Similar rapid onset of action and magnitude of effect of fexofenadine and cetirizine as assessed by inhibition of histamine-induced wheal-and-flare reaction.
BACKGROUND
Histamine-induced wheal-and-flare studies are useful, objective tests for determining differences in the peripheral H1-receptor blockade activities of antihistamines.


OBJECTIVE
To evaluate the time of occurrence of 95% inhibition of histamine-induced wheal and flare after administration of fexofenadine hydrochloride, 180 mg, or cetirizine, 10 mg.


METHODS
Forty-two volunteers (aged 18-60 years) were included in a randomized, double-blind, crossover study. Skin prick tests were undertaken using histamine (100 mg/mL) before treatment and 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, and 4.0 hours after treatment. Wheal and flare areas were evaluated, and the time to occurrence of 95% inhibition and the frequency of subjects exhibiting 95% inhibition before median time to 95% inhibition were calculated.


RESULTS
Mean +/- SD time to 95% wheal inhibition was 2.46 +/- 0.71 hours with fexofenadine and 2.55 +/- 0.57 hours with cetirizine. The estimated mean difference between fexofenadine and cetirizine (-7 minutes in favor of fexofenadine; 2-sided 95% confidence interval, -21 to +7 minutes) was not statistically significant (P = .34). For wheal, 29% of subjects receiving fexofenadine and 24% receiving cetirizine achieved 95% inhibition before the median time of inhibition (2.5 hours). An exact permutation test yielded a P = .37. For flare, 26% of subjects receiving fexofenadine and 10% receiving cetirizine achieved 95% inhibition before the median time of inhibition (3 hours; P = .12 by exact permutation test).


CONCLUSIONS
Fexofenadine and cetirizine have comparable onset of action times and similar frequencies of inhibition, as evaluated by the occurrence of 95% inhibition of histamine-induced wheal and flare.
Purohit
Ashok
A
INSERM U425/EA3771, Faculte de Pharmacie, Illkirch, and Service de Pneumologie, Hôpitaux Universitaires, Strasbourg, France.
N'Gom
A Severin
AS
Deslandes
Bruno
B
Pauli
Gabrielle
G
Frossard
Nelly
N
D000293:Adolescent; D000328:Adult; D017332:Cetirizine / Q000494:pharmacology*; D018592:Cross-Over Studies; D005260:Female; D006632:Histamine / Q000494:pharmacology; D006634:Histamine H1 Antagonists / Q000494:pharmacology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012882:Skin Tests; D016593:Terfenadine / Q000031:analogs & derivatives* / Q000494:pharmacology*; D014581:Urticaria / Q000139:chemically induced / Q000188:drug therapy
D006634:Histamine H1 Antagonists; D016593:Terfenadine; D006632:Histamine; C093230:fexofenadine; D017332:Cetirizine