1. 2-20 micrograms/kg/minute by continuous IV infusion¹.
2. Begin at a low dose and titrate by monitoring clinical response.
3. Maximum recommended dose 20 micrograms/kg/minute².
4. If doses greater than 10 – 15 micrograms/kg/min are required then dobutamine or noradrenaline may be added¹.
5. Administer via a central line (UVC, Longline, or Surgical CVL). If no central access available, use a large vein.
6. Usual dilution 30 mg/kg (0.75 ml/kg) dopamine to make 50 ml with Normal Saline or D5W
   
   1 ml/hour = 10 micrograms/kg/minute.
    

Dopamine (mg) in 50ml IV solution =

3  x weight (kg) x dose (micrograms/kg/min)                     IV Rate (ml/hr)

Indications

1. To improve cardiac output, blood pressure and urine output in critically ill infants with hypotension.

Contraindications

1. Hypersensitivity to sympathomimetic amines and sulfites.
2. Uncorrected tachyarrhythmias.

Precautions²

1. Hypovolaemia- correct before commencing dopamine
2. Hyperthyroidism
3. Caution if administration concurrent with phenytoin.

Clinical Pharmacology

Dopamine is a sympathomimetic catecholamine which exhibits alpha adrenergic, beta adrenergic, and dopaminergic agonism. The mechanism of action in neonates is controversial. Relative effects of dopamine at different doses are uncertain because of developmental differences in:

• endogenous noradrenaline stores
• alpha and beta adrenergic, and dopaminergic receptor functions
• the ability of the neonatal heart to increase stroke volume. Responses tend to be individualised.

Dopamine is metabolised very rapidly and is effective only when administered intravenously by continuous infusion. The half-life of dopamine effect is 2 minutes, which is the same as the other catecholamines. No information available on protein binding. 97% is excreted in the urine as metabolites.

Drug effects are dose dependent:

• Low dose: 2-5 micrograms/kg/minute. Little effect seen on heart rate or cardiac output. Increased blood flow accompanied by increased urine output.
• Intermediate doses: 5-15 micrograms/kg/minute. An increase in cardiac contractility and cardiac output results in increased normal blood flow and heart rate.
• High dose: 15 micrograms/kg/minute. Alpha adrenergic effects begin to dominate: increased systemic and pulmonary vascular resistance,a decrease in blood flow, and a reduction in cardiac output in the neonate especially in the first few days of life³. Decrease in normal perfusion.

Possible Adverse Effects¹

1. Venous irritation, soft tissue injury at the site of IV injection.
2. Vomiting, tachycardia, vasoconstriction, hypotension.
3. Infusions > 20 micrograms/kg/minute are associated with an increased risk of dysrhythmias eg. tachycardia and, bradycardia, and vasoconstriction¹
4. Less common: bradycardia, hypertension.

Special Considerations

1. Dosage range is determined by type of desired clinical effect. Start at the lower end of the desired range and titrate according to clinical response.
2. Volume loading is considered before commencing dopamine infusion.
3. Use with caution in patients with persistent pulmonary hypertension of the newborn.
4. Suggested treatment for tissue sloughing following IV infiltration: inject a 1 mg/ml solution of phentolamine into the affected area. The usual amount needed is 1-5 ml, depending on the size of the infiltrate.
5. Dopamine effects are prolonged and intensified by beta blockers.
6. General anaesthetic: increased risk of arrhythmias or hypertension.
7. Phenytoin may lower blood pressure.
8. Acidosis decreases effectiveness of dopamine.
9. Administration via the UAC is not recommended¹