Description

Simple

A medication used to treat allergic symptoms such as itchy skin and a runny nose.

Clinical

A selective H1-antagonist for the symptomatic treatment of seasonal allergic rhinitis and chronic idiopathic urticaria.

Overview

Fexofenadine is an over-the-counter second-generation antihistamine used in the treatment of various allergic symptoms.[10] It is selective for the H1 receptor, carries little-to-no activity at off-targets, and does not cross the blood-brain barrier[9] - this is in contrast to previous first-generation antihistamines, such as [diphenhydramine], which readily bind to off-targets that contribute to side effects such as sedation.[1] Fexofenadine is the major active metabolite of [terfenadine][7] and is administered as a racemic mixture in which both enantiomers display approximately equivalent antihistamine activity.[9]

Pharmacology

Indication

In the United States, fexofenadine is indicated for the symptomatic treatment of allergic rhinitis in patients ≥2 years old and chronic idiopathic urticaria in patients ≥6 months old.[10] In C... Read more

Pharmacodynamic

Fexofenadine relieves allergy symptoms by antagonizing the actions of histamine, an endogenous compound predominantly responsible for allergic symptomatology.[10] The relatively long duration... Read more

Mechanism of action

The H1 histamine receptor is responsible for mediating hypersensitivity and allergic reactions. Exposure to an allergen results in degranulation of mast cells and basophils, which then release histamine and other inflammatory mediators. Histamine binds to, and activates, H1 rec... Read more

Absorption

Fexofenadine is rapidly absorbed following oral administration and its absolute bioavailability is approximately 33%.[9] The Tmax following oral administration is approximately 1-3 hour... Read more

Protein binding

Fexofenadine is 60-70% bound to plasma proteins,[10] primarily to albumin and α1-acid glycoprotein. The extent of protein binding is decreased to 56-68% and 56-75% in patients with... Read more

Volume of distribution

The volume of distribution is approximately 5.4-5.8 L/kg.[ Read more

Clearance

The oral clearance of fexofenadine is approximately 50.6 L/h and the renal clearance is approximately 4.32 L/h.[9]

Half life

The terminal elimination half-life is approximately 11-15 hours.[9, Read more

Route of elimination

Approximately 80% of an ingested dose is eliminated in the feces, likely largely unchanged due to fexofenadine's limited metabolism, and 11% is eliminated in the urine.[ Read more

Toxicity

No deaths were observed following the oral administration of up to 5000 mg/kg in both mice and rats (equivalent to approximately 100-200x the recommended human dose). Single doses of up to 800 mg and chronic exposure of up to 690 mg twice daily for 1 month in humans did not result in clinically sign... Read more

Adverse Effects

Contraindications

  • Hypersensitivity:
    • true
  • Regions: US

Food Interactions

  • Avoid fruit juice. Fruit juices like grapefruit, orange, and apple may reduce bioavailability and overall exposure to the medication.
  • Take with or without food. Co-administration with food does not significantly affect absorption.

Interactions

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  • Paracetamol(acetaminophen)
  • Paxil(paroxetine)
  • Pamelor(nortriptyline)
  • Panadol(acetaminophen)
  • Patanol(olopatadine ophthalmic)
  • Pataday(olopatadine ophthalmic)
  • Parnate(tranylcypromine)
  • Pazeo(olopatadine ophthalmic)
2,5-Dimethoxy-4-ethylamphetamine
2,5-Dimethoxy-4-ethylamphetamine may decrease the sedative and stimulatory activities of Fexofenadine.
2,5-Dimethoxy-4-ethylthioamphetamine
2,5-Dimethoxy-4-ethylthioamphetamine may decrease the sedative and stimulatory activities of Fexofenadine.
4-Bromo-2,5-dimethoxyamphetamine
4-Bromo-2,5-dimethoxyamphetamine may decrease the sedative and stimulatory activities of Fexofenadine.
Acetylcysteine
The excretion of Fexofenadine can be decreased when combined with Acetylcysteine.
Acetylsalicylic acid
The excretion of Fexofenadine can be decreased when combined with Acetylsalicylic acid.
Acyclovir
The excretion of Fexofenadine can be decreased when combined with Acyclovir.
Afatinib
The serum concentration of Fexofenadine can be increased when it is combined with Afatinib.
Almasilate
Almasilate can cause a decrease in the absorption of Fexofenadine resulting in a reduced serum concentration and potentially a decrease in efficacy.
Aloglutamol
Aloglutamol can cause a decrease in the absorption of Fexofenadine resulting in a reduced serum concentration and potentially a decrease in efficacy.
Aluminium
Aluminium can cause a decrease in the absorption of Fexofenadine resulting in a reduced serum concentration and potentially a decrease in efficacy.
Aluminium acetoacetate
Aluminium acetoacetate can cause a decrease in the absorption of Fexofenadine resulting in a reduced serum concentration and potentially a decrease in efficacy.
Aluminium glycinate
Aluminium glycinate can cause a decrease in the absorption of Fexofenadine resulting in a reduced serum concentration and potentially a decrease in efficacy.
Aluminium phosphate
Aluminium phosphate can cause a decrease in the absorption of Fexofenadine resulting in a reduced serum concentration and potentially a decrease in efficacy.
Aluminum hydroxide
Aluminum hydroxide can cause a decrease in the absorption of Fexofenadine resulting in a reduced serum concentration and potentially a decrease in efficacy.
Ambrisentan
The serum concentration of Ambrisentan can be increased when it is combined with Fexofenadine.
Aminohippuric acid
The excretion of Fexofenadine can be decreased when combined with Aminohippuric acid.
Amiodarone
The serum concentration of Amiodarone can be increased when it is combined with Fexofenadine.
Amphetamine
Amphetamine may decrease the sedative and stimulatory activities of Fexofenadine.
Amprenavir
The excretion of Fexofenadine can be decreased when combined with Amprenavir.
Apalutamide
The serum concentration of Fexofenadine can be decreased when it is combined with Apalutamide.
11 References
  1. 1 . Smith SM, Gums JG: Fexofenadine: biochemical, pharmacokinetic and pharmacodynamic properties and its unique role in allergic disorders. Expert Opin Drug Metab Toxicol. 2009 Jul;5(7):813-22. doi: 10.1517/17425250903044967.PubMed: 19545214
  2. 2 . Bachert C: A review of the efficacy of desloratadine, fexofenadine, and levocetirizine in the treatment of nasal congestion in patients with allergic rhinitis. Clin Ther. 2009 May;31(5):921-44. doi: 10.1016/j.clinthera.2009.05.017.PubMed: 19539095
  3. 3 . Markham A, Wagstaff AJ: Fexofenadine. Drugs. 1998 Feb;55(2):269-74; discussion 275-6.PubMed: 9506246
  4. 4 . Golightly LK, Greos LS: Second-generation antihistamines: actions and efficacy in the management of allergic disorders. Drugs. 2005;65(3):341-84.PubMed: 15669879
  5. 5 . Molimard M, Diquet B, Benedetti MS: Comparison of pharmacokinetics and metabolism of desloratadine, fexofenadine, levocetirizine and mizolastine in humans. Fundam Clin Pharmacol. 2004 Aug;18(4):399-411.PubMed: 15312146
  6. 6 . Akamine Y, Miura M: An update on the clinical pharmacokinetics of fexofenadine enantiomers. Expert Opin Drug Metab Toxicol. 2018 Apr;14(4):429-434. doi: 10.1080/17425255.2018.1459565. Epub 2018 Apr 11.PubMed: 29635947
  7. 7 . Devillier P, Roche N, Faisy C: Clinical pharmacokinetics and pharmacodynamics of desloratadine, fexofenadine and levocetirizine : a comparative review. Clin Pharmacokinet. 2008;47(4):217-30.PubMed: 18336052
  8. 8 . Yu J, Zhou Z, Tay-Sontheimer J, Levy RH, Ragueneau-Majlessi I: Intestinal Drug Interactions Mediated by OATPs: A Systematic Review of Preclinical and Clinical Findings. J Pharm Sci. 2017 Sep;106(9):2312-2325. doi: 10.1016/j.xphs.2017.04.004. Epub 2017 Apr 13.PubMed: 28414144
  9. 9 . DPD Approved Drugs: Allegra® oral tablets Link
  10. 10 . Allegra (Fexofenadine Hydrochloride) FDA Label Link
  11. 11 . FDA Approved Drug Products: Allegra-D® extended-release tablets Link