Discriminating measures of bronchodilator drug efficacy and potency

Equivalent bronchodilation with budesonide/formoterol combination via Easyhaler and Turbuhaler in patients with asthma

BACKGROUND

Therapeutic equivalence of Budesonide/formoterol Easyhaler compared to Symbicort Turbuhaler has been previously demonstrated with in vitro and pharmacokinetic studies. This study was performed to confirm equivalent bronchodilator efficacy of the products in asthmatic patients.

METHODS

A randomised, single-dose, 4-period crossover study was carried out in a double-blind, double-dummy manner in 11 study sites. The studied doses were 320/9 μg and 1280/36 μg of budesonide/formoterol delivered by Easyhaler and Turbuhaler. Spirometry was performed before and 10 min, 20 min and 1, 2, 3, 4, 6, 8, 10 and 12 h after administration of the study treatments. The primary efficacy endpoint was average 12-h forced expiratory volume in 1 s (FEV₁). The secondary efficacy endpoints were maximum FEV₁ and FEV₁ at 12 h post-dose.

RESULTS

72 asthma patients with reversible airway obstruction were randomised to receive study treatments. 53 patients completed all study periods according to the protocol and had sufficient data available to calculate the primary endpoint. They were included in the per-protocol analyses. The assay sensitivity of the study was shown as the common slope of average 12-h FEV₁ between doses was 0.063 (95% CI 0.032-0.093) and showed statistical significance (p < 0.001). In equivalence testing, the difference in average 12-h FEV₁ between the treatments (Easyhaler-Turbuhaler) was 0.013 l at the lower dose and -0.028 l at the higher dose, and their 95% confidence intervals (CIs) (-0.047 to 0.073 and -0.087 to 0.032, respectively) fell within the range of a clinically non-relevant difference. The results of the secondary efficacy endpoints were in line with the results of the primary endpoint. All treatments were well tolerated.

CONCLUSIONS

The results confirm equivalent bronchodilator efficacy of Budesonide/formoterol Easyhaler compared to Symbicort Turbuhaler.

TRIAL REGISTRATION

This trial was registered on ClinicalTrials.gov, Identifier: NCT02308098.

Dyspnea perception and reversibility of methacholine-induced unlimited airway narrowing in asthmatics

The hypothesis was that asthmatics might experience impaired perception of dyspnea and salbutamol-induced reversibility during unlimited airway narrowing. A total of 38 asthmatics (18 to 59 years of age) were examined. All patients underwent the methacholine challenge test. According to the dose-response curve to methacholine, they were categorized as having either unlimited airway narrowing (UAN group) (n = 20) or response plateau (RP group) (n = 18). Reversibility of methacholine-induced bronchoconstriction was measured 20 minutes after the inhalation of 400 microg of salbutamol to compare postbronchodilator FEV1 with baseline FEV1. Dyspnea perception was evaluated using the Borg Scale to calculate a perception score at a 20% decrease in FEV1 (PS20) and the slope alpha of the regression line between the changes in Borg scores and the reduction in FEV1 as percentage of the baseline value. Subjects in the UAN group exhibited significantly lower PS20 compared with the RP group (1.45+/- 0.23 vs. 2.84 +/- 0.35, p = 0.002); the mean of the slope values was higher in the RP group than it was in the UAN group (0.150 +/- 0.015 vs. 0.095 +/- 0.006, p = 0.003). Salbutamol-induced reversibility was significantly lower in the UAN group (81 +/- 1.4 % of baseline FEV1) compared with patients from the RP group (91 +/- 1.1% of baseline FEV1; p < 0.001). In conclusion, asthmatics during methacholine-induced unlimited airway narrowing exhibit diminished perception of dyspnea and lower bronchial reversibility to the baseline 20 minutes after inhalation of salbutamol. This suggests that more careful monitoring of the lung function for timely recognition of asthma deteriorations and adequate bronchodilatory therapy during severe acute attacks should be recommended for such patients.

Evidence based guidelines--a step too far?

The growth of clinical guidelines has helped to improve the standard of patient care with the archetypal document being the British Thoracic Society's guidelines on asthma management. In recent years however the fashion has evolved to style guidelines according to the tenants of 'evidence based medicine'. We examine the evidence behind this fashion and conclude that there is a grave danger of bias and distortion of the data from this approach.

The inhalers of the future? A review of dry powder devices on the market today

International agreements to ban the use of environmentally damaging chlorofluorocarbons (CFCs) have signalled an end to the traditional CFC-propelled pressurised metered dose inhaler (pMDI) which has long been the mainstay of topical asthma therapy. The need for acceptable and cost-effective replacement inhalers, combined with opportunities to develop generic formulations of patent-expired drugs, has fueled a lively response from the pharmaceutical industry. Improvements in pMDI design and reformulation with propellants such as hydrofluoroalkanes may offer significant advantages over CFC-pMDIs and prolong the widespread use of pressurised drug delivery systems for many years to come. In the longer term, however, another likely candidate for success in providing economical, efficient and acceptable inhaled therapies is the breath-actuated, multiple-dose dry powder inhaler (DPI). This review concentrates on the multiple-dose DPIs available within Europe today.