OPTIVAR® (azelastine hydrochloride ophthalmic solution), 0.05% is a sterile ophthalmic solution containing azelastine hydrochloride, a relatively selective H1 -receptor antagonist for topical administration to the eyes. Azelastine hydrochloride is a white crystalline powder with a molecular weight of 418.37. Azelastine hydrochloride is sparingly soluble in water, methanol and propylene glycol, and slightly soluble in ethanol, octanol, and glycerine. Azelastine hydrochloride is a racemic mixture with a melting point of 225°C. The chemical name for azelastine hydrochloride is (±)-1-(2H)-phthalazinone,4-[(4-chlorophenyl) methyl]-2-(hexahydro-1-methyl-1H-azepin-4-yl)-, monohydrochloride and is represented by the following chemical structure:

Astelin® (azelastine hydrochloride) Nasal Spray, 137 micrograms (mcg), is an antihistamine formulated as a metered-spray solution for intranasal administration. Azelastine hydrochloride occurs as a white, almost odorless, crystalline powder with a bitter taste. It has a molecular weight of 418.37. It is sparingly soluble in water, methanol, and propylene glycol and slightly soluble in ethanol, octanol, and glycerine. It has a melting point of about 225°C and the pH of a saturated solution is between 5.0 and 5.4. Its chemical name is (±)-1-(2H)-phthalazinone,4-[(4-chlorophenyl) methyl]-2-(hexahydro-1-methyl-1H-azepin-4-yl)-, monohydrochloride. Its molecular formula is C22H24CIN3O•HCl with the following chemical structure:

ASTEPRO (azelastine hydrochloride) Nasal Spray 0.1%, 137 micrograms (mcg), is an antihistamine formulated as a metered-spray solution for intranasal administration. ASTEPRO (azelastine hydrochloride) Nasal Spray 0.15%, 205.5 micrograms (mcg), is formulated as a metered-spray solution for intranasal administration.