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Class: Antiallergic Agents
- Histamine H1-receptor Antagonists
Chemical Name: 3-Amino-9,13b-dihydro-1H-dibenz[c,f]imidazo[1,5-a]azepine
Molecular Formula: C16H15N3
CAS Number: 80012-43-7
Brands: Elestat

Medically reviewed by Last updated on June 22, 2020.


Relatively selective histamine H1-receptor antagonist1 with mast-cell stabilizing properties.2

Uses for Epinastine

Allergic Conjunctivitis

Prevention of ocular itching associated with allergic conjunctivitis.1

Epinastine Dosage and Administration


Ophthalmic Administration

Apply topically to the eye as an ophthalmic solution.1 Not for injection or oral use.1


Available as epinastine hydrochloride; dosage expressed in terms of the salt.1

Pediatric Patients

Allergic Conjunctivitis

Children ≥3 years of age: 1 drop of a 0.05% solution in each eye twice daily for up to 8 weeks.1

Continue therapy throughout period of exposure (i.e., until pollen season is over or until exposure to offending allergen is terminated), even in absence of symptoms.1


Allergic Conjunctivitis

1 drop of a 0.05% solution in each eye twice daily for up to 8 weeks.1

Continue therapy throughout period of exposure (i.e., until pollen season is over or until exposure to offending allergen is terminated), even in absence of symptoms.1

Cautions for Epinastine


  • Known hypersensitivity to epinastine or any ingredient in the formulation.1


Specific Populations


Category C.1


Distributed into milk in rats; not known whether distributed into human milk.1 Use with caution.1

Pediatric Use

Safety and efficacy not established in children <3 years of age.1

Geriatric Use

No overall differences in safety and efficacy relative to younger adults.1 11

Common Adverse Effects

Ocular discomfort (e.g., burning, folliculosis, hyperemia, pruritus), infection (e.g., cold symptoms, upper respiratory infections).1

Interactions for Epinastine

No formal drug interaction studies to date.11

Epinastine Pharmacokinetics



Limited systemic exposure following topical application to the eye.1 No increase in systemic absorption following multiple dosing.1

Peak plasma concentrations attained approximately 2 hours after ophthalmic administration.1


Rapid onset (within 3–5 minutes).1


8 hours.1



Does not penetrate blood-brain barrier.1

Distributed into milk in rats; not known whether distributed into human milk.1

Plasma Protein Binding




Less than 10% is metabolized.1

Elimination Route

55 or 30% of IV dose excreted unchanged in urine or feces, respectively.1


Approximately 12 hours.1





Tightly closed bottle at 15–25°C.1


  • Inhibits the release of mediators (e.g., histamine) from cells involved in hypersensitivity reactions (e.g., mast cells).1 2

  • Exhibits mast-cell stabilizing properties.2

  • Exhibits some affinity for histamine H2, α1- and α2-adrenergic, and 5-HT2 receptors.1

Advice to Patients

  • Importance of learning and adhering to proper administration techniques to avoid contamination of the solution with common bacteria that can cause ocular infections.1 9 Serious damage to the eye and subsequent loss of vision may result from using contaminated ophthalmic solutions.1 9

  • Importance of delaying insertion of contact lenses for at least 10 minutes after epinastine instillation, since benzalkonium chloride preservative may be absorbed by soft lenses; importance of not wearing contact lenses in the presence of ocular redness.1 9

  • Not indicated for contact lens-related ocular irritation.1 9

  • Importance of reporting any worsening of symptoms or new-onset ocular pain/discomfort.9

  • Importance of women informing clinician if they are or plan to become pregnant or plan to breast-feed.9

  • Importance of informing clinicians of existing or contemplated concomitant therapy, including prescription and OTC drugs, as well as any concomitant illnesses.1

  • 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.

Epinastine Hydrochloride


Dosage Forms


Brand Names




0.05% (of epinastine hydrochloride)

Elestat (with benzalkonium chloride)


AHFS DI Essentials™. © Copyright 2021, Selected Revisions July 1, 2005. American Society of Health-System Pharmacists, Inc., 4500 East-West Highway, Suite 900, Bethesda, Maryland 20814.


1. Allergan. Elestat (epinastine hydrochloride) ophthalmic solution 0.05% prescribing information. Irvine, CA; 2003 Oct. 2

2. Food and Drug Administration Center for Drug Evaluation and Research. Clinical Pharmacology and Biopharmaceutics review: epinastine. Executive Summary. December 19, 2002.

3. Abelson MB, Gomes P, Crampton HJ et al. Efficacy and tolerability of ophthalmic epinastine assessed using the conjunctival antigen challenge model in patients with a history of allergic conjunctivitis. Clin Ther. 2004; 26:35-47.

4. Whitcup SM, Bradford R, Lue J et al. Efficacy and tolerability of ophthalmic epinastine: a randomized, double-masked, parallel-group, active- and vehicle-controlled environmental trial in patients with seasonal allergic conjunctivitis. Clin Ther. 2004; 26:29-34.

5. Ciprandi G, Buscaglia S, Cerqueti PM et al. Drug treatment of allergic conjunctivitis: a review of the evidence. Drugs. 1992; 43:154-76.

6. Morrow GL, Abbott RL. Conjunctivitis. Am Fam Physician. 1998; 57:735-46.

7. Titi MJ. A critical look at ocular allergy drugs. Am Fam Physician. 1996; 53:2637-42.

8. Galindez OA, Kaufman HE. Coping with the itchy-burnies: the management of allergic conjunctivitis. Ophthalmology. 1996; 103:1335-6.

9. Food and Drug Administration. Elestat consumer information. 2003 Dec 04. From FDA website.

10. Tasaka K. Epinastine: An update of its pharmacology, metabolism, clinical efficacy and tolerability in the treatment of allergic diseases. Drugs Today. 2000; 36:735-57.

11. Allergan. Irvine, CA: Personal communication.