Investigation of Design Features on the Performance of 3D-Printed Dry Powder Inhalers.
Part 2: swirl pipe design
Yuqing Ye1,2, Ziyi Fan1, Ying Ma1,2 & Jesse Zhu*1
1Western University, 1151 Richmond Street, London, N6A 3K7, Canada
2Suzhou Inhal Pharma Co., Ltd., 502-Bldf A SIP, 108 Yuxi Road, Suzhou, 215125, China
*Corresponding author: Dr. Jesse Zhu; E-mail address: jzhu@uwo.ca
Summary
Inhaled therapy has undergone a rapid expansion in dry powder inhalers (DPIs) in the past fifty years to treat pulmonary diseases. Despite their popularity, the development of DPIs has been constricted by low and inconsistent pulmonary drug delivery efficiency as well as significant drug loss in the mouth-throat region. Inhaler design has been a crucial player in powder dispersion and aerosolization. To improve the inhaler performance, swirl pipe designs with different diameters (3, 6, 9 mm) were introduced and incorporated into the mouthpiece of a capsule-based inhaler, and then evaluated by experimental analysis and numerical analysis using a carrier-based formulation. The results illustrate that the swirl pipe design can promote drug-carrier separation by introducing strong turbulent flow. Such “promotion” is much more prominent in the narrower swirl pipe (3 mm). However, the API retention in the device is remarkably high, up to 40%, which is likely due to the sudden configuration transition and particle-wall impaction as well. Therefore, the aerosolization performance of the inhaler with the swirl pipe design is compromised with undesirable results. Summarily, the swirl pipe design has the capability of increasing drug-carrier separation but generates high drug retention in the device. Further modifications to the swirl pipe design will be made to improve its aerosolization performance.
Key Message
Swirl pipe design can decrease drug deposition in the pre-separator (mouth-throat region) by promoting separation between API and carrier particles yet produce undesirably high drug retention in the inhaler with narrower swirl pipe and therefore a compromised aerosolization performance, which is likely due to the rapid configuration transition and high particle-wall impaction.