Usage
Azelastine is prescribed for the symptomatic relief of seasonal and perennial allergic rhinitis (hay fever), vasomotor rhinitis (non-allergic runny nose), and allergic conjunctivitis (eye allergies). It belongs to the pharmacological class of antihistamines, specifically second-generation H1-receptor antagonists. Azelastine works by competitively binding to histamine H1 receptors, thus preventing histamine from binding and triggering allergic symptoms. It also inhibits the release of inflammatory mediators involved in allergic reactions.
Alternate Names
Azelastine hydrochloride is the chemical name. Brand names for azelastine nasal spray include Astelin, Astepro, and Dymista (in combination with fluticasone). Brand names for azelastine eye drops include Optivar.
How It Works
Pharmacodynamics: Azelastine exerts its therapeutic effect by antagonizing the H1 receptor, leading to a reduction in histamine-mediated responses like vasodilation, increased vascular permeability, and itching. It also stabilizes mast cells, preventing the release of other inflammatory mediators.
Pharmacokinetics: Nasal azelastine is rapidly absorbed, reaching peak plasma concentration in approximately 1-3 hours. It undergoes minimal first-pass metabolism. Ophthalmic azelastine also achieves peak concentration rapidly. Azelastine is metabolized in the liver, primarily by CYP enzymes. It is eliminated predominantly through feces and urine, with a half-life of around 22 hours.
Mode of Action: Azelastine selectively binds to H1 receptors on the surface of mast cells, basophils, and smooth muscle cells, preventing histamine from binding. This inhibits histamine-mediated vasodilation, vascular permeability changes, and mucus secretion, thereby relieving allergic symptoms.
Receptor Binding/Enzyme Inhibition: Azelastine competitively binds to H1 receptors. It does not significantly inhibit CYP enzymes.
Elimination Pathways: Primarily hepatic metabolism followed by excretion through both renal and fecal routes.
Dosage
Standard Dosage
Adults:
- Nasal Spray: 1 or 2 sprays per nostril twice daily (BID) or 2 sprays per nostril once daily (QD). Maximum: 4 sprays per nostril in a 24-hour period.
- Eye Drops: 1 drop per affected eye BID.
Children:
- Nasal Spray (6-11 years): 1 spray per nostril BID. Maximum: 2 sprays per nostril in a 24-hour period.
- Nasal Spray (2-5 years): 1 spray per nostril BID (Astelin 0.1% solution only).
- Nasal Spray (<2 years): Not recommended.
- Eye Drops (3 years and older): 1 drop per affected eye BID.
- Eye Drops (<3 years): Not recommended.
Special Cases:
- Elderly Patients: No specific dosage adjustments are generally recommended, but it is suggested to start with a lower dose and titrate as needed.
- Patients with Renal Impairment: No dose adjustments are recommended.
- Patients with Hepatic Dysfunction: No specific dosage adjustments are recommended, but caution should be exercised due to hepatic metabolism.
- Patients with Comorbid Conditions: Dose adjustment may be needed in patients with severe comorbidities. Consult specialist advice where necessary.
Clinical Use Cases
Azelastine is not typically used in clinical scenarios like intubation, surgical procedures, mechanical ventilation, ICU use, or emergency situations. Its use is primarily limited to the outpatient management of allergic rhinitis and conjunctivitis.
Dosage Adjustments
No dosage adjustments are necessary based on renal or hepatic dysfunction. However, individual patient factors and response to therapy should always be considered.
Side Effects
Common Side Effects:
- Nasal: Bitter taste, nasal dryness, irritation, sneezing, epistaxis (nosebleed).
- Ophthalmic: Burning or stinging, temporary blurred vision.
- Systemic: Headache, drowsiness, fatigue.
Rare but Serious Side Effects:
- Allergic reactions (rash, itching, swelling, difficulty breathing).
Long-Term Effects:
No specific long-term adverse effects have been reported with azelastine use.
Adverse Drug Reactions (ADR):
Severe allergic reactions can occur, though rarely.
Contraindications
- Hypersensitivity to azelastine.
Drug Interactions
- CNS Depressants: Concurrent use with alcohol or other CNS depressants may potentiate sedative effects.
- CYP450 Interactions: Azelastine is minimally metabolized by CYP enzymes, thus significant drug interactions are less likely.
Pregnancy and Breastfeeding
- Pregnancy: Azelastine is classified as Pregnancy Category C. Use only if the potential benefit justifies the potential risk to the fetus.
- Breastfeeding: It is unknown if azelastine is excreted in human milk. Caution is advised.
Drug Profile Summary
- Mechanism of Action: H1 receptor antagonist, mast cell stabilizer.
- Side Effects: Bitter taste, nasal dryness, headache, drowsiness.
- Contraindications: Hypersensitivity.
- Drug Interactions: CNS depressants.
- Pregnancy & Breastfeeding: Category C; caution advised.
- Dosage: See above for details.
- Monitoring Parameters: Symptom control, adverse effects.
Popular Combinations
Azelastine is sometimes combined with fluticasone propionate (a corticosteroid) in a nasal spray called Dymista, offering enhanced efficacy for allergic rhinitis.
Precautions
- General Precautions: Monitor for allergic reactions.
- Specific Populations: Use with caution in pregnancy and breastfeeding.
- Lifestyle Considerations: Avoid alcohol during treatment.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Azelastine?
A: See Dosage section above for details.
Q2: How does Azelastine differ from first-generation antihistamines?
A: Azelastine is a second-generation antihistamine that is less sedating compared to first-generation antihistamines.
Q3: Can Azelastine be used in children?
A: Yes, nasal spray is approved for children above 2 years (some formulations from 6 years) and eye drops for children over 3 years old. Refer to the dosage section for age-specific recommendations.
Q4: What should patients do if they miss a dose?
A: Patients should take the missed dose as soon as they remember. However, if it is close to the time for the next dose, they should skip the missed dose and resume their regular schedule.
Q5: Can Azelastine be used during pregnancy?
A: Azelastine is a Pregnancy Category C drug. Consult a doctor to assess the risks and benefits before use during pregnancy.
Q6: Are there any interactions between Azelastine and other medications?
A: Concomitant use with CNS depressants might increase sedation.
Q7: What are the most common side effects of azelastine nasal spray?
A: Bitter taste, nasal dryness, and headache are among the frequently reported side effects.
Q8: How quickly does azelastine nasal spray work?
A: Azelastine nasal spray typically provides symptom relief within 15-30 minutes.
Q9: Can azelastine be used to treat eye allergies?
A: Yes, azelastine ophthalmic solution is specifically formulated to treat allergic conjunctivitis.
