The effect of cetirizine on sulfidoleukotriene production by blood leukocytes in children with allergic rhinitis

Cetirizine Decreases Interleukin-4, Interleukin-5, and Interferon-γ Gene Expressions in Nasal-Associated Lymphoid Tissue of Sensitized Mice

Although the action of cetirizine dihydrochloride (cetirizine), a potent histamine H1 receptor antagonist, has been well known, its effect on the cytokine profiles in the nasal immune inductive site has not been elucidated yet. We studied the effect of cetirizine on the cytokine profiles in the nasal-associated lymphoid tissue (NALT), which is a principal mucosal lymphoid tissue of the respiratory tract in rodents. Two different doses of cetirizine were given intraorally for 5 days before the nasal challenge of ovalbumin in sensitized mice. The sensitized group was given normal saline instead of cetirizine, and the nonsensitized group had no sensitization or medication. The cytokine gene expressions in the NALT taken from the mice were investigated with real-time quantitative reverse-transcription polymerase chain reaction. The effect of cetirizine on the allergic symptom score, histamine threshold, and the eosinophil count in the nasal septal mucosa were examined also. Compared with the normal mice, the sensitized mice showed significantly increased levels of interleukin (IL)-4 and IL-5 gene expression although the increase of interferon (INF)-γ gene expression was not significant. In the cetirizine groups, the levels of expression of IL-4, IL-5, and INF-γ in the NALT were significantly decreased compared with the sensitized group. The cetirizine groups also showed decreased allergic symptom score, histamine threshold, and eosinophil count in the nasal septal mucosa compared with the sensitized group. In conclusion, cetirizine reduced the levels of expression of IL-4, IL-5, and INF-γ in the NALT of ovalbumin-sensitized mice. Cetirizine also reduced the acute allergic symptom, histamine sensitivity, and eosinophil count in the nasal septal mucosa.

Analysis of exhaled leukotrienes in nonasthmatic adult patients with seasonal allergic rhinitis

BACKGROUND

Leukotrienes (LTs) are increased in exhaled breath condensate (EBC) in patients with asthma. So far no data have been reported about LT levels in nonasthmatic patients with seasonal allergic rhinitis (SAR). The aim of the study was to find out whether the LT levels in EBC were increased in the nonasthmatic adult patients with SAR both during and after the pollen season in comparison with healthy controls and to assess the changes of the LT levels after the pollen season.

METHODS

Twenty-nine nonasthmatic adult patients with SAR underwent measurement of exhaled LTs in the EBC during and after the pollen season. Leukotrienes B(4), C(4), D(4) and E(4) were analysed by a specific and sensitive gas chromatography/mass spectrometry (GC/MS) assay and compared with 50 healthy nonsmoking controls. Spirometry, skin prick tests and nonspecific IgE were evaluated.

RESULTS

Leukotrienes concentrations (B(4), E(4) but not D(4)) were significantly increased in and after the pollen season in patients with SAR in comparison with healthy controls. In most of the samples, LT C(4) was undetectable. The values of all exhaled LTs were significantly decreased after the pollen season compared with the seasonal baseline: LTB(4) (P = 0.023), LTD(4) (P = 0.020), LTE(4) (P = 0.047).

CONCLUSIONS

Levels of exhaled LTB(4) and LTE(4) were higher in SAR patients than in healthy controls and decreased after the pollen season as compared with levels in season. The SAR patients with the highest in season LT levels had also the post-season levels elevated and this may be an early marker of inflammatory process in the lower airways despite the absence of clinical symptoms of asthma.

Second-Generation Antihistamines

Antihistamines are useful medications for the treatment of a variety of allergic disorders. Second-generation antihistamines avidly and selectively bind to peripheral histamine H1 receptors and, consequently, provide gratifying relief of histamine-mediated symptoms in a majority of atopic patients. This tight receptor specificity additionally leads to few effects on other neuronal or hormonal systems, with the result that adverse effects associated with these medications, with the exception of noticeable sedation in about 10% of cetirizine-treated patients, resemble those of placebo overall. Similarly, serious adverse drug reactions and interactions are uncommon with these medicines. Therapeutic interchange to one of the available second-generation antihistamines is a reasonable approach to limiting an institutional formulary, and adoption of such a policy has proven capable of creating substantial cost savings. Differences in overall efficacy and safety between available second-generation antihistamines, when administered in equivalent dosages, are not large. However, among the antihistamines presently available, fexofenadine may offer the best overall balance of effectiveness and safety, and this agent is an appropriate selection for initial or switch therapy for most patients with mild or moderate allergic symptoms. Cetirizine is the most potent antihistamine available and has been subjected to more clinical study than any other. This agent is appropriate for patients proven unresponsive to other antihistamines and for those with the most severe symptoms who might benefit from antihistamine treatment of the highest potency that can be dose-titrated up to maximal intensity.

Allergic rhinitis and asthma in children: disease management and outcomes

Antihistamines and inhaled glucocorticoids, which can be targeted toward multiple points in the "allergic cascade" underlying allergic rhinitis and asthma, extend the promise of enhanced outcomes in children with allergic rhinitis, asthma, or both. Antihistamine therapy confers significant relief of subjective ratings of seasonal and perennial allergic symptoms (e.g., rhinorrhea, congestion, sneezing, pruritus), whereas topical steroids alleviate such discomfort while also improving objective anatomic and functional indices of nasal patency (e.g., nasal peak inspiratory flow). Youngsters with asthma also experience substantial clinical benefits from inhaled steroids, which improve objective measures of pulmonary function and reduce rescue beta 2-agonists for symptom management and quality-of-life enhancement. This paper reviews recent clinical findings on the role of antihistamines and topical corticosteroids in pediatric allergy and asthma management, as well as the favorable effects of these medications on both objective and subjective health outcomes.

New insights into the second generation antihistamines

Second generation antihistamines are recognised as being highly effective treatments for allergy-based disease and are among the most frequently prescribed and safest drugs in the world. However, consideration of the therapeutic index or the benefit/risk ratio of the H1 receptor antagonists is of paramount importance when prescribing this class of compounds as they are used to treat non-life threatening conditions. There are many second generation antihistamines available and at first examination these appear to be comparable in terms of safety and efficacy. However, the newer antihistamines in fact represent a heterogeneous group of compounds, having markedly differing chemical structures, adverse effects, half-life, tissue distribution and metabolism, spectrum of antihistaminic properties, and varying degrees of anti-inflammatory effects. With regard to the latter, there is growing awareness that some of these compounds might represent useful adjunct medications in asthma therapy. In terms of safety issues, the current second generation grouping includes compounds with proven cardiotoxic effects and others with the potential for adverse drug interactions. Moreover, some of the second generation H1 antagonists have given cause for concern regarding their potential to cause a degree of somnolence in some individuals. It can be argued, therefore, that the present second generation grouping is too large and indistinct since this was based primarily on the concept of separating the first generation sedating compounds from nonsedating H1 antagonists. Although it is too early to talk about a third generation grouping of antihistamines, future membership of such a classification could be based on a low volume of distribution coupled with a lack of sedating effects, drug interactions and cardiotoxicity.

Pharmacological inhibition of leukotriene actions

Leukotrienes represent a group of lipid mediators that play a very important role in a wide variety of pathological conditions. The presence of leukotrienes in inflammatory sites has been extensively documented, and accordingly research efforts have been directed towards the development of drugs that interfere with the formation or effects of leukotrienes. Although clinical application of such drugs has been disappointing in the past, recent discoveries of more potent and selective drugs seem to be promising. This review attempts to highlight some of these exciting developments.