What is the recommended dose of chlorpheniramine (antihistamine) syrup for an 11-year-old boy weighing 30 kg, given a concentration of 2 mg in 5 ml?

Chlorpheniramine Dosage for an 11-Year-Old Boy Weighing 30 kg

For an 11-year-old boy weighing 30 kg, the appropriate dose of chlorpheniramine syrup (2 mg/5 ml) is 2 mg (5 ml) given 3-4 times daily, not exceeding 8 mg (20 ml) per day.

Dosage Calculation

The dosage of chlorpheniramine for children is age-dependent and weight-dependent:

• For children 6-12 years old: 2 mg (5 ml) every 4-6 hours
• Maximum daily dose: 8 mg (20 ml) per day

Since this 11-year-old patient falls within the 6-12 years age group and weighs 30 kg, the standard pediatric dosing applies.

Administration Guidelines

• Administer the medication orally
• Can be given with or without food
• Space doses evenly throughout the day (every 4-6 hours)
• Do not exceed 4 doses in 24 hours

Clinical Considerations

Efficacy

• Therapeutic serum concentrations of chlorpheniramine in children range from 2.3 to 12.1 ng/ml for symptom suppression 1
• The medication has a large volume of distribution (7.0 ± 2.8 L/kg in children), suggesting significant tissue binding is important for its efficacy 1

Pharmacokinetics

• Half-life in children: 13.1 ± 6.3 hours 1
• Clearance rate in children: 7.2 ± 3.2 ml/min/kg 1
• The medication may take 30-60 minutes to start working

Safety Considerations

• Monitor for common side effects:

  • Drowsiness
  • Dry mouth
  • Blurred vision
  • Constipation
  • Urinary retention

• Avoid concurrent use with other antihistamines or medications with anticholinergic properties

• Use caution if the child has asthma, as antihistamines may thicken bronchial secretions

Special Populations

For children with renal or hepatic impairment, dose reduction may be necessary as chlorpheniramine is primarily metabolized by the liver and excreted by the kidneys.

Common Pitfalls to Avoid

1. Incorrect concentration calculation: Always verify the concentration of the syrup (2 mg/5 ml in this case)

2. Weight verification: Always document and verify the child's weight in kilograms before prescribing 2

3. Overdosing: Avoid exceeding the maximum daily dose of 8 mg for this age group

4. Drug interactions: Be aware of potential interactions with other medications that may have additive sedative effects

5. Sustained-release formulations: These are generally not recommended for children under 12 years of age

By following these guidelines, chlorpheniramine can be safely and effectively administered to this 11-year-old patient for the treatment of allergic conditions.