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Zaditor: Relief of Ocular Itching

Last updated on October 7, 2021


Brand Name: Zaditor
Active Ingredient: ketotifen fumarate
Indication: Provides temporary relief from itching of the eye due to allergic conjunctivitis
Dosage Form(s): opthalmic solution, 0.025%
Company Name: Ciba Vision
Availability: Not approved for marketing as of Aug 99


Following a priority review, Zaditor (ketotifen) was approved by the FDA on July 2, 1999. The priority review was granted because, as an antihistamine for ocular itching, Zaditor is in a different class from other currently approved ocular itching drugs. Ketotifen capsules are marketed by Novartis, Ciba’s parent company, outside the United States for the systemic treatment of bronchial allergies and asthma.

How it Works

Zaditor (ketotifen) is a histamine antagonist and mast cell stabilizer. This dual activity prevents mast cell degranulation, which limits the release of inflammatory mediators; secondly, the mediators from cells involved from hypersensitivity reactions are directly inhibited by ketotifen. Other currently approved drugs for this indication rely primarily on the direct inhibition of the activity of histamine and other inflammatory mediators in the eye.

Zaditor (ketotifen): Clinical Study Results

Although the systemic use of ketotifen has been well documented for the management of allergies and related bronchospastic disorders, there is little published information about the clinical activity of the drug in eye drop formulation. No specific results of clinical studies are noted in the direction circular for Zaditor (ketotifen), and a Medline search did not identify any clinical studies that used this drug. However, in vitro studies have shown the antihistaminic activity of ketotifen to be equal to that of emedastine and more than 5,000 times more potent than that of brompheniramine.

Published results of a clinical trial using a 0.1% ophthalmic preparation of ketotifen found a 91% effectiveness rate in reducing conjunctivitis caused by pollinosis, and this effect was typically evident within the first three days of treatment.

The recommended dose is one drop in the affected eye every 8 to 12 hours, thereby providing relatively convenient twice or three-times-a-day dosing.

What the Patient Should Know

Worsening of conjunctival irritation, headaches, and rhinitis were the most commonly reported adverse events during the controlled clinical studies of Zaditor (ketotifen). However, the occurrences were generally mild. In an effort to avoid contamination of the dropper tip and solution, the tip of the dropper should not touch the eyelids or surrounding areas. Also, the bottle should be kept tightly closed when not being used. Contact lenses should not be inserted for at least 10 minutes after using Zaditor (ketotifen). Zaditor is not intended to treat irritation due to contact lenses, and contact lenses should not be used if the eye is red.

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