Calcium Channel Blockers in Pediatrics

Key Points

CCBs block voltage-gated calcium channels in cardiac and smooth muscle
First-line agents for various pediatric cardiovascular conditions
Different classes have varying selectivity for cardiac vs. vascular tissue
Require careful dose titration and monitoring in pediatric populations
Available in various formulations suitable for different age groups

Primary Indications

Hypertension
Supraventricular tachycardia
Vasospastic conditions
Migraine prophylaxis
Raynaud's phenomenon

Drug Classification

Dihydropyridines (DHP)

First Generation
- Nifedipine (short-acting)
- Nicardipine
Second Generation
- Amlodipine
- Felodipine
- Isradipine
Third Generation
- Lercanidipine
- Clevidipine

Non-Dihydropyridines

Phenylalkylamines
- Verapamil
Benzothiazepines
- Diltiazem

Clinical Pharmacology

Mechanism of Action

Primary Action
- Blockade of L-type calcium channels
- Reduction in intracellular calcium
- Decreased smooth muscle contraction
- Reduced cardiac conductivity (non-DHP)
Tissue Selectivity
- DHP: Primarily vascular
- Non-DHP: Both cardiac and vascular

Pharmacokinetics

Absorption

Variable oral bioavailability (20-85%)
Significant first-pass metabolism
Food effects vary by agent

Distribution

High protein binding (>90%)
Large volume of distribution
Good tissue penetration

Metabolism

Primarily hepatic via CYP3A4
Active metabolites for some agents
Age-dependent clearance rates

Therapeutic Applications

Hypertension Management

First-line Agents
- Amlodipine: Primary choice for chronic therapy
- Clevidipine: Acute hypertensive crisis
- Nicardipine: IV therapy for urgent cases
Clinical Considerations
- Age-specific responses
- Combination therapy strategies
- Long-term management plans

Arrhythmia Management

Verapamil Use
- SVT in children >1 year
- Rate control in atrial fibrillation
- Contraindicated in infants
Diltiazem Applications
- Acute rate control
- Chronic rhythm management
- Limited pediatric data

Other Indications

Migraine prophylaxis
Vasospastic disorders
Post-operative hypertension
Kawasaki disease

Administration & Dosing

Amlodipine

Initial Dose
- 1-5 years: 0.1 mg/kg/day
- 6-17 years: 2.5-5 mg daily
Maximum Dose
- 1-5 years: 0.6 mg/kg/day
- 6-17 years: 10 mg daily

Nicardipine IV

Initial Rate
- 0.5-1 μg/kg/min
Titration
- Increase by 0.5-1 μg/kg/min every 15-30 minutes
- Maximum: 3 μg/kg/min

Verapamil

SVT (Acute)
- Initial: 0.1-0.2 mg/kg IV
- Maximum single dose: 5 mg
- Contraindicated <1 year
Oral Therapy
- 4-8 mg/kg/day divided q8h
- Maximum: 480 mg/day

Monitoring & Safety

Adverse Effects

DHP CCBs
- Peripheral edema
- Flushing
- Headache
- Gingival hyperplasia
Non-DHP CCBs
- Heart block
- Bradycardia
- Constipation
- Heart failure exacerbation

Monitoring Parameters

Baseline Assessment
- ECG
- Blood pressure
- Liver function
- Renal function
Ongoing Monitoring
- Regular BP checks
- Heart rate monitoring
- Signs of edema
- Growth assessment
- Drug interactions

Further Reading