Fexofenadine, the active metabolite of
terfenadine, is a selective
histamine H1 receptor antagonist that does not cross the blood brain barrier and appears to display some anti-inflammatory properties.
Fexofenadine is rapidly absorbed (onset of relief < or = 2 hours) and has a long duration of action, making it suitable for once daily administration. Clinical trials (< or = 2 weeks' duration) have shown
fexofenadine 60 mg twice daily and 120 mg once daily to be as effective as
loratadine 10 mg once daily, and
fexofenadine 120 mg once daily to be as effective as
cetirizine 10 mg once daily in the overall reduction of symptoms of
seasonal allergic rhinitis. When given in combination,
fexofenadine and extended release
pseudoephedrine had complementary activity.
Fexofenadine was effective in relieving the symptoms of
sneezing, rhinorrhoea, itchy nose palate or throat, and itchy, watery, red eyes in patients with
seasonal allergic rhinitis. There were often small improvements in nasal congestion that were further improved by
pseudoephedrine.
Fexofenadine produced greater improvements in quality of life than
loratadine to an extent considered to be clinically meaningful, and enhanced patients' quality of life when added to
pseudoephedrine treatment. Although no comparative data with other H1 antagonists exist,
fexofenadine 180 mg once daily was effective in reducing the symptoms of
chronic idiopathic urticaria for up to 6 weeks.
Fexofenadine was well tolerated in clinical trials in adults and adolescents and the adverse event profile was similar to placebo in all studies. The most frequently reported adverse event during
fexofenadine treatment was
headache, which occurred with a similar incidence to that seen in placebo recipients.
Fexofenadine does not inhibit cardiac K+ channels and is not associated with prolongation of the corrected QT interval. When given alone or in combination with
erythromycin or
ketoconazole, it was not associated with any
adverse cardiac events in clinical trials. As it does not cross the blood brain barrier,
fexofenadine is free of the
sedative effects associated with first generation
antihistamines, even at dosages of up to 240 mg/day.
CONCLUSIONS: