R06AX26 - Fexofenadine |
Propably not porphyrinogenic |
PNP |
Rationale
Fexofenadine is not an inducer or an irreversible inhibitor of Cytochrome P450 enzymes. There are no indications of porphyrinogenic effects connected with the pharmacodynamic properties of the drug.
Chemical description
Fexofenadine is a butyrophenone-derivative antihistamine. The drug is the active carboxylic acid metabolite of terfenadine.
Therapeutic characteristics
Fexofenadine is a selective histamine H1-receptor antagonist, and it is used in the symptomatic relief of allergic conditions including seasonal allergic rhinitis. It is administered orally. Fexofenadine is not suspected to have any potentially porphyrinogenic side effects.
Metabolism and pharmakokinetics
Only about 5% of the total dose of fexofenadine is metabolised, mostly by the intestinal mucosa, with 0.5 to 1.5% of the dose undergoing hepatic biotransformation by the cytochrome P450 system. Fexofenadine is a substrate of CYP 3A4 and an inhibitor of CYP 2D6, but is not listed as an inducer or irreversible inhibitor of Cytochome P450 enzymes (Rendic 2002).
IPNet drug reports
Uneventful use reported in 1 patient with acute porphyria.
References
- Scientific articles
- Rendic, S. Summery of information on human CYP enzymes: human P450 metabolism. Drug metabolism reviews 2002; 34(1&2), 83-448. #1025
- Devillier P, Roche N et al. Clinical pharmacokinetics and pharmacodynamics of desloratadine, fexofenadine and levocetirizine, a comparative review. Clin Pharmacokinet 2008; 47 (4): 217-230 PMID 18336052. #4722
- Drug reference publications
- Sweetman SC, editor. Martindale: The complete drug reference. Fexofenadine. Pharmaceutical Press 2009. #2923
- Summary of Product Characteristics
- The electronic Medicines Compendium (emc). Summary of Product Characteristics (SPC). Telfast. #2924
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