Vaptans in Pediatric Medicine
Key Points
- Vasopressin receptor antagonists (vaptans) are selective V2 receptor blockers
- Primary use in euvolemic and hypervolemic hyponatremia
- Limited FDA approval in pediatric population
- Emerging role in ADPKD management
Mechanism of Action
- Competitive blockade of V2 receptors
- Increased free water excretion (aquaresis)
- Normalization of serum sodium levels
Tolvaptan (Samsca®, Jinarc®)
Drug Information
- Selective V2 receptor antagonist
- Oral administration
- Half-life: 12 hours
Pediatric Dosing
| Indication |
Age Group |
Initial Dose |
Maximum Dose |
| ADPKD |
≥4 years |
0.05-0.1 mg/kg/day |
0.4 mg/kg/day |
| Hyponatremia |
≥12 years |
7.5-15 mg daily |
60 mg daily |
Approved Indications
- Autosomal Dominant Polycystic Kidney Disease (ADPKD)
- Slowing kidney growth
- Preserving renal function
- Euvolemic/Hypervolemic Hyponatremia
Conivaptan (Vaprisol®)
Clinical Profile
- Dual V1a/V2 receptor antagonist
- IV formulation only
- Limited pediatric data
Usage Guidelines
| Parameter |
Details |
Notes |
| Loading Dose |
20-40 mg |
Over 30 minutes |
| Maintenance |
20-40 mg/day |
Continuous infusion |
| Duration |
2-4 days |
Maximum 4 days |
Clinical Management
Patient Selection Criteria
- Pre-treatment Assessment
- Confirmed diagnosis
- Volume status evaluation
- Exclusion of contraindications
- Required Baseline Tests
- Comprehensive metabolic panel
- Liver function tests
- Serum osmolality
- Urine studies
Treatment Initiation Protocol
| Step |
Action |
Monitoring |
| 1 |
Fluid restriction |
Input/Output charting |
| 2 |
Initial dose administration |
Vital signs q4h |
| 3 |
Response assessment |
Na+ q6h initially |
Safety & Monitoring
Adverse Effects
- Common
- Thirst
- Polyuria
- Dehydration
- Serious
- Hepatotoxicity
- Rapid sodium correction
- Osmotic demyelination
Monitoring Requirements
| Parameter |
Frequency |
Critical Values |
| Serum Sodium |
Q4-6h initially |
>12 mEq/L/24h |
| Liver Function |
Monthly |
3x ULN |
| Fluid Status |
Daily |
>5% weight loss |
Risk Mitigation
- Regular monitoring schedule
- Dose adjustments based on response
- Patient/family education
- Emergency plan for complications
Further Reading
