Dobutamine

[PHW2:p198-199]

Structure

[PHW2:p198]

Direct-acting synthetic catecholamine

Derivative of isoprenaline

 

 

[MCQ:Q218]

Dextro: beta ++++, ?alpha1 antagonist

Levo: alpha1++, beta +

Pharmacodynamics

Mechanism of action

Beta1 effect predominate

Some beta2 effects as well

Effects

[PHW2:p198]

CVS

Direct stimulation of beta1 receptor

Increased contractility, HR, MVO2

Some decrease in SVR due to beta2 stimulation

Overall BP is increased
* Unlike the variable BP effect with isoprenaline

 

May precipitate arrhythmia

Avoid in patients with cardiac outflow obstruction (e.g. aortic stenosis, cardiac temponade)

 

Splanchnic

No effect on splanchnic circulation

Urine output may increase due to increased CO

 

Pharmacokinetics

[PHW2:p199]

Rapidly metabolised by COMT

Inactive metabolites are excreted in urine after conjugation

Halflife = 2 min

 

Pharmaceutics

250mg in 20mL water (with sodium metabisulphite)

250mg in 5mL water (with ascorbic acid)

Clinical

Used to augment low cardiac output states associated with MI, cardiac surgery, cardiogenic shock

Dose range 0.5 - 20 microgram/kg/min

 

Also used in cardiac stress testing