DOBUTamine

DOBUTamine

Indication

• To increase cardiac output

Pharmacology

• A synthetic catecholamine which is similar in structure to dopamine
• Not effective when given orally because of rapid first-pass effect
• Pharmacological effects are due to direct interactions with both alpha and beta adrenergic receptors; does not appear to be involved in the release of norepinephrine nor does it act at dopaminergic receptors
• A racemic (ie. 2 enantiomeric forms) mixture is used clinically; the (-) isomer is an alpha₁ receptor agonist, the (+) isomer is an alpha₁ receptor antagonist; both isomers appear to have agonist activity at beta₁ and beta₂ receptors
• Stimulation of alpha₁ receptors results in constriction of systemic arterioles
• Stimulation of beta₂ receptors results in dilation of systemic arterioles
• Stimulation of beta₁ receptors results in increased rate, contractility and conduction velocity of the heart
• DOBUTamine has relatively more prominent inotropic (contraction) than chronotropic (rate) effects on the heart; this, however, has not been a consistent finding in clinical studies
• DOBUTamine is about 4 times as potent as dopamine in terms of contractile potency at comparable, low doses. At higher doses dobutamine decreases peripheral resistance (presumably because the beta₂ vasodilator effect predominates over the alpha₁ constrictor effect) in contrast to dopamine which increases peripheral resistance (due to alpha₁ receptor stimulation)
• As the result of:
  • A positive inotropic effect, and
  • A decrease in peripheral resistance,
  • Blood pressure may remain unchanged or be only slightly elevated; heart rate is usually not substantially changed

Side Effects

• Significant increases in heart rate and blood pressure have been reported in some patients
• Heart rate > 200 BPM and systolic BP > 90 mmHg should be avoided. The situation should be re-assessed and the dosage adjusted accordingly.
• Less frequent adverse effects include vomiting and ectopic heart beats

Precautions

• Local: blanching, tissue ischemia or necrosis may occur with extravasation. 

Dose

• The initial recommended dose for continuous infusion is 1-2 mcg/kg/min; this may be titrated to 7.5 to 10 mcg/kg/min given as a continuous infusion, up to a maximum of 20 mcg/kg/min

• DOBUTamine standard concentrations for NICU implemented Oct 1, 2014:

  1 kg or less   1 mg/mL

  over 1 kg      2 mg/mL

• Infusion standard concentration for weight to be ordered along with desired therapeutic dosing through HUGO, rate will be calculated electronically

Supplied

• 12.5 mg/mL, 10 mL vial
• Supplied by pharmacy as standard concentrations of 1mg/mL (supplied as 50mg/50mL of IV fluid ordered) and 2mg/mL (100mg/50mL of IV fluid ordered)
• Standard Concentration Reference Sheets can be found on the NICU Intranet here