RELESTAT

Indications

• Allergic conjunctivitis
• Itching associated with allergic reactions in the eyes

Dosage

Children: For children aged 3 years and older, the recommended dose is one drop in the affected eye(s) twice daily. Refer to BNF for Children for specific guidance.

Adults: The recommended adult dose is one drop in the affected eye(s) twice daily.

Mechanism of action

Epinastine has a multiaction effect that inhibits the allergic response in three ways: it stabilizes mast cells by preventing mast cell degranulation, which controls the allergic response; it prevents histamine binding to both the H1- and H2-receptors, thereby stopping itching and providing lasting protection; and it prevents the release of proinflammatory chemical mediators from blood vessels to halt the progression of the allergic response.

Pharmacodynamics

Epinastine is an antihistamine that acts as a direct H1-receptor antagonist and also inhibits the release of histamine from mast cells. It is specifically indicated for preventing itching associated with allergic conjunctivitis. Epinastine shows selectivity for H1-receptors while also exhibiting affinity for H2-receptors and other receptors such as alpha-1, alpha-2, and 5-HT2. Importantly, it does not cross the blood-brain barrier, minimizing the risk of central nervous system side effects.

Pharmacokinetics

Epinastine is administered topically and is designed for localized action in the eyes. Due to its structure and mechanism, it does not penetrate the blood-brain barrier, which contributes to its safety profile regarding CNS-related side effects. Its pharmacokinetic properties detail a rapid onset of action with a localized effect, making it effective for treating symptoms of allergic conjunctivitis.

Adverse effects

• Eye irritation
• Burning sensation in the eyes
• Dry eyes
• Headache

Precautions

• Use with caution in patients with a history of hypersensitivity to epinastine or any of its components.
• Avoid contact with soft contact lenses.
• Patients should be advised to wash their hands before using the eye drops.

Pregnancy

There are no adequate and well-controlled studies in pregnant women. Epinastine should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

Breast-feeding

It is not known whether epinastine is excreted in human milk. Caution should be exercised when administering to nursing mothers.

Storage

Store at room temperature, away from light and moisture. Do not freeze.

Formulations

• Eye drops (0.05% solution)

Indications

• Seasonal allergic conjunctivitis
• Allergic conjunctivitis

Dosage

Children: For children aged 12-17 years, apply twice daily for a maximum of 8 weeks. For children aged 3-11 years, apply 2-3 times a day for maximum treatment duration of 8 weeks.

Adults: Apply twice daily for a maximum of 8 weeks.

Mechanism of action

Epinastine hydrochloride is a selective H1-receptor antagonist. It inhibits the action of histamine at the H1 receptor sites in the conjunctiva and nasal mucosa, thereby reducing the symptoms associated with allergic reactions. Additionally, it has mast cell stabilizing properties, preventing the release of histamine and other inflammatory mediators.

Pharmacodynamics

Upon application to the eye, epinastine reduces the symptoms of allergic conjunctivitis, such as itching and redness, by blocking the H1 receptors and stabilizing mast cells. Its onset of action is typically rapid, providing quick relief from symptoms.

Pharmacokinetics

Epinastine hydrochloride is administered topically as eye drops, which allows for localized action with minimal systemic absorption. The systemic bioavailability is low, reducing the risk of systemic side effects. The drug is primarily metabolized in the liver and excreted via urine. The pharmacokinetic profile supports its use with minimal systemic exposure, making it suitable for managing localized allergic reactions.

Adverse effects

• Drowsiness
• Eye irritation
• Headache
• Dry mouth
• Conjunctival haemorrhage
• Vision disorders
• Palpitations
• Vascular disorders
• Hyperhidrosis
• Mydriasis
• Nausea

Interactions

• Other antihistamines
• Sedating agents
• Sympathomimetics
• Vasoconstrictors

Precautions

• Use with caution in patients with pre-existing eye disorders
• Monitor for drowsiness and other CNS effects

Pregnancy

Epinastine hydrochloride should be used in pregnancy only if the potential benefit justifies the potential risk to the fetus.

Breast-feeding

It is not known whether epinastine is excreted in human milk. Caution should be exercised when administering to nursing mothers.

Storage

Store below 25 degrees Celsius. Protect from light. Do not freeze.

Formulations

• Epinastine hydrochloride 500 micrograms per 1 ml eye drops

Mechanism of action

Epinastine has a multiaction effect that inhibits the allergic response in 3 ways: 1. stabilizes mast cells by preventing mast cell degranulation to control the allergic response, 2. prevents histamine binding to both the H1- and H₂-receptors to stop itching and provide lasting protection, and 3. prevents the release of proinflammatory chemical mediators from the blood vessel to halt progression of the allergic response.

Pharmacodynamics

Epinastine is an antihistamine and an inhibitor of histamine release from the mast cell for topical administration to the eyes. Epinastine is indicated for the prevention of itching associated with allergic conjunctivitis. Epinastine is a topically active, direct H₁-receptor antagonist and an inhibitor of the release of histamine from the mast cell. Epinastine is selective for the histamine H₁-receptor and has affinity for the histamine H2 receptor. Epinastine also possesses affinity for the a1-, a2-, and 5-HT₂ -receptors. Epinastine does not penetrate the blood/brain barrier and, therefore, is not expected to induce side effects of the central nervous system.