Relestat

Approved Indications:

• Allergic Conjunctivitis:
• Relief of ocular itching associated with seasonal allergic conjunctivitis (SAC) and perennial allergic conjunctivitis (PAC).
• Used in both mild and moderate to severe forms of allergic eye disease.
• Ocular Redness and Irritation:
• Adjunctive relief of ocular redness caused by histamine-mediated reactions.

Off-Label / Clinically Accepted Uses:

• Vernal Keratoconjunctivitis (VKC): Short-term symptomatic relief.
• Prevention of Allergic Flare-Ups: Prophylactic use during allergen exposure for patients with seasonal allergic conjunctivitis.

Adults and Children ≥3 years:

• Ocular Drops: Instill 1 drop in each affected eye twice daily (approximately 12 hours apart).
• Duration: Continuous use during periods of allergen exposure; usually limited to several weeks as needed.

Special Populations:

• Pediatrics (<3 years): Safety and efficacy not established; avoid use.
• Elderly: No specific dose adjustment required; monitor for ocular tolerance.
• Renal/Hepatic Impairment: No significant systemic absorption; dose adjustment generally not required.

Administration Instructions:

• Wash hands before administration.
• Avoid contact with the tip of the dropper to prevent contamination.
• If using other ocular medications, separate administration by at least 10–15 minutes.

Epinastine Hydrochloride is a selective H1 histamine receptor antagonist with additional mast cell stabilizing properties. By blocking H1 receptors on conjunctival and corneal cells, it prevents histamine-induced ocular itching, redness, and vasodilation. The drug also inhibits mast cell degranulation, reducing the release of histamine and other pro-inflammatory mediators, thereby suppressing both immediate and late-phase allergic responses in the eye. This dual action provides rapid relief of symptoms and prolonged prevention of allergic flare-ups.

• Absorption: Minimal systemic absorption after ocular instillation; peak plasma levels are very low.
• Distribution: Predominantly local action in ocular tissues; systemic distribution negligible.
• Metabolism: Metabolized primarily in the liver via oxidative pathways.
• Elimination: Excreted mainly via urine and feces as metabolites; systemic exposure is minimal.
• Half-Life: Systemic half-life approximately 16–18 hours, though clinical effect is primarily local.
• Onset of Action: Symptom relief typically within 5–15 minutes of administration.
• Duration of Effect: Approximately 12 hours per dose.

• Pregnancy: Category C (FDA) – Animal studies show no teratogenicity at therapeutic doses; human data limited. Use only if potential benefits justify the risk.
• Lactation: Minimal systemic absorption; excretion in breast milk likely very low. Use with caution or monitor infant if necessary.
• Data Limitations: Insufficient controlled studies in pregnant or lactating women.

• Primary Class: Antihistamine
• Subclass: H1-receptor antagonist; topical ophthalmic

• Known hypersensitivity to Epinastine Hydrochloride or any component of the formulation.
• Severe ocular infections where antihistamine use may mask symptoms.

• Ocular Irritation: May cause transient burning or stinging upon instillation.
• Contact Lens Use: Remove lenses before application; wait at least 10 minutes before reinsertion.
• High-Risk Patients: Caution in patients with glaucoma, severe dry eye, or corneal damage.
• Avoid Contamination: Prevent dropper tip contact with eye or surfaces.
• Systemic Effects: Rare due to minimal absorption; monitor if concomitant systemic H1 antihistamines used.

Common Adverse Effects:

• Ocular: mild burning, stinging, or discomfort at the site of instillation
• Transient blurred vision

Rare / Serious Adverse Effects:

• Allergic reaction: eyelid swelling, rash
• Systemic effects: headache, dizziness (very rare due to minimal absorption)

Timing / Dose Dependence:

• Most adverse effects are transient and occur shortly after instillation; not dose-dependent under standard dosing.

• Other Topical Ophthalmic Medications: Administer at least 10–15 minutes apart to avoid dilution or reduced efficacy.
• Systemic H1 Antihistamines: No significant pharmacokinetic interactions expected; additive mild sedation possible.
• Enzyme Systems: Minimal systemic metabolism; no significant CYP450 interactions reported.
• Alcohol or CNS Depressants: Not expected to interact due to minimal systemic absorption.

• Guideline Endorsement: Recommended as a first-line topical therapy for allergic conjunctivitis in pediatric and adult patients.
• Dosing Updates: Maintains twice-daily dosing; no significant changes in approved dosage.
• Safety Emphasis: Reinforced importance of avoiding contamination and monitoring for ocular irritation.
• Pediatric Use: Approved for children ≥3 years; safety below this age not established.

• Temperature: 15°C–25°C (59°F–77°F)
• Humidity & Light: Protect from moisture and light; keep bottle tightly closed.
• Handling Precautions: Do not touch the dropper tip to any surface; avoid freezing.
• Reconstitution: Not required; solution ready for use.
• Shelf-Life After Opening: Use within 4 weeks to ensure sterility.