Azelastine Hydrochloride: Uses, Structure, Properties, and Safety Guide

Azelastine Hydrochloride is a potent second-generation antihistamine widely used for managing allergic rhinitis and conjunctivitis. Its distinctive structure, chemical properties, and precise mechanism of action have made it an essential medication in allergy treatment. This detailed blog delves into the structure, properties, pharmacology, uses, and safety of Azelastine Hydrochloride.

1. Structure of Azelastine Hydrochloride

Understanding the molecular structure of Azelastine Hydrochloride helps explain its efficacy in allergy management.

2D Structure Azelastine Hydrochloride

The 2D structure of Azelastine Hydrochloride showcases its phthalazinone backbone, functionalized with benzyl and dimethylamino groups. These elements contribute to its high affinity for histamine H1 receptors, minimizing allergic reactions.

3D Structure Azelastine Hydrochloride

The 3D conformation of Azelastine Hydrochloride reveals its spatial geometry, emphasizing its receptor-binding capabilities. The molecule’s planar regions optimize interactions with H1 receptor sites, enhancing its antihistamine activity.

2. Names and Identifiers

Azelastine Hydrochloride is well-documented under various scientific names and identifiers.

• IUPAC Name: 1-(2H-benzimidazol-2-yl)-1-(4-chlorobenzyl)-2-(dimethylamino)propane hydrochloride
• Molecular Formula: C22H24ClN3O · HCl
• Molecular Weight: 418.37 g/mol
• CAS Registry Number: 79307-93-0
• Synonyms: Astelin, Astepro, Optivar

These identifiers make Azelastine Hydrochloride easily recognizable across scientific and medical communities.

3. Chemical and Physical Properties

The chemical and physical properties of Azelastine Hydrochloride contribute significantly to its pharmacological effectiveness.

These properties enable its formulation into nasal sprays and ophthalmic solutions for targeted application.

4. Drug and Medication Information

Azelastine Hydrochloride is primarily used in treating allergic conditions through various formulations.

Formulations

• Nasal Sprays:
  • 0.1% and 0.15% concentrations.
• Ophthalmic Solutions:
  • 0.05% concentration.

Mechanism of Action

Azelastine Hydrochloride works by:

• Blocking H1 Receptors: Reduces histamine-induced inflammation and symptoms.
• Inhibiting Inflammatory Mediators: Prevents the release of leukotrienes and cytokines, offering dual-action relief.

Dosage and Administration

• For Allergic Rhinitis: 1-2 sprays per nostril twice daily.
• For Allergic Conjunctivitis: 1 drop in each affected eye twice daily.

Consult a healthcare professional for personalized dosage guidelines.

5. Pharmacology and Biochemistry

Azelastine Hydrochloride’s pharmacology is rooted in its antihistaminic and anti-inflammatory properties.

Pharmacokinetics

• Absorption: Rapid with intranasal and ophthalmic use.
• Bioavailability: ~40% via nasal administration.
• Half-Life: ~22 hours, allowing prolonged symptom relief.
• Metabolism: Liver metabolism via cytochrome P450 enzymes.
• Excretion: Primarily renal.

Pharmacodynamics

Azelastine Hydrochloride binds selectively to H1 receptors, stabilizing mast cells and reducing allergic inflammation. Its dual-action mechanism improves patient outcomes by addressing both immediate and delayed allergic symptoms.

6. Uses and Side Effects

Primary Uses

• Seasonal Allergic Rhinitis: Alleviates symptoms like sneezing, congestion, and postnasal drip.
• Allergic Conjunctivitis: Reduces redness, itching, and watering of the eyes.
• Non-Allergic Rhinitis: Manages chronic nasal irritation caused by non-allergic triggers.

Benefits

• Rapid onset of action (within 15 minutes).
• Long-lasting relief (up to 12 hours).

Side Effects

Azelastine Hydrochloride is generally well-tolerated. Common side effects include:

• Bitter taste in the mouth.
• Nasal dryness or irritation.
• Mild drowsiness.

Rare side effects may include severe allergic reactions such as swelling, rash, or difficulty breathing. Consult a healthcare provider if side effects persist.

7. Safety and Hazards

Safety Profile

Azelastine Hydrochloride is safe for most individuals when used as directed. However:

• Pregnancy and Breastfeeding: Use with caution; consult a physician.
• Children: Safe with age-appropriate dosage.

Handling Precautions

• Store in a cool, dry place, away from direct sunlight.
• Keep out of reach of children.

Chemical Safety

Environmental Impact

Azelastine Hydrochloride has minimal ecological risk due to its rapid degradation in aquatic systems.