Comparative studies of inhaled corticosteroids in asthma

Performance of Turbuhaler((R)) in Patients with Acute Airway Obstruction and COPD, and in Children with Asthma : Understanding the Clinical Importance of Adequate Peak Inspiratory Flow, High Lung Deposition, and Low In Vivo Dose Variability

The dry-powder inhaler (DPI) Turbuhaler((R)) has been on the market for nearly two decades. Products containing terbutaline, formoterol, budesonide, and the combination budesonide/formoterol are widely used by patients with asthma and COPD. Most patients and physicians find Turbuhaler((R)) easy to use, and local side effects are rare. This is thought to arise from the lack of additives or only small amounts in the formulation, in addition to minimal deposition of the drug in the oropharynx and on the vocal cords during inspiration.The function of Turbuhaler((R)) has frequently been questioned. This article aims to review and clarify some key issues that have been challenged in the literature (e.g. the effectiveness of Turbuhaler((R)) in patients with more restricting conditions), to discuss the importance of lung deposition, and to explain the low in vivo variability associated with Turbuhaler((R)) and the lack of correlation with the higher in vitro variability.Turbuhaler((R)), like other DPIs, is flow dependent to some degree. However, a peak inspiratory flow (PIF) through Turbuhaler((R)) of 30 L/min gives a good clinical effect. These PIF values can be obtained by patients with conditions thought to be difficult to manage with inhalational agents, such as asthmatic children and adult patients with acute severe airway obstruction and COPD. Excellent clinical results with Turbuhaler((R)) in large controlled studies in patients with COPD and acute severe airway obstruction provide indirect evidence that medication delivered via Turbuhaler((R)) reaches the target organ.Due to the large amount of small particles and the moderate inbuilt resistance in Turbuhaler((R)), which opens up the vocal cords during inhalation, Turbuhaler((R)) is associated with a high lung deposition (25-40% of the delivered dose) compared with pressurized metered-dose inhalers (pMDIs) and other DPIs. A good correlation has been found between lung deposition and clinical efficacy. A high lung deposition always results in the best ratio between clinical efficacy and risk of unwanted systemic activity. Studies with Turbuhaler((R)) also show that the in vivo variation in lung deposition is significantly lower compared with a pMDI or, for example, the Diskus((R)) inhaler, and much lower than the in vitro dose variability seen in laboratory tests. Turbuhaler((R)) appears to be a reliable DPI which can be used with confidence by patients with airway diseases, including those with clinical conditions believed to be difficult to manage with inhalational therapy.

Effects of nebulized high-dose budesonide on moderate-to-severe acute exacerbation of asthma in children: a randomized, double-blind, placebo-controlled study

BACKGROUND AND OBJECTIVE

The efficacy of inhaled corticosteroids (ICS) in asthma exacerbation are yet to be clarified. The aim of this study was to investigate the efficacy of nebulized ICS in children with moderate-to-severe acute exacerbation of asthma in an emergency room setting in order to elucidate the potential use of ICS as the first-line therapy in the management of acute exacerbation of asthma.

METHODS

This was a prospective, randomized, double-blind, placebo-controlled study. Paediatric patients with moderate-to-severe acute exacerbation of asthma in emergency room were randomized to receive nebulized salbutamol and ipratropium bromide, with the addition of nebulized high-dose budesonide (BUD group, n = 60) or normal saline (control group, n = 58), three doses in the first hour.

RESULTS

The improvement in forced expiratory volume in 1 s was similar in both groups at 0 h after three doses of nebulization, but there was significantly further improvement at 1 and 2 h in the BUD group (0.095 ± 0.062 L and 0.100 ± 0.120 L, respectively) compared with the control group (0.059 ± 0.082 L and 0.021 ± 0.128 L, respectively), P = 0.013 and 0.001, respectively. Complete remission rate was significantly higher (84.7% vs 46.3%, P = 0.004) and need for oral corticosteroids was significantly lower (16.9% vs 46.3%, P = 0.011) in BUD group than in control group.

CONCLUSION

On the basis of nebulized short-acting bronchodilators, addition of nebulized high-dose budesonide resulted in clinical improvement in children with moderate-to-severe acute exacerbation of asthma, suggesting that nebulized high-dose ICS can be used as first-line therapy for non-life-threatening acute exacerbation of asthma in children.

A comparative study of inhaled ciclesonide 160 microg/day and fluticasone propionate 176 microg/day in children with asthma

Ciclesonide (CIC) is an inhaled corticosteroid (ICS) with high anti-inflammatory activity and low incidence of local and systemic adverse effects. The objective of this study was to compare the efficacy and safety of CIC with fluticasone propionate (FP) in children and adolescents with persistent asthma. This was a 12-week, randomized, double blind, parallel-group study. After a 2-to 4-week baseline period, a total of 556 children (ages 6-15 years) with asthma (forced expiratory volume in 1 sec [FEV(1)], 50% to 90% predicted) were treated twice daily with CIC 80 microg (ex-actuator, equivalent to 100 microg ex-valve) or FP 88 microg (ex-actuator, equivalent to 100 microg ex-valve) administered via a hydrofluoroalkane-propelled metered-dose inhaler. A statistically significant increase from baseline was observed in FEV(1) for both CIC (285 +/- 16 ml) and FP (285 +/- 15 ml) (P < 0.0001 for both) and in morning and evening peak expiratory flow (P < 0.0001 for both). Significant improvements were seen in asthma symptoms, use of rescue medication, and asthma symptom-free days in both treatment groups, without any differences between the treatment groups in changes from baseline. Two FP-treated patients experienced oral candidiasis and one patient experienced voice alteration. Creatinine-adjusted 24-hr urine cortisol levels increased from baseline levels by 10% in the CIC group (P < 0.05) and by 6% in the FP group (not significant). The efficacy and safety of CIC 160 microg/day were comparable to those of FP 176 microg/day in children with asthma.

Potency ratio fluticasone propionate (Flixotide Diskus)/budesonide (Pulmicort Turbuhaler)

In the choice of, or switch between, various inhaled corticosteroids (ICS) it is important to know equipotent doses for clinical treatment effects of the alternatives. Various ICS do have different inherent potency. Further, the ICS are delivered from inhalers that may differ markedly in output characteristics and drug delivery to intrapulmonary airways. Therefore, clinical efficacy comparisons must include drug-inhaler comparisons. We estimated the therapeutic potency ratio of the Flixotide Diskus (fluticasone propionate, FP) and the Pulmicort Turbuhaler (budesonide, BUD) in steroid-naive asthma patients, using a dose-reduction technique (FP 500-0 mcg/day, BUD 800-0 mcg/day). The dose defining end point was loss of asthma control in this paper denoted as exacerbation. In total, 282 patients with proven asthma were enrolled in the study, and 103 in the FP group and 98 in the BUD group completed the study per protocol. In total, 80 patients in the FP-group and 79 in the BUD-group experienced a dose defining exacerbation. The exacerbation frequency increased in a dose-dependent way as the dose was titrated down. From these data the potency difference between the present drug inhaler combinations, Flixotide Diskus and Pulmicort Turbuhaler, was calculated to be between 1.50:1 (95% CI 1.10:1-2.05:1) and 1.75:1 (CI 1.26:1-2.43:1) depending on if patients with insufficient steroid-response were excluded from the calculations or not. In these steroid-naïve patients, the potency difference was evident only at low daily doses, below 200 mcg.

Idealhalers or realhalers? A comparison of Diskus and Turbuhaler

Medication for the treatment of asthma and chronic obstructive pulmonary disease should be given locally by inhalation. There is, however, no such thing as an ideal inhaler, or 'Idealhaler', which has all desired properties with no drawbacks. In this short review, we have compared the relative merits of the two most commonly used dry powder inhalers -- Turbuhaler and Diskus. Clinical effect is related to the amount of inhaled drug that reaches the lungs, and this in turn depends on the amount of fine particles generated at inhalation. Turbuhaler is more than twice as effective as Diskus at generating fine particles, and the higher lung deposition with Turbuhaler is accompanied by a lower variability in lung deposition. Compared with Diskus, the lung deposition with Turbuhaler is affected less by factors such as humidity.

In vitro comparison of nebulised budesonide (Pulmicort Respules®) and beclomethasone dipropionate (Clenil® per Aerosol)

This study compared the in vitro performance of two inhaled corticosteroid products for nebulisation, Pulmicort Respules(budesonide 0.5 mg/mL) and Clenil) per Aerosol (beclomethasone dipropionate (BDP) 0.4 mg/mL). Each product was used in combination with three different nebulisers (2 mL/test, 5 min run time) and the dose to the lungs was determined according to standard methods. The shape of the suspended particles in each product was studied using scanning electron microscopy (SEM). Overall, a higher fine particle dose was achieved with Pulmicort Respules versus Clenil per Aerosol, with estimated dose to the lungs of 8-14 and 3-6% of nominal dose, respectively. SEM showed that budesonide particles were small, typically approximately 2-3 microm in diameter, whereas those of BDP were needle-shaped and up to approximately 10 microm long. The more favourable particle shape and size of suspended budesonide may explain the higher fine particle dose with Pulmicort Respules versus Clenil per Aerosol.

Therapeutic margin of budesonide in patients with mild to severe asthma

BACKGROUND

The therapeutic margin of a drug is the difference between the optimal effective dose and the dose at which unacceptable adverse effects occur. This margin is particularly important in the case of therapies that are used long term for the control of chronic illnesses, such as inhaled corticosteroids (ICSs) in the treatment of asthma. Because data from controlled clinical studies indicate that the available ICSs have similar clinical efficacy, the safety profile is central to differentiating between them on the basis of their therapeutic margins. The main safety concern with long-term use and high doses of ICSs is systemic exposure that could result in such unwanted effects as cortisol suppression, a reduction in the final adult height of pediatric patients, and decreased bone mineral density.

OBJECTIVE

This article reviews data from clinical trials, including long-term prospective studies, to compare the therapeutic margin of budesonide with those of other second-generation ICSs and to determine whether there are variations in the therapeutic margin with different delivery devices, severities of disease, or patient age.

RESULTS

Based on the tolerability data for budesonide from short-term (6-12 wk) and long-term (1-9 y) studies in patients with mild to moderate persistent asthma, the dose-response and dose-tolerability curves for budesonide delivered by dry-powder inhaler can be plotted in parallel. The margin between these curves-the therapeutic margin-is favorable and consistent in pediatric and adult patients and at all degrees of asthma severity. Fewer tolerability data are available for other ICSS.

CONCLUSION

Whereas budesonide has clinical efficacy similar to that of other currently available ICSs, it has a good safety profile-and hence a favorable therapeutic margin-that is supported by long-term clinical data. Budesonides favorable therapeutic margin is probably a result of its pharmacokinetic and physical properties.

Role of budesonide as maintenance therapy for children with asthma

Asthma is a chronic inflammatory disease of the airways. Inhaled corticosteroids are recognized as the preferred long-term control medication for persistent asthma based on their anti-inflammatory properties and significant evidence of efficacy. Inhaled budesonide is the most carefully characterized inhaled corticosteroid for childhood asthma. It is available for administration in children down to six months of age and to date has an excellent safety profile.

Cost-effectiveness analysis of inhaled corticosteroids in asthma: a review of the analytical standards

PURPOSE

To determine whether published cost-effectiveness studies on inhaled corticosteroids (ICS) in asthma adhered to basic analytical standards as defined in health economic textbooks and in guidelines assessing and comparing efficacy and safety.

METHODS

Original cost-effectiveness studies published between 1990 and 2000 in general medical or economic journals were reviewed to assess the adherence to five fundamental methodological principles: (1) design of the study, (2) choice of perspective and corresponding costs, (3) choice of outcome measure, (4) marginal cost analysis, and (5) sensitivity analysis and discussion about external validity. For each principle, the studies were ranked as high, medium or low quality.

RESULTS

Most of the 18 studies included were ranked medium on the first two principles. The studies adhered to a higher degree to the remaining three principles. Only three studies were high ranked in all five principles. The number of principles fulfilled increased over time. Studies comparing pharmaceutical products from competing companies were typically short-term studies, designed for other purposes than health economic analyses, and, in general, did not use therapeutically equivalent dosing.

CONCLUSIONS

Attention should be drawn to the study design, the weak correspondence between perspective and costs, and especially to the impact of bias in health economic results when comparing different doses of ICSs.