Emedastine

Class: Antiallergic Agents
- Histamine H1-receptor Antagonists
ATC Class: S03AA07
VA Class: OP900
Chemical Name: 1-(2-Ethoxyethyl)-2-(hexahydro-4-methyl-1H-1,4-diazepin-1-yl)benzimidazole fumerate (1:2)
Molecular Formula: C₁₇H₂₆N₄O•2C₄H₄O₄
CAS Number: 87233-62-3
Brands: Emadine

Medically reviewed by Drugs.com on Jun 21, 2021. Written by ASHP.

• Uses
• Dosage
• Cautions
• Interactions
• Pharmacokinetics
• Patient advice
• Preparations

Introduction

Relatively selective histamine H₁-receptor antagonist; a benzimidazole derivative.

Uses for Emedastine

Allergic Conjunctivitis

Symptomatic relief of allergic conjunctivitis.

Emedastine Dosage and Administration

Administration

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

Ophthalmic Administration

Remove soft contact lenses prior to administration of each dose (since benzalkonium chloride preservative may be absorbed by the lenses); may reinsert lenses 10 minutes after administration if eyes are not red.

If more than one topical ophthalmic drug is used, administer the drugs at least 5 minutes apart.

Avoid contamination of the solution container.

Do not use if solution is discolored.

Dosage

Available as emedastine difumarate; dosage expressed in terms of emedastine.

Pediatric Patients

Allergic Conjunctivitis

Ophthalmic

Children ≥3 years of age: 1 drop of a 0.05% solution in the affected eye(s) up to 4 times daily.

Adults

Allergic Conjunctivitis

Ophthalmic

1 drop of a 0.05% solution in the affected eye(s) up to 4 times daily.

Cautions for Emedastine

Contraindications

• Known hypersensitivity to emedastine or any ingredient in the formulation.

Warnings/Precautions

Specific Populations

Pregnancy

Category B.

Lactation

Distributed into milk in rats following oral administration; not known whether distributed into human milk following topical application to the eye. Use with caution.

Pediatric Use

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

Adverse effect profile in children 3–16 years of age is similar to that in individuals ≥17 years of age.

Geriatric Use

No substantial differences in safety and efficacy relative to younger adults.

Common Adverse Effects

Headache.

Interactions for Emedastine

No formal drug interaction studies to date.

Emedastine Pharmacokinetics

Absorption

Bioavailability

Limited systemic exposure following topical application to the eye; plasma concentrations usually are undetectable.

Onset

Rapid onset.

Duration

Long duration.

Elimination

Metabolism

Metabolized in the liver principally to 5- and 6-hydroxyemedastine following oral administration; metabolites appear to undergo further oxidation to form 5′-oxo analogs.

Elimination Route

44% of an oral dose is recovered in urine within 24 hours.

Half-life

3–4 hours following oral administration.

Stability

Storage

Ophthalmic

Solution

Tightly closed bottle at 4–30°C.

Actions

• Inhibits the histamine-stimulated conjunctival vascular permeability response in a concentration-dependent manner.

• Potency is about 100, 357, or 5813 times that of levocabastine, pheniramine, or antazoline, respectively, on a molar basis.

Advice to Patients

• Importance of learning and adhering to proper administration techniques to avoid contamination of the solution container.

• Importance of removing soft contact lenses prior to administration of each dose. Delay reinsertion for 10 minutes after administration if eyes are not red; do not wear contact lenses if eye(s) are red. Not indicated for contact lens-related irritation.

• Importance of administering different topical ophthalmic preparations at least 5 minutes apart.

• 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 therapy, including prescription and OTC drugs as well as any concomitant illnesses.

• Importance of informing patients 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.

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