Overview
Loratadine is a second-generation antihistamine used for symptomatic relief of allergic rhinitis and chronic idiopathic urticaria. It selectively blocks peripheral H1 receptors with minimal sedation due to poor blood-brain barrier penetration. The drug provides 24-hour relief with once-daily dosing.
Mechanism of Action
Loratadine is a selective peripheral histamine H1-receptor antagonist that competitively inhibits histamine binding at H1 receptors. It has minimal affinity for cholinergic, alpha-adrenergic, or serotonin receptors, resulting in reduced sedative effects compared to first-generation antihistamines.
Indications
- Temporary relief of symptoms due to hay fever or other upper respiratory allergies: runny nose, itchy/watery eyes, sneezing, itching of nose or throat
- Symptomatic relief of chronic idiopathic urticaria (hives)
Common Doses
- 10 mg tablet
- 5 mg/5 mL syrup
- 10 mg orally disintegrating tablet
Dosage
Adults and children 6 years and over: 10 mg (1 tablet) once daily. For orally disintegrating tablets: place on tongue; tablet disintegrates with or without water. Do not exceed 1 tablet in 24 hours. Children under 6 years, patients with liver or kidney impairment: consult physician.
Contraindications
- Hypersensitivity to loratadine or any component of the formulation
- Patients with severe hepatic impairment
Side Effects
- Headache
- Somnolence (drowsiness)
- Fatigue
- Dry mouth
- Nausea
- Nervousness
- Pharyngitis
Interactions
- Erythromycin, ketoconazole, cimetidine: may increase loratadine plasma concentrations
- Alcohol: may potentiate CNS depressant effects
- Other CNS depressants: additive sedative effects
Counseling Points
- Take once daily as directed; do not exceed recommended dose
- Orally disintegrating tablets can be taken with or without water
- May cause drowsiness; assess individual response before driving
- Store at room temperature, protect from moisture
- Consult physician if symptoms persist or worsen