Livocitrijan (Levocetirizine)
Livocitrijan is a brand name for levocetirizine, a second-generation selective H₁-receptor antagonist (antihistamine). It is the active R-enantiomer of cetirizine.
Mechanism of Action
Levocetirizine competitively and selectively blocks peripheral H₁ histamine receptors. Compared to its parent compound cetirizine, it has approximately twice the binding affinity for H₁ receptors, allowing effective action at half the dose. It has minimal CNS penetration relative to first-generation antihistamines.
Indications
| Indication | Details |
|---|
| Allergic rhinitis (AR) | Seasonal and perennial |
| Chronic idiopathic urticaria | Relieves itch, wheals, and flare |
| Allergic conjunctivitis | Symptomatic relief |
| Atopic dermatitis | Adjunct for pruritus |
Dosing
| Population | Standard Dose |
|---|
| Adults & children ≥12 years | 5 mg once daily (evening) |
| Children 6–11 years | 2.5 mg once daily |
| Children 6 months–5 years | 1.25 mg once daily |
| Renal impairment (CrCl 30–50 mL/min) | 2.5 mg once daily |
| Renal impairment (CrCl 10–30 mL/min) | 2.5 mg every 48 hours |
| Severe renal failure / hemodialysis | Contraindicated |
Best taken in the evening to minimize any residual drowsiness.
Advantages Over First-Generation Antihistamines
According to Rhinitis guidelines (p. 22), second-generation antihistamines like levocetirizine significantly reduce the risk of:
- Sedation and performance impairment
- Poor sleep quality
- Anticholinergic effects: dry eyes, dry mouth, constipation, urinary hesitancy/retention
Side Effects
- Common: Somnolence (less than first-generation), headache, dry mouth, fatigue, nasopharyngitis
- Less common: Nausea, dizziness, weight gain with long-term use
- Rare: Hypersensitivity reactions (urticaria, angioedema, anaphylaxis)
Contraindications
- Severe renal impairment (CrCl < 10 mL/min) or end-stage renal disease on hemodialysis
- Known hypersensitivity to levocetirizine, cetirizine, or hydroxyzine
- Children under 6 months
Key Pharmacokinetic Properties
| Parameter | Value |
|---|
| Bioavailability | ~100% (oral) |
| Onset of action | ~1 hour |
| Peak plasma (Tmax) | ~0.9 hours |
| Half-life (t½) | ~6–10 hours |
| Protein binding | ~91–92% |
| Elimination | ~85% renal (unchanged) |
Because most elimination is renal and unchanged, dose adjustment is essential in renal impairment.
Comparison with Other Second-Generation Antihistamines
| Drug | Sedation | Onset | Renal Dose Adj. |
|---|
| Levocetirizine | Low | Fast (~1h) | Yes |
| Fexofenadine | Very low | Moderate | No |
| Loratadine | Very low | Moderate | No |
| Desloratadine | Very low | Moderate | No |
| Cetirizine | Low-moderate | Fast | Yes |
Levocetirizine is generally preferred when rapid onset is needed and when a well-tolerated, once-daily agent is appropriate. Its primary limitation is the need for dose reduction in renal impairment, unlike fexofenadine or loratadine.