Alpatin0.05%

Alpatin is a second-generation antihistamine and mast cell stabilizer used in two distinct formulations with different, FDA-recognized/guideline-supported indications:

Ophthalmic solution (0.05%) — FDA-approved

• Prevention of itching associated with allergic conjunctivitis.

Oral tablets — approved in select markets outside the US (e.g., Japan); not FDA-approved

• Allergic rhinitis (sneezing, nasal discharge, nasal congestion).
• Urticaria (hives).
• Pruritus (itching) associated with skin conditions such as eczema/dermatitis and prurigo, used as an adjunct to topical therapy.

Where oral Alpatin is not locally approved, its use for these indications should follow the treating physician's judgment.

Each formulation of Epinastine Hydrochloride contains the active ingredient epinastine hydrochloride:

• Ophthalmic solution: 0.05% (0.5 mg/mL) sterile, isotonic ophthalmic solution containing benzalkonium chloride as a preservative.
• Oral tablets (in markets where marketed): commonly available as 10 mg and 20 mg tablets.

Alpatin is a topically and systemically active second-generation (non-sedating) antihistamine that acts as a direct, selective histamine H1-receptor antagonist and also inhibits release of histamine and other mediators from mast cells. As an ophthalmic solution, it is used to relieve itching from allergic conjunctivitis; as an oral tablet in some countries, it is used for allergic rhinitis, urticaria, and pruritic skin conditions.

Second-generation (non-sedating) antihistamine / selective histamine H1-receptor antagonist and mast cell stabilizer; ophthalmic anti-allergic agent.

Epinastine Hydrochloride is a direct H1-receptor antagonist with additional mast-cell-stabilizing activity, reducing release of histamine and other inflammatory mediators. It also has affinity for H2 receptors and some other receptors at higher concentrations, but its clinical antiallergic effect is primarily H1-mediated.

Pharmacokinetics:

• Ophthalmic: Systemic absorption after topical ocular administration is minimal.
• Oral: Epinastine is well absorbed, undergoes minimal hepatic metabolism, has low blood-brain barrier penetration (contributing to a low sedation profile), and is eliminated predominantly unchanged via the kidneys.

Ophthalmic solution: For topical ocular use only. Tilt the head back, pull down the lower eyelid, and instill one drop into the pocket formed; avoid letting the dropper tip touch the eye, eyelid, fingers, or any surface. Close the eye gently for 1–2 minutes after instillation.

Oral tablets (where marketed): Swallow with water, with or without food, at the same time(s) each day as directed by the physician.

No clinically significant drug interactions have been established for ophthalmic Alpatin due to its minimal systemic absorption after topical ocular use.

For oral Alpatin (where marketed), concurrent use with alcohol or other central nervous system depressants (sedatives, hypnotics) may cause additive drowsiness, and concurrent use with other antihistamines may increase anticholinergic/sedative effects; such combinations should be used cautiously and under medical supervision.

Ophthalmic solution:

• Common (approximately 1–10%): burning/stinging sensation, follicular conjunctivitis, conjunctival hyperemia (redness), pruritus (itching), and increased lacrimation.
• Less common: cold-like or upper respiratory tract symptoms (causal relationship to the drug uncertain).

Oral tablets (where marketed):

• Headache, mild somnolence (drowsiness), dry mouth, nasopharyngitis, and gastrointestinal upset (nausea) have been reported.

Patients should contact a physician if any side effect is severe or persistent.

Pregnancy: Animal reproduction studies with Alpatin have not demonstrated harm to the fetus at doses substantially higher than the human therapeutic exposure, but adequate and well-controlled studies in pregnant women are lacking. Alpatin should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus; consult a physician before use.

Lactation: Epinastine is excreted into the milk of lactating animals; whether it is excreted in human breast milk is unknown. Caution is advised, and a physician should be consulted before using Alpatin while breastfeeding.

Ophthalmic solution:

• For topical ocular use only; not for injection or oral use.
• To avoid contamination, do not touch the dropper tip to the eye, eyelid, fingers, or any surface, and keep the bottle tightly closed when not in use.
• Alpatin ophthalmic solution should not be used to treat contact-lens-related irritation. The solution contains benzalkonium chloride, which may be absorbed by soft contact lenses; patients should remove contact lenses before instillation and wait at least 10 minutes before reinserting them.
• Do not use if the eye is red without consulting a physician first, as this may indicate a condition other than allergic conjunctivitis.

Oral tablets (where marketed):

• Dose adjustment may be needed in patients with renal impairment, as the drug is predominantly excreted by the kidneys (see Use in Special Populations).
• Although sedation is uncommon at recommended doses, patients should assess their individual response before driving or operating machinery.

See Contraindications for hypersensitivity and Pregnancy and Lactation for use during pregnancy/breastfeeding.

Specific human overdose data for Alpatin are limited. Accidental ingestion of ophthalmic solution or excessive oral intake may theoretically cause exaggerated antihistaminic effects such as drowsiness, dry mouth, or dizziness. There is no specific antidote. In case of suspected overdose or accidental ingestion, seek immediate medical attention or contact a poison control center/emergency services; supportive care should be provided as directed by a physician.

Store the ophthalmic solution at 20°C to 25°C (68°F to 77°F); brief excursions between 15°C and 30°C (59°F to 86°F) are permitted. Keep the bottle tightly closed when not in use. Oral tablets should be stored at room temperature (below 30°C), away from light and moisture. Keep all forms of Alpatin out of reach of children.

Renal impairment: Oral Alpatin is predominantly excreted unchanged by the kidneys; dose reduction or extended dosing intervals may be needed in patients with renal impairment, per local physician guidance. No specific dose adjustment is described for the ophthalmic solution due to minimal systemic absorption.

Hepatic impairment: Specific dosing data are limited; use with caution and physician oversight.

Elderly: Clinical studies of the ophthalmic solution have not shown differences in safety or effectiveness between elderly and younger patients.

Pediatric: See Pediatric Uses.

For allergic conjunctivitis, Alpatin ophthalmic solution should be continued throughout the period of allergen exposure, even if symptoms improve or resolve, to maintain control. For oral use (where marketed), duration depends on the condition being treated (e.g., short courses for acute urticaria versus longer, physician-directed courses for chronic allergic rhinitis) and should follow the prescriber's instructions.

Antihistamines (H1-receptor antagonists); Mast cell stabilizers; Ophthalmic anti-allergic/antihistamine agents.

Epinastine Hydrochloride selectively and directly blocks histamine H1 receptors, preventing histamine from binding and triggering allergic symptoms such as itching, redness, and swelling. It additionally stabilizes mast cell membranes, reducing further release of histamine and other allergic mediators. Its limited penetration across the blood-brain barrier contributes to a low potential for sedation compared with first-generation antihistamines.

Ophthalmic solution: Safety and efficacy have been established for children 2 years of age and older at the same dosage as adults; safety and efficacy in children below 2 years have not been established.

Oral tablets (where marketed): Pediatric use follows local, weight/age-based labeling in the countries where the oral form is approved; oral Alpatin is not FDA-approved for any age group in the United States, and its use in children should be guided by a pediatrician.