Nedocromil sodium is rapidly effective in the therapy of seasonal allergic rhinitis

Therapeutic management of allergic diseases

Allergic diseases are characterized by the activation of inflammatory cells and by a massive release of mediators. The aim of this chapter was to describe succinctly the modes of action, indications, and side effects of the major antiallergic and antiasthmatic drugs. When considering the ideal pharmacokinetic characteristics of a drug, a poorly metabolized drug may confer a lower variability in plasma concentrations and metabolism-based drug interactions, although poorly metabolized drugs may be prone to transporter-based disposition and interactions. The ideal pharmacological properties of a drug include high binding affinity, high selectivity, and appropriate association and dissociation rates. Finally, from a patient perspective, the frequency and route of administration are important considerations for ease of use.

Inhibition of release of vasoactive and inflammatory mediators in airway and vascular tissues and macrophages by a chinese herbal medicine formula for allergic rhinitis

Herbal therapies are being used increasingly for the treatment of allergic rhinitis. The aim of this study was to investigate the possible pharmacological actions and cellular targets of a Chinese herbal formula (RCM-101), which was previously shown to be effective in reducing seasonal allergic rhinitis symptoms in a randomized, placebo-controlled clinical trial. Rat and guinea pig isolated tissues (trachea and aorta) were used to study the effects of RCM-101 on responses to various mediators. Production of leukotriene B₄ in porcine neutrophils and of prostaglandin E₂ and nitric oxide (NO) in Raw 264.7 cells were also measured. In rat and guinea pig tracheal preparations, RCM-101 inhibited contractile responses to compound 48/80 but not those to histamine (guinea pig preparations) or serotonin (rat preparations). Contractile responses of guinea pig tracheal preparations to carbachol and leukotriene C_4, and relaxant responses to substance P and prostaglandin E₂ were not affected by RCM-101. In rat aortic preparations, precontracted with phenylephrine, endothelium-dependent relaxant responses to acetylcholine and endothelium-independent relaxant responses to sodium nitroprusside were not affected by RCM-101. However, RCM-101 inhibited relaxations to l-arginine in endothelium-denuded rat aortic preparations, which had been pre-incubated with lipopolysaccharide. RCM-101 did not affect leukotriene B₄ formation in isolated porcine neutrophils, induced by the calcium ionophore A23187; however, it inhibited prostaglandin E₂ and NO production in lipopolysaccharide-stimulated murine macrophages (Raw 264.7 cells).The findings indicate that RCM-101 may have multiple inhibitory actions on the release and/or synthesis of inflammatory mediators involved in allergic rhinitis.

Experimental models for the evaluation of treatment of allergic rhinitis

OBJECTIVE

To review the experimental models used for the clinical evaluation of treatments for allergic rhinitis.

DATA SOURCES

Peer-reviewed clinical studies and review articles were selected from the PubMed database using the following relevant keywords: allergic rhinitis in combination with efficacy, wheal and flare, nasal challenge, park, cat room, or exposure unit. Regulatory guidance documents on allergic rhinitis were also included.

STUDY SELECTION

The authors' knowledge of the field was used to limit references with emphasis on recent randomized and controlled studies. References of historical significance were also included.

RESULTS

Traditional outpatient studies are universally accepted in the evaluation of treatment for allergic rhinitis. Experimental models provide ancillary information on efficacy at different stages of treatment development. Skin histamine and allergen challenge, as well as direct nasal challenge with histamine and allergen, are often used as early steps in assessing drug efficacy. Exposure units, park settings, and cat rooms better approximate real life by drawing on the natural mode of allergen exposure and delivering the sensitizing allergen to allergic individuals in the ambient air. Park studies make use of allergens in the outdoors, whereas cat rooms and exposure units present the sensitizing allergens indoors, with the latter providing consistent predetermined allergen levels. Exposure unit and park studies are acknowledged for the determination of onset of action and are also suited to the measurement of duration of effect and other measures of efficacy. Onset and duration of effect are 2 important pharmacodynamic properties of antihistamines and nasal corticosteroids as determined by the Allergic Rhinitis and Its Impact on Asthma and the European Academy of Allergology and Clinical Immunology workshop group.

CONCLUSIONS

All challenge models serve as important instruments in the evaluation of antiallergic medications and provide additional information to complement traditional studies.

Comparative clinical efficacy, onset and duration of action of levocetirizine and desloratadine for symptoms of seasonal allergic rhinitis in subjects evaluated in the Environmental Exposure Unit (EEU)

The Environmental Exposure Unit, an indoor pollen challenge system to test anti-allergic medications, was used to compare the onset and duration of action and the efficacy of levocetirizine and desloratadine, two recently developed H1-antagonists. In this double-blind, placebo-controlled, parallel-group study, qualified subjects were randomised to once-daily levocetirizine 5 mg (n = 141), desloratadine 5 mg (n = 140) or placebo (n = 92) and exposed to ragweed pollen on two consecutive days (7 h and 6 h). Symptoms were self-rated every 30 min. On both days, levocetirizine produced a greater improvement in the major symptom complex score (primary efficacy variable) than desloratadine (p = 0.015); both were better than placebo (p < 0.001). Levocetirizine acted earlier (1 h vs. 3 h) and produced greater symptom relief at 24 h than desloratadine (p = 0.003). Levocetirizine also alleviated nasal obstruction better than desloratadine (p = 0.007) on day 1; and better than placebo (p = 0.014) after the second dose on day 2, which was not observed with desloratadine. Levocetirizine and desloratadine were safe and well tolerated.

Allergic rhinitis: past, present and the future

Allergic rhinitis represents a global health issue affecting between 10% to 25% of the world population, with increasing prevalence over the last decade. Although often trivialized by patients and doctors, allergic rhinitis is a significant cause of morbidity, in addition to its substantial economic impact. While allergic rhinitis is an inflammatory disorder of the upper airways, inflammation alone is insufficient to explain the chronic nature of the disease. An exciting concept which has recently emerged in asthma concerns the role of the bronchial epithelium as a key regulator of airway inflammatory and remodelling responses in asthma. It has been shown by our group that the disruption and alteration in the function of the lower airway epithelium in asthma leads to the generation of a variety of stimuli that lead to the restructuring of the airway wall. This raises interesting questions regarding a similar role for the upper airway epithelium in allergic rhinitis. This review aims to interpret past and current research into allergic rhinitis, and to address specific areas where future research is warranted, particularly in relation to the possibility of an altered upper airway epithelial phenotype in allergic rhinitis.

Allergy for the laryngologist

Allergic disease can affect any portion of the respiratory tract, including the larynx, trachea, bronchial tree, nasal cavity, paranasal sinuses, nasopharynx, and pharynx. This review evaluates laryngeal manifestations of allergic disease and the impact of allergic mechanisms in disorders, within the scope of laryngology.

Speed of onset of action of Tilarin

Two studies have been carried out specifically to examine the speed of onset of action of intranasal nedocromil sodium 1% (Tilarin) for the relief of symptoms due to ragweed allergic rhinitis. One, a multicentre placebo-controlled comparative study using a QID regimen, 1 spray per nostril, was designed to assess the speed of onset of action of nedocromil sodium during the first week of treatment in patients with rhinitis symptoms, and to evaluate the efficacy and safety of nedocromil sodium during 6 weeks of treatment (1). A 1-week baseline, the start of which was timed to coincide with the start of the ragweed season, was followed by 6 weeks double-blind trial treatment; only patients (n = 166) who were symptomatic at the end of baseline were included in the double-blind phase. Non-parametric analyses of all variables including a summary score (stuffy nose, runny nose, itchy nose and sneezing) showed that the onset of action of nedocromil sodium occurred on the first day of treatment. Further, patients using nedocromil sodium had less symptoms during the 10 days of peak pollen, at which time physician assessment showed reduced mucosal oedema and nasal discharge, and both patient and clinician opinions favoured nedocromil sodium. No significant adverse events were reported during this 6-week study. In the second study (2), 104 patients were randomly allocated to receive either nedocromil sodium or placebo, QID. They then spent 10 hours per day for 2 consecutive days in Iowa City Park during the peak of the ragweed season. Only patients showing significant symptoms of seasonal allergic rhinitis (SAR) during 3 hourly baseline assessments were included. Over the 2-day period, symptom scores for stuffy nose, runny nose, itchy nose and sneezing, and global symptom summary scores, were recorded at 19 hourly time points. At home in the evening, patients recorded symptom scores for the post-exposure period. In comparison with placebo, nedocromil sodium significantly improved rhinitis symptoms within 2 hours, and this reduction in SAR symptoms was maintained throughout the 2-day exposure period. Post exposure symptom summary scores were also significantly lower in patients treated with nedocromil sodium than in those patients treated with placebo. Overall, very few adverse events were reported, none of them serious. In conclusion, nedocromil sodium 1% nasal spray acts rapidly, within 2 hours on the first day of treatment, to reduce ongoing symptoms of SAR. Relief of rhinitis symptoms is maintained throughout the peak pollen period with nedocromil sodium QID, which appears to be a safe and well tolerated treatment for ragweed SAR.

Nedocromil sodium reduces allergen-induced plasma extravasation in the guinea pig nasal mucosa by inhibition of tachykinin release

The effect of topically applied (10 microliters) nedocromil sodium (NS) and sodium cromoglycate (CS) on the plasma extravasation induced by local application of ovalbumin (5%, 10 microliters) into the respiratory nasal mucosa of sensitized guinea pigs pretreated with the neutral endopeptidase inhibitors, phosphoramidon, was studied. Topical NS (220 nmol, 10 microliters) reduced by 57% the Evans blue dye extravasation caused by local application of ovalbumin into the nasal mucosa, whereas CS (220 nmol, 10 microliters) was without effect. The tachykinin NK1 receptor antagonist CP-99994 (2 mumol/kg, i.v.) reduced by 45% the plasma extravasation induced by antigen challenge. The combination of NS and CP-99994 did not increase further the inhibition caused by NS alone. Plasma extravasation evoked by instillation of bradykinin (50 nmol), which causes this response by releasing tachykinins from sensory nerves, was markedly reduced by NS, but not by CS. Plasma extravasation evoked by installation of substance P, which acts directly on the endothelial cells, was not affected by NS. We conclude that the reduction by NS of the plasma extravasation induced by antigen challenge in the nasal mucosa of sensitized guinea pigs is due to the inhibition of tachykinin release from sensory nerve endings.

The cellular basis for allergic rhinitis

In both seasonal and perennial rhinitis there is epithelial mast cell accumulation and tissue infiltration by eosinophils. Activation of these cells can be observed by electron microscopy and by elevated levels of tryptase and eosinophil cationic protein in nasal lavage fluid. Furthermore, seasonal increases in the antigen presenting cell (Langerhans' cell) are also evident. Investigations into the mechanisms involved in cell accumulation and activation reveals upregulation of leucocyte endothelial adhesion molecules and an increase in interleukin-4 (IL-4) in naturally occurring rhinitis, while mRNA for IL-4, IL-5 and granulocyte macrophage colony stimulating factor activity and lavage tumour necrosis factor-alpha (TNF alpha) levels are increased following local allergen challenge. These cytokines may be derived from a variety of sources, including mast cells, eosinophils and T-lymphocytes, and contribute to the underlying inflammatory process in rhinitis.