Allegra (Fexofenadine, Telfast, Fastofen, Tilfur)
Fexofenadine (Allegra, Telfast, Fastofen, Tilfur) 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 (brand names include Triludan and Seldane), an antihistamine with potentially serious contraindications. Fexofenadine, like other second and third-generation antihistamines, does not readily cross the blood-brain barrier, and so causes less drowsiness than first-generation histamine-receptor antagonists. It works by being an antagonist to the H1 receptor.
Usage
Fexofenadine is indicated for relief of symptoms associated with seasonal allergic rhinitis and treatment of chronic idiopathic urticaria.
Dosage
Chronic idiopathic urticaria: Children 6 months to < 2 years: 15 mg twice daily
Chronic idiopathic urticaria, seasonal allergic rhinitis:
Children 2–11 years: 30 mg twice daily
Children ≥ 12 years and Adult: 60 mg twice daily or 180 mg once daily
Elderly: Starting dose: 60 mg once daily; adjust for renal impairment
Dosage forms
Suspension: 6 mg/mL (30 mL, 300 mL) [raspberry cream]
Tablet: 30 mg, 60 mg, 180 mg
Common side effects
Nausea
Dizziness
Vomiting
Weakness
Drowsiness, sleepiness
Fatigue
Diarrhea
Unusual bowel movements
Headache
Overdose
Reports of fexofenadine overdose are infrequent, and because of this, the effects are not well established. No deaths occurred in testing on mice, at 5000 mg/kg, which is 110 times the maximum recommended dose for an adult human. Further research shows no deaths in rats at the same concentration, which equates four hundred times the recommended dose in an adult human. Research on humans ranges from a single 800 mg dose, to a twice-daily 690 mg dose for a month, with no clinically significant adverse effects, when compared to a placebo.
Drug interactions
When taken with fluoxetine, fexofenadine may induce drowsiness.
History
The older antihistaminic agent terfenadine was found to metabolize into the related carboxylic acid, fexofenadine. Fexofenadine was found to retain all of the biological activity of its parent while giving fewer adverse reactions in patients, so terfenadine was replaced in the market by its metabolite. Fexofenadine was originally synthesized in 1993 by Massachusetts-based biotechnology company Sepracor, which then sold the development rights to Hoechst Marion Roussel (now part of Sanofi-Aventis), and was later approved by the Food and Drug Administration (FDA) in 1996. AMRI holds the patents to the intermediates and production of fexofenadine HCl along with Roussel. Since that time, it has achieved blockbuster drug status with global sales of $1.87B USD in 2004 (with $1.49B USD coming from the United States). AMRI received royalty payments from Aventis that enabled the growth of AMRI.
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