Fexofenadine
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Fexofenadine
Allegra, Allegra Allergy 24 Hour, Mucinex Allergy (combo) — all now OTC in US
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Summary
Common uses
Seasonal allergic rhinitis0, Chronic idiopathic urticaria0
Pharmacy
Starting dose
60 mg PO BID or 180 mg PO once daily
Preparations
30, 60, 180 mg tablets; 30 mg ODT; 6 mg/mL oral suspension; all OTC
US FDA Max
180 mg/d (adults)
Pharmacology
Routes
Oral
Onset
1-2 hours
Duration
12-24 hours
Half-life
~14 hours[1]
Bioavailability
~33% (oral; fruit juices including grapefruit, orange, and apple reduce absorption substantially via OATP1A2 inhibition — distinctive interaction not seen with most other H1s)[1]
Pregnancy
Generally considered safe; loratadine and cetirizine have more pregnancy data and are typically preferred.[citation needed]
Legal status
OTC in US
Purported mechanism
Fexofenadine is the active carboxylated metabolite of terfenadine (the latter withdrawn for QT-prolonging cardiotoxicity); it selectively antagonizes peripheral H1 receptors with minimal blood-brain barrier penetration and no significant CYP-mediated metabolism, giving it among the lowest-sedation and lowest-interaction profiles in the second-generation class.0 Mostly excreted unchanged in feces and urine; P-glycoprotein substrate (the basis of the fruit-juice interaction).
References
edit- ↑ 1.0 1.1 FDA Prescribing Information, Allegra (fexofenadine HCl), Sanofi-Aventis (now OTC), current revision. https://www.accessdata.fda.gov/drugsatfda_docs/label/2010/020786s022,020872s019,021963s010lbl.pdf