Second-Generation Topical H1 Receptor Antagonists
Azelastine and olopatadine are the two FDA-approved second-generation topical H1 receptor antagonists available for intranasal use in allergic rhinitis. 1
Intranasal Formulations
Azelastine
- Astelin 0.1% solution (137 µg per spray): Approved for seasonal allergic rhinitis and vasomotor rhinitis in patients ≥6 years
- Dosing: Ages 6-11 years: 1 spray twice daily; Ages ≥12 years: 1-2 sprays twice daily or 2 sprays daily
- Astepro 0.15% solution (205.5 µg per spray): Approved for seasonal and perennial allergic rhinitis in patients ≥6 years, with improved taste formulation (sorbitol and sucralose added) 1
Olopatadine
- Patanase 0.6% (665 µg per spray): Approved for seasonal allergic rhinitis in patients ≥6 years
- Dosing: Ages 6-11 years: 1 spray twice daily; Ages ≥12 years: 2 sprays twice daily 1
Clinical Advantages
Intranasal antihistamines demonstrate superiority to oral antihistamines for nasal congestion and show benefit even in patients who fail oral antihistamine treatment. 1 The targeted delivery increases dosage to nasal tissues while limiting systemic effects, with somnolence rates of only 0.4-3% in recent studies (comparable to placebo), far lower than the 11% quoted in early studies. 1
Common Side Effects
- Bitter taste (most common complaint)
- Epistaxis
- Headache
- Minimal somnolence 1
Ophthalmic Formulations
For ocular allergies, second-generation topical H1 receptor antagonists with dual action (antihistamine and mast cell stabilizer properties) include:
- Azelastine (Optivar)
- Olopatadine (Pataday, Patanol)
- Epinastine (Elestat)
- Ketotifen (Alaway, Zaditor) 2, 3
These dual-action ophthalmic agents have onset of action within 30 minutes and are suitable for both acute and longer-term treatment of allergic conjunctivitis, generally demonstrating superior efficacy compared to other ocular agents in preventing or treating ocular itching. 2, 3
Clinical Positioning
While intranasal antihistamines are highly effective, they are often considered second-line therapy after nasal steroids or oral antihistamines due to taste aversion, increased cost, and more frequent dosing requirements. However, they represent appropriate first-line therapy for specific patients, particularly those with prominent nasal congestion or those who have failed oral antihistamines. 1 Taste varies between formulations, so trialing a second formulation may be beneficial if the first causes taste aversion but provides symptomatic benefit. 1