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. 2014 Feb;31(2):360-72.
doi: 10.1007/s11095-013-1165-6. Epub 2013 Aug 16.

Development of a high efficiency dry powder inhaler: effects of capsule chamber design and inhaler surface modifications

Srinivas R B Behara  1 , Dale R Farkas, Michael Hindle, P Worth Longest
Affiliations

Development of a high efficiency dry powder inhaler: effects of capsule chamber design and inhaler surface modifications

Srinivas R B Behara et al. Pharm Res. 2014 Feb.

Abstract

Purpose: The objective of this study was to explore the performance of a high efficiency dry powder inhaler (DPI) intended for excipient enhanced growth (EEG) aerosol delivery based on changes to the capsule orientation and surface modifications of the capsule and device.

Methods: DPIs were constructed by combining newly designed capsule chambers (CC) with a previously developed three-dimensional (3D) rod array for particle deagglomeration and a previously optimized EEG formulation. The new CCs oriented the capsule perpendicular to the incoming airflow and were analyzed for different air inlets at a constant pressure drop across the device. Modifications to the inhaler and capsule surfaces included use of metal dispersion rods and surface coatings. Aerosolization performance of the new DPIs was evaluated and compared with commercial devices.

Results: The proposed capsule orientation and motion pattern increased capsule vibrational frequency and reduced the aerosol MMAD compared with commercial/modified DPIs. The use of metal rods in the 3D array further improved inhaler performance. Coating the inhaler and capsule with PTFE significantly increased emitted dose (ED) from the optimized DPI.

Conclusions: High efficiency performance is achieved for EEG delivery with the optimized DPI device and formulation combination producing an aerosol with MMAD < 1.5 μm, FPF<5 μm/ED > 90%, and ED > 80%.

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Figures

Fig. 1
Fig. 1
Images of the CC1-3D inhaler including (a) surface model of the composite device with an internal 3D rod array, (b) an opened device for capsule loading with a size 3 capsule, and (c) the prototyped device for experimental testing. Panel (b) illustrates the device separated at the interface between the capsule chamber (CC) analyzed in this study and the previously optimized downstream flow passage (mouthpiece) and 3D rod array.
Fig. 2
Fig. 2
Images of the capsule chambers: (a) top view with dimensions and a size 3 capsule in place, (b) side view illustrating height of all capsule chambers, and (c) capsule aperture position on the capsule. Air inlet holes differentiate the capsule chambers considered with (d) 2 inline inlets (CC1), (e) 2 inlets staggered by 1.65 mm (CC5), and (f) one central inlet (CC6).
Fig. 3
Fig. 3
Still images of capsule motion in the chambers showing an approximate neutral position, maximum clockwise and counterclockwise rocking at a 4 kPa pressure drop using CC-3D inhalers with capsules chambers CC1, CC2 and CC3.
Fig. 4
Fig. 4
Number of capsule-wall impactions per second for two air inlets and different inlet hole offset distances. Cases considered were CC1 (offset from central axis: 0 mm), CC2 (offset from central axis: 0.4125 mm) and CC3 (offset from central axis: 0.825 mm).
Fig. 5
Fig. 5
Comparison of aerosolization performance [n=3; Mean (SD)] of CC1-3Dm-PTFE with commercial and modified powder inhaler devices (batch 2 powders). (a) Percent albuterol sulphate as a function of device and capsule retentions, (b) fine particle fractions less than 5 and 1 µm, and (c) mass median aerodynamic diameters.
See this image and copyright information in PMC

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