Questions and Answers
What is the therapeutic classification of Fexofenadine?
When was Fexofenadine approved by the FDA?
1996
What is the mechanism of action of Fexofenadine?
It competes with histamine for binding to histamine (H1) receptor sites.
Fexofenadine has a half-life of over ___ hours.
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What are the common adverse effects of Fexofenadine?
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Fexofenadine readily crosses the blood-brain barrier.
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What should be done for a Fexofenadine overdose?
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Which of the following is a drug interaction with Fexofenadine?
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Match the drugs similar to Fexofenadine with their names:
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Study Notes
Fexofenadine (Allegra) Overview
- Fexofenadine is a second-generation H1-receptor antagonist classified as an antihistamine, used for allergic rhinitis and minor allergies.
Therapeutic Effects and Uses
- FDA approved in 1996 for allergic rhinitis, effective when taken before symptoms arise.
- Reduces nasal congestion, sneezing, and eye tearing; long half-life allows once or twice daily dosing.
- Available in various forms: regular tablets, orally disintegrating tablets, and suspension.
- Also approved for chronic idiopathic urticaria; combined with pseudoephedrine in Allegra-D for added decongestant effect.
Mechanism of Action
- Competes with histamine for binding at H1 receptor sites but does not prevent histamine release.
Pharmacokinetics
- Administered orally (capsules, tablets, suspension).
- Rapid absorption, does not cross the blood-brain barrier, unclear if secreted in breast milk, 60-70% plasma protein bound.
- Primarily metabolized in the liver; 80% excreted renally, 11% in feces.
- Onset of action within 1 hour; half-life approximately 14.4 hours with a duration of 12-24 hours.
Adverse Effects
- Major advantage over first-generation antihistamines: low incidence of drowsiness.
- Minor adverse effects include headache, nausea, dyspepsia, and dysmenorrhea.
- Increased incidence of viral infections reported; some patients may experience anticholinergic effects, like dry mouth.
Contraindications/Precautions
- Hypersensitivity to fexofenadine is the only contraindication.
- Patients with advanced chronic kidney disease (CKD) should receive dosage adjustments.
Drug Interactions
- Drowsiness may occur at high doses or with CNS depressants, including alcohol.
- Concomitant use with ketoconazole or erythromycin raises plasma concentrations of fexofenadine.
- Antacids containing aluminum or magnesium can hinder absorption.
- Grapefruit, orange, or apple juice may decrease bioavailability when taken with fexofenadine.
Pregnancy Category
- Classified as Category C, indicating risk cannot be ruled out.
Treatment of Overdose
- Symptoms of overdose include CNS depression, dry mouth, and dizziness.
- No specific antidote; supportive treatment is recommended for symptom management.
Similar Drugs
- Acrivastine with pseudoephedrine (Semprex-D)
- Azelastine (Astelin, Astepro, Optivar)
- Cetirizine (Zyrtec)
- Desloratadine (Clarinex)
- Diphenhydramine (Benadryl, others)
- Loratadine (Claritin)
- Olopatadine (Patanase, Patanol)
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Description
Test your knowledge of the prototype drug Fexofenadine (Allegra) with these flashcards. Learn about its classifications, therapeutic effects, and uses, crucial for mastering pharmacology concepts in your Pharm II exam. Perfect for students seeking a comprehensive review before their exam.
