Dry powder inhalation, part 2: the present and future

ABSTRACT

Introduction

The manufacture of modern dry powder inhalers (DPIs), starting with the Spinhaler (Fisons) in 1967, was only possible thanks to a series of technological developments in the 20^th century, of which many started first around 1950. Not until then, it became possible to design and develop effective, cheap and mass-produced DPIs. The link between these technological developments and DPI development has never been presented and discussed before in reviews about the past and present of DPI technology.

Areas covered

The diversity of currently used DPIs with single dose, multiple-unit dose and multi-dose DPIs is discussed, including the benefits and drawbacks of this diversity for correct use and the efficacy of the therapy. No specific databases or search engines otherwise than PubMed and Google have been used.

Expert opinion

Considering the relatively poor efficacy regarding lung deposition of currently used DPIs, the high rates of incorrect inhaler use and inhalation errors and the poor adherence to the therapy with inhalers, much effort must be put in improving these shortcomings for future DPI designs. Delivered fine particle doses must be increased, correct inhaler handling must become more intuitive and simpler to perform, and the use of multiple inhalers must be avoided.

KEYWORDS:

• Adherence
• capsule DPI
• carbon foot print
• compliance
• dry powder inhaler
• lactose
• Multi-dose reservoir DPI

Article highlights

• The present of dry powder inhalation started in the late 1960s with the invention of the capsule-based Fisons Spinhaler

• In a very short period of 20 years DPIs diversified into three different categories of capsule, multiple unit-dose and multi-dose reservoir inhalers and nearly all developed concepts from this pioneer period (approx. 1970–1990) are currently still in use

• Similar as from MDIs and nebulizers, but for different reasons, only a part of the dose from DPIs reaches the site of action. Hence, dry powder inhalation still has a great potential for improvement

• The compliance with the instructions for correct DPI use and good adherence to the therapy should challenge designers of future DPIs to make incorrect use more difficult and inhaler performance more robust

• The environmental impact of inhalation is currently under discussion, but device designers should watch out for making wrong decisions in DPI design to reduce their rather insignificant carbon footprint

Acknowledgments

The authors thank Dr. Karlheinz Seyfang and Dr. Marco Laackmann from Harro Hoefliger, Germany for their valuable information and interesting discussions about DPI (capsule and cartridge) filling and assembling.

Declaration of interest

The employer (University of Groningen, the Netherlands) of AH de Boer, P Hagedoorn and F Grasmeijer receives royalties from the sales of the Genuair and Cyclops^TM dry powder inhalers. The employer (PureIMS, Roden, the Netherlands) of F Grasmeijer is the manufacturer of the Cyclops^TM dry powder inhaler. 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.

Additional information

Funding

This paper was not funded.