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Azelastine is formulated to have a very long half life and a very high affinity for the H1 receptor it affects.
North Arlington, NJ-Azelastine hydrochloride (Optivar, MedPointe Healthcare) is not new to the anti-allergy drug armamentarium, having entered the market in about 2000, but it continues to be highly beneficial for many patients because of its multimodal mechanism of action, according to John Favetta, MD.
Dr. Favetta, who has a large population of patients with ocular allergies in his private practice in North Arlington, NJ, tends to use azelastine for those who have mild to moderate, and in some cases severe, symptoms of seasonal and perennial allergic conjunctivitis.
"The drug seems to work very well. We even use it for giant papillary conjunctivitis occurring in contact lens wearers or patients exposed to suture knots who develop inflammatory changes in the upper and lower eyelids," he explained.
Pharmacokinetics of azelastine
Azelastine is formulated to have a very long half life, according to Dr. Favetta, and a very high affinity for the H1 receptor that it affects.
"In my opinion, the multimechanistic nature of a drug is the characteristic that is desirable in an ideal eye drop. It should have very good antihistamine qualities, which azelastine does, and this is the reason it works so quickly," Dr. Favetta explained. "The drug should also stabilize mast cells, as azelastine does. Finally, the drug should be able to inhibit additional inflammatory cells within the emerging inflammatory cascade. Azelastine is unique in that respect, in that it is long acting and affects both the early and late phases of the allergic inflammatory cascade."
He compared azelastine with a similar drug, olopatadine hydrochloride (Patanol, Alcon Laboratories), which entered the market in 1996 and was indicated for the treatment of itching associated with allergic conjunctivitis. Olopatadine is an antihistamine and a mast-cell stabilizer. In comparison, azelastine has those two properties, and can reduce platelet activating factor and reduce the formation of leukotrienes, which are in the late-phase reaction of the allergic response and prolong the allergic reaction. Azelastine also can decrease eosinophilic chemotaxis, that is, the migration of inflammatory cells into the affected area, according to Dr. Favetta.
"With the ability to reduce eosinophilic chemotaxis, the inflammatory response can be reduced. So when comparing apples and apples, azelastine is a superior drug," he emphasized.
And while this description paints a picture of an almost perfect drug for patients with ocular allergies, the drug does not work for every patient.
"In some patients, the drug has no effect and in others it causes a taste perversion that is undesirable. The beneficial effects, however, outweigh the negative ones in the small percentages of patients for whom the drug has no benefit," he commented.
Dr. Favetta described a few patients in his practice that illustrate the effect of azelastine.
Case 1 was that of an 11-year-old child who presented with severe allergic conjunctivitis in the spring of 2006. After being examined, she received a prescription for azelastine and was asked to return for reexamination in 3 weeks. Two hours later, a call from the child's pharmacy indicated that azelastine was not covered by her insurance and another drug was substituted. Within 1 week of treatment with the substitute drug, the child returned to the office because of lack of improvement in her condition. Because the family had a fixed income and was unable to pay for azelastine, Dr. Favetta provided the patient with samples of the drug, which resulted in marked improvement in her condition.
Case 2 involved a 42-year-old woman who wore 2-week disposable contact lenses. She presented with multiple ineffective antiallergy medications and the complaint that she cannot wear her contact lenses for longer than 2 hours at a time because of intense itching, redness, and burning.