N. Frossard et al., ONSET OF ACTION IN THE NASAL ANTIHISTAMINIC EFFECT OF CETIRIZINE AND LORATADINE IN PATIENTS WITH ALLERGIC RHINITIS, Allergy, 52(2), 1997, pp. 205-209
Several studies have compared the cutaneous efficacy of cetirizine and
loratadine and their onset of action. We assessed the nasal effect of
these two antihistamines in a randomized, double-blind, crossover, pl
acebo-controlled trial in order to compare objectively their efficacy
and onset of action in the noses of patients with allergic rhinitis. N
asal challenge was performed by nebulization of increasing doubling do
ses of histamine (0, 0.04-1.28 mg/nostril) in 12 patients (eight men,
four women, aged 22-39 years). Nasal airway resistance (NAR) was measu
red by posterior rhinomanometry either 1.5 h or 4 h after intake of ce
tirizine (10 mg), loratadine (10 mg), or placebo. Baseline NAR was ide
ntical between all study days (2.60-2.88 cmH(2)O . 1(-1). s). One and
a half hours after intake, the increase in NAR induced by histamine wa
s significantly reduced by both cetirizine and loratadine in contrast
to placebo. However, with cetirizine the nasal obstruction was signifi
cantly lower than with loratadine (P < 0.05). Four hours after intake,
a similar inhibition of the nasal obstruction caused by histamine was
observed with both cetirizine and loratadine (P < 0.05). In conclusio
n, this study found cetirizine and loratadine to have similar nasal ef
ficacy at therapeutic dosage 4 h after intake, whereas cetirizine was
more effective than loratadine 1.5 h after intake. In agreement with t
he results observed in the skin, our study suggests a more rapid onset
of action of cetirizine in the nose in allergic rhinitis.