Azelastine, a phthalazinone compound, is a second generation histamine H1 receptor antagonist which has shown clinical efficacy in relieving the symptoms of allergic rhinitis when administered as either an oral or intranasal formulation. It is thought to improve both the early and late phase symptoms of rhinitis through a combination of antihistaminic, antiallergic and anti-inflammatory mechanisms. Symptom improvements are evident as early as 30 minutes, after intranasal administration of azelastine [2 puffs per nostril (0.56mg)] and are apparent for up to 12 hours in patients with seasonal allergic rhinitis (SAR). The effect on nasal blockage is variable: in some studies objective and/or subjective assessment showed a reduction in blockage, whereas in other studies there was no improvement. Intranasal azelastine 1 puff per nostril twice daily is generally as effective as standard doses of other antihistamine agents including intranasal levocabastine and oral cetirizine, ebastine, loratadine and terfenadine at reducing the overall symptoms of rhinitis. The relative efficacies of azelastine and intranasal corticosteroids (beclomethasone and budesonide) remain unclear. However, overall, the corticosteroids tended to improve rhinitis symptoms to a greater extent than the antihistamine. Azelastine was well tolerated in clinical trials and postmarketing surveys. The most frequently reported adverse events were bitter taste, application site irritation and rhinitis. The incidence of sedation did not differ significantly between azelastine and placebo recipients and preliminary report showed cardiovascular parameters were not significantly altered in patients with perennial allergic rhinitis (PAR).
Conclusion: Twice-daily intranasal azelastine offers an effective and well tolerated alternative to other antihistamine agents currently recommended for the symptomatic relief of mild to severe SAR and PAR in adults and children (aged > or = 12 years in the US; aged > or = 6 years in some European countries including the UK). The rapid onset, confined topical activity and reduced sedation demonstrated by the intranasal formulation of azelastine may offer an advantage over other antihistamine agents, although this has yet to be confirmed.