Sinacet

Approved Indications:

• Seasonal Allergic Rhinitis: Relief of nasal and ocular symptoms in adults and children (≥6 months).
• Perennial Allergic Rhinitis: Treatment of persistent allergic symptoms throughout the year.
• Chronic Idiopathic Urticaria: Management of itching and wheals in adults and children (≥6 months).

Clinically Accepted Off-Label Uses:

• Atopic Dermatitis (as adjunct): Reduces pruritus in mild to moderate cases.
• Allergic Conjunctivitis: Symptom relief when associated with allergic rhinitis.

Route: Oral (tablet or oral solution)

Adults and Adolescents (≥12 years):

• 5 mg once daily in the evening.

Children:

• 6–11 years: 2.5 mg once daily.
• 6 months–5 years: 1.25 mg once daily (oral solution).

Elderly:

• Use with caution. Dose adjustment may be needed based on renal function.

Renal Impairment (CrCl-based adjustment):

• 50–80 mL/min (mild): 2.5 mg once daily.
• 30–49 mL/min (moderate): 2.5 mg every other day.
• <30 mL/min (severe): 2.5 mg twice a week.
• <10 mL/min (end-stage): Contraindicated.

Hepatic Impairment:

• No adjustment required. Use caution if renal impairment coexists.

Levocetirizine is the active R-enantiomer of cetirizine and functions as a potent and selective antagonist of peripheral histamine H₁-receptors. It inhibits histamine-mediated effects, such as vasodilation, increased vascular permeability, and sensory nerve stimulation, which cause allergy symptoms like sneezing, itching, and rhinorrhea. It also reduces eosinophil recruitment, thereby exerting mild anti-inflammatory effects. Unlike first-generation antihistamines, it minimally crosses the blood–brain barrier, reducing sedation risk.

• Absorption: Rapid and complete oral absorption.
• Bioavailability: ~100%.
• Tmax: 0.9 hours (fasted).
• Distribution Volume (Vd): ~0.4 L/kg.
• Protein Binding: ~90%.
• Metabolism: Minimal (~14% metabolized, mainly via CYP3A4).
• Elimination Half-Life: 7 to 10 hours.
• Excretion: ~85% excreted unchanged in urine.
• Dialysis: Not significantly removed.

• Pregnancy: FDA Category B. No proven risk in humans. Use if benefits outweigh potential risks.
• Lactation: Excreted in breast milk. Use caution; monitor the infant for sedation or irritability.
• Recommendation: Use during pregnancy and breastfeeding only when clearly indicated.

• Primary Class: Non-sedating antihistamine.
• Subclass: Second-generation H₁-receptor antagonist.
• Enantiomer: R-enantiomer of cetirizine.

• Hypersensitivity to Levocetirizine, cetirizine, hydroxyzine, or any component of the formulation.
• Severe renal impairment (CrCl <10 mL/min).
• Hereditary problems of galactose intolerance, Lapp lactase deficiency, or glucose-galactose malabsorption (with oral solution or tablet).

• Renal Impairment: Adjust dosage accordingly.
• CNS Effects: Although rare, somnolence may occur. Caution advised with activities requiring alertness.
• Alcohol/CNS Depressants: May increase drowsiness. Avoid combination.
• Behavioral Effects (Pediatrics): Monitor for agitation, irritability, or sleep disturbance in young children.

Common:

• Central Nervous System: Somnolence, headache, fatigue.
• Gastrointestinal: Dry mouth, nausea.
• Respiratory: Nasopharyngitis, cough.

Uncommon:

• Dizziness, abdominal pain, pharyngitis.

Rare but Serious:

• Hypersensitivity (e.g., rash, urticaria, angioedema, anaphylaxis).
• Seizures (especially in predisposed patients).
• Behavioral changes (hallucinations, aggression, insomnia in children).

• Alcohol and CNS depressants: Additive sedative effects.
• Theophylline (≥400 mg): May reduce clearance of Levocetirizine slightly.
• Ritonavir: May increase cetirizine levels; similar effects expected with Levocetirizine (clinically minimal).
• CYP450: No significant interaction—Levocetirizine undergoes minimal hepatic metabolism.

• Pediatric Approval Expanded: Approved for use in infants ≥6 months.
• Clinical Guidelines (2024): Recognized as a first-line agent in allergic rhinitis and chronic urticaria per updated WHO/EAACI guidelines.
• New Safety Data: Long-term use up to 18 months in children confirmed as well-tolerated in global safety reviews.

• Tablets and Oral Solution:
  Store at 20°C to 25°C (68°F to 77°F); allowable range: 15°C–30°C.
  Protect from moisture and light.
  Do not freeze oral solution.
  Keep tightly closed after opening.
  Discard oral solution within 90 days after first opening.