Once-daily drug is physician’s go-to therapy for ocular allergy

TAKE HOME:

Alan G. Kabat, OD, discusses why olopatadine 0.2% is his preferred anti-allergy medication for managing mild-to-moderate seasonal allergic conjunctivitis.

Dr. Kabat

By Cheryl Guttman Krader; Reviewed by Alan G. Kabat, OD

Memphis, TN-Topical antihistamine-mast cell stabilizers are regarded as the mainstay treatment for seasonal allergic conjunctivitis (SAC) because of their safety, tolerability, and ability to provide prompt and ongoing relief.

While this class of dual-acting agents contains several medications, including over-the-counter and prescription agents, Alan G. Kabat, OD, said that olopatadine HCl 0.2% (Pataday, Alcon Laboratories) is his “go-to” product for managing patients with mild-to-moderate SAC.

“There are other safe and effective options for treating SAC,” said Dr. Kabat, professor, Southern College of Optometry, Memphis, TN. “However, I like the science supporting olopatadine. It is a highly selective H1 antagonist and has demonstrated superiority for efficacy and tolerability when compared with multiple other anti-allergy agents in head-to-head trials.”

“The published study results mirror my clinical practice experience,” he said. “I use olopatadine 0.2% to treat my own ocular allergy, and when I prescribe it for patients with SAC, I know I can rely on it to be successful 99% of the time.”

Dr. Kabat noted that the comparator trials were conducted using the original formulation of olopatadine that contained 0.1% of the active ingredient. Results of a clinical trial using a conjunctival allergen challenge model established that olopatadine 0.2% once daily dosing was as effective as olopatadine 0.1% twice a day for preventing ocular itching associated with allergic conjunctivitis [Curr Eye Res. 2007;32:1017-22].

“Olopatadine 0.2% is just one of two antihistamine-mast cell stabilizers that is approved for once-daily dosing,” Dr. Kabat said. “Patients like the convenience of that schedule and it is particularly nice for contact lens wearers who do not have to remove their lenses during the day to instill a second dose.”

“In fact, contact lens wearers whose eyes are irritated and uncomfortable toward the end of the day may find particular benefit from instilling their daily drop of olopatadine 0.2% in the evening after they take out their lenses,” he said.

In a worst-case scenario where the environmental allergen load is extremely high, patients might achieve better round-the-clock allergy control if they use olopatadine 0.2% twice a day, he added. Patients with a more severe flare-up of their allergy may need treatment with a topical corticosteroid.

Safety allows self-treatment

Taking into account the efficacy and favorable safety of olopatadine 0.2%, Dr. Kabat said that for demonstrated trustworthy patients who regularly return for follow-up visits, he is very comfortable writing a prescription for olopatadine 0.2% with open refills. Patients are instructed to begin using the medication a few weeks prior to the onset of allergy season and to continue using it for the duration of the season.

“Ideally, patients who are known to have SAC should start using their antihistamine-mast cell stabilizer as a preventive strategy before allergen levels begin to increase,” Dr. Kabat said. “The reality, however, is that most patients turn to their allergy medication as rescue therapy only after they are bothered by their signs and symptoms.”

“In either case, it is helpful to allow dependable patients to have medication on hand so that they can self-treat,” he said. “This approach will also reduce the possibility that they turn to over-the-counter anti-allergy medications, which are attractive because of their convenience but not as effective as olopatadine 0.2% and other prescription antihistamine-mast cell stabilizers.”

Dispelling dry eye myth

Although there has been some discussion about differential antimuscarinic effects of ophthalmic antihistamines, Dr. Kabat noted there has never been any translational work showing that these pharmacologic differences are clinically meaningful with respect to propensity to cause or exacerbate dry eye.

In a randomized, double-masked clinical trial including 52 patients with allergic conjunctivitis and dry eye who were assigned to use olopatadine 0.2% or saline once daily for 1 week, there were no significant differences between treatment groups at the end of the study in evaluations of tear film break-up time, corneal and conjunctival staining, tear volume and flow, Schirmer test, injection, or symptom evaluations [Curr Med Res Opin. 2008;24:441-447].

“Oral antihistamines, and particularly older generation agents such as diphenhydramine, act at the level of the autonomic nervous system and can cause drying of the ocular surface,” Dr. Kabat said. “However, it has never been shown conclusively that any topical medications with antihistaminic activity cause or worsen dry eye.”

“In contrast, it is my anecdotal observation that patients with allergic conjunctivitis and comorbid dry eye have a reduction in their dry eye symptoms when using a medication that effectively controls their ocular allergy.”

Alan G. Kabat, OD

E: alan.kabat@alankabat.com

Dr. Kabat is a consultant to Alcon Laboratories.

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