Azelastine hydrochloride: a review of pharmacology, pharmacokinetics, clinical efficacy and tolerability.

Azelastine hydrochloride (Astelin) nasal spray 0.1% solution is a second-generation intranasal antihistamine available in the US for treatment of both seasonal allergic rhinitis (SAR) and nonallergic vasomotor rhinitis (VMR). Searches of journal articles including the title word 'azelastine' from 1979 through the present were conducted by the product manufacturer primarily through Medline and EMBASE but also included, at various times, Dialog, Biosis, Toxline, and Diogenes (an adverse-event database). One limitation of the present review is that it could not exclude the possibility of publication bias, whereby findings from smaller studies and/or trials with negative findings may not have been published. Azelastine is a phthalazinone derivative with H(1)-receptor binding approximately tenfold greater than chlorpheniramine on a milligram-per-milligram basis. Azelastine has demonstrated a wide range of pharmacologic effects on chemical mediators of inflammation including leukotrienes, kinins, and platelet activating factor in vitro and in vivo. The molecule also has been shown to downregulate intercellular adhesion molecule-1 expression and to reduce inflammatory cell migration in patients with rhinitis. Well-controlled studies in SAR and VMR demonstrated that azelastine nasal spray improves nasal symptoms of rhinitis, including congestion and postnasal drip, and has a rapid onset of action that appears likely due to topical activity. Azelastine nasal spray has demonstrated greater efficacy when used in combination with fluticasone propionate nasal spray when compared to either agent alone, and this combination may provide benefit for patients with moderate-to-severe rhinitis. Bitter taste is the most common side effect associated with azelastine nasal spray and this problem can be mitigated by the dosing technique recommended by the manufacturer in the product labeling. The incidence of somnolence also may be reduced with the recommended administration technique. Azelastine is an effective, rapid-acting, and well-tolerated second-generation antihistamine that improves nasal symptoms associated with SAR and VMR. Clinical studies demonstrated that azelastine nasal spray can improve symptoms of SAR in patients who remained symptomatic after treatment with oral antihistamines and that azelastine nasal spray in combination with fluticasone nasal spray provided significantly (p < 0.05) greater relief than either agent alone in patients with SAR.