Effect of montelukast on single-dose theophylline pharmacokinetics

Potential Effects of Leukotriene Receptor Antagonist Montelukast in Treatment of Neuroinflammation in Parkinson's Disease

Parkinson’s disease (PD) is a neurodegenerative disorder where misfolded alpha-synuclein-enriched aggregates called Lewy bodies are central in pathogenesis. No neuroprotective or disease-modifying treatments are currently available. Parkinson’s disease is considered a multifactorial disease and evidence from multiple patient studies and animal models has shown a significant immune component during the course of the disease, highlighting immunomodulation as a potential treatment strategy. The immune changes occur centrally, involving microglia and astrocytes but also peripherally with changes to the innate and adaptive immune system. Here, we review current understanding of different components of the PD immune response with a particular emphasis on the leukotriene pathway. We will also describe evidence of montelukast, a leukotriene receptor antagonist, as a possible anti-inflammatory treatment for PD.

Drug interactions

Drugs for allergy are often taken in combination with other drugs, either to treat allergy or other conditions. In common with many pharmaceuticals, most such drugs are subject to metabolism by P450 enzymes and to transmembrane transport. This gives rise to considerable potential for drug-drug interactions, to which must be added consideration of drug-diet interactions. The potential for metabolism-based drug interactions is increasingly being taken into account during drug development, using a variety of in silico and in vitro approaches. Prediction of transporter-based interactions is not as advanced. The clinical importance of a drug interaction will depend upon a number of factors, and it is important to address concerns quantitatively, taking into account the therapeutic index of the compound.

Effect of multiple doses of montelukast on the pharmacokinetics of rosiglitazone, a CYP2C8 substrate, in humans

AIMS

To investigate the effect of multiple dosing with montelukast, a selective leukotriene-receptor antagonist, on the pharmacokinetics of rosiglitazone, a CYP2C8 substrate, in humans.

METHODS

A two-period, randomized crossover study was conducted in 10 healthy subjects. After administration of oral doses of placebo or 10 mg montelukast daily for 6 days, 4 mg rosiglitazone was administered and plasma samples were obtained for 24 h and analyzed for rosiglitazone and N-desmethylrosiglitazone using high-performance liquid chromatography with fluorescence detection.

RESULTS

During the montelukast phase, the total area under the time-concentration curve (AUC) and peak plasma concentration of rosiglitazone were 102% (90% CI 98, 107%) and 98% (90% CI 92, 103%) of the corresponding values during the placebo phase, respectively. Multiple dosing with montelukast did not affect the oral clearance of rosiglitazone significantly (90% CI 94, 105%; P = 0.50). The AUC ratio and plasma concentration ratios of N-desmethylrosiglitazone : rosiglitazone were not changed by multiple dosing with montelukast (90% CI 90, 103%; P = 0.14).

CONCLUSIONS

Multiple doses of montelukast do not inhibit CYP2C8-mediated rosiglitazone metabolism in vivo despite in vitro findings indicating that montelukast is a selective CYP2C8 inhibitor.

Spotlight on montelukast in asthma in children 2 to 14 years of age

Montelukast is a cysteinyl leukotriene receptor antagonist which is used as a preventive treatment for persistent asthma in patients > or =2 years of age. In children aged 6 to 14 years montelukast (5 mg/day) treatment resulted in a significant increase in FEV1 (forced expiratory volume in 1 second, primary clinical outcome) during an 8-week randomized, double-blind trial. Moreover, significant improvements were observed for a range of secondary endpoints assessing symptoms, exacerbation rates, beta-agonist usage and quality of life. Concomitant administration of montelukast (5 mg/day) and inhaled budesonide (200 microg twice daily) resulted in a trend towards an increase in FEV1 (p=0.06, primary endpoint) and a statistically significant reduction in both as-needed beta2-agonist usage and the percentage of days with asthma exacerbations compared with budesonide plus placebo. No significant differences were observed in asthma-related quality of life between the two groups. During clinical trials both improvements in lung function and reductions in as-needed beta2-agonist usage were generally observed within 1 day after initiation of therapy in children 2 to 14 years of age with persistent asthma. Data from a randomized, nonblind trial in 6- to 11-year-old children and a 6-month extension to this trial suggest that both compliance to therapy and patient satisfaction are greater for montelukast than for either inhaled cromolyn sodium (sodium cromoglycate) or inhaled beclomethasone. In addition, patients and parents preferred oral montelukast over cromolyn sodium. In 2- to 5-year-old children with persistent asthma, montelukast (4 mg/day) treatment resulted in significant improvements in a range of outcomes, such as as-needed beta2-agonist usage, symptom scores and percentage of days with asthma symptoms, as assessed during a randomized, double-blind trial primarily designed to assess tolerability. Data from small randomized, double-blind trials suggest that montelukast reduces exercise-induced bronchoconstriction in 6- to 14-year-old children. Montelukast is generally well tolerated. The frequency of adverse events in montelukast-treated children of all ages was comparable to that in patients receiving placebo.

CONCLUSION

Oral montelukast has shown efficacy as a preventive treatment for asthma during clinical trials in children aged 2 to 14 years. The drug offers benefits over more standard therapies such as inhaled cromolyn sodium and nedocromil in terms of compliance and convenience. In addition, the drug offers significant benefits when added to inhaled corticosteroids (according to secondary endpoints). Montelukast offers an effective, well tolerated and convenient treatment option for children with 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.

[Pharmacological profile and clinical effects of montelukast sodium (Singulair chewable tablet), an antiasthmatic agent]

Montelukast (Singulair) is an antiasthmatic agent that has the chemical structure of a quinoline. Montelukast has a high affinity for the CysLT1 receptor and a potency that is not influenced by human serum protein. Montelukast antagonizes contractions of guinea-pig trachea induced by LTD4 in a competitive manner. Intravenous montelukast inhibited bronchoconstriction induced by LTD4 in guinea pigs. Oral montelukast inhibited increased airway resistance induced by antigen in squirrel monkeys. Montelukast also inhibited both inflammatory and immunologic responses induced by either LTD4 or antigen in guinea pigs and rats. Plasma concentrations of montelukast after oral administration of 10 mg in humans were shown to be over the effective level for at least 24 h. These lines of evidence support the effectiveness of a regimen of 10 mg/day for asthmatic symptoms in humans. In a number of clinical experiments, montelukast not only improved asthmatic symptoms and respiratory indices, but also inhibited airway inflammation and exercise-induced bronchoconstriction. These effects persisted during extended treatment. Montelukast produced an additive effect to basic therapy with an inhaled steroid. There were no differences in the incidence and magnitude of adverse effects between montelukast and placebo groups in clinical experiments. Montelukast is expected to serve as a first line of asthmatic therapy because of its consistent efficacy and good safety profile and it is associated with good compliance in patients because of its simple regimen of one 10 mg tablet/day.

Montelukast: a review of its therapeutic potential in asthma in children 2 to 14 years of age

Montelukast is a cysteinyl leukotriene receptor antagonist which is used as a preventive treatment for persistent asthma in patients > or =2 years of age. In children aged 6 to 14 years montelukast (5 mg/day) treatment resulted in a significant increase in FEV(1) (forced expiratory volume in 1 second, primary clinical outcome) during an 8-week randomized, double-blind trial. Moreover, significant improvements were observed for a range of secondary endpoints assessing symptoms, exacerbation rates, beta-agonist usage and quality of life. Concomitant administration of montelukast (5 mg/day) and inhaled budesonide (200 microg twice daily) resulted in a trend towards an increase in FEV(1) (p = 0.06, primary endpoint) and a statistically significant reduction in both as-needed beta(2)-agonist usage and the percentage of days with asthma exacerbations compared with budesonide plus placebo. No significant differences were observed in asthma-related quality of life between the two groups. During clinical trials both improvements in lung function and reductions in as-needed beta(2)-agonist usage were generally observed within 1 day after initiation of therapy in children 2 to 14 years of age with persistent asthma. Data from a randomized, nonblind trial in 6- to 11-year-old children and a 6-month extension to this trial suggest that both compliance to therapy and patient satisfaction are greater for montelukast than for either inhaled sodium cromoglycate or inhaled beclomethasone. In addition, patients and parents preferred oral montelukast over sodium cromoglycate. In 2- to 5-year-old children with persistent asthma, montelukast (4 mg/day) treatment resulted in significant improvements in a range of outcomes, such as as-needed beta(2)-agonist usage, symptom scores and percentage of days with asthma symptoms, as assessed during a randomized, double-blind trial primarily designed to assess tolerability. Data from small randomized, double-blind trials suggest that montelukast reduces exercise-induced bronchoconstriction in 6- to 14-year-old children. Montelukast is generally well tolerated. The frequency of adverse events in montelukast-treated children of all ages was comparable to that in patients receiving placebo.

CONCLUSION

Oral montelukast has shown efficacy as a preventive treatment for asthma during clinical trials in children aged 2 to 14 years. The drug offers benefits over more standard therapies such as inhaled sodium cromoglycate and nedocromil in terms of compliance and convenience. In addition, the drug offers significant benefits when added to inhaled corticosteroids (according to secondary endpoints). Montelukast offers an effective, well tolerated and convenient treatment option for children with asthma.

Use of oral montelukast in the treatment of asthma

Montelukast, a new leukotriene modifier, has several benefits in the treatment of asthma in adults and children including improved relief of asthma symptoms, rapid onset, a safety profile comparable with placebo, and oral, once-daily dosing means excellent adherence.

Antileukotrienes in asthma: present situation

Leukotrienes are key mediators in asthma. Over the last 5 years, several antileukotrienes, including three receptor antagonists (montelukast, pranlukast and zafirlukast) and one 5-lipoxygenase inhibitor (zileuton), have been marketed and, to date, this class of drugs is being used widely. Still, their definite place in the asthma treatment algorithm is not yet established. These novel drugs have not yet all been evaluated in the same depth, but they have all been shown to possess anti-inflammatory properties and to be effective in chronic asthma treatment. Zafirlukast and montelukast are particularly efficacious in exercise-induced asthma and zileuton appears valuable for treating aspirin-intolerant asthmatics. Clinical comparisons to other anti-asthma drugs are still sparse. The corticosteroid-sparing effect of antileukotrienes is fairly well established except for zileuton, even though this drug has been evaluated most thoroughly in terms of its anti-inflammatory effects. Montelukast is the antileukotriene most extensively evaluated in children and zafirlukast has recently been approved for use in children in the USA, although not yet in Europe. Therapeutic regimes are quite variable depending on the drug, but all of the antileukotrienes marketed to date are taken orally; hence, compliance is usually greater than that with inhaled medication. Response to antileukotrienes appears to depend on the individual patients' characteristics, in particular on genetic polymorphisms related to leukotriene metabolism. All drugs of this class are well tolerated and only in the case of zileuton is there potential for hepatic adverse effects. The diagnosis of Churg-Strauss syndrome made among patients taking antileukotrienes seems to be more related to the withdrawal of corticosteroids than to the antileukotrienes themselves.

Drug interactions with cisapride: clinical implications

Cisapride, a prokinetic agent, has been used for the treatment of a number of gastrointestinal disorders, particularly gastro-oesophageal reflux disease in adults and children. Since 1993, 341 cases of ventricular arrhythmias, including 80 deaths, have been reported to the US Food and Drug Administration. Marketing of the drug has now been discontinued in the US; however, it is still available under a limited-access protocol. Knowledge of the risk factors for cisapride-associated arrhythmias will be essential for its continued use in those patients who meet the eligibility criteria. This review summarises the published literature on the pharmacokinetic and pharmacodynamic interactions of cisapride with concomitantly administered drugs, providing clinicians with practical recommendations for avoiding these potentially fatal events. Pharmacokinetic interactions with cisapride involve inhibition of cytochrome P450 (CYP) 3A4, the primary mode of elimination of cisapride, thereby increasing plasma concentrations of the drug. The macrolide antibacterials clarithromycin, erythromycin and troleandomycin are inhibitors of CYP3A4 and should not be used in conjunction with cisapride. Azithromycin is an alternative. Similarly, azole antifungal agents such as fluconazole, itraconazole and ketoconazole are CYP3A4 inhibitors and their concomitant use with cisapride should be avoided. Of the antidepressants nefazodone and fluvoxamine should be avoided with cisapride. Data with fluoxetine is controversial, we favour the avoidance of its use. Citalopram, paroxetine and sertraline are alternatives. The HIV protease inhibitors amprenavir, indinavir, nelfinavir, ritonavir and saquinavir inhibit CYP3A4. Clinical experience with cisapride is lacking but avoidance with all protease inhibitors is recommended, although saquinavir is thought to have clinically insignificant effects on CYP3A4. Delavirdine is also a CYP3A4 inhibitor and should be avoided with cisapride. We also recommend avoiding coadministration of cisapride with amiodarone, cimetidine (alternatives are famotidine, nizatidine, ranitidine or one of the proton pump inhibitors), diltiazem and verapamil (the dihydropyridine calcium antagonists are alternatives), grapefruit juice, isoniazid, metronidazole, quinine, quinupristin/dalfopristin and zileuton (montelukast is an alternative). Pharmacodynamic interactions with cisapride involve drugs that have the potential to have additive effects on the QT interval. We do not recommend use of cisapride with class Ia and III antiarrhythmic drugs or with adenosine, bepridil, cyclobenzaprine, droperidol, haloperidol, nifedipine (immediate release), phenothiazine antipsychotics, tricyclic and tetracyclic antidepressants or vasopressin. Vigilance is advised if anthracyclines, cotrimoxazole (trimethoprim-sulfamethoxazole), enflurane, halothane, isoflurane, pentamidine or probucol are used with cisapride. In addition, uncorrected electrolyte disturbances induced by diuretics may increase the risk of torsade de pointes. Patients receiving cisapride should be promptly treated for electrolyte disturbances.

Tolerability of montelukast

The tolerability of a medication, especially in children with asthma, is linked to a number of key factors. These include clinical effectiveness, adverse effects, frequency of drug regimen, ease and route of administration. and taste. Montelukast is unusual in that, in most countries, a licence for children aged > or =6 years was granted at the same time as the adult licence. This is related to a variety of evidence. which includes pharmacological and adult studies suggesting the specificity and safety of the drug at many times the licensed dose, and a tolerability profile similar to that with placebo or inhaled corticosteroids in both adult and paediatric studies. The most common adverse effects in paediatric studies were headache, asthma and upper respiratory tract infection at rates not statistically significantly different from those with placebo. Up to July 1999, more than 2 million patients worldwide have received montelukast, of whom nearly 220,000 have received the paediatric formulation. In the UK, one prescribing database suggests that, of children who commenced montelukast therapy, less than 25% discontinued the drug. This implies that montelukast is effective and well tolerated in most children. Adverse effect monitoring by regulatory bodies has revealed little that would not be expected on the basis of the results of clinical trials. Montelukast has been associated with Churg-Strauss syndrome in a very small number of adults. In most. the syndrome was associated with corticosteroid withdrawal, which may have unmasked the condition. Churg-Strauss syndrome has not been reported in children. Its clinical effectiveness, lack of major adverse effects, oral route of administration, palatability and the once-daily regimen combine to make montelukast a generally well tolerated medication in children.

Montelukast: a review of its therapeutic potential in persistent asthma

Montelukast is a cysteinyl leukotriene receptor antagonist used to treat persistent asthma in patients aged > or = 6 years. The drug has a rapid onset of action. Improvements in lung function and reductions in as-needed beta2-agonist usage are apparent within 1 day of initiating montelukast treatment in adults and adolescents (aged > or = 15 years treated with 10 mg/day) or children (aged 6 to 14 years treated with 5 mg/day) with persistent asthma as shown in clinical trials. In two 12-week, multicentre, randomised, double-blind studies in adults and adolescents aged > or = 15 years with persistent asthma [forced expiratory volume in 1 second (FEV1) = 50 to 85% predicted] there was significantly (p < 0.05) greater improvement in FEV1, symptom scores, peak expiratory flow (PEF), as-needed beta2-agonist use, peripheral eosinophil counts and health-related quality of life (QOL) in patients treated with montelukast 10 mg/day than in recipients of placebo. Improvements were significantly greater in patients treated with inhaled beclomethasone 400 microg/day than in recipients of montelukast 10 mg/day in 1 of these studies. Nonetheless, 42% of montelukast recipients experienced > or = 11% improvement in FEV1, the median improvement in this parameter in beclomethasone-treated patients. In an 8-week multicentre, randomised, double-blind, study in children aged 6 to 14 years with persistent asthma (FEV1 50 to 85% predicted), montelukast 5 mg/day produced significantly greater improvements in FEV1, clinic PEF, as-needed beta2-agonist use, peripheral eosinophil counts, asthma exacerbations and QOL scores than placebo. The combination of montelukast 10 mg/day plus inhaled beclomethasone 200 microg twice daily provided significantly better asthma control than inhaled beclomethasone 200 microg twice daily in adults with poorly controlled asthma (mean FEV1 = 72% predicted) despite 4 weeks treatment with inhaled beclomethasone. Patients receiving the combination experienced significant improvements in FEV1 and morning PEF, significant reductions in daytime symptom scores, as-needed beta2 agonist usage and night-time awakenings with asthma, and had significantly lower peripheral blood eosinophil counts after 16 weeks in this multicentre, randomised, double-blind, placebo-controlled study. Among adults (FEV1 > or = 70%) treated with montelukast 10 mg/day for 12 weeks, inhaled corticosteroid dosages were titrated downward by 47% (vs 30% in placebo recipients), 40% of patients were tapered off of inhaled corticosteroids (vs 29%), and significantly fewer patients (16 vs 30%) experienced failed corticosteroid rescues in a multicentre, randomised, double-blind study. During clinical studies, the frequency of adverse events in montelukast-treated adults, adolescents and children was similar to that in placebo recipients. In conclusion, montelukast is well tolerated and effective in adults and children aged > or = 6 years with persistent asthma including those with exercise-induced bronchoconstriction and/or aspirin sensitivity. Furthermore, montelukast has glucocorticoid sparing properties. Hence, montelukast, as monotherapy in patients with mild persistent asthma, or as an adjunct to inhaled corticosteroids is useful across a broad spectrum of patients with persistent asthma.

Montelukast: data from clinical trials in the management of asthma

OBJECTIVE

To review the pharmacology, pharmacokinetics, clinical efficacy, and adverse effects of montelukast, a leukotriene receptor antagonist used to treat asthma, and to discuss the therapeutic role of montelukast as long-term medication and difficulties associated with the management of asthma.

DATA SOURCES

A MEDLINE search (up to May 1999) was conducted to identify relevant English-language publications, including preclinical studies, clinical trials, and recent reviews.

STUDY SELECTION

All available published reports of controlled, clinical trials of montelukast in adults and children with asthma were summarized, including pharmacokinetic and pharmacologic effects of montelukast.

DATA EXTRACTION

Information on the safety and efficacy of montelukast was evaluated on the basis of patient selection, study design, methodology, and statistical significance as compared with placebo or inhaled corticosteroid treatment.

DATA SYNTHESIS

Montelukast is approved for the prophylaxis and chronic treatment of asthma at a dose of 10 mg once daily for adolescents (> or =15 y) and adults and 5 mg once daily for children (6-14 y). In placebo-controlled clinical trials, montelukast significantly improved pulmonary lung function (as measured by forced expiratory volume in 1 sec), significantly reduced beta2-agonist use, and significantly improved patient-reported end points in adults and children (> or =6 y) with chronic asthma. In adults, a similar magnitude of improvement in lung function is seen with or without inhaled corticosteroid use; the effects of montelukast may be additive to those of inhaled corticosteroids and permit the reduction of the required dose of inhaled corticosteroids. In cases of exercise-induced asthma (adults and children), montelukast treatment attenuates the fall in pulmonary function following exercise. It attenuates both the early- and late-phase responses of asthma after allergen inhalation. Improvements in asthma control are similar in asthmatic patients who are aspirin-sensitive or not aspirin-sensitive and can be seen within one day of treatment. Tolerance does not develop, and the adverse events do not differ from those of placebo.

CONCLUSIONS

Montelukast is indicated for the prophylaxis of chronic asthma in adults and children (> or =6 y). It may be considered for use as first-line therapy in patients with mild persistent asthma or for additional control in patients who are still symptomatic while receiving treatment with inhaled corticosteroids. It may also be used for additional control in aspirin-sensitive asthmatic patients. Consideration may be given for using montelukast to allow tapering of the dose of inhaled corticosteroids while maintaining clinical stability. Chronic treatment with montelukast can provide additional control of symptoms during exercise, but inhaled beta2-agonists remain first-line therapy for prophylaxis and treatment.