ACE Inhibitor Selection and Dosing for an 18kg Pediatric Patient with Heart Failure
For an 18kg child with heart failure, start with enalapril 0.1 mg/kg/day (1.8mg) once daily or divided twice daily, titrating up to a target of 0.5 mg/kg/day (9mg daily) as tolerated. 1
Why Enalapril is the Preferred Choice
- Enalapril is the most widely studied and used ACE inhibitor in pediatric heart failure, with established safety and efficacy data in children 1
- Enalapril can be administered once or twice daily, improving adherence compared to captopril's three-times-daily dosing 1
- For this 18kg patient, the practical dosing is straightforward: start at approximately 2mg once daily (rounding from 1.8mg for ease of administration) 1
Specific Dosing Protocol for This Patient
Initial dose:
- Start with 0.1 mg/kg/day = 1.8-2mg once daily (can divide into twice daily if preferred) 1
Titration schedule:
- Increase dose every 2 weeks minimum if tolerated 2
- Double the dose at each titration step 2
- Target dose: 0.5 mg/kg/day = 9mg daily (can be given once or divided twice daily) 1
Maximum dose considerations:
- Pediatric studies have used up to 0.5 mg/kg/day safely 1
- The absolute maximum would be 9mg daily for this weight, though some protocols allow higher in older children 3
Alternative: Captopril (Second-Line Choice)
If enalapril is unavailable or not tolerated:
- Starting dose: 0.3 mg/kg/day = 5.4mg daily divided into three doses (approximately 2mg three times daily) 1
- Target dose: Up to 1.5 mg/kg/day = 27mg daily divided three times daily 1
- The three-times-daily dosing makes this less practical than enalapril 1
Critical Monitoring Requirements
Before starting:
- Baseline blood pressure, renal function (creatinine), and potassium 2
- Assess for volume depletion and optimize diuretic dose first 4
Within 1-2 weeks of initiation and after each dose increase:
- Blood pressure (watch for symptomatic hypotension) 2
- Serum creatinine (up to 50% increase from baseline is acceptable) 2
- Serum potassium (keep <5.0 mEq/L) 2
Ongoing:
- Monitor at least every 2 weeks during titration 2
- Continue monitoring every 1-2 months once at target dose 2
Common Pitfalls and How to Avoid Them
Hypotension within first 5 days:
- Most common early complication in pediatrics 1
- Usually resolves with dose reduction or temporary cessation 1
- Reduce diuretic dose first if no signs of congestion 2
- Do not stop ACE inhibitor unless hypotension is severe or prolonged 2
Renal dysfunction:
- Expect small increases in creatinine—this is acceptable 2
- Creatinine increases up to 50% above baseline are tolerable 2
- If creatinine rises more than 50%, halve the ACE inhibitor dose and recheck 2
- Stop nephrotoxic drugs (NSAIDs) if available 2
Hyperkalemia:
- Avoid potassium supplements and potassium-sparing diuretics when possible 2
- If potassium rises above 5.5 mEq/L, reduce ACE inhibitor dose 2
Administration Pearls
- Start low, go slow: Begin with the lowest dose to prevent first-dose hypotension 1
- Some ACE inhibitor is better than none: If target dose cannot be reached, use the highest tolerated dose 2
- Never stop abruptly: Sudden discontinuation can cause clinical deterioration 2, 5
- Combine with other heart failure medications: ACE inhibitors work best alongside diuretics, and often digoxin or beta-blockers 1