Dobutamine

Chemical

Synthetic catecholamine with predominate β1 activity

Use

Inotrope in low cardiac output states

Presentation

250mg / 20mL Clear, colourless solution

Racemixture of 2 isomers

  • Dextro (+) = potent β1 agonist & α1 antagonist
  • Levo (–) = potent α1 agonist
  • ∴α1 effects neutralised

Dose

1 – 20mcg/kg/min

Route

IV

Onset

Immediate

DoA

t½ 2 mins

MoA

β agonist → selective β1 agonist

  • β1 → G5 → Activates AC → ↑cAMP → ↑Ca2+
  • Effects of ↑Ca2+
    • Heart: +ve ino, chrono, dromotropy
    • Metabolism: ↑lipolysis, ↑FFAs
    • Renal: ↑renin, ↑AII, VC

Small effect @ β2 receptors ∴may VD vessels

PD

CVS

  • ↑FoC
  • ↑HR
  • ↑Myocardial O2 consumption
  • BP usually ↑ despite ↓SVR from β2 effects

PK

A

N/A

D

0.2L/kg

M

Rapidly by COMT

E

t½ B = 2 mins. Metabolites conjugated & excreted in urine 

Adverse Effects

Arrhythmias

↑ventricular response due to ↑ AV conduction

Avoid with outflow obstruction → AoS/Tamponade

Tachyphylaxis