Inhibition of allergen-induced wheal and flare reactions by levocetirizine and desloratadine.
(49/98)
WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT: The reproducible and standardized histamine-induced wheal and flare model helps identify the objective effectiveness of antihistamines in humans, as well as their differences in onset and duration of action. Some of the newest antihistamines have already been compared in a head-to-head setting using this model. However, their objective action at inhibiting the allergen-induced wheal and flare response has not been reported yet. WHAT THIS STUDY ADDS: The time-response study presented here shows the objective activity of two of the newest generation of antihistamines, levocetirizine and desloratadine, at inhibiting the allergen-induced wheal and flare response in a randomized, cross over, placebo-controlled trial. This model is interesting to the clinical setting since allergic subjects are recruited, and the response to allergen involves mast cell degranulation and release of numerous vasoactive and pro-inflammatory mediators additionally to histamine. In addition, this study reports receptor occupancy for both antihistamines at therapeutic dosage, leading to analysis of potential differences in activity. This study clearly shows the potential anti-inflammatory properties of desloratadine and levocetirizine in their skin activity when allergen is the challenging agent as occurs in the clinical situation. AIMS: To evaluate the inhibitory activity of the new-generation antihistamines levocetirizine and desloratadine at their therapeutic doses on the allergen-induced wheal and flare reaction at 1.5 h, 4 h, 7 h, 12 h and 24 h postdose, and to measure their plasma and skin concentrations. METHODS: A double-blind, randomized, cross-over, placebo-controlled study in 18 allergic subjects was carried out. The time-response of the wheal and flare reaction areas under the curve (AUC) were compared by anova. RESULTS: Both antihistamines significantly (P < 0.001) inhibited the allergen-induced wheal and flare reactions compared with placebo. Levocetirizine was significantly more potent than desloratadine. Mean +/- SEM wheal AUC(0-24 h) was 506.4 +/- 81.0 with levocetirizine and 995.5 +/- 81.0 mm(2) h with desloratadine as compared with placebo (1318.5 +/- 361.0 mm(2) h). Flare AUC(0-24 h) was 5927.3 +/- 1686.5 and 15838.2 +/- 1686.5 mm(2) h, respectively [P < 0.001 for both compared with placebo (22508.2 +/- 7437.1 mm(2) h)]. Levocetirizine showed significant inhibition of wheal and flare already at 1.5 h postdose compared with placebo (P +info)
Treatment of chronic urticaria with narrowband ultraviolet B phototherapy: a randomized controlled trial.
(50/98)
Comparative efficacy of levocetirizine, desloratidine and fexofenadine by histamine wheal suppression test.
(51/98)
BACKGROUND: Histamine is the major mediator of allergic reactions. Newer H1 antihistaminics like levocetirizine, fexofenadine, and desloratadine are used in the treatment of seasonal and perennial allergic rhinitis and urticaria. The ability to block the cutaneous response to intradermal histamine is used to evaluate the potential of antihistamines. AIMS: To compare the potency, onset, and duration of action of the commonly used antihistamines-levocetirizine, fexofenadine, and desloratadine. METHODS: Thirty volunteers were given three single doses of levocetirizine, fexofenadine and desloratadine at weekly intervals. A pretest was performed by using the intradermal histamine prick test. After administration of the drugs, the intradermal test was repeated at (1/2), 1, 2, 3, 6 and 24 h, and the sizes of the wheal were measured. The mean values were taken and were compared by using Levene's t-test. RESULTS: At 30 min, fexofenadine showed a statistically significant suppression of wheal size compared to levocetirizine and desloratadine. Two and three hours after administration, levocetirizine and fexofenadine showed statistically significant inhibition of wheal size while only levocetirizine had this effect after six hours when compared to desloratadine. Desloratadine showed greater inhibition of wheal size at the end of 24 h when compared to levocetirizine and fexofenadine but this was not statistically significant. CONCLUSIONS: Fexofenadine had the earliest onset of action while levocetirizine showed maximum inhibition of wheal response after three and six hours. (+info)
Participation of histamine H3 receptors in experimental allergic rhinitis of mice.
(52/98)
The present study was performed to study the participation of histamine H(3) receptors in nasal symptoms using Sch 50971, a potent and selective agonist of the H(3) receptor. Repeated topical application of antigen caused an increase in sneezing and nasal rubbing in sensitized mice. Oral administration of Sch 50971 and imetit, specific H(3)-receptor agonists, resulted in an inhibition of nasal symptoms induced by an antigen similar to an H(1)-receptor antagonist, cetirizine. Furthermore, simultaneous use of H(3)-receptor agonists, Sch 50971 or imetit, and an H(1)-receptor antagonist, cetirizine, caused a significant inhibitory effect on nasal symptoms at doses that showed no effect when used separately. The number of eosinophils in the nasal mucosa of mice sensitized with antigen was significantly decreased by cetirizine; however, Sch 50971 and imetit had no effect on eosinophil infiltration. These results clearly indicate that H(3) receptors are involved in the etiology of nasal allergy, and the stimulation of H(3) receptors may be useful as a novel therapeutic approach in nasal allergy. (+info)
Levocetirizine modulates lymphocyte activation in patients with allergic rhinitis.
(53/98)
Levocetirizine, a second generation non-sedating antihistamine that blocks the H(1) histamine receptor, may exhibit immunoregulatory properties that augment its primary pharmacological mechanism. To investigate this possibility, 13 Kuwaiti seasonal allergic rhinitis (SAR) patients were treated with levocetirizine for four weeks in comparison with a 7-member placebo-treated control group, followed by clinical evaluation and flow cytometric analysis of peripheral venous blood for inflammatory cell and lymphocyte subpopulation profiles. Relative to the controls, levocetirizine-treated patients exhibited an expected reduction in early phase allergic symptoms, including sneezing (P<0.001), nasal itching (P<0.01), nasal congestion, and running nose (P<0.001); reduced percentages of eosinophils (P<0.05); and three subpopulations of activated T lymphocytes: CD4+CD29+, CD4+CD212+, and CD4+CD54+ (P<0.05). Levocetirizine treatment also correlated with a significant increase in the percentage of CD4+CD25+ T cells (P<0.001). The ability of levocetirizine to reduce percentage representation of cell phenotypes known to contribute to inflammatory tissue damage (eosinophils, CD4+CD29+, CD4+CD212+, and CD4+CD54+) and expand percentages of CD4+CD25+, which may include protective immunoregulatory (Treg) cells, indicates that the drug has pharmacological potential beyond the immediate effects of H(1) histamine-receptor inhibition. Although the present data does not define a therapeutic mechanism, the results reported here establish important trends that may be used to guide future mechanistic examination of immunoregulatory capacity of H(1) inhibitors. (+info)
Quality of life in patients with persistent allergic rhinitis treated with montelukast alone or in combination with levocetirizine or desloratadine.
(54/98)
BACKGROUND: Persistent allergic rhinitis often impairs quality of life. OBJECTIVE: We assessed the extent to which treating persistent allergic rhinitis with montelukast, desloratadine, and levocetirizine alone or in combination improved quality of life. METHODS: A 32-week randomized, double-blind, placebo-controlled, crossover study was performed in 2 arms: 20 patients received montelukast 10 mg/d and/or desloratadine 5 mg/d or placebo; 20 patients received montelukast 10 mg/d and/or levocetirizine 5 mg/d or placebo. The treatment periods were separated by 2-week washout periods. Quality of life was assessed on the day before starting treatment and on the last day of each treatment period using the Rhinoconjunctivitis Quality of Life Questionnaire. Sleep problems were also assessed. RESULTS: In the desloratadine plus montelukast arm, the mean (SEM) quality of life score before treatment was 3.1 (0.41). After placebo, this score was 2.16 (0.43), after desloratadine it was 1.79 (0.38), after montelukast it was 1.48 (0.37), and after montelukast plus desloratadine it was 1.59 (0.37). In the montelukast plus levocetirizine arm, the mean quality of life score before treatment was 2.58 (0.49). After placebo it was 1.78 (0.46), after levocetirizine it was 1.38 (0.42), after montelukast it was 1.36 (0.37), and after montelukast plus levocetirizine it was 1.26 (0.39). CONCLUSIONS: Placebo, montelukast, desloratadine and levocetirizine significantly improved quality of life. Combining montelukast with either levocetirizine or desloratadine gave additional benefits in comparison to each agent alone and could be considered for patients whose quality of life is impaired by persistent allergic rhinitis. (+info)
Histamine 2 blocker potentiates the effects of histamine 1 blocker in suppressing histamine-induced wheal.
(55/98)
BACKGROUND: Histamine is responsible for the wheal and flare reaction in various allergic conditions. Classical antihistamines are the drugs which block the H 1 receptors and are widely used in various allergic conditions, whereas H 2 blockers are mainly used for acid peptic disease. Although H 1 receptor-mediated actions of histamine are primarily responsible for vasodilatation, vasopermeability, and itching, it has been observed that combined blocking of both H1 and H2 receptors may provide better relief. AIM: To compare the efficacy of levocetirizine (H1 blocker) versus levocetirizine and ranitidine (H2 blocker) in suppressing histamine-induced wheal. METHODS: Fifteen volunteers were given a single dose of levocetirizine 5 mg on day 1 and a single dose of levocetirizine 5 mg with ranitidine 150 mg twice a day on day 7. A pretest was performed by intradermal histamine prick test. After administration of the drugs, the prick test was repeated at 1 hour, 2, 3, 6, and 24 hours, and the size of the wheal measured and statistically analyzed. RESULTS: At 1 hour, there was no statistically significant difference in the wheal size between levocetirizine alone and the combination of levocetirizine and ranitidine. Levocetirizine with ranitidine resulted in statistically significant reduction of wheal size at 2, 3, 6, and 24 hours when compared with levocetirizine alone. CONCLUSION: H2 blocker potentiates the effects of an H1 blocker in suppressing histamine-induced wheal. (+info)
Participation of proteinase-activated receptor-2 in passive cutaneous anaphylaxis-induced scratching behavior and the inhibitory effect of tacrolimus.
(56/98)
Proteinase-activated receptor-2 (PAR2) may be an important regulator of skin mast cell function during cutaneous inflammation and hypersensitivity. However, little is known of the role of PAR2 in allergic pruritus, because mast cells, which are thought to be responsible for this symptom, can release a number of different pruritogens. In the present study, we investigated the effects of several agents on passive cutaneous anaphylaxis-induced scratching behavior in ICR mice. As a result, cetirizine and ketanserin produced dose-dependent inhibition of scratching behavior induced by passive cutaneous anaphylaxis. Combined cetirizine with ketanserin exhibited significant inhibitory effects for the number of passive cutaneous anaphylaxis-induced scratching behavior. Pretreatment of the experimental animals with PAR2-neutralizing antibody and protease inhibitor leupeptin significantly inhibited passive cutaneous anaphylaxis-induced scratching behavior. Furthermore, we found that topical application of tacrolimus significantly reduced the number of scratching behavior induced by passive cutaneous anaphylaxis in a dose-dependent manner. Combined cetirizine with tacrolimus also exhibited significant inhibitory effects for the number of passive cutaneous anaphylaxis-induced scratching behavior. Tacrolimus in doses of 3% and 10% significantly inhibited tryptase-induced scratching behavior. These results suggest that PAR2 may be involved in passive cutaneous anaphylaxis-induced scratching behavior and tacrolimus produces an anti-allergic pruritus effect in ICR mice. (+info)