Azelastine is a newer H1 blocker, has good topical activity and additionally suppresses histamine release and inflammatory reactions caused by LTs (by inhibiting lipoxygenase) and PAF. It has been demonstrated to reduce intracellular adhesion molecule-1 (ICAM-1) expression on nasal mucosa after intranasal administration. It has a t½ of 24 hours, however due to the active metabolite, it has a prolonged duration of action. Its metabolism is inhibited by CYP 3A4 inhibitors. For seasonal and perennial allergic rhinitis, it is administered as a nasal spray that offers immediate symptomatic relief that lasts for 12 hours. Local side effects include nasal stinging and impaired taste perception. Some somnolence has been reported on nasal application and a tendency to weight gain noted after oral use.
Drug class
H1 antihistamine, 2nd generation
Available preparations
azelastine hydrochloride
- Tablet: 4 mg
- Nasal spray: 0.14 mg/puff aerosol
- Eye drop: 0.05% ophthalmic solution
Dosage
- Adult: 0.28 mg intranasal, once or twice daily
- Children: 0.14 mg intranasal, once or twice daily (not recommended below 6-year age)
Common uses
- Seasonal allergic rhinitis such as rhinorrhea, sneezing, and nasal pruritus
- Vasomotor rhinitis such as rhinorrhea, nasal congestion and postnasal drip
- Ocular itching associated with allergic conjunctivitis
- Sinusitis
Side effects
Common:
- Bitter taste
- Nasal burning
- Paroxysmal sneezing
Rare side effects:
- Somnolence (on oral as well as intranasal application)
- Headache
- Weight gain (after oral use)
Pharmacological characteristics (PK, PD)
- Onset of action: 15 minutes (intranasal formulations), 3 minutes (ophthalmic solutions)
- Duration of action: 12 hours
- Half-life (t1/2): 24 hours
- Metabolized by CYP 3A4 to active metabolite, hence metabolism inhibited by CYP 3A4 inhibitors
- Systemic bioavailability after intranasal application: 40% with Cmax 3-4 hours
- After oral dose, 75% (approx.) excreted in feces