What is the appropriate dosage of amitriptyline for a child with nocturnal enuresis?

Amitriptyline Duration for Nocturnal Enuresis in Children

If treatment is successful, continue amitriptyline at the lowest effective dose with mandatory drug holidays of at least 2 weeks every 3 months to prevent tolerance, which is otherwise quite high with this medication 1.

Initial Treatment Period

• Evaluate response after 1 month of treatment 1
• The anti-enuretic effect should appear within this timeframe
• If no response after 1 month, consider alternative therapy

Dosing Strategy

Starting dose:

• 25 mg at bedtime for children ≤9 years old
• 50 mg at bedtime for children >9 years old 1

For partial responders:

• Add desmopressin at standard dose (0.2-0.4 mg)
• Critical caveat: Restrict fluid intake during evening and night when combining these medications 1

Long-Term Management Protocol

If treatment is successful:

1. Taper to lowest effective dose that maintains dryness 1

2. Mandatory drug holidays: At least 2 weeks off medication every 3 months 1

   • This is essential to decrease tolerance risk
   • Use these breaks to assess if medication is still needed

3. Continue for at least 3 months if maintaining relief of symptoms 2

Critical Safety Considerations

Before prescribing, you must exclude:

• History of palpitations or syncope in the child
• Sudden cardiac death in the family
• Unstable arrhythmia in the family
• If any of these exist, obtain prolonged ECG to exclude long QT syndrome 1

Storage warning:

• Amitriptyline is potentially cardiotoxic and fatal in overdose
• Must be kept securely locked and away from younger siblings 1

Common Side Effects to Monitor

• Mood changes
• Nausea
• Insomnia
• These often appear before beneficial effects but may gradually disappear even if treatment continues 1

Position in Treatment Algorithm

Amitriptyline (and other tricyclics like imipramine) is third-line therapy only 1. Use it when:

• Alarm therapy has failed AND
• Family cannot afford desmopressin OR
• At tertiary care facilities for therapy-resistant cases

The guideline evidence is clear that due to cardiotoxicity concerns, tricyclic antidepressants should not be first-line treatment despite their 50% response rate 1.