Design of dry powder inhalers to improve patient outcomes: it’s not just about the device

ABSTRACT

Introduction

Up to 50% of asthma/COPD patients make critical errors in dose preparation and dose inhalation with current marketed DPIs which negatively impact clinical outcomes. Others fail to adhere to their chronic treatment regimen.

Areas covered

For this review, we describe how a human-factors approach to design of a dry powder inhaler can be used to improve usability, proficiency, and functionality of DPIs, while effectively mitigating critical errors associated with DPIs. The review highlights the critical importance of utilizing improved formulations with monomodal aerodynamic particle size distributions to reduce variability associated with oropharyngeal filtering of particles, flow rate dependence, and co-formulation effects.

Expert opinion

Much of the variability in dose delivery with DPIs is associated with limitations of the bimodal APSDs inherent in current lactose blend formulations. Evidence supports that improved lung targeting and dose consistency can be achieved with drug-device combination products comprising spray-dried powders. Unfortunately, no data exists to assess whether these advances observed in in vitro and in vivo dose delivery studies will translate into improved clinical outcomes. Given the significant percentage of patients that receive suboptimal drug delivery with current DPIs it would behoove the industry to assess the efficacy of new approaches.

KEYWORDS:

• Asthma
• COPD
• dose inhalation errors
• dry powder inhaler
• human factors
• spray drying
• total lung dose

Article highlights

• Up to 50% of patients commit critical errors when using dry powder inhalers that lead to reduced disease control.

• Many other patients fail to adhere to their chronic treatment regimen.

• The present review discusses a human factors strategy around the design of dry powder inhalers that mitigate dose preparation, dose inhalation, and treatment adherence errors.

• To improve patient outcomes, it is critical that the formulation and device work in concert.

• Utilizing improved formulations that more effectively bypass drug deposition in the upper respiratory tract is deemed critical, as it improves lung targeting, reduces off-target adverse events and mitigates critical dose inhalation errors associated with oropharyngeal filtering of particles, variations in inspiratory pressure profile, and co-formulation effects.

• If key opinion leaders believe that clinical outcomes are impacted by critical errors in dose inhalation and treatment adherence, then there should be a strong motivation to assess the impact on patient outcomes for technologies that effectively mitigate these errors.

Declaration of interest

J Weers is an employee of cystetic Medicines, Inc. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Acknowledgments

The author thanks David Maltz, Mark Glusker and the Aspire design team for their collaboration and development of the Aspire DPI, and Danforth Miller for helpful suggestions in editing the manuscript.

Additional information

Funding

This paper was not funded.