Class: Antiallergic Agents
- Histamine H1-receptor Antagonists
Chemical Name: 6,11-dihydro-11-(1-methyl-4-piperidinylidene)-5H-imidazo[2,1-b]  benzazepine-3-carboxaldehyde
Molecular Formula: C19H21N3O
CAS Number: 147084-10-4
Medically reviewed by Drugs.com. Last updated on April 26, 2021.
Histamine H1-receptor antagonist.
Uses for Alcaftadine
Prevention of ocular itching associated with allergic conjunctivitis.
Alcaftadine Dosage and Administration
Apply topically to the eye as an ophthalmic solution. For topical ophthalmic use only.
Remove contact lenses prior to each dose (since benzalkonium chloride preservative may be absorbed by soft lenses); may reinsert lenses after 10 minutes following administration if eyes are not red.
Avoid contamination of the solution container.
Children ≥2 years of age: 1 drop of a 0.25% solution in each eye once daily.
1 drop of a 0.25% solution in each eye once daily.
No special population recommendations at this time.
Cautions for Alcaftadine
Manufacturer states none known.
Not known whether alcaftadine is distributed into milk. Use with caution.
Safety and efficacy not established in children <2 years of age. Safety evaluated in children ≥3 years of age; efficacy in children 2–9 years of age extrapolated from demonstrated efficacy in adults and children ≥10 years of age.
No overall differences in safety and efficacy relative to younger patients.
Common Adverse Effects
Ocular effects: Irritation, burning, and/or stinging upon instillation; redness; pruritus.
Nonocular effects: Nasopharyngitis, headache, influenza.
Interactions for Alcaftadine
No formal drug interaction studies to date.
Not metabolized by CYP enzymes; does not substantially inhibit major CYP enzymes in vitro.
Appears rapidly in systemic circulation following topical application to eye. Peak plasma concentrations of alcaftadine and its active metabolite occur at a median of 15 minutes and at 1 hour, respectively, after administration.
Rapid; effect on ocular itching apparent at 3 minutes after conjunctival antigen challenge.
Effect on ocular itching shown to persist for 16 hours.
Not known whether distributed into milk.
Plasma Protein Binding
Alcaftadine: About 39%.
Carboxylic acid metabolite: About 63%.
Metabolized by cytosolic, non-CYP enzymes to an active carboxylic acid metabolite.
Carboxylic acid metabolite is eliminated mainly in urine (based on data for oral alcaftadine).
Carboxylic acid metabolite: About 2 hours.
Plasma concentrations of alcaftadine and carboxylic acid metabolite are below limit of quantitation by 3 and 12 hours, respectively, after administration of alcaftadine ophthalmic solution.
Histamine H1-receptor antagonist.
Inhibits release of mediators (e.g., histamine) from cells involved in hypersensitivity reactions (e.g., mast cells) and decreases chemotaxis and activation of eosinophils.
Advice to Patients
Importance of learning and adhering to proper administration techniques to avoid contamination of the solution. Keep dropper bottle tightly closed when not in use.
Importance of delaying insertion of contact lenses for ≥10 minutes after alcaftadine instillation to prevent absorption of benzalkonium chloride by soft lenses; do not wear contact lenses if eyes are red.
Not indicated for contact lens-related ocular irritation.
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 concomitant illnesses.
Importance of informing patients of other important precautionary information. (See Cautions.)
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.
AHFS DI Essentials™. © Copyright 2021, Selected Revisions May 6, 2011. American Society of Health-System Pharmacists, Inc., 4500 East-West Highway, Suite 900, Bethesda, Maryland 20814.
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