Combination therapy of long-acting beta agonists and inhaled corticosteroids in the management of chronic asthma

Orally inhaled fixed-dose combination products for the treatment of asthma and chronic obstructive pulmonary disease: not simple math

Over the past decade, orally inhaled fixed-dose combination products (FDCs) have emerged as an important therapeutic class for the treatment of asthma and chronic obstructive pulmonary disease. However, the conceptual simplicity of inhaled FDCs belies both the complexity of their development, and the profound advantages they offer patients. The benefits of combining agents are not merely additive, and range from increased compliance via simple convenience to complex receptor-level synergies. Similarly, though, the development challenges often exceed the sum of their parts. FDC formulation and analytical method development is generally more complex than for two monotherapy products. Likewise, FDC clinical programs can easily eclipse those of their monotherapy peers and their inherent complexity is often furthered by the diverse regulatory requirements for worldwide approval. As such, the proposition of developing an orally inhaled FDC for global registration often represents a significant increase in both the potential rewards and assumed risks of drug development.

Asthmatics able to step down from inhaled corticosteroid treatment without loss of asthma control have low serum eotaxin/CCL11

INTRODUCTION

The addition of a long-acting beta2 agonist (LABA) to inhaled corticosteroid (ICS) may control asthma better than ICS alone. Eosinophil markers may predict symptom severity in asthma.

OBJECTIVES

The effect of combination treatment on moderate to severe asthmatics not selected to respond rapidly to steroid deprivation was compared with monotherapy. The ability of serum markers to predict symptom severity was assessed.

METHODS

Asthmatics treated adequately with ICS (750-1000 mcg ICS daily) were randomised to receive ICS (fluticasone propionate) + LABA (salmeterol) (500 mcg/50 mcg bd) or ICS alone (500 mcg bd). If asthma was controlled at clinic visits every 6 weeks, ICS dose was tapered until asthma exacerbated (hospitalisation, ICS above study medication, peak flow variation, decline in forced expiratory volume in 1 s and/or use of rescue medication), or placebo was maintained for 6 weeks. Efficacy of the treatments was compared. Serum cytokines and chemokines were compared among the groups reporting severe, mild or no symptoms.

RESULTS

There was no difference between the treatment arms in the clinical analysis. Nine patients could be maintained on placebo for 6 weeks, 36 developed mild symptoms and 16 developed severe symptoms. Patients on placebo for 6 weeks had significantly lower serum eotaxin at baseline than patients with symptoms. Patients with mild symptoms had intermediate serum eotaxin concentrations.

CONCLUSION

Patients with asthma controlled on ICS respond heterogeneously to ICS tapering. Serum eotaxin/CCL11 may be useful in predicting the severity of symptoms patients develop during steroid tapering and should be evaluated in guiding asthma treatment.

Engineering of crystalline combination inhalation particles of a long-acting beta2-agonist and a corticosteroid

PURPOSE

Engineering of inhalation particles incorporating, in each individual particle, a combination of a long-acting beta-agonist and a glucocorticosteroid in a pre-determined and constant ratio for delivery via a dry powder inhaler (DPI).

METHODS

Individual crystalline particles containing both the glucocorticosteroid fluticasone propionate (FP) and long-acting beta-agonist salmeterol (SX) were prepared, in a ratio of 10:1, using the solution atomization and crystallization by sonication (SAX) process. Combination drug particles were characterized by particle size, morphology, crystallinity and aerosolisation efficiency using inertial impaction.

RESULTS

Combination drug particles were spherical and crystalline, with a median diameter of 4.68 +/- 0.01 microm. Aerosolisation of formulations containing combination drug particles resulted in greater uniformity in delivery ratios of both actives across all stages of the impactor before and after storage.

CONCLUSIONS

Actives in a pre-determined dose ratio can be crystallised in a single particle using the SAX process.

The rush to adrenaline: drugs in sport acting on the beta-adrenergic system

Athletes attempt to improve performance with drugs that act on the beta-adrenergic system directly or indirectly. Of three beta-adrenoceptor (AR) subtypes, the beta(2)-AR is the main target in sport; they have bronchodilator and anabolic actions and enhance anti-inflammatory actions of corticosteroids. Although demonstrable in animal experiments and humans, there is little evidence that these properties can significantly improve performance in trained athletes. Their actions may also be compromised by receptor desensitization and by common, naturally occurring receptor mutations (polymorphisms) that can influence receptor signalling and desensitization properties in individuals. Indirectly acting agents affect release and reuptake of noradrenaline and adrenaline, thereby influencing all AR subtypes including the three beta-ARs. These agents can have potent psychostimulant effects that provide an illusion of better performance that does not usually translate into improvement in practice. Amphetamines and cocaine also have considerable potential for cardiac damage. beta-AR antagonists (beta-blockers) are used in sports that require steadiness and accuracy, such as archery and shooting, where their ability to reduce heart rate and muscle tremor may improve performance. They have a deleterious effect in endurance sports because they reduce physical performance and maximum exercise load. Recent studies have identified that many beta-AR antagonists not only block the actions of agonists but also activate other (mitogen-activated PK) signalling pathways influencing cell growth and fate. The concept that many compounds previously regarded as 'blockers' may express their own spectrum of pharmacological properties has potentially far-reaching consequences for the use of drugs both therapeutically and illicitly.

Update on glucocorticoid action and resistance

Extensive development of inhaled and oral glucocorticoids has resulted in highly potent molecules that have been optimized to target activity to the lung and minimize systemic exposure. These have proved highly effective for most asthmatic subjects, but despite these developments, there are a number of subjects with asthma who fail to respond to even high doses of inhaled or even oral glucocorticoids. Advances in delineating the fundamental mechanisms of glucocorticoid pharmacology, especially the concepts of transactivation and transrepression and cofactor recruitment, have resulted in better understanding of the molecular mechanisms whereby glucocorticoids suppress inflammation. The existence of multiple mechanisms underlying glucocorticoid insensitivity raises the possibility that this might indeed reflect different diseases with a common phenotype, and studies examining the efficacy of potential new agents should be targeted toward subgroups of patients with severe corticosteroid-resistant asthma who clearly require effective new drugs and other approaches to improved asthma control.

Inhaled steroids do not decrease bone mineral density but increase risk of fractures: data from the GIUMO Study Group

Although the negative effect of systemic steroids on bone is well documented, there is not clear evidence about possible adverse effects of inhaled steroids on bone metabolism and fractures. A cross-sectional study was performed on 105 women suffering from bronchial asthma treated with inhaled steroids and 133 controls. Bone mineral density (BMD) was measured by quantitative ultrasonography (QUS) at the calcaneus and by dual X-ray absorptiometry (DXA), at both the lumbar spine and proximal femur. Patients suffering from bronchial asthma showed no statistically significant changes in BMD as measured by DXA or QUS, compared with controls. A higher prevalence of fractures was found in the group of women with bronchial asthma, with an age-adjusted odds ratio of 2.79 (95% CI: 1.19-6.54). Inhaled steroids do not appear to decrease BMD, but are associated with an increased risk of fracture in women.

Beta-adrenoceptor responses of the airways: for better or worse?

Beta2-adrenoceptor agonists are the first-line treatment of asthma and chronic obstructive pulmonary disease (COPD), in which a short-acting beta2-adrenoceptor agonist is used as required for relief of bronchoconstriction. A long-acting beta2-adrenoceptor agonist may be added to an inhaled corticosteroid as step 3 in the management of chronic asthma. Long-acting beta2-adrenoceptor agonists may also be added in treatment of COPD. This review examines the beneficial and detrimental effects of beta2-adrenoceptor agonists. The beneficial effects of beta2-adrenoceptor agonists are mainly derived from their bronchodilator activity which relieves the bronchiolar narrowing and improves air flow. The potential anti-inflammatory actions of stabilizing mast cell degranulation and release of inflammatory and bronchoconstrictor mediators, is considered. Other potential beneficial responses include improvements in mucociliary clearance and inhibition of extravasation of plasma proteins that is involved in oedema formation in asthma. The side effects of beta2-adrenoceptor agonists are primarily related to beta2-adrenoceptor-mediated responses at sites outside the airways. Of major concern has been the development of tolerance and this is discussed in relation to incidence of increased morbidity and mortality to asthma over the past three decades. A clinical aspect of beta2-adrenoceptor pharmacology in recent years has been the recognition of genetic polymorphism of the receptor and how this affects responses to and tolerance to beta2-adrenoceptor agonists. A controversial feature of beta2-adrenoceptor agonists is their stereoisomerism and whether the inactive (S)-isomer of salbutamol had detrimental actions in the commercially used racemate. The consensus is that despite these adverse properties, beta2-adrenoceptor agonist remains the most useful pharmacological agents in the management of asthma and COPD.