Nedocromil sodium. An updated review of its pharmacological properties and therapeutic efficacy in asthma

Towards personalized medicine for the treatment of equine asthma

Although horses with asthma share similar clinical signs, the heterogeneity of the disease in terms of severity, triggering factors, inflammatory profile, and pathological features has hindered our ability to define biologically distinct subgroups. The recognition of phenotypes and endotypes could enable the development of precision medicine, including personalized, targeted therapy, to benefit affected horses. While in its infancy in horses, this review outlines the phenotypes of equine asthma and discusses how knowledge gained from targeted therapy in human medicine can be applied to evaluate the potential opportunities for personalized medicine in equine asthma and to suggest avenues for research to advance this emerging field.

Mast cell stabilisers

Mast cells play a critical role in type 1 hypersensitivity reactions. Indeed, mast cell mediators are implicated in many different conditions including allergic rhinitis, conjunctivitis, asthma, psoriasis, mastocytosis and the progression of many different cancers. Thus, there is intense interest in the development of agents which prevent mast cell mediator release or which inhibit the actions of such mediators once released into the environment of the cell. Much progress into the design of new agents has been made since the initial discovery of the mast cell stabilising properties of khellin from Ammi visnaga and the clinical approval of cromolyn sodium. This review critically examines the progress that has been made in the intervening years from the design of new agents that target a specific signalling event in the mast cell degranulation pathway to those agents which have been developed where the precise mechanism of action remains elusive. Particular emphasis is also placed on clinically used drugs for other indications that stabilise mast cells and how this additional action may be harnessed for their clinical use in disease processes where mast cells are implicated.

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.

Pharmacotherapy of asthma

The pharmacotherapy of asthma is a complex and evolving topic. A detailed understanding of the pathophysiologic processes involved in the asthmatic response forms the basis for understanding the actions of drugs used to treat this condition. Likewise, a solid comprehension of the medicinal chemistry and pharmacologic properties of the numerous agents involved in the treatment of asthma is critical for rationalizing drug choices and understanding potential side effects. Asthma is addressed at several points in the PharmD curriculum at South University including in the Pathophysiology (quarter 2), Integrated Sequence III (quarter 6), and Critical Care (quarter 9) courses. Various teaching strategies are employed throughout, along with weekly case-based recitations. The content presented here includes a synopsis of the pathophysiology and pharmacology from our Integrated Sequence III block on inflammatory diseases and asthma. A short review of pertinent pathophysiology is followed by a detailed presentation on the various classes of asthma drugs which includes their chemistry, mechanism of action, pharmacokinetics, toxicity, and interactions. This presentation is designed to prepare students for asthma therapeutics, which follows next in the schedule. The complexities of asthma pharmacotherapy are stressed along with current controversies and future drug development.

Nedocromil sodium and levocabastine reduce the symptoms of conjunctival allergen challenge by different mechanisms

BACKGROUND

Nedocromil sodium and levocabastine are widely used for the treatment of ocular allergy, but their mechanisms of action are unclear.

OBJECTIVE

We sought to compare the efficacy and mechanisms of action of nedocromil sodium and levocabastine in reducing conjunctival symptoms after ocular allergen challenge.

METHODS

We performed a double-blind, placebo-controlled study in which 48 subjects were randomized to 3 groups to receive nedocromil sodium (2%), levocabastine (0.05%), or placebo eye drops twice daily for 2 weeks before ocular challenge with 10 microL of ryegrass extract. Symptoms and tear histamine and PGD(2) concentrations were determined before challenge and at 10, 20, 30, 60, 180, and 360 minutes after challenge. Bulbar biopsy specimens were taken at 6 and 24 hours after challenge to assess conjunctival inflammatory cell numbers, adhesion molecule expression, and mast cell-associated IL-4, IL-5, IL-6, IL-13, and TNF-alpha levels.

RESULTS

Both drugs significantly reduced total symptom scores (P <.05) at all times after challenge compared with placebo. Itching, hyperemia, and lacrimation were most affected. Nedocromil sodium treatment reduced tear concentrations of histamine (by 77%) and PGD(2) (by 70%) at 30 minutes after challenge (both P <.05). In biopsy specimens nedocromil sodium reduced the number of 3H4-positive mast cells (purportedly the secreted form of IL-4) by 49% at 6 hours and 59% at 24 hours (both P <.05). Levocabastine reduced intercellular adhesion molecule 1 expression by 52% at 6 hours and 45% at 24 hours (both P <.05).

CONCLUSION

Nedocromil sodium and levocabastine both reduced the conjunctival symptoms after ocular allergen challenge but appeared to work by different mechanisms. Nedocromil sodium reduced mast cell function, whereas levocabastine appeared to have primarily antihistaminic actions, although it also reduced the expression of intercellular adhesion molecule 1.

The effects of cromolyn sodium and nedocromil sodium in early asthma prevention

The possibility of irreversible obstruction and therefore the need for early intervention is being much debated. Some investigators suggested that delay in starting inhaled corticosteroids will result in irreversible obstruction. Our own long-term study, specifically designed to detect irreversible obstruction showed that a step-wise approach (starting with cromolyn sodium and switching to inhaled corticosteroids if clinical control and pulmonary function tests are not satisfactorily controlled) resulted in an increase in pulmonary function and not a deterioration. There was no evidence that a delay in starting inhaled corticosteroids will result in irreversible obstruction or clinical worsening. However, delay in starting cromolyn sodium in patients treated with bronchodilators alone did result in worsening pulmonary function tests and worse clinical outcomes. One study from Finland and another study from Australia came to the same conclusion. Even though some studies with cromolyn sodium did not show benefit in the first year of life, other studies did show a good response. The choice between nonsteroidal drugs, such as cromolyn sodium and inhaled corticosteroids as first-line drugs, has to be made on the risk/benefit ratio of these drugs. Although in severe asthma inhaled corticosteroids have greater efficacy, in mild-to-moderate asthma there is comparable efficacy, and the nonsteroidal drugs have better safety. A step-wise approach is still a logical approach

Pharmacologic therapy of asthma during pregnancy

Asthma is a common, potentially serious medical complication during pregnancy. Optimal clinical and pharmacologic management is necessary to mitigate maternal and fetal complications. Mild asthma may be managed in most cases with inhaled beta 2-mimetics. Anti-inflammatory therapy is recommended for the treatment of moderate and severe asthma. Based on limited human experience, beclomethasone is currently the recommended inhaled corticosteroid during pregnancy. However, other inhaled corticosteroids may have advantages compared to beclomethasone because of reduced systemic absorption, which may adversely affect intrauterine growth. Based upon theoretic considerations, theophylline is now considered a secondary therapy, but data demonstrating the superiority of inhaled corticosteroids versus theophylline during pregnancy are lacking.

A retrospective assessment of cost avoidance associated with the use of nedocromil sodium metered-dose inhaler in the treatment of patients with asthma

A retrospective analysis of patient charts was performed for a single, multioffice pulmonary practice in Toronto, Ontario. Canada, to assess hospital care utilization and associated cost reductions after asthma prophylaxis with nedocromil sodium inhalation aerosol. Data were obtained from 310 adult patients with mild, moderate, or severe asthma who were treated in the practice between January 1988 and June 1994 and who had been placed on nedocromil sodium for at least 1 year. The number of office visits increased with nedocromil sodium therapy due to initial surveillance of the new medication, but no other changes were made in the usual protocol for each visit. After initiation of nedocromil sodium therapy, patients showed better asthma control as measured by improvements in pulmonary function scores and by reduced hospital utilization (both emergency department visits and hospital admissions). It is likely that the improvements in asthma control could result in cost savings, and savings projections for the Canadian health care system were made using the retrospective data collected for asthma-related hospital services. Prospective data are needed to confirm our findings.

A comparative study of the clinical efficacy of nedocromil sodium and placebo. How does cromolyn sodium compare as an active control treatment?

Nedocromil sodium and cromolyn sodium are the only two currently available nonsteroid anti-inflammatory agents for treatment of asthma. Clinical differences between the two agents remain under continuous investigation with reports differentiating the two on the basis of atopy of the patient and reversibility of bronchoconstriction. This study investigated the efficacy of nedocromil sodium (4 mg, qid) for treatment of mild-to-moderate asthma in comparison to placebo using cromolyn sodium (2 mg, qid) as an active control treatment. Patients were primarily allergic asthmatics (with at least 15% reversibility) previously maintained on a regimen of regular bronchodilator therapy. During a 2-week run-in period, the patient's slow-release theophylline therapy was removed, and the patients were randomized to treatment after deterioration of asthma control (asthma symptom summary score of 3 for 7 of the 14 days). After 8 weeks of treatment, patients were returned to as occasion requires bronchodilator therapy, as per the 2-week baseline period. The results demonstrate that patients treated with nedocromil sodium showed statistically significant improvements during the primary time period (mean weeks 3 through 8) over placebo-treated patients as evidenced by all indexes of asthma symptoms, pulmonary function measures, and decreased bronchodilator reliance (p<0.05). Patients treated with cromolyn sodium demonstrated similar improvements over placebo-treated patients. Comparisons between nedocromil sodium and cromolyn sodium showed the two agents to be comparable in this group of primarily allergic patients with reversible disease. Between-group differences were noted for 3 of the 13 variables (nighttime asthma, FEV1, and forced expiratory flow rate between 25 % and 75% of the FVC) in favor of cromolyn sodium when the data were pooled during the primary time period. The number of patients missing 1 or more days from work/school/regular activity due to asthma was significantly fewer compared with placebo, and favoring nedocromil sodium over cromolyn sodium. No differences were observed among the three treatments for adverse events. This study demonstrated that in primarily allergic patients with reversible airways disease, nedocromil sodium and cromolyn sodium are both significantly more effective than placebo for treatment of mild-to-moderate asthma.

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.

The use of twice daily nedocromil sodium in the treatment of asthma

The efficacy and safety of nedocromil sodium inhalation aerosol (4 mg of Tilade administered by metered-dose inhaler) given twice daily was compared with placebo in 112 patients with mild-to-moderate asthma who had been receiving maintenance therapy with oral or inhaled bronchodilators or both. After a 2-week run-in period and a subsequent 2-week baseline period, patients were randomized to active treatment (n = 56) or placebo (n = 56) for 8 weeks. All maintenance bronchodilators were withdrawn before the baseline period, and patients entered the treatment period only after demonstrating a specified level of asthma symptoms. Twice daily administration of nedocromil sodium improved all asthma symptoms in these patients who had symptoms as a result of the withdrawal of their maintenance theophylline and/or oral and inhaled beta 2-agonist bronchodilators. During the primary time period (treatment weeks 5 to 8), statistically significant between-group differences favored nedocromil sodium for the asthma summary score (primary variable, p = 0.001), daytime asthma (p = 0.001), and sleep difficulty caused by asthma (p = 0.006). Furthermore, significant reductions in the use of as-needed rescue medications were reported in the nedocromil sodium group (p = 0.003) compared with the placebo group. Final overall opinions of treatment effectiveness expressed by physicians (p = 0.016) and patients (p = 0.002) strongly favored nedocromil sodium.

A double-blind study of the efficacy of nedocromil sodium in the management of asthma in patients using high doses of bronchodilators

The effects of nedocromil sodium were assessed in 110 patients with asthma who experienced asthma symptoms despite the use of high doses of inhaled bronchodilators. During the baseline period, antiinflammatory agents were not permitted, and patients were treated with inhaled beta-agonists on an as-needed basis. Patients who required 12 or more puffs of albuterol and experienced continuing asthma symptoms for 7 of the 14 baseline days were randomized to treatment groups. Subjects received either nedocromil sodium (4 mg) or placebo four times a day for 10 weeks. Statistically significant (p < 0.05) between-treatment differences (weeks 3 to 10), favoring nedocromil sodium, were determined for the asthma summary score, daytime asthma severity, asthmatic cough, morning peak flow rates, reduction of as-needed bronchodilator use, physician's assessment of asthma severity, and patient and physician opinions of treatment effectiveness. By trial end (week 10), sleep difficulty caused by asthma decreased 29% in the nedocromil sodium group and 4% in the placebo group (p = 0.006). Nedocromil sodium was well tolerated and improved asthma control while reducing the inhaled bronchodilator load of these patients with moderately severe asthma.

Nedocromil sodium 2% eye drops for twice-daily treatment of seasonal allergic conjunctivitis: a Swedish multicentre placebo-controlled study in children allergic to birch pollen

This was a multicentre, double-blind, randomized group comparative study in which 77 children, aged 6-16 years, received 2% nedocromil sodium eye drops and 72 received placebo, one drop into each eye twice daily. The treatment period was 4 weeks, covering the peak birch pollen season. Prior to the start of the season, patients who had attended the clinic the previous 2 years because of seasonal allergic conjunctivitis (SAC) to birch pollen, entered a one week baseline period during which symptoms were assessed, dairy cards completed, and routine sampling of blood and urine carried out. The double-blind treatment period then commenced at the onset of the birch pollen season. Patients/parents kept daily diary record cards of eye symptom severity and concomitant therapy. Conjunctivitis was mild in both treatment groups but nedocromil sodium was more effective than placebo in controlling symptoms. During the 2-3 weeks of peak pollen counts, this therapeutic effect was statistically significant for itching (P < 0.01), watering (P < 0.05) and total symptom score (P < 0.01), but was not significant for grittiness (P = 0.08) or redness (P = 0.06). Global opinions of efficacy showed no difference between treatments, due to a high placebo effect (however, the diary card data indicated a significant improvement with nedocromil sodium). We therefore conclude that nedocromil sodium 2% eye drops, administered twice daily, is an effective treatment for SAC in children.

A double blind placebo controlled group comparative study of ophthalmic sodium cromoglycate and nedocromil sodium in the treatment of vernal keratoconjunctivitis

In a 4 week double masked comparative study, patients received 2% nedocromil sodium (48), 2% sodium cromoglycate (48), or placebo eye drops (42), four times daily, for the treatment of vernal keratoconjunctivitis (VKC). Clinical examinations of eye condition and symptom severity were made before and after a 1 week baseline before starting test treatment, and after 1, 2, and 4 weeks of treatment. Patients kept daily diary card records of symptom severity and concomitant therapy. At the clinic, significant improvements were seen with both active treatments after 2-4 weeks. During the final visit, significant benefits over placebo were recorded for five ocular signs with nedocromil sodium and three with sodium cromoglycate, bulbar and lower tarsal chemosis being better controlled by nedocromil sodium (p < 0.05 v sodium cromoglycate). Diary card trends showed improvement with all three treatments, which was greatest with nedocromil sodium and least with placebo. Compared with placebo, both the active drugs produced statistically significant improvements in general eye condition during weeks 1-2, and nedocromil sodium significantly reduced itching within the first week. Overall, nedocromil sodium had the greatest effect on symptoms, although diary card data revealed no statistically significant differences between the two active drugs. In conclusion, both 2% nedocromil sodium and 2% sodium cromoglycate were effective in controlling VKC when administered four times daily into the eyes, while the marked anti-inflammatory activity of nedocromil sodium was apparent in its more pronounced overall therapeutic effect.

Effect of nedocromil sodium on polymorphonuclear leukocyte plasma membrane

The effect of nedocromil sodium on the plasma membrane fluidity of polymorphonuclear leukocytes (PMNs) was investigated by measuring steady-state fluorescence anisotropy of 1-[4-trimethylammonium-phenyl]-6-phenyl- 1,3,5-hexatriene (TMA-DPH) incorporated in the membrane. Our results show that nedocromil sodium 300 muM significantly decreased membrane fluidity of PMNs. The decrease in membrane fluidity of PMNs induced by fMLP was abolished in the presence of nedocromil sodium. These data suggest that nedocromil sodium interferes with the plasma membranes of PMNs and modulates their activities.

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.