Azelastine hydrochloride

Azelastine hydrochloride is an orally effective antihistamine useful in the treatment of asthma and nasal allergy. It appears to inhibit release of histamine, in addition to antagonizing its action.

White or almost white, crystalline powder.

Orally active H1-hystamine receptor antagonist. Antihistaminic

Azelastine Hydrochloride is the hydrochloride salt form of azelastine, a phthalazinone derivative with antihistaminergic activity. Azelastine hydrochloride exhibits histamine H1-receptor antagonist activity in isolated tissues, animal models, and humans. Azelastine hydrochloride nasal solution is administered as a racemic mixture, and no difference in pharmacologic activity was noted between the enantiomers in vitro studies. The major metabolite, desmethylazelastine, also possesses H1-receptor antagonist activity. It competes with histamine for the H1 receptor, thereby diminishing the actions of histamine on effector cells and decreasing the histamine-mediated symptoms of allergic reaction, such as bronchoconstriction, vasodilation, increased capillary permeability and spasmodic contractions of gastrointestinal smooth muscle.

ChEBI: The hydrochloride salt of azelastine.

(±)-4-[(4-chlorophenyl)methyl]-2-(hexahydro-l-methyl-1H-azepin-4-yl)-l-(2H)-phthalazinone monohydrochloride (Optivar), is a whitecrystalline powder that is sparingly soluble in water,methanol, and propylene glycol and slightly soluble inethanol, octanol, and glycerine. The commercial preparationis available as a 0.05% sterile ophthalmic solution fortopical administration to the eyes. Each milliliter of azelastinesolution contains 0.5-mg azelastine hydrochlorideequivalent to 0.457 mg of azelastine base, the preservativebenzalkonium chloride (0.125 mg), and inactive ingredientsincluding disodium edetate dihydrate, hydroxypropylmethylcellulose,sorbitol solution, sodium hydroxide, andwater for injection. The solution has a pH of approximately5.0 to 6.5 and an osmolality of approximately 271to 312 mOsm/L.
The recommended dose of azelastine solution is 1 dropinstilled into each affected eye twice a day. This drugproduct is for ocular administration only and not for injectionor oral use. Absorption of azelastine following ocularadministration is relatively low (less than 1 ng/rnL).Absorbed drug undergoes extensive oxidative N-demethylationby CYP, and the parent drug and metabolite are eliminatedprimarily in the feces. The most frequently reportedadverse reactions are transient eye burning or stinging,headaches, and bitter taste. Azelastine solution should beused with caution during pregnancy or while nursing, becauseits safety has not been studied under these circumstances.

Poison by ingestion andintravenous routes. An experimental teratogen. Otherexperimental reproductive effects. When heated todecomposition it emits toxic fumes of NOx and HCl.