THERAPEUTIC FOCUS

Drop the Itch

Eye drop relieves itching associated with allergic conjunctivitis.

Marc Bloomenstein, O.D., F.A.A.O.

Ask any allergic conjunctivitis patient to name the condition's worst symptom, and most will reply: “the itching.” The reason: The itching associated with allergic conjunctivitis cannot be rubbed for relief. In fact, doing so actually exacerbates the itching, as the eye releases additional histamine—the cause of the itching in the first place—in response. In my practice, I've begun prescribing these patients a drug that prevents allergic conjunctivitis-associated itching as well as other aspects of the allergic cascade. It's called alcaftadine ophthalmic solution 0.25%, (Lastacaft, Allergan).

Here, I provide an overview of the drug, its efficacy and its use in my practice.

Overview

Lastacaft 0.25% is an H1 histamine receptor antagonist that received FDA approval for the prevention of itching associated with allergic conjunctivitis in patients age two and older in July 2010. Specifically, the once-daily drug (one drop in each eye) inhibits the release of histamine from mast cells and also demonstrates a decrease of chemotaxis and the inhibition of eosinophil activation.

In addition to its active ingredient (alcaftadine 0.25%), Lastacaft is comprised of the inactive ingredients edetate disodium, monobasic sodium phosphate, purified water, sodium chloride, sodium hydroxide and/or hydrochloric acid to adjust pH.¹ (The drug has a pH of 7 and an osmolarity of approximately 290 mOsm/kg.) Further, it contains the preservative benzalkonium chloride (BAK) 0.005%.

The most common ocular adverse events seen in clinical trials were eye irritation, burning, and/or stinging upon instillation, eye redness and eye pruritus in less than 4% of Lastacaft-treated eyes.¹ The most frequent non-ocular adverse events seen in clinical trials were nasopharyngitis, headache and influenza in less than 3% of Lastacaft-treated subjects. (The drug's safety was evaluated in a randomized clinical study of 909 subjects through six weeks.)

The drug comes in an opaque, white low-density polyethylene bottle with a white polypropylene cap. As is the case with all eye drop medications I prescribe, I educate those to whom I prescribe Lastacaft to avoid touching their eyelids and the surrounding areas with the dropper tip and to keep the bottle tightly shut when they're not using it to both minimize contaminating the dropper tip and the medication itself.

Efficacy

Lastacaft's efficacy was tested via conjunctival allergen challenge (CAC) studies. These studies present a known allergen to a subject's eye and assess both the onset and duration of a medication. Specifically, the subject uses the medication 15 minutes before exposure to the known allergen, and he then rates itching at three, five and seven minutes post-allergen exposure. To determine a medication's duration of effectiveness, the subject uses the drug 16 hours before exposure to the allergen and also rates itching at three, five and seven minutes post-allergen exposure.

Lastacaft 0.25% inhibits the release of histamine from mast cells and also demonstrates a decrease of chemotaxis and the inhibition of eosinophil activation.

In three randomized, placebo-controlled trials, which included 274 allergic conjunctivitis patients, Lastacaft was shown to significantly decrease itching vs. vehicle, and patients reported an onset of effect at three minutes post-instillation. Further, the Lastacaft subjects reported the drug's duration of effect at 16 hours post-instillation.

In practice

Allergic conjunctivitis not only affects our patients' eyes, but also their quality of life. I've especially noticed this with my contact lens wearers. They love being spectacle free, yet have no choice but to forgo lens wear until the condition subsides. Lastacaft has made me a hero to many of these patients, as the drug has enabled these patients to have continuous lens wear. Moreover, all those allergic conjunctivitis patients to whom I've prescribed the drug have told me they appreciate its one-drop dosing convenience as well as its fast action and prolonged effect.

As doctors of the eye we are the “eyes” for our patients' vision and their ocular comfort. Having the ability to provide a medication that not only relieves the worst part of allergic conjunctivitis but also prevents other aspects of the allergic cascade, reinforces the importance of our role as a member of their health-care team. OM

1. Lastacaft Prescribing information. www.allergan.com/assets/pdf/lastacaft_pi.pdf. (Accessed May 17, 2011.)

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Dr. Bloomenstein is director of optometric services at the Schwartz Laser Eye Center in Scottsdale, Ariz. He's a founding member of the Optometric Council on Refractive Technology. E-mail him at drbloomenstein@schwartzlaser.com, or send comments to optometricmanagement@gmail.com.