Ketotifen (Monograph)

Brand name: Zaditor
Drug class: Antiallergic Agents
- Histamine H1-receptor Antagonists
- Mast-cell Stabilizers
ATC class: S01GX08
VA class: OP900
Chemical name: 10H-Benzo(4,5)cyclohepta(1,2-b)thiophen-10-one,4,9-dihydro-4-(1-methyl-4-piperidinylidene)
Molecular formula: C₁₉H₁₉NOS
CAS number: 34580-13-7

Medically reviewed by Drugs.com on Feb 19, 2025. Written by ASHP.

Introduction

Relatively selective histamine H₁-receptor antagonist and mast-cell stabilizer.

Uses for Ketotifen

Allergic Conjunctivitis

Self-medication for temporary relief of ocular itching associated with allergic conjunctivitis (i.e., conjunctivitis due to pollen, grass, ragweed, or animal hair or dander).

Ketotifen Dosage and Administration

Administration

Ophthalmic Administration

Apply topically to the eye as an ophthalmic solution.

Dosage

Available as ketotifen fumarate; dosage expressed in terms of ketotifen.

Pediatric Patients

Allergic Conjunctivitis

Ophthalmic

One drop of a 0.025% solution in the affected eye(s) twice daily (at an interval of 8–12 hours) for those ≥3 years of age.

Adults

Allergic Conjunctivitis

Ophthalmic

One drop of a 0.025% solution in the affected eye(s) twice daily (at an interval of 8–12 hours).

Prescribing Limits

Pediatric Patients

Allergic Conjunctivitis

Ophthalmic

Do not administer more frequently than twice daily.

Adults

Allergic Conjunctivitis

Ophthalmic

Do not administer more frequently than twice daily.

Cautions for Ketotifen

Contraindications

Known hypersensitivity to ketotifen or any ingredient in the formulation.

Warnings/Precautions

Specific Populations

Pregnancy

Category C.

Lactation

Distributed into milk in rats following oral administration. Cautious use is recommended.

Pediatric Use

Safety and efficacy not established in children <3 years of age.

Should not be used in children <3 years of age unless otherwise directed by a clinician.

Common Adverse Effects

Conjunctival injection, headaches, rhinitis. Some events may be related to the underlying ocular disease.

Ketotifen Pharmacokinetics

Absorption

Bioavailability

Minimally absorbed following topical application to the eye.

Onset

Within minutes after topical application to the eye.

Stability

Storage

Ophthalmic

Solution

4–25°C.

Do not use if solution changes color or becomes cloudy.

Actions

Suppresses the release of mediators from cells involved in hypersensitivity reactions and decreases chemotaxis and activation of eosinophils.

Advice to Patients

Importance of learning and adhering to proper administration techniques to avoid contamination of the product.
Importance of delaying insertion of contact lenses for at least 10 minutes after ketotifen instillation to prevent absorption of benzalkonium chloride by contact lenses.
Not indicated for contact lens-related irritation.
Importance of reporting new-onset eye pain or discomfort, visual disturbances, eye redness, worsening of itching, or itching lasting >72 hours.
Importance of seeking quick medical attention if preparation is ingested orally.
Importance of women informing clinicians if they are or plan to become pregnant or plan to breast-feed.
Importance of informing clinicians of existing or contemplated concomitant therapy, including prescription and OTC drugs, as well as any other concomitant illnesses.
Importance of informing patient of other important precautionary information. (See Cautions.)

Preparations

Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.

Please refer to the ASHP Drug Shortages Resource Center for information on shortages of one or more of these preparations.