What intravenous (IV) beta blocker can be used as an alternative to oral propranolol (propranolol) in an infant who is not tolerating it?

Intravenous Beta Blocker Alternatives for Infants Not Tolerating Oral Propranolol

Esmolol is the preferred intravenous beta blocker for infants who cannot tolerate oral propranolol due to its ultra-short half-life, rapid onset of action, and excellent safety profile.

Recommended IV Beta Blocker Options

First-line Option: Esmolol

• Dosing: Start with 500 mcg/kg IV bolus over 1 minute, followed by an infusion of 50-300 mcg/kg/min 1
• Advantages:
  • Ultra-short half-life (approximately 9 minutes) 2
  • Rapid onset of action (achieves 90% of steady-state beta-blockade within 5 minutes) 2
  • Effects disappear within 18 minutes after discontinuation 2
  • Beta-1 selective, minimizing bronchospasm risk
  • Allows for precise titration in infants

Alternative Option: Labetalol

• Dosing: Initial dose of 0.25 mg/kg IV given slowly over 2 minutes 3
• Can be administered as continuous infusion (diluted to 1 mg/mL) at 0.4-1.0 mg/kg/hour 3
• Advantages:
  • Combined alpha and beta blocking properties
  • Relatively short half-life (5-8 hours) compared to oral propranolol 3

Monitoring Requirements

During IV Beta Blocker Administration

• Continuous cardiac monitoring (ECG)
• Blood pressure measurements every 5-10 minutes during initiation
• Heart rate monitoring (refer to normal ranges in Table 2 from guidelines) 4
• Respiratory status monitoring
• Blood glucose monitoring in at-risk infants (preterm, low birth weight, poor feeding) 4

Normal Vital Sign Parameters for Infants

• Heart Rate: 100-190 beats/min (awake), 90-160 beats/min (sleeping) 4
• Blood Pressure: Systolic 72-104 mmHg, Diastolic 37-56 mmHg 4
• Hypotension threshold: Systolic <70 mmHg 4

Special Considerations

High-Risk Infants Requiring Inpatient Monitoring

• Infants <4 weeks of age
• Preterm infants
• Those with faltering growth or feeding difficulties
• Infants with comorbidities (cardiac, respiratory, metabolic, or neurological disorders) 4

Precautions

• Monitor for hypotension, which is the principal adverse effect (may be more common with esmolol) 5, 6
• Have glucose available for immediate administration if hypoglycemia occurs
• Avoid in infants with significant bradycardia, heart block, or decompensated heart failure 1

Management of Adverse Effects

• For hypotension: reduce infusion rate or temporarily discontinue
• For hypoglycemia: administer glucose and temporarily hold medication
• For bradycardia: reduce dose or temporarily discontinue

Transition Back to Oral Therapy

When the infant can tolerate oral medications again:

• Begin oral propranolol 15 minutes after discontinuing IV beta blocker
• Start at a lower dose (0.5-1 mg/kg/day in three divided doses) 4
• Gradually increase to target dose of 2 mg/kg/day in three divided doses 4

Special Situations

For Infants with PHACES Syndrome

• Requires cardiac assessment (ECG and ECHO) before starting any beta blocker 4
• Consider lower starting doses and slower titration 4

For Infants with Beta Blocker Resistance

• Consider glucagon (20-30 μg/kg, maximum 1 mg) administered IV over 5 minutes if beta blocker effects need to be rapidly reversed 4

Remember that while IV beta blockers provide a temporary solution, the goal should be to transition back to oral propranolol therapy when tolerated, as it remains the standard of care for infantile hemangioma management.