Allet

Approved Indications:

• Allergic Conjunctivitis (Ophthalmic Use):
  Treatment of signs and symptoms of seasonal and perennial allergic conjunctivitis, including ocular itching, redness, and tearing.
• Seasonal Allergic Rhinitis (Nasal Spray Use):
  Relief of nasal symptoms such as sneezing, nasal pruritus, rhinorrhea, and nasal congestion in patients aged 6 years and older.

Clinically Accepted Off-Label Uses:

• Perennial Allergic Rhinitis:
  Used in some cases for year-round nasal allergy symptoms when continuous antihistamine therapy is needed.
• Allergic Dermatoses (Topical Form in Some Regions):
  Occasionally used off-label for the relief of pruritus associated with allergic skin conditions.

Route of Administration:

• Ophthalmic (eye drops)
• Intranasal (nasal spray)
• Oral (not commonly available in all countries)

Ophthalmic Solution (for Allergic Conjunctivitis):

• Adults and children ≥3 years:
• 0.1% or 0.2% solution: 1 drop in each affected eye twice daily (BID), approximately 6 to 8 hours apart.
• 0.7% solution: 1 drop in each affected eye once daily (QD).

Nasal Spray (for Seasonal Allergic Rhinitis):

• Adults and adolescents ≥12 years:
  1 spray (665 mcg) in each nostril twice daily (BID).
• Children 6 to 11 years:
  1 spray in each nostril twice daily (BID).

Special Populations:

• Renal or Hepatic Impairment:
  No dose adjustment required, but caution is advised in severe cases due to limited data.
• Elderly:
  No dosage adjustment necessary; monitor for increased sensitivity.

Administration Instructions:

• Ophthalmic: Avoid contact with the dropper tip. Remove contact lenses before use and wait at least 10 minutes before reinsertion.
• Nasal: Shake bottle gently before use. Prime the spray before first use or if unused for several days.

Olopatadine hydrochloride is a dual-action antiallergic agent that functions as a selective histamine H1 receptor antagonist and mast cell stabilizer. It blocks the action of histamine released during allergic responses by competitively binding to H1 receptors, thereby reducing symptoms such as itching, tearing, and inflammation. Additionally, it stabilizes mast cells and inhibits the release of inflammatory mediators like leukotrienes and cytokines, helping to prevent both early-phase and late-phase allergic reactions. This mechanism is effective in both ocular and nasal tissues.

• Absorption:
• Ophthalmic and Nasal Use: Minimal systemic absorption
• Oral Use (if available): Rapid absorption with peak plasma concentration at ~0.5 to 1 hour
• Bioavailability (Oral): ~60–70%
• Distribution:
• Volume of distribution: ~100–200 L
• Plasma protein binding: ~55–70%
• Metabolism:
  Primarily via direct glucuronidation and oxidation; minimal CYP450 involvement.
• Elimination:
• Half-life: ~8–12 hours (oral)
• Excretion: 60–70% via urine (mostly unchanged); remainder in feces

• Pregnancy:
• FDA Category C
• Animal studies have shown adverse fetal effects at high doses; no adequate controlled studies in pregnant women. Use only if clearly needed.
• Lactation:
• Unknown if olopatadine is excreted in human milk.
• Caution advised, particularly with systemic or high-dose intranasal use.

• Primary Class:
  Antihistamine
• Subclass:
• Selective H1 Receptor Antagonist
• Mast Cell Stabilizer
• Antiallergic Agent

• Hypersensitivity to olopatadine or any formulation component
• Use in children under:
• 3 years (ophthalmic)
• 6 years (nasal spray)
• Contact lens wear during administration of ophthalmic formulations containing benzalkonium chloride

• Contact Lens Use:
  Ophthalmic solution contains benzalkonium chloride, which may discolor or be absorbed by soft contact lenses. Remove lenses before use.
• Sedation:
  Although rare with topical use, systemic absorption from oral or intranasal use may cause drowsiness or fatigue.
• Ocular Effects:
  Temporary burning or stinging upon instillation is common.
• Rebound Effects:
  Although rare, prolonged use of nasal antihistamines may lead to reduced efficacy or nasal dryness.
• Use in Pediatrics:
  Ensure age-appropriate use; avoid in children below minimum age threshold per formulation.

Common Adverse Effects:

• Ophthalmic:
• Eye irritation or burning
• Headache
• Dry eye
• Blurred vision
• Foreign body sensation
• Nasal:
• Bitter taste
• Epistaxis (nosebleed)
• Sore throat
• Nasal dryness
• Cough
• Systemic (oral):
• Drowsiness
• Dry mouth
• Dizziness

Rare/Serious Side Effects:

• Hypersensitivity reactions (e.g., rash, urticaria)
• Conjunctival swelling or discharge
• Palpitations (rare and usually associated with systemic exposure)

Onset:
Most side effects are mild, transient, and occur within minutes to hours of administration.

• CNS Depressants:
  Potential additive sedative effects with alcohol, benzodiazepines, or antihistamines (systemic formulations).
• Alcohol:
  May enhance CNS depression and sedation, especially with oral or intranasal use.
• CYP450 Enzymes:
  Minimal metabolism via CYP system; low potential for CYP-mediated drug interactions.
• Decongestants or Corticosteroids (Nasal):
  May be used concurrently, but monitor for enhanced nasal dryness or irritation.

• ARIA Guidelines (Allergic Rhinitis and its Impact on Asthma):
  Support the use of intranasal antihistamines like olopatadine for rapid relief of allergic rhinitis symptoms.
• FDA Labeling:
  Extended-release ophthalmic formulation (0.7%) approved for once-daily use to improve compliance.
• Combination Formulations:
  Combination with montelukast or corticosteroids for synergistic allergy control is increasingly used in clinical practice.

• Storage Temperature:
  Store between 20°C and 25°C (68°F to 77°F)
• Permitted range: 15°C to 30°C
• Protection:
• Keep tightly closed
• Protect from excessive light and moisture
• Handling Instructions:
• Ophthalmic: Discard opened bottle after 4 weeks
• Nasal: Store upright and shake gently before use
• Do not freeze
• Keep out of reach of children