Peak inspiratory flow rates generated through the Novolizer and the Turbuhaler dry powder inhaler devices by children with stable asthma

The Confusing World of Dry Powder Inhalers: It Is All About Inspiratory Pressures, Not Inspiratory Flow Rates

Dry powder inhalers (DPIs) all have the ability to aerosolize dry powders, but they each offer different operating mechanisms and resistances to inhaled airflow. This variety has resulted in both clinician and patient confusion concerning DPI performance, use, and effectiveness. Particularly, there is a growing misconception that a single peak inspiratory flow rate (PIFR) can determine a patient's ability to use a DPI effectively, regardless of its design or airflow resistance. For this review article, we have sifted through the relevant literature concerning DPIs, inspiratory pressures, and inspiratory flow rates to provide a comprehensive and concise discussion and recommendations for DPI use. We ultimately clarify that the controlling parameter for DPI performance is not the PIFR but the negative pressure generated by the patient's inspiratory effort. A pressure drop ∼≥1 kPa (∼10 cm H2O) with any DPI is a reasonable threshold above which a patient should receive an adequate lung dose. Overall, we explore the underlying factors controlling inspiratory pressures, flow rates and dispensing, and dispersion characteristics of the various DPIs to clarify that inspiratory pressures, not flow rates, limit and control a patient's ability to generate sufficient flow for effective DPI use.

What to consider before prescribing inhaled medications: a pragmatic approach for evaluating the current inhaler landscape

Inhaled therapies are the cornerstone of treatment in asthma and chronic obstructive pulmonary disease, and there are a multitude of devices available. There is, however, a distinct lack of evidence-based guidance for healthcare providers on how to choose an appropriate inhaler. This review aims to summarise recent updates on topics related to inhaler choice, and to offer practical considerations for healthcare providers regarding currently marketed devices. The importance of choosing the right inhaler for the right patient is discussed, and the relative merits of dry powder inhalers, pressurised metered dose inhalers, breath-actuated pressurised metered dose inhalers, spacers and soft mist inhalers are considered. Compiling the latest studies in the devices therapy area, this review focuses on the most common types of handling errors, as well as the comparative rates of incorrect inhalation technique between devices. The impact of device-specific handling errors on inhaler performance is also discussed, and the characteristics that can impair optimal drug delivery, such as inhalation flow rate, inhalation volume and particle size, are compared between devices. The impact of patient perceptions, behaviours and problems with inhalation technique is analysed, and the need for appropriate patient education is also highlighted. The continued development of technology in inhaler design and the need to standardise study assessment, endpoints and patient populations are identified as future research needs. The reviews of this paper are available via the supplemental material section.

The Impact of Inspiratory Flow Rate on Drug Delivery to the Lungs with Dry Powder Inhalers

Current marketed dry powder inhalers utilize the energy from patient inspiration to fluidize and disperse bulk powder agglomerates into respirable particles. Variations in patient inspiratory flow profiles can lead to marked differences in total lung dose (TLD), and ultimately patient outcomes for an inhaled therapeutic. The present review aims to quantitate the flow rate dependence in TLD observed for a number of drug/device combinations using a new metric termed the Q index. With this data in hand, the review explores key attributes in the design of the formulation and device that impact flow rate dependence. The review also proposes alternative in vitro methods to assess flow rate dependence that more closely align with in vivo observations. Finally, the impact of variations in flow rate on lung function for inhaled bronchodilators is summarized.

Assessing the performance of two dry powder inhalers in preschool children using an idealized pediatric upper airway model

High prevalence of pulmonary diseases in childhood requires inhalable medication even for young children. Little is known about the efficiency of aerosol therapy especially in preschool children. One factor which limits the lung dose is the upper airway geometry. Based on clinical data a recently developed idealized pediatric upper airway model (children 4-5 years) was used to investigate the performance of two dry powder inhalers (Easyhaler and Novolizer). In vitro investigations were first examined using steady flow rates and an inhalation volume of 1L. Chosen flow rates were 28, 41 and 60L/min (Easyhaler) and 45, 60 and 75L/min (Novolizer). Afterwards inhalation profiles simulated by an electronic lung were included. The investigations showed high amounts of drug particles (up to 80%) which were deposited in the upper airway model. The pulmonary deposition in vitro using the Easyhaler was about 28% (28-60L/min) and 22% (inhalation profile). Using the Novolizer in vitro pulmonary doses of 8-12% (45-75L/min) and about 5% (inhalation profile) were observed. The idealized model shows good performance reproducibility of dry powder inhalers. We have shown that age-dependent models might be appropriate tools for formulation and device development in pediatric age groups.

Efficacy and safety of two dry-powder inhalers for the administration of mometasone furoate in asthma patients

OBJECTIVE

Mometasone furoate (MF) is a new, potent synthetic inhaled corticosteroid. Worldwide, MF is administered via a dry-powder inhaler that contains multiple doses. As a preparation that would be more cost-effective, single-dose MF capsules were developed in Brazil. The objective of the present study was to evaluate the efficacy and safety of the two inhalers for MF administration in patients with asthma.

METHODS

A randomized, multicenter, open-label, parallel-group clinical trial involving 74 adult patients with moderate, persistent asthma who were randomized into two groups to receive approximately 400 µg of MF once a day for 60 days, either via the multiple-dose inhaler or via the newly developed single-dose inhaler.

RESULTS

No significant differences were observed between the two groups regarding the primary endpoints (FEV1 and rescue medication use) or the secondary endpoints (morning PEF, tolerability, and safety, the last as assessed on the basis of hypothalamic-pituitary-adrenal axis function).

CONCLUSIONS

The use of the single-dose inhaler developed in Brazil for MF administration is as effective and safe as is that of a standard inhaler in the treatment of patients with asthma.