Nedocromil sodium: an overview

The Effects of Long-Term Administration of Sodium Nedocromil on Bronchial Hypereactivity

The effect of long-term treatment with sodium nedocromil on airway hypereactivity was investigated in two groups of 20 patients each. Group I patients presented with allergic asthma while Group II patients presented with intrinsic asthma. For each subject of the two groups, the base FEV1 was measured and nebulized methacholine was administrated in consecutively higher concentrations until a decrease in FEV1 of >20 % was observed. Following measurement, all patients included in the study were treated with 12 mg of sodium nedocromil per day for 12 months. At the end of the treatment, bronchial hyperreactivity was evaluated for a second time by administering the same dosage of methacholine that originally produced a decline in FEV1 of >20 %. In Group I patients (allergic asthma) mean FEV1 was 3126 ml, before challenge, while after methacholine challenge FEV1 was 2400ml. Following 1-year of sodium nedocromil administration the FEV1 was 2601ml (P<0.05). Before treatment, the mean fall in FEV1, following methacholine challenge, was 23.67% while following a 1-year-long sodium nedocromil administration this value reduced to 15.70% (P<0.05). Correspondingly, PC20 was 5.59 while after sodium nedocromil administration it increased to 11.66 (P<0.05). In Group II patients (intrinsic asthma) mean FEV1 was 2750 ml, before challenge, while after methacholine challenge FEV1 was 2066ml. Following 1-year of sodium nedocromil administration the FEV1 was 2223ml (P<0.05). Before treatment, the mean fall in FEV1, following methacholine challenge, was 27.65 % while following a 1-year-long sodium nedocromil administration this value reduced to 21.92 % (P<0.05). Correspondingly, PC20 was 5.91 while after sodium nedocromil administration it increased to 6.19 (P<0.05). The results suggest a positive effect of long-term sodium nedocromil administration in bronchial hyperreactivity for both groups of patients.

Leukotrienes, leukotriene receptor antagonists and leukotriene synthesis inhibitors in asthma: an update. Part I: synthesis, receptors and role of leukotrienes in asthma

Asthma is a chronic inflammatory disease associated with airflow obstruction. Airflow obstruction results from contraction of airway smooth muscle, mucosal oedema, increased secretion of mucus and infiltration of the airway wall by inflammatory cells, particularly eosinophils. Leukotrienes are thought to contribute to the pathophysiology of asthma. Leukotrienes are synthesised from arachidonic acid by a specific synthesis pathway whose key enzyme is 5-lipoxygenase. Cysteinyl leukotrienes (leukotrienes C4, D4 and E4) have been shown to mimic all the pathologic changes that are characteristic of asthma, whereas leukotriene B4 does not appear to exert biological properties relevant to asthma. Cysteinyl leukotrienes bind to two receptor subtypes: CysLT1 and CysLT2. Most of the biological properties of cysteinyl leukotrienes relevant to asthma are mediated through CysLT1 receptor stimulation.

Inflammation in asthma: the cornerstone of the disease and target of therapy

Asthma is a chronic disease associated with variable levels of airflow obstruction. Considerable evidence has been obtained to show that airway inflammation is a major factor in the pathogenesis of asthma in associated bronchial hyperresponsiveness, and in the level of disease severity. The inflammatory pattern in asthma is multicellular in nature, with mast cells, neutrophils, eosinophils, T lymphocytes, and epithelial cells participating in the response. Furthermore, it is known that mediators, cytokines, and chemokines from these cells contribute to the orchestration of the inflammatory process. Because airway inflammation appears to be a critical etiologic feature of asthma, it has become the target of therapy. In this review the features of airway inflammation will be examined, and the effect of therapeutic agents on markers of airway injury will be discussed. Establishing, understanding, and finally controlling the features of airway inflammation have given insight to disease pathogenesis and the effectiveness of various treatments. The integral role of inhaled corticosteroids in modifying the complex inflammatory component of asthma will be explored, with special focus on the high degree of efficacy associated with this treatment--vis-á-vis other therapeutic agents--in preventing or blocking specific proinflammatory markers.

Current issues for establishing inhaled corticosteroids as the antiinflammatory agents of choice in asthma

Airway inflammation appears to be present even in the mildest of asthma, and inhaled corticosteroids now form the mainstay of asthma therapy. Inhaled corticosteroids largely avoid the adverse effects associated with oral steroids and are now recommended in newly detected disease. Inhaled corticosteroids reduce airway inflammation, airway hyperresponsiveness, and the symptoms of asthma and improve lung function, irrespective of the patient's age or asthma severity. Several different inhaled corticosteroids are available as therapeutic options for the treatment of asthma, and these include fluticasone propionate, beclomethasone dipropionate, and budesonide. The efficacy and safety of inhaled corticosteroids are compared in this article, and inhaled corticosteroid therapy is also compared with other therapies. Recently, there has been a consensus that the optimal use of inhaled corticosteroids for asthma management is using a "start high--go low" approach, and the reasons for this are discussed.

Neural mechanisms and axon reflexes in asthma. Where are we?

For many years, asthma has been classified as a "neural" disease, with an imbalance between constrictor and dilator nerves being responsible for the symptomatology. Although, nowadays, asthma is recognized as an inflammatory disorder of the airways, neural mechanisms remain very important; axon reflexes, in particular, have received a lot of attention in recent years. In this commentary, an overview is given on the innervation of the airways and its relevance in asthma, and potential new insights in airways innervation are discussed. In a second part, the role of axon reflexes is highlighted. Although neuropeptides such as substance P and neurokinin A are present in human airways, where they produce many of the features characteristic of asthma, and although there is an elevation of their content in induced sputum from asthmatics, there is still no clear direct evidence for the existence of operational axon reflexes in human airways. Most of the research focused on this subject is performed in guinea pigs, where such an axon reflex clearly operates in the airways. In these animals, different receptors have been identified on C-fiber endings, which, upon stimulation, cause inhibition of neuropeptide release. Some of these receptors have also been identified on human airway nerves. Therefore, it has been suggested that modulation of axon reflexes could be of potential benefit in asthma treatment. Indeed, some drugs (e.g. sodium cromoglycate, nedocromil sodium, and ketotifen), which have been demonstrated to partially inhibit neuropeptide release in guinea pig airways, have anti-inflammatory effects on neuropeptide release in guinea pig airways, do not seem to have any anti-inflammatory effects in human asthma. Other drugs, however, such as beta2-mimetics, which have a much more pronounced inhibitory effect in asthma. In conclusion, although there is a lot of indirect evidence for the existence of axon reflex mechanisms in human airways, most of the data now available are derived from animal studies. The key question of whether axon reflexes are operational in human airways remains unanswered. Hopefully, the near future will bring a solution to this enigma with the introduction of very potent tachykinin antagonists for the treatment of human asthma.

Asthma: An Important Disease to Otolaryngologists — Part III: Anti-Inflammatory Therapy

Asthma is a chronic inflammatory disease of the lower respiratory tract which is triggered by exposure to allergens or other airway irritants, and is commonly encountered in otolaryngologic practice. This three-part review is designed to assist otolaryngologists in recognizing and managing asthmatic patients. Part one summarized current knowledge of the pathophysiology and increasing prevalence of asthma, and its assessment and diagnosis. Part two discussed asthma management by environmental controls, anti-inflammatory therapies, and patient education, and compared pharmacologic treatments which are not primarily anti-inflammatory. These include mucolytic, anticholinergic, antihistamine, theophylline and beta agonist drugs. In this final part, anti-inflammatory treatments for asthma control are critically reviewed, including a balanced discussion of cromolyn, nedocromil, glucocorticoids, allergy immunotherapy, and the appropriate indications, possible toxicities and reasonable precautions for their use.

Delayed anti-inflammatory action of nedocromil sodium in the rat paw is dependent on de novo protein synthesis

Nedocromil sodium is commonly suggested to reduce allergic inflammation by inhibiting mediator release from mast cells. However, nedocromil also exhibits a wide range of additional anti-inflammatory activities, including inhibition of increased vascular permeability induced by individual mediators such as histamine. In the present study, we have further characterized the mode of action of nedocromil in a rat model for hind paw edema. Mast cell-dependent edema was induced with compound 48/80 (edema response mainly due to 5-hydroxytryptamine release), and direct mediator-induced plasma extravasation was evoked by exogenous 5-hydroxytryptamine (both agents injected locally). Local pretreatment with nedocromil for 20 min dose-dependently inhibited the edema evoked by compound 48/80 more effectively than that induced by 5-hydroxytryptamine. However, after 2 h pretreatment, both the 5-hydroxytryptamine-and compound 48/80-induced edema responses were inhibited to approximately the same extent by a range of concentrations of nedocromil, as well as by dexamethasone. Local inhibition of RNA/protein synthesis with actinomycin-D abolished the effects of both dexamethasone and nedocromil (2 h local pretreatment). We thus conclude that nedocromil can produce an 'anti-exudative' effect that is independent of inhibition of mast cell mediator release, is slow in onset, and requires de novo protein synthesis.

Clinical pharmacology of asthma. Implications for treatment

The past 10 years have seen three important changes in the philosophy of managing asthma. First, histological studies using fibreoptic bronchoscopy have led to the recognition that asthma is an inflammatory condition of the bronchial mucosa and is not simply caused by smooth muscle spasm. Secondly, there has been some disenchantment with the long term use of regular beta 2-adrenergic agonists as these agents do not appear to control bronchial inflammation and have been associated with deaths from asthma. Thirdly, there has been a general shift away from physician-centred management towards patient-oriented management plans. These three separate strands have led to the development of regional and international consensus documents that emphasise the use of regular anti-inflammatory treatment to control bronchial inflammation and reduce symptoms. With the emphasis on finding the minimum amount of treatment, several traditional anti-asthma medications have been downgraded in importance. The introduction of self-management plans is to be welcomed, but it is important that these new strategies for treating asthma are properly evaluated so that the benefits they confer can be ascertained and maximised.

Allergic Rhinosinusitis: The Total Rhinologic Disease

Allergic rhinosinusitis has three forms of therapy: pharmacotherapy, immunotherapy, and surgical therapy. Pharmacotherapeutically, there are six classes of drugs that give symptomatic relief: mucolytics, decongestants, anticholinergic agents, antihistamines, mast cell stabilizers, and corticosteroids. All six classes are discussed individually and in detail.

For immunotherapeutic therapy of allergic rhinosinusitis, there are four types of skin testing in current use: scratch testing, prick testing, single intradermal testing, and skin end point titration testing. Only the latter is able to quantitate the antigenicity of each antigen, and thus the treatment vial made from only this type of skin testing can adequately treat all antigens to which the patient is sensitive. These differences in testing and vial mixing are explained.

The last form of therapy is surgical therapy, which corrects the obstructive phenomenon caused by allergic rhinosinusitis. The procedures described are reduction inferior turbinectomies and endoscopic sinus surgery.

It is felt by the authors that the specialist who is uniquely positioned to offer a patient suffering from allergic rhinosinusitis all three forms of therapy is the rhinologist.

Role of mast cells in peritoneal adhesion formation

Postoperative adhesions are a major cause of bowel obstruction and infertility. Since mast cells in the intestinal wall have been shown to degranulate after bowel manipulation, we investigated a possible role for these cells in peritoneal adhesion formation. Adhesions were created in weanling rats using cecal scraping and the application of 95% ethanol. The rats were treated with saline or one of two mast cell stabilizers, disodium cromoglycate (DSCG) or nedocromil sodium (NED), intraperitoneally 30 minutes before laparotomy and at the time of abdominal closure. The adhesions were assessed blindly 1 week later using a standardized scale. When the results in rats treated with DSCG were compared with those in rats treated with saline, the DSCG rats had significant attenuation of adhesion formation at 2 mg/kg (1.05 +/- 1.0 versus 2.15 +/- 0.8) and 10 mg/kg (1.2 +/- 0.9 versus 2.71 +/- 0.5). The application of NED decreased adhesions at a dose of 100 mg/kg (1.33 +/- 1.2 versus 2.4 +/- 0.8) but not at 10 mg/kg (2.4 +/- 0.8 versus 2.4 +/- 0.8). Histologic analysis using toluidine blue staining was done to assess the effect of DSCG on mast cell degranulation in the same adhesion model. DSCG significantly decreased the number of degranulated mast cells in the bowel wall when compared with saline (7.16 +/- 0.6 mast cells/high-power field [hpf] versus 12.4 +/- 1.9 mast cells/hpf). These data suggest that mast cells play an important role in the initial stages of peritoneal adhesion formation. In the future, pharmacologic inhibition of mast cell degranulation may be a useful adjunct for the prevention of postoperative adhesions.

The long-term effect of nedocromil sodium on the maximal degree of airway narrowing to methacholine in atopic asthmatic subjects

Airway hyperresponsiveness in asthma is characterized by increased airway sensitivity and by excessive maximal airway narrowing. Long-term inhalation therapy with nedocromil sodium has been shown to reduce increased airway sensitivity in asthma. However, it is unknown whether it also attenuates excessive airway narrowing. We studied the long-term effects of nedocromil on the maximal degree of airway narrowing to methacholine. Twenty-seven atopic asthmatic adults (21-39 years), with a measurable maximal-response plateau on the dose-response curve (20-55% fall in FEV1), were randomly allocated into two parallel treatment groups. They received either inhaled nedocromil 4 mg q.i.d. or placebo, for 8 weeks following a 2 week baseline period. Every 2 weeks, complete dose-response curves to inhaled methacholine were obtained. The response was measured by FEV1 and by volume history standardized partial expiratory flow-volume curves (V40p). A maximal-response plateau was considered if three or more of the highest data points fell within a 5% response range, the maximal response being the average value on the plateau (MFEV1, MV40p). Airway sensitivity was defined as the provocative concentration of methacholine causing a 20% fall in FEV1 (PC20FEV1) or 40% fall in V40p (PC40 V40p). Twenty-four subjects completed the study. Baseline FEV1 or V40p did not change during either treatment (P greater than 0.07). There were no significant changes in MFEV1 or MV40p during treatment with nedocromil (P greater than 0.07). Neither were these changes significantly different between the two groups (P greater than 0.25).(ABSTRACT TRUNCATED AT 250 WORDS)

Auranofin in the treatment of steroid dependent asthma: a double blind study

BACKGROUND

Long term administration of oral corticosteroids in patients with asthma may be associated with serious side effects. Non-steroidal anti-inflammatory drugs, including gold salts, have been shown to reduce the need for systemic corticosteroid treatment in uncontrolled studies. The effect of oral gold (auranofin) on asthma symptoms, lung function, and the need for oral prednisone treatment was investigated.

METHODS

A 26 week randomised, double blind, placebo controlled, parallel group trial of auranofin was performed in 32 patients with moderately severe chronic asthma who required an oral corticosteroid dose of at least 5 mg prednisone a day (or equivalent) or 2.5 mg/day prednisone plus more than 800 micrograms/day inhaled corticosteroids. Auranofin was given orally in a dose of 3 mg twice daily. Asthma symptoms, lung function, and adverse effects were assessed at regular intervals. After 12 weeks of treatment prednisone dosage was tapered down by 2.5 mg every two weeks if the patient was clinically stable. Asthma exacerbations were treated with short courses of high doses of oral steroids.

RESULTS

Twenty eight of the 32 patients, 13 in the placebo group and 15 in the auranofin group, completed the study. The total corticosteroid reduction achieved after 26 weeks of treatment was significantly greater (4 mg) in the auranofin group than in the placebo group (0.3 mg). The number of exacerbations requiring an increase of steroids was greater in the placebo group (2.1) than in the active group (0.9). A significant increase in FEV1 of 6.4% predicted occurred in the auranofin group during the study and there was a reduction of asthma symptoms such as wheezing and cough. There was no difference between the groups in peak flow measurements or in the number of asthma attacks. The incidence of side effects of auranofin was low, but exacerbations of constitutional eczema were noticeable.

CONCLUSION

Auranofin provides an effective adjunct to treatment for steroid dependent asthma, leading to a reduction of oral steroid dose.

Nedocromil sodium inhibits airway hyperresponsiveness and eosinophilic infiltration induced by repeated antigen challenge in guinea-pigs

1. Repeated exposure to ovalbumin aerosol produced significant increases in epithelial eosinophils of airways of all sizes and produced increased pulmonary resistance (RL) to inhaled acetylcholine (ACh) in guinea-pigs. 2. Nedocromil sodium 10 mg ml-1, by nebulization prior to each ovalbumin (OA) challenge inhibited both the airway eosinophilia and hyperresponsiveness to ACh. 3. Nedocromil sodium pretreatment (10 mg ml-1 by nebulization) 10 min prior to OA completely inhibited the acute bronchoconstrictor response to OA. 4. Our findings suggest that nedocromil sodium inhibits airway hyperresponsiveness by inhibiting eosinophilic infiltration, or by simultaneously inhibiting mechanisms involved in both processes.

A comparison of inhaled beclomethasone dipropionate and nedocromil sodium as additional therapy in asthma

We have compared the effects of inhaled beclomethasone dipropionate (BDP) 400 micrograms day-1 with inhaled nedocromil sodium (NDS) 16 mg day-1 as additional therapy in adults with asthma not fully controlled by regular beta-2-agonist inhalers with, or without, oral theophyllines. Seventeen subjects were entered into a 2-week baseline phase, and subsequently in a double-blind crossover fashion into two 8-week phases of daily BDP or NDS. Subjects recorded daily peak expiratory flow rates, morning and evening (PEF am and pm), symptom scores and beta-2-agonist inhaler use. Thirteen subjects completed the study and the last 2 weeks of each phase were analysed. Compared to baseline, both BDP and NDS caused a significant improvement in PEF am (P less than 0.05), PEF pm (P less than 0.05) and the 'amplitude % mean' (P less than 0.001). Both drugs gave a highly significant improvement in all symptom scores. There was no significant difference between BDP and NDS for PEF am, PEF pm, amplitude % mean, cough and daytime asthma score. However, beta-2-agonist inhaler use and scores for nocturnal asthma and morning tightness were all significantly better in the BDP phase, and may have contributed to its better overall subjective performance. Thus, both NDS and BDP resulted in a significant improvement in asthma control in the subjects studied, and both drugs caused a similar improvement in PEF.