Epinastine is a topical ophthalmic H1-antagonist and an inhibitor of mast cell histamine release. It is indicated for the prevention of ocular pruritus associated with allergic conjunctivitis. The ophthalmic product formulation is long-acting, allowing for twice daily administration. The FDA approved epinastine 0.05% ophthalmic solution on October 17, 2003.
General Administration Information
For storage information, see the specific product information within the How Supplied section.
Route-Specific Administration
Ophthalmic Administration
-For topical application to the eye only.
-Wash hands before and after use. Tilt the head back slightly and pull the lower eyelid down with the index finger. Squeeze the prescribed number of drops into the conjunctival sac and gently close eyes for 1 to 2 minutes. Do not blink.
-Care should be taken to avoid contamination. Do not touch the tip of the dropper to the eye, fingertips, or other surface.
-Instruct patients to remove contact lenses prior to instilling the ophthalmic solution; contact lenses may be reinserted 10 minutes after administration of the ophthalmic solution.
-Do not share ophthalmic drops between patients.
The most frequently (1 to 10%) reported ocular adverse events of epinastine use include ocular irritation (burning sensation in the eye), folliculosis, hyperemia, and ocular pruritus. Increased lacrimation was reported post-marketing.
The most frequently reported non-ocular event with epinastine use was infection (including cold symptoms and upper respiratory infections) seen in approximately 10% of patients. Headache, rhinitis, sinusitis, increased cough, and pharyngitis were reported in approximately 1 to 3% of patients. Some events were similar or related to the underlying condition being studied.
No overall differences in safety or effectiveness have been observed between elderly and younger patients receiving epinastine ophthalmic solution.
Epinastine ophthalmic solution is formulated with the preservative benzalkonium chloride 0.01%, which may be absorbed by soft contact lenses. Users of soft contact lenses should not administer epinastine while wearing contact lenses. Contact lenses may be inserted 10 minutes after instilling the drug. Do not use epinastine to treat contact lens related ocular irritation.
Epinastine is classified as pregnancy risk category C. Epinastine reduced pup body weight gain in rats following oral doses that exceeded 90,000 times the maximum recommended ocular human dose (MROHD) of 0.0014 mg/kg/day on a mg/kg basis. No adequate and well-controlled studies in pregnant women have been performed. Use epinastine during pregnancy only if the potential benefits to the mother outweigh the possible risks to the fetus. When use is necessary during pregnancy, proper lacrimal occlusion after dosage will help limit the risk of maternal systemic absorption.
According to the manufacturer, it is not known whether epinastine is excreted into human milk and caution should be exercised when epinastine is administered to women who are breast-feeding. However, the systemic absorption of epinastine is very low after ophthalmic administration; therefore, clinically significant amounts of the drug would not be expected in breast-milk. Consider the benefits of breast-feeding, the risk of potential infant drug exposure, and the risk of an untreated or inadequately treated condition. When use of epinastine ophthalmic solution is necessary during breast-feeding, proper lacrimal occlusion after dosage will help limit the risk of maternal systemic absorption. If a breast-feeding infant experiences an adverse effect related to a maternally administered drug, healthcare providers are encouraged to report the adverse effect to the FDA.
For the prevention of ocular pruritus associated with allergic conjunctivitis:
Ophthalmic dosage:
Adults: Instill 1 drop in each affected eye twice daily. Continue treatment through period of allergen exposure, even when symptoms are absent.
Adolescents and Children 2 to 17 years: Instill 1 drop in each affected eye twice daily. Continue treatment through period of allergen exposure, even when symptoms are absent.
Maximum Dosage Limits:
-Adults
2 drops/day ophthalmic solution in each affected eye.
-Geriatric
2 drops/day ophthalmic solution in each affected eye.
-Adolescents
2 drops/day ophthalmic solution in each affected eye.
-Children
2 years and older: 2 drops/day ophthalmic solution in each affected eye.
younger than 2 years: Safety and efficacy have not been established.
-Infants
Safety and efficacy have not been established.
-Neonates
Safety and efficacy have not been established.
Patients with Hepatic Impairment Dosing
Specific guidelines for dosage adjustments in hepatic impairment are not available; it appears that no dosage adjustments are needed.
Patients with Renal Impairment Dosing
Specific guidelines for dosage adjustments in renal impairment are not available; it appears that no dosage adjustments are needed.
*non-FDA-approved indication
There are no drug interactions associated with Epinastine products.
Epinastine is a topically active, direct H1-receptor antagonist. Epinastine also inhibits histamine release from mast cells. Epinastine is a relatively selective H1-antagonist which has some affinity for the H2-receptor. Following topical ocular administration, epinastine blocks H1-receptors and inhibits histamine-stimulated vascular permeability in the conjunctiva. As a result, emedastine relieves the ocular pruritus associated with allergic conjunctivitis. Epinastine also has affinity for the alpha-1, alpha-2, and 5-HT2 receptors. Epinastine does not cross the blood brain barrier, and therefore is not expected to induce CNS side effects.
Epinastine is administered topically to the eye. Epinastine is 64% bound to plasma proteins. Approximately 55% of an intravenous dose is recovered in the urine as unchanged drug, with about 30% recovered in the feces. Less than 10% is metabolized. Renal elimination occurs primarily via active tubular secretion. The total systemic clearance is approximately 56 L/hr and the terminal plasma elimination half-life is about 12 hours.
Affected cytochrome P450 isoenzymes and drug transporters: None
-Route-Specific Pharmacokinetics
Other Route(s)
Ophthalmic Route
Systemic absorption following ocular administration is low, with peak plasma concentrations of approximately 0.04 (+/- 0.014) ng/mL at about 2 hours. The onset of action for epinastine following conjunctival antigen challenge is 3 to 5 minutes, and the duration of effect is about 8 hours. No evidence of tachyphylaxis has been observed (studied up to 8 weeks).