Clinical effects of pranlukast, an oral leukotriene receptor antagonist, in mild-to-moderate asthma: a 4 week randomized multicentre controlled trial

G Protein-Coupled Receptors in Asthma Therapy: Pharmacology and Drug Action

Asthma is a heterogeneous inflammatory disease of the airways that is associated with airway hyperresponsiveness and airflow limitation. Although asthma was once simply categorized as atopic or nonatopic, emerging analyses over the last few decades have revealed a variety of asthma endotypes that are attributed to numerous pathophysiological mechanisms. The classification of asthma by endotype is primarily routed in different profiles of airway inflammation that contribute to bronchoconstriction. Many asthma therapeutics target G protein-coupled receptors (GPCRs), which either enhance bronchodilation or prevent bronchoconstriction. Short-acting and long-acting β 2-agonists are widely used bronchodilators that signal through the activation of the β 2-adrenergic receptor. Short-acting and long-acting antagonists of muscarinic acetylcholine receptors are used to reduce bronchoconstriction by blocking the action of acetylcholine. Leukotriene antagonists that block the signaling of cysteinyl leukotriene receptor 1 are used as an add-on therapy to reduce bronchoconstriction and inflammation induced by cysteinyl leukotrienes. A number of GPCR-targeting asthma drug candidates are also in different stages of development. Among them, antagonists of prostaglandin D2 receptor 2 have advanced into phase III clinical trials. Others, including antagonists of the adenosine A2B receptor and the histamine H4 receptor, are in early stages of clinical investigation. In the past decade, significant research advancements in pharmacology, cell biology, structural biology, and molecular physiology have greatly deepened our understanding of the therapeutic roles of GPCRs in asthma and drug action on these GPCRs. This review summarizes our current understanding of GPCR signaling and pharmacology in the context of asthma treatment. SIGNIFICANCE STATEMENT: Although current treatment methods for asthma are effective for a majority of asthma patients, there are still a large number of patients with poorly controlled asthma who may experience asthma exacerbations. This review summarizes current asthma treatment methods and our understanding of signaling and pharmacology of G protein-coupled receptors (GPCRs) in asthma therapy, and discusses controversies regarding the use of GPCR drugs and new opportunities in developing GPCR-targeting therapeutics for the treatment of asthma.

Addition of anti-leukotriene agents to inhaled corticosteroids for adults and adolescents with persistent asthma

BACKGROUND

Asthma management guidelines recommend low-dose inhaled corticosteroids (ICS) as first-line therapy for adults and adolescents with persistent asthma. The addition of anti-leukotriene agents to ICS offers a therapeutic option in cases of suboptimal control with daily ICS.

OBJECTIVES

To assess the efficacy and safety of anti-leukotriene agents added to ICS compared with the same dose, an increased dose or a tapering dose of ICS (in both arms) for adults and adolescents 12 years of age and older with persistent asthma. Also, to determine whether any characteristics of participants or treatments might affect the magnitude of response.

SEARCH METHODS

We identified relevant studies from the Cochrane Airways Group Specialised Register of Trials, which is derived from systematic searches of bibliographic databases including the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, PsycINFO, the Allied and Complementary Medicine Database (AMED), the Cumulative Index to Nursing and Allied Health Literature (CINAHL) and the trial registries clinicaltrials.gov and ICTRP from inception to August 2016.

SELECTION CRITERIA

We searched for randomised controlled trials (RCTs) of adults and adolescents 12 years of age and older on a maintenance dose of ICS for whom investigators added anti-leukotrienes to the ICS and compared treatment with the same dose, an increased dose or a tapering dose of ICS for at least four weeks.

DATA COLLECTION AND ANALYSIS

We used standard methods expected by Cochrane. The primary outcome was the number of participants with exacerbations requiring oral corticosteroids (except when both groups tapered the dose of ICS, in which case the primary outcome was the % reduction in ICS dose from baseline with maintained asthma control). Secondary outcomes included markers of exacerbation, lung function, asthma control, quality of life, withdrawals and adverse events.

MAIN RESULTS

We included in the review 37 studies representing 6128 adult and adolescent participants (most with mild to moderate asthma). Investigators in these studies used three leukotriene receptor antagonists (LTRAs): montelukast (n = 24), zafirlukast (n = 11) and pranlukast (n = 2); studies lasted from four weeks to five years. Anti-leukotrienes and ICS versus same dose of ICSOf 16 eligible studies, 10 studies, representing 2364 adults and adolescents, contributed data. Anti-leukotriene agents given as adjunct therapy to ICS reduced by half the number of participants with exacerbations requiring oral corticosteroids (risk ratio (RR) 0.50, 95% confidence interval (CI) 0.29 to 0.86; 815 participants; four studies; moderate quality); this is equivalent to a number needed to treat for additional beneficial outcome (NNTB) over six to 16 weeks of 22 (95% CI 16 to 75). Only one trial including 368 participants reported mortality and serious adverse events, but events were too infrequent for researchers to draw a conclusion. Four trials reported all adverse events, and the pooled result suggested little difference between groups (RR 1.06, 95% CI 0.92 to 1.22; 1024 participants; three studies; moderate quality). Investigators noted between-group differences favouring the addition of anti-leukotrienes for morning peak expiratory flow rate (PEFR), forced expiratory volume in one second (FEV1), asthma symptoms and night-time awakenings, but not for reduction in β2-agonist use or evening PEFR. Anti-leukotrienes and ICS versus higher dose of ICSOf 15 eligible studies, eight studies, representing 2008 adults and adolescents, contributed data. Results showed no statistically significant difference in the number of participants with exacerbations requiring oral corticosteroids (RR 0.90, 95% CI 0.58 to 1.39; 1779 participants; four studies; moderate quality) nor in all adverse events between groups (RR 0.96, 95% CI 0.89 to 1.03; 1899 participants; six studies; low quality). Three trials reported no deaths among 834 participants. Results showed no statistically significant differences in lung function tests including morning PEFR and FEV1 nor in asthma control measures including use of rescue β2-agonists or asthma symptom scores. Anti-leukotrienes and ICS versus tapering dose of ICSSeven studies, representing 1150 adults and adolescents, evaluated the combination of anti-leukotrienes and tapering-dose of ICS compared with tapering-dose of ICS alone and contributed data. Investigators observed no statistically significant difference in % change from baseline ICS dose (mean difference (MD) -3.05, 95% CI -8.13 to 2.03; 930 participants; four studies; moderate quality), number of participants with exacerbations requiring oral corticosteroids (RR 0.46, 95% CI 0.20 to 1.04; 542 participants; five studies; low quality) or all adverse events (RR 0.95, 95% CI 0.83 to 1.08; 1100 participants; six studies; moderate quality). Serious adverse events occurred more frequently among those taking anti-leukotrienes plus tapering ICS than in those taking tapering doses of ICS alone (RR 2.44, 95% CI 1.52 to 3.92; 621 participants; two studies; moderate quality), but deaths were too infrequent for researchers to draw any conclusions about mortality. Data showed no improvement in lung function nor in asthma control measures.

AUTHORS' CONCLUSIONS

For adolescents and adults with persistent asthma, with suboptimal asthma control with daily use of ICS, the addition of anti-leukotrienes is beneficial for reducing moderate and severe asthma exacerbations and for improving lung function and asthma control compared with the same dose of ICS. We cannot be certain that the addition of anti-leukotrienes is superior, inferior or equivalent to a higher dose of ICS. Scarce available evidence does not support anti-leukotrienes as an ICS sparing agent, and use of LTRAs was not associated with increased risk of withdrawals or adverse effects, with the exception of an increase in serious adverse events when the ICS dose was tapered. Information was insufficient for assessment of mortality.

Efficacy and Safety of Modified Pranlukast (Prakanon(®)) Compared with Pranlukast (Onon(®)): A Randomized, Open-Label, Crossover Study

INTRODUCTION

Pranlukast is a leukotriene receptor antagonist (LTRA) that is used as an additional controller of mild to moderate asthma. This study compared the efficacy and side effects of two bioequivalent preparations of pranlukast: original pranlukast (Onon(®); Ono Pharmaceutical, Japan) and a modified formulation of pranlukast (Prakanon(®); Yuhan Co, Korea) in patients with mild to moderate asthma.

METHODS

Of the 34 subjects screened, 30 patients who were using standard medication to control asthma and scored less than 20 points on the Asthma Control Test(™) (ACT) were assigned randomly to one of the two groups in a prospective, open label, crossover study: group 1 received Prakanon(®) (150 mg/day) and group 2 received Onon(®) (450 mg/day) for 8 weeks each; after a 1-week rest period, the groups were switched to the alternative medication for further 8 weeks and monitored for 2 more weeks without study medication. Evaluation parameters included the ACT, quality of life questionnaire adult Korean asthmatics (QLQAKA), pulmonary function tests, peripheral blood tests, vital signs, and adverse events.

RESULTS

Thirty patients were enrolled and 21 completed the trial: 10 in group 1 and 11 in group 2. The baseline data of the two groups did not differ. No statistical significant differences were observed in efficacy and lung function at each time and in changes from baseline value between the two kinds of pranlukast. The final asthma control rate was 81% with Prakanon(®) and 76% with Onon(®). There were no differences in vital signs and laboratory data at each time and in changes from baseline value between the two drugs. There were no differences in adverse events between the two drugs. The most common side effect was abdominal pain. Drug compliance was high, without differences between the two drugs.

CONCLUSION

These findings suggest that Prakanon(®) which is an improved formulation of pranlukast at a lower dose than the original formulation, Onon(®), has a similar efficacy and side effect profile in the control of persistent asthma.

Leukotriene-receptor antagonists versus placebo in the treatment of asthma in adults and adolescents: a systematic review and meta-analysis

BACKGROUND

Leukotriene-receptor antagonists (LTRAs) are recommended as an alternative treatment in patients with mild asthma, but their effect compared with placebo is unclear.

PURPOSE

To determine the benefits and harms of LTRAs as monotherapy or in combination with inhaled corticosteroids compared with placebo in adults and adolescents with asthma.

DATA SOURCES

MEDLINE and the Cochrane Central Register of Controlled Trials from inception through June 2015.

STUDY SELECTION

Peer-reviewed, English-language, randomized, controlled trials in patients with asthma that reported the effect of LTRAs versus placebo on measures of asthma control.

DATA EXTRACTION

Three researchers extracted data on study population, interventions, outcome measures, and adverse events. One researcher assessed risk of bias.

DATA SYNTHESIS

Of the 2008 abstracts that were screened, 50 trials met eligibility criteria. Random-effects meta-analyses of 6 trials of LTRA monotherapy showed that LTRAs reduced the risk for an exacerbation (summary risk ratio [RR], 0.60 [95% CI, 0.44 to 0.81]). In 4 trials of LTRAs as add-on therapy to inhaled corticosteroids, the summary RR for exacerbation was 0.80 (CI, 0.60 to 1.07). Leukotriene-receptor antagonists either as monotherapy or as add-on therapy to inhaled corticosteroids increased FEV1, whereas FEV1 percentage of predicted values was improved only in trials of LTRA monotherapy. Adverse event rates were similar in the intervention and comparator groups.

LIMITATION

Variation in definitions and reporting of outcomes, high risk of bias in some studies, heterogeneity of findings, possible selective outcome reporting bias, and inability to assess the effect of asthma severity on summary estimates.

CONCLUSION

Leukotriene-receptor antagonists as monotherapy improved asthma control compared with placebo, but which patients are most likely to respond to treatment with LTRAs remains unclear.

PRIMARY FUNDING SOURCE

National Institutes of Health.

Structure-based drug design using GPCR homology modeling: toward the discovery of novel selective CysLT2 antagonists

3D structure of CysLT2 receptor was constructed by using homology modeling and molecular simulations. The binding pocket of CysLT2 receptor and the proposition of the interaction mode between CysLT2 and HAMI3379 were identified. A series of dicarboxylated chalcones was then virtually evaluated through molecular docking studies. A total of six compounds 13a-f with preferable scores was further synthesized and tested for CysLT2 antagonistic activities by determination of the cytosolic free Ca(2+) levels in HEK293 cells. Compounds 13e and 13f exhibited potent and selective CysLT2 antagonistic activities with IC50 values being 7.5 and 0.25 μM, respectively.

Anti-leukotriene agents compared to inhaled corticosteroids in the management of recurrent and/or chronic asthma in adults and children

BACKGROUND

Anti-leukotrienes (5-lipoxygenase inhibitors and leukotriene receptors antagonists) serve as alternative monotherapy to inhaled corticosteroids (ICS) in the management of recurrent and/or chronic asthma in adults and children.

OBJECTIVES

To determine the safety and efficacy of anti-leukotrienes compared to inhaled corticosteroids as monotherapy in adults and children with asthma and to provide better insight into the influence of patient and treatment characteristics on the magnitude of effects.

SEARCH METHODS

We searched MEDLINE (1966 to Dec 2010), EMBASE (1980 to Dec 2010), CINAHL (1982 to Dec 2010), the Cochrane Airways Group trials register, and the Cochrane Central Register of Controlled Trials (Dec 2010), abstract books, and reference lists of review articles and trials. We contacted colleagues and the international headquarters of anti-leukotrienes producers.

SELECTION CRITERIA

We included randomised trials that compared anti-leukotrienes with inhaled corticosteroids as monotherapy for a minimum period of four weeks in patients with asthma aged two years and older.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed the methodological quality of trials and extracted data. The primary outcome was the number of patients with at least one exacerbation requiring systemic corticosteroids. Secondary outcomes included patients with at least one exacerbation requiring hospital admission, lung function tests, indices of chronic asthma control, adverse effects, withdrawal rates and biological inflammatory markers.

MAIN RESULTS

Sixty-five trials met the inclusion criteria for this review. Fifty-six trials (19 paediatric trials) contributed data (representing total of 10,005 adults and 3,333 children); 21 trials were of high methodological quality; 44 were published in full-text. All trials pertained to patients with mild or moderate persistent asthma. Trial durations varied from four to 52 weeks. The median dose of inhaled corticosteroids was quite homogeneous at 200 µg/day of microfine hydrofluoroalkane-propelled beclomethasone or equivalent (HFA-BDP eq). Patients treated with anti-leukotrienes were more likely to suffer an exacerbation requiring systemic corticosteroids (N = 6077 participants; risk ratio (RR) 1.51, 95% confidence interval (CI) 1.17, 1.96). For every 28 (95% CI 15 to 82) patients treated with anti-leukotrienes instead of inhaled corticosteroids, there was one additional patient with an exacerbation requiring rescue systemic corticosteroids. The magnitude of effect was significantly greater in patients with moderate compared with those with mild airway obstruction (RR 2.03, 95% CI 1.41, 2.91 versus RR 1.25, 95% CI 0.97, 1.61), but was not significantly influenced by age group (children representing 23% of the weight versus adults), anti-leukotriene used, duration of intervention, methodological quality, and funding source. Significant group differences favouring inhaled corticosteroids were noted in most secondary outcomes including patients with at least one exacerbation requiring hospital admission (N = 2715 participants; RR 3.33; 95% CI 1.02 to 10.94), the change from baseline FEV(1) (N = 7128 participants; mean group difference (MD) 110 mL, 95% CI 140 to 80) as well as other lung function parameters, asthma symptoms, nocturnal awakenings, rescue medication use, symptom-free days, the quality of life, parents' and physicians' satisfaction. Anti-leukotriene therapy was associated with increased risk of withdrawals due to poor asthma control (N = 7669 participants; RR 2.56; 95% CI 2.01 to 3.27). For every thirty one (95% CI 22 to 47) patients treated with anti-leukotrienes instead of inhaled corticosteroids, there was one additional withdrawal due to poor control. Risk of side effects was not significantly different between both groups.

AUTHORS' CONCLUSIONS

As monotherapy, inhaled corticosteroids display superior efficacy to anti-leukotrienes in adults and children with persistent asthma; the superiority is particularly marked in patients with moderate airway obstruction. On the basis of efficacy, the results support the current guidelines' recommendation that inhaled corticosteroids remain the preferred monotherapy. 

Placebo effect model in asthma clinical studies: longitudinal meta-analysis of forced expiratory volume in 1 second

OBJECTIVE

Our objective was to describe the time course of the placebo effect in asthma and quantitatively investigate the affective factors of the placebo effect for the placebo response simulation during the asthma clinical study design.

METHODS

We conducted a systemic search of public data sources for the study-level forced expiratory volume in 1 second (FEV(1)) to build the placebo effect model for studies by oral or inhaled administrations simultaneously. The administration routes, types of inhalation device, mean patient age, mean male proportion, baseline FEV(1), disease severity, year of publication, inhaled corticosteroid status during the treatment, and dropout rate were tested as covariates.

RESULTS

There are 34 literature sources containing 178 mean values for FEV(1) presenting the individual observations from about 3,703 patients. The exponential models adequately described the time course of placebo effect with the typical value of the maximum placebo effect (P(max)) of 0.060 L. Dropout rate incorporated in the residual error model and the disease severity (mild to moderate and moderate to severe) at baseline were covariates that remained in the final model.

CONCLUSIONS

The placebo effect is adequately described by an exponential model over time. By incorporating the dropout rate in the residual error model, the estimation precision was improved. The model could predict the placebo response profile in mild to severe asthmatic patients for the asthma clinical study design and could also be a structure model of the placebo effect for the pure drug effect evaluation in the asthma clinical trials.

Leukotriene D(4) induces AP-1 but not NFkappaB signaling in intestinal epithelial cells

We have previously shown that leukotriene D(4) (LTD(4)), a known pro-inflammatory mediator, induces increased survival and proliferation of intestinal epithelial cells. In this study we examined whether LTD(4) functions via activation of the transcription factors NFkappaB and AP-1, which are potent inducers of mitogenesis. We found that the NFkappaB inhibitory protein IkappaBalpha was not degraded upon LTD(4) stimulation. Furthermore, nuclear translocation of the classical p65 or alternative p52 subunits of NFkappaB was not observed. Accordingly, LTD(4) stimulation failed to induce NFkappaB transcriptional activity. Instead we found that LTD(4) induced phosphorylation of c-Jun-N-terminal kinase (JNK) and transcriptional activity of AP-1, which could be reduced by a JNK inhibitor. Moreover, LTD(4) induced cell proliferation, and this effect was also blocked upon addition of a JNK inhibitor. Our findings show for the first time that JNK/AP-1 but not NFkappaB is a downstream target of LTD(4) in intestinal epithelial cells, suggesting that AP-1 is an important mediator of LTD(4)-induced mitogenic effects.

Long-term follow-up of pulmonary function in bronchial asthma patients treated with pranlukast

Clinical studies have shown that pranlukast, a selective cysteinyl leukotriene antagonist, is effective for bronchial asthma. In the present paper, we retrospectively analyzed long-term asthma control by pranlukast treatment in patients treated with inhaled corticosteroids. We analyzed medical records and asthma diaries of 21 patients (9 males, 12 females) (52.1 +/- 3.5 years of age) with bronchial asthma who experienced increase of more than 10 L/min in peak expiratory flow in the first 4 weeks of treatment with pranlukast (450 mg/day) and were subsequently treated with pranlukast for more than 1 year. They all received inhaled corticosteroids (400-1600 microg/day of beclomethasone dipropionate or equivalent). We examined clinical control in terms of time course of self-monitored peak expiratory flow. During the analyzed period, the dose of inhaled corticosteroids was tapered in 4 patients, constant in 15 patients and increased in 2 patients. In 19 patients treated with unchanged or tapered dose of inhaled corticosteroids, improvement in the increase of mean PEF at 4-week treatment was maintained for 1 year. No difference in the add-on effect of pranlukast was observed in patients treated with less than 800 microg and more than or equal to 800 microg of inhaled corticosteroids. Four patients underwent reduction of inhaled corticosteroids in the analyzed period and PEF was well-maintained and even increased by pranlukast treatment. In 11 patients in whom data for 3 years were available, the improvement in PEF persisted for 3 years. Although the present investigation is a retrospective analysis, these data may suggest that pranlukast has no tachyphylaxis and its effect continues for more than 1 year.

Anti-leukotriene agents compared to inhaled corticosteroids in the management of recurrent and/or chronic asthma in adults and children

BACKGROUND

Anti-leukotrienes agents are currently being studied as alternative first line agents to inhaled corticosteroids in mild to moderate chronic asthma.

OBJECTIVES

To compare the safety and efficacy of anti-leukotriene agents with inhaled glucocorticoids (ICS) and to determine the dose-equivalence of anti-leukotrienes to daily dose of ICS.

SEARCH STRATEGY

We searched MEDLINE (1966 to Aug 2003), EMBASE (1980 to Aug 2003), CINAHL (1982 to Aug 2003), the Cochrane Airways Group trials register, and the Cochrane Central Register of Controlled Trials (August 2003), abstract books, and reference lists of review articles and trials. We contacted colleagues and international headquarters of anti-leukotrienes producers.

SELECTION CRITERIA

Randomised controlled trials that compared anti-leukotrienes with inhaled corticosteroids during a minimal 30-day intervention period in asthmatic patients aged 2 years and older.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed the methodological quality or trials and extracted trial data. The primary outcome was the rate of exacerbations requiring systemic corticosteroids. Secondary outcomes included lung function, indices of chronic asthma control, adverse effects and withdrawal rates.

MAIN RESULTS

27 trials (including 1 trial testing two protocols) met the inclusion criteria; 13 were of high methodological quality; 20 are published in full-text. All trials pertained to patients with mild to moderate persistent asthma. Only 3 trials focused on children and adolescents. Trial duration varied from 4 to 37 weeks. In most trials, daily dose of ICS was 400 mcg of beclomethasone or equivalent. Patients treated with anti-leukotrienes were 65% more likely to suffer an exacerbation requiring systemic steroids [Relative Risk 1.65; 95% Confidence Interval (CI) 1.36 to 2.00]. Twenty six (95% CI: 17 to 47) patients must be treated with anti-leukotrienes instead of inhaled corticosteroids to cause one extra exacerbation. Significant differences favouring ICS were noted in secondary outcomes where()the improvement in FEV(1) reached 130 mL [13 trials; 95% CI: 50, 140 mL ]. Other significant benefits of ICS were seen for symptoms, nocturnal awakenings, rescue medication use, symptom-free days, and quality of life. Anti-leukotriene therapy was associated with 160% increased risk of withdrawals due to poor asthma control. Twenty nine (95% CI 20 to 48) patients must be treated with anti-leukotrienes instead of inhaled corticosteroids to cause one extra withdrawal due to poor control. Risk of side effects was not different between groups.

REVIEWERS' CONCLUSIONS

Inhaled steroids at a dose of 400 mcg/day of beclomethasone or equivalent are more effective than anti-leukotriene agents given in the usual licensed doses. The exact dose-equivalence of anti-leukotriene agents in mcg of ICS remains to be determined. Inhaled glucocorticoids should remain the first line monotherapy for persistent asthma.

Bronchial mast cells are the dominating LTC4S-expressing cells in aspirin-tolerant asthma

The increased bronchial production of leukotriene C4 (LTC4) in asthma is assumed to derive from infiltrating eosinophils expressing LTC4-synthase (LTC4S). Multicolor immunohistofluorescence examination of bronchial cryosections from 30 treated, untreated, or bronchial antigen-provoked aspirin-tolerant individuals with asthma and nine control subjects revealed that the dominating LTC4S-expressing cells were mast cells (> 80%), and not eosinophils. Whereas 95% of the mast cells expressed high levels of LTC4S, only 8-27% of the eosinophils expressed low levels. Image analysis revealed a significantly higher LTC4S expression levels in mast cells than in eosinophils. The bronchial mRNA levels for LTC4S did not correlate with the densities of LTC4S-positive eosinophils or mast cells. Treated individuals with asthma with more than 12% reversibility had significantly higher density of LTC4S-positive mast cells than those with less reversibility, and it correlated significantly with reduction in lung function (FEV1-predicted), both before and after salbutamol inhalation. Thus, mucosal mast cells, and not eosinophils, were the dominating LTC4S-containing cells in both untreated and treated aspirin-tolerant asthma. The density of LTC4S-positive mast cells correlated, moreover, with both the reduction in lung function and the degree of reversibility in treated asthma.

Pranlukast: a review of its use in the management of asthma

Pranlukast (Onon, Azlaire), is an orally administered, selective, competitive antagonist of the cysteinyl leukotrienes (LT) C(4), LTD(4) and LTE(4). It is indicated for the prophylactic treatment of chronic bronchial asthma in paediatric and adult patients. The efficacy of pranlukast 225mg twice daily in adults with mild to moderate asthma was demonstrated in double-blind, placebo- or azelastine-controlled studies of 4 or 8 weeks' duration. The drug at this dosage was superior to both comparators in improving mean attack scores and morning and/or evening peak expiratory flow rates, and decreasing the use of rescue bronchodilators (p < 0.05). In limited clinical studies, pranlukast 225mg twice daily appeared to be as effective as montelukast 10mg once daily and zafirlukast 40mg twice daily in adults with mild to moderate asthma. Tachyphylaxis was absent when the drug was administered for up to 4 years. In patients requiring high-dose inhaled corticosteroid therapy, pranlukast 225 mg twice daily plus a halved dosage of inhaled corticosteroid was as effective as the original dosage of inhaled corticosteroid. Pranlukast was also effective in patients with mild to severe asthma in a clinical practice setting. In a double-blind trial, greater improvements in most outcome measures were observed with pranlukast than with oxatomide in children and adolescents with asthma. In clinical trials, pranlukast was well tolerated in adult and paediatric patients with asthma, with an adverse event profile similar to that of placebo. Gastrointestinal events and hepatic function abnormalities were the most commonly reported adverse events. No clinically significant differences in adverse event profiles between pranlukast, zafirlukast or montelukast were shown in limited comparisons. Although Churg-Strauss syndrome has been noted in pranlukast recipients, a direct causal relationship is unlikely.

CONCLUSIONS

Pranlukast is a well tolerated and effective preventative treatment in adult and paediatric patients with persistent asthma of all severities. In some patients, pranlukast may be beneficial when added to low-dose inhaled corticosteroids; it may also be a viable alternative to increasing inhaled corticosteroid dosages. The efficacy of pranlukast relative to placebo has been confirmed; its efficacy relative to other therapy awaits further investigation. Nonetheless, pranlukast is a useful therapeutic option (with as-required short-acting beta(2)-agonists), either as preventative monotherapy for the treatment of mild persistent asthma or in conjunction with inhaled corticosteroids in the management of moderate or severe persistent asthma.

Benefit-risk assessment of antileukotrienes in the management of asthma

Antileukotrienes are a relatively new class of anti-asthma drugs that either block leukotriene synthesis (5-lipoxygenase inhibitors) like zileuton, or antagonise the most relevant of their receptors (the cysteinyl leukotriene 1 receptor [CysLT1]) like montelukast, zafirlukast or pranlukast. Hence, their major effect is an anti-inflammatory one. With the exception of pranlukast, the other antileukotrienes have been studied and marketed in the US and Europe for long enough to establish that they are useful drugs in the management of asthma. Their effects, significantly better than placebo, seem more pronounced in subjective measurements (i.e. symptoms scores or quality-of-life tests) than in objective parameters (i.e. forced expiratory volume in 1 second or peak expiratory flow rate). Also, there is some evidence that these drugs work better in some subsets of patients with certain genetic polymorphisms - probably related to their leukotriene metabolism - or patients with certain asthma characteristics. There are a small number of comparative studies only, and with regard to long-term asthma control differences between the agents have not been evaluated. Nevertheless, their overall effect appears comparable with sodium cromoglycate (cromolyn sodium) or theophylline, but significantly less than low-dose inhaled corticosteroids. Antileukotrienes have been shown to have a degree of corticosteroid-sparing effect, but salmeterol appears to perform better as an add-on drug. Montelukast is probably the most useful antileukotriene for continuous treatment of exercise-induced asthma, performing as well as salmeterol without inducing any tolerance. All antileukotrienes are taken orally; their frequency of administration is quite different ranging from four times daily (zileuton) to once daily (montelukast). Antileukotrienes are well tolerated drugs, even though zileuton intake has been related to transitional liver enzyme elevations in some cases. Also Churg-Strauss syndrome (a systemic vasculitis), has been described in small numbers of patients taking CysLT1 antagonists. It is quite probable that this disease appears as a consequence of an 'unmasking' effect when corticosteroid dosages are reduced in patients with severe asthma once CysLT1 antagonists are introduced, but more data are needed to definitely establish the mechanism behind this effect. Overall, however, the benefits of antileukotrienes in the treatment of asthma greatly outweigh their risks.

Long-term observations of the clinical course after step down of corticosteroid inhalation therapy in adult chronic asthmatics: correlation with serum levels of eosinophil cationic protein

BACKGROUND

Symptoms often deteriorate in well-controlled asthmatics after a step down in inhaled beclomethasone dipropionate (iBDP) therapy if the serum concentration of eosinophil cationic protein (sECP) is high. This deterioration is significantly abrogated by pranlukast, a leukotriene receptor antagonist, or by seratrodast, a thromboxane A2 receptor antagonist. However, these results were based on short-term (less than 6 months) observations.

METHODS

We studied 35 well-controlled adult asthmatics. We assigned the patients into different groups according to their sECP levels before the step down: (i) group A, sECP < 25 microg/L; (ii) group B, sECP > or = 25 microg/L; and (iii) group C, sECP > or = 25 microg/L but patients treated with pranlukast or seratrodast. We began the study with a step down in iBDP therapy (initial step down), then followed the clinical course of the asthma for 2 years. During the study period, we decreased, increased or maintained the iBDP dose on the basis of the stepwise approach described in the National Institutes of Health guidelines. We monitored the time and frequency of exacerbation and evaluated the iBDP dose required to control the asthma symptoms.

RESULTS

The rates of exacerbation after the step down were high in groups A and B. In group A, the conditions were again qualified for the step down in all patients, but this was not the case for most group B patients. From 15 to 21 months after the initial step down, the average dose of iBDP required to control symptoms was significantly higher in group B than in group A patients (P = 0.0127-0.0373). The exacerbation rate in group C after 12 months tended to be lower than in the other two patient groups (P = 0.0743). In group C, the average dose of iBDP from 9 to 24 months after the initial step down was significantly lower than before the step down (P < 0.0001) and was not significantly different from the mean dose of iBDP in groups A or B.

CONCLUSIONS

High sECP in well-controlled asthma may indicate the necessity for a higher iBDP dose over a long period than when the sECP concentration is not high. Even if sECP is high, pranlukast or seratrodast help to prevent exacerbation of asthma and enable successful step down in iBDP therapy for at least 2 years thereafter.

Addition of anti-leukotriene agents to inhaled corticosteroids for chronic asthma

BACKGROUND

Anti-leukotriene (AL) agents are being considered as "add-on" therapy to inhaled corticosteroids (ICS), in chronic asthma.

OBJECTIVES

To examine the safety and efficacy of daily AL plus ICS compared to ICS alone, and determine the corticosteroid-sparing effect of AL when added to ICS in chronic asthma.

SEARCH STRATEGY

We searched Medline, Embase, Cinahl (until September 2001), reference lists of review articles and trials, contacted international headquarters of AL manufacturers and ATS meeting abstracts (1998-2000).

SELECTION CRITERIA

Randomised placebo-controlled trials of asthmatics aged 2 years and older with at least one month intervention.

DATA COLLECTION AND ANALYSIS

Two reviewers assessed quality and extracted data independently. Trials were grouped by asthma control at baseline (symptomatic or well-controlled) and dose of ICS in the control group (same or double).

MAIN RESULTS

Of 438 citations, 13 (12 adult and 1 paediatric) trials met inclusion criteria. Seven were published in full-text. In symptomatic patients, addition of licensed doses of anti-leukotrienes to ICS resulted in a non-significant reduction in the risk of exacerbations requiring systemic steroids: Relative Risk (RR) 0.61; 95% Confidence Interval (CI) 0.36,1.05). A modest improvement group difference in PEF was seen (Weighted Mean Difference (WMD) 7.71 L/min; 95%CI 2.98, 12.44 L/min) together with beta2-agonist use (WMD= -0.32 puffs/day; 95%CI -0.0.08, -0.56). No trials that compared the use of licensed doses of anti-leukotrienes with doubling-dose of inhaled glucocorticoids could be pooled. In ICS-sparing studies in patients who were well controlled at baseline, addition of anti-leukotrienes produced no overall difference in dose of inhaled glucocorticoids (WMD -44.4 mcg/d, 95%CI -147.9, 59.0 mcg/d), but it was associated with fewer withdrawals due to poor asthma control (RR= 0.56, 95%CI 0.35, 0.89).

REVIEWER'S CONCLUSIONS

There is insufficient evidence to firmly support the use of licensed doses of anti-leukotrienes as add-on therapy to inhaled glucocorticoids. Addition of anti-leukotrienes to inhaled glucocorticoids may slightly improve asthma control, but the available data do not permit this strategy to be recommended as a substitute for increasing the dose of inhaled glucocorticoids. Addition of anti-leukotrienes may be associated with superior asthma control after glucocorticoid tapering, but a glucocorticoid-sparing effect cannot be quantified at present.

Anti-leukotriene agents compared to inhaled corticosteroids in the management of recurrent and/or chronic asthma in adults and children

BACKGROUND

Anti-leukotrienes agents are currently being studied as alternative first line agents to inhaled corticosteroids in mild to moderate chronic asthma.

OBJECTIVES

To compare the safety and efficacy of anti-leukotriene agents with inhaled glucocorticoids (ICS) and to determine the dose-equivalence of anti-leukotrienes to daily dose of ICS.

SEARCH STRATEGY

Medline (1966 to Jan 2002), Embase (1980 to Jan 2002), and Cinahl (1982 to Jan 2002) were searched and reference lists of review articles and trials. We contacted colleagues and international headquarters of anti-leukotrienes producers.

SELECTION CRITERIA

Randomised controlled trials that compared leukotriene antagonists with inhaled corticosteroids during a minimal 30-day intervention period in asthmatic patients aged 2 years and older.

DATA COLLECTION AND ANALYSIS

Two reviewers performed assessments of methodological quality and data extraction independently and blindly. The primary outcome was the rate of exacerbations requiring systemic corticosteroids. Secondary outcomes included lung function, indices of chronic asthma control, adverse effects and withdrawal rates.

MAIN RESULTS

14 trials met the inclusion criteria; 10 were of high methodological quality; 8 are published in full-text. All were in mild-to-moderate chronic asthma, Two included children or adolescents. Trial duration was 4 - 37 weeks. In most trials, daily dose of ICS was 400 mcg of beclomethasone-equivalent. Patients treated with anti-leukotrienes were 60% more likely to suffer an exacerbation requiring systemic steroids [12 trials; Relative Risk 1.61; 95% Confidence Interval (CI) 1.15, 2.25]. Significant differences favouring ICS were noted in most secondary outcomes, eg improvement in FEV1 [7 trials; Weighted Mean Difference 120 ml; 95% CI: 80, 170 ml ]; symptom scores [5 trials: Standardized Mean Difference 0.3; 95% CI 0.2, 0.4]. Other significant benefits of ICS were seen for nocturnal awakenings, rescue medication use, and quality of life. Risk of side effects was not different between groups, but anti-leukotriene therapy was associated with 30% increased risk of "withdrawals for any cause" or "withdrawals due to poor asthma control".

REVIEWER'S CONCLUSIONS

For most asthma outcomes, ICS at 400 mcg/day of beclomethasone-equivalent are more effective than anti-leukotriene agents given in the usual licensed doses. The exact dose-equivalence of anti-leukotriene agents in mcg of ICS remains to be determined.