Small molecule
PubChem CID 3348
Fexofenadine
Allegra
- Mechanism of action
- Second-generation H1 histamine receptor antagonist
- In plain language
- Blocks histamine at the receptors outside the brain that trigger sneezing, itching, and hives, without crossing into the brain to cause drowsiness.
- How it works
- Fexofenadine hydrochloride, the active carboxylic acid metabolite of terfenadine, is a selective, competitive H1-receptor antagonist that inhibits histamine binding at peripheral effector sites in the vasculature, respiratory tract, and skin. It lacks significant anticholinergic or alpha1-adrenergic blocking activity, distinguishing it from first-generation antihistamines. Because fexofenadine is a substrate for P-glycoprotein and does not readily cross the blood-brain barrier, it produces minimal CNS penetration, accounting for its low sedation potential relative to first-generation agents. Onset of antihistaminic effect occurs within one hour of dosing, with therapeutic activity sustained over a 12- to 24-hour dosing interval.
- Therapeutic applications
- Indicated for relief of symptoms associated with seasonal allergic rhinitis, including sneezing, rhinorrhea, and itchy/watery eyes, and for treatment of the uncomplicated skin manifestations of chronic idiopathic urticaria, including pruritus and reduction in the number and size of hives.
- Class
- Small molecule
- Therapeutic area
- Allergy / Immunology
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