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Information |
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Drug Groups
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approved |
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Description
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Fexofenadine hydrochloride (Allegra) is an antihistamine drug used in the treatment of hayfever and similar allergy symptoms. It was developed as a successor of and alternative to terfenadine. Fexofenadine, like other second and third-generation antihistamines, does not readily pass through the blood-brain barrier, and so causes less drowsiness than first-generation histamine-receptor antagonists. |
| Indication |
For management of Seasonal allergic rhinitis |
| Pharmacology |
Fexofenadine is a second-generation, long lasting H1-receptor antagonist (antihistamine) which has a selective and peripheral H1-antagonist action. Histamine is a chemical that causes many of the signs that are part of allergic reactions, such as the swelling of tissues. Histamine is released from histamine-storing cells (mast cells) and attaches to other cells that have receptors for histamine. The attachment of the histamine to the receptors causes the cell to be "activated," releasing other chemicals which produce the effects that we associate with allergy. Fexofenadine blocks one type of receptor for histamine (the H1 receptor) and thus prevents activation of cells by histamine. Unlike most other antihistamines, Fexofenadine does not enter the brain from the blood and, therefore, does not cause drowsiness. Fexofenadine lacks the cardiotoxic potential of terfenadine, since it does not block the potassium channel involved in repolarization of cardiac cells. |
| Toxicity |
Side effects include dizziness, drowsiness, and dry mouth. |
| Affected Organisms |
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Humans and other mammals |
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| Biotransformation |
Approximately 5% of the total dose is metabolized, by cytochrome P450 3A4 and by intestinal microflora. |
| Absorption |
33% |
| Half Life |
14.4 hours |
| Protein Binding |
60%-70% |
| References |
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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.
[Pubmed]
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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.
[Pubmed]
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Markham A, Wagstaff AJ: Fexofenadine. Drugs. 1998 Feb;55(2):269-74; discussion 275-6.
[Pubmed]
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Golightly LK, Greos LS: Second-generation antihistamines: actions and efficacy in the management of allergic disorders. Drugs. 2005;65(3):341-84.
[Pubmed]
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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]
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