Levocetirizine Dosing in Pediatric Patients
For children aged 12-24 months, levocetirizine should be dosed at 0.125 mg/kg twice daily, and for children aged 2-5 years, the dose is 1.25 mg (2.5 mL of oral solution) twice daily. 1, 2
Age-Based Dosing Recommendations
Infants and Toddlers (12-24 months)
- Dose: 0.125 mg/kg twice daily 2, 3
- This weight-based dosing accounts for the rapid oral clearance of levocetirizine in very young children, which increases with body weight at a rate of 0.044 L/h/kg 1
- Twice-daily dosing is necessary in this age group because the elimination half-life is approximately 4.1 hours, significantly shorter than in adults 2
Young Children (2-5 years)
- Dose: 1.25 mg (2.5 mL oral solution) twice daily 4
- This standardized dose has been validated in clinical trials for seasonal allergic rhinitis in children 4
Older Children (6-12 years)
- Dose: 5 mg once daily 4
- The once-daily dosing in older children provides equivalent exposure to adults taking the recommended 5 mg daily dose 5
Pharmacokinetic Rationale
The higher per-kilogram dosing requirement in younger children is driven by their increased weight-normalized clearance compared to adults. 1, 5
- In children weighing 8-20 kg, the clearance (CL/F) ranges from 0.60 to 1.13 L/h, with volume of distribution (V/F) ranging from 5.1 to 12.8 L 5
- Peak plasma levels of approximately 286 ng/mL occur within 1 hour of administration in toddlers 2
- Steady-state trough levels of 78-110 ng/mL maintain therapeutic efficacy with twice-daily dosing 2
Safety Profile
Long-term safety has been established in children as young as 12 months, with an 18-month study showing no significant differences in adverse events between levocetirizine and placebo. 3
- Adverse event rates were similar between levocetirizine (96.9%) and placebo (95.7%), with most events related to upper respiratory infections or gastroenteritis rather than medication effects 3
- No significant differences were observed in growth parameters, developmental milestones, or laboratory values 3
- Treatment discontinuation due to adverse events occurred in only 2.0% of children receiving levocetirizine versus 1.2% on placebo 3
Clinical Efficacy Considerations
- The twice-daily dosing regimen of 0.125 mg/kg in children aged 12-48 months yields the same systemic exposure (AUC) as adults receiving 5 mg once daily 5
- Pharmacodynamic studies demonstrate 100% inhibition of histamine-induced wheal and 98-100% inhibition of flare response at steady state 2
- Clinical trials in seasonal allergic rhinitis showed 94.1% relative improvement over placebo with sustained efficacy over 6 weeks 4
Important Clinical Caveats
Factors that do NOT influence levocetirizine dosing include: eosinophilia, allergen sensitization status, presence of allergic disease, gastroenteritis/diarrhea, or most concomitant medications 1