2008-05-07T12:48:00.001-07:00

[edit] Usage
For seasonal allergies the recommended dose for adults and children 12 years or older is 60 mg twice daily or 180 mg once daily. Children 6-11 years of age should be given 30 mg twice daily. For chronic urticaria, adults and children 12 years or older should use 60 mg twice daily, and children 6-11 years of age should use 30 mg twice daily. Take Fexofenadine with water (not fruit juice).[2] Fexofenadine can be taken with or without food.

[edit] 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.

[edit] 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.[3] Fexofenadine was developed by Hoechst Marion Roussel (now part of Sanofi-Aventis) and 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.

[edit] Synthesis
Fexofenadine may be synthesized as shown from piperidine-4-carboxylate ester and 4-bromophenylacetonitrile (where Ph=phenyl).[3]

To produce the piperidine piece, two phenyl groups are first introduced using a Grignard reaction on the ester, giving a tertiary alcohol. The amine group is then alkylated with a protected aldehyde, then the aldehyde is recovered by deprotection with acid. The remaining piece of the molecule is produced by a double alkylation by iodomethane of the carbanion derived from the nitrile. The nitrile group is then hydrolyzed to a carboxylic acid. The aryl bromide is then lithiated to produce the organolithium compound, which can be coupled with the aldehyde piece to give (after workup) fexofenadine.

[edit] Notes
^ IngentaConnect - Fexofenadine, an H1-receptor antagonist, partially ...
^ MedlinePlus Drug Information: Fexofenadine
^ a b Daniel Lednicer (1999). The Organic Chemistry of Drug Synthesis 6. New York: Wiley Interscience, 38-40. ISBN 0-471-24510-0.

[edit] References
Synthesis: J. Org. Chem. 1994, 59, 2620.
Biological effects: Mol. Pharmacol. 1993, 44, 1240.

Allegra. Yes or no?