Loratadine is a second-generation, non-sedating antihistamine widely used for the management of allergic conditions. It is commonly formulated as 10 mg tablets (including chewable forms) and works by selectively blocking peripheral histamine H1 receptors, thereby reducing the effects of histamine released during allergic reactions.

Indications

Loratadine is indicated for the relief of symptoms associated with:

• Allergic Rhinitis (seasonal and perennial)
• Chronic Idiopathic Urticaria
• Other allergic manifestations such as sneezing, nasal discharge, itching, and watery eyes

Mechanism of Action

Loratadine acts as a selective inverse agonist at H1 receptors, preventing histamine from binding and triggering allergic symptoms. Due to its limited penetration across the blood–brain barrier, it produces minimal central nervous system sedation compared to first-generation antihistamines.

Pharmacokinetics

• Absorption: Rapid after oral administration
• Onset of action: 1–3 hours
• Duration: ~24 hours (supports once-daily dosing)
• Metabolism: Extensively metabolized in the liver via CYP3A4 and CYP2D6 to an active metabolite (desloratadine)
• Elimination half-life: ~8 hours (loratadine), longer for its active metabolite

Dosage (General Guidance)

• Adults and children ≥6 years: 10 mg once daily
• Dose adjustments may be required in hepatic impairment

Warnings & Precautions

• Use cautiously in patients with liver dysfunction
• Products containing aspartame should be used with caution in patients with Phenylketonuria
• Generally well tolerated; possible side effects include headache, fatigue, dry mouth, and rarely drowsiness

Advantages

• Long-acting, once-daily dosing
• Minimal sedation compared to older antihistamines
• Suitable for daytime use without significant impairment of alertness

Patient Disclaimer

This summary is based on authoritative academic and nonprofit medical sources (e.g., university pharmacology references and organizations such as the National Institutes of Health and MedlinePlus). It is intended for educational purposes only and does not replace professional medical advice. Always consult a healthcare provider before using this medication, especially for children, during pregnancy, or if you have chronic medical conditions.

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