Inspiratory flow profile and usability of the NEXThaler, a multidose dry powder inhaler, in asthma and COPD

Background

Inhaler selection is important when managing respiratory conditions; a patient’s inhalation technique should be appropriate for the selected device, and patients should ideally be able to use a device successfully regardless of disease severity. The NEXThaler is a multidose dry-powder inhaler with a breath-actuated mechanism (BAM) and dose counter that activates only following inhalation, so effectively an ‘inhalation counter’. We assessed inspiratory flow through the NEXThaler in two studies and examined whether inhalation triggered the BAM.

Methods

The two studies were open-label, single-arm, and single visit. One study recruited patients with asthma aged ≥ 18 years; the other recruited patients with chronic obstructive pulmonary disease (COPD) aged ≥ 40 years. All patients inhaled twice through a placebo NEXThaler. The inspiratory profile through the device was assessed for each inhalation using acoustic monitoring, with flow at and time to BAM firing, peak inspiratory flow (PIF), and total inhalation time assessed.

Results

A total of 40 patients were enrolled in the asthma study: 20 with controlled asthma and 20 with partly controlled/uncontrolled asthma. All patients were able to trigger the BAM, as evidenced by the inhalation counter activating on closing the device. Mean flow at BAM firing following first inhalation was 35.0 (range 16.3–52.3) L/min; mean PIF was 64.6 (35.0–123.9) L/min. A total of 72 patients were enrolled in the COPD study, with data analysed for 69 (mean forced expiratory volume in 1 s 48.7% predicted [17–92%]). As with the asthma study, all patients, regardless of airflow limitation, were able to trigger the BAM. Mean flow at BAM firing following first inhalation was 41.9 (26.6–57.1) L/min; mean PIF was 68.0 (31.5–125.4) L/min. Device usability was rated highly in both studies, with 5 min sufficient to train the patients, and a click heard shortly after inhalation in all cases (providing feedback on BAM firing).

Conclusions

Inhalation flows triggering the BAM in the NEXThaler were similar between patients with controlled and partly controlled/uncontrolled asthma, and were similar across COPD airflow limitation. All enrolled patients were able to activate the device.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-021-01430-9.

Experimental and computational study of the effect of breath-actuated mechanism built in the NEXThaler® dry powder inhaler

The breath-actuated mechanism (BAM) is a mechanical unit included in NEXThaler^® with the role of delaying the emission of the drug until the inhalation flow rate of the patient is sufficiently high to detach the drug particles from their carriers. The main objective of this work was to analyse the effect of the presence of BAM on the size distribution of the emitted drug and its airway deposition efficiency and distribution. Study of the hygroscopic growth of the emitted drug particles and its effect on the deposition was another goal of this study. Size distributions of Foster^® NEXThaler^® drug particles emitted by dry powder inhalers with and without BAM have been measured by a Next Generation Impactor. Three characteristic inhalation profiles of asthmatic patients (low, moderate and high flow rates) were used for both experimental and modelling purposes. Particle hygroscopic growth was determined by a new method, where experimental measurements are combined with simulations. Upper airway and lung deposition fractions were computed assuming 5s and 10s breath-hold times. By the inclusion of BAM the fine particle fraction of the steroid component increased from 24 to 30% to 47-51%, while that of bronchodilator from 25-34% to 52-55%. The predicted upper airway steroid and bronchodilator doses decreased from about 60% to 35-40% due to BAM. At the same time, predicted lung doses increased from about 20%-35% (steroid) and from 22% to 38% (bronchodilator) for the moderate flow profile and from about 25% to 40% (steroid) and from 29% to 47% (bronchodilator) for the high inhalation flow profile. Although BDP and FF upper airway doses decreased by a factor of about two when BAM was present, lung doses of both components were about the same in the BAM and no-BAM configurations at the weakest flow profile. However, lung dose increased by 2-3% even for this profile when hygroscopic growth was taken into account. In conclusion, the NEXThaler^® BAM mechanism is a unique feature enabling high emitted fine particle fraction and enhanced drug delivery to the lungs.