Kinetics of emitted mass—A study with three dry powder inhaler devices

• Published in: Chemical engineering science Vol. 66; no. 21; pp. 5284 - 5292
• Main Authors: Behara, Srinivas Ravindra Babu, Kippax, Paul, Larson, Ian, Morton, David A.V., Stewart, Peter
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01-11-2011; Elsevier
• Subjects: Aerosol concentration; Aerosols; Air flow; Applied sciences; Chemical engineering; Devices; Dry powder inhaler device; Drying; Emittance; Emitted mass; Exact sciences and technology; Inhalers; Kinetics; Laser diffraction; Non-linear regression modelling; Sulfates; HH; II; SS; BERM; DH; k CCEM; Dry powder inhaler device; TPC; LH300; EM; Non-linear regression modelling; AL; Emitted mass; Aerosol concentration; RH; CCEM; MERM; Laser diffraction; AIC; Kinetics; DPI; MI; Non linear regression; Real time; Modeling; Real time system; Powder; Air flow; Laser; Aerosols; Particle size measurement; Sizing
• ISSN: 0009-2509; 1873-4405
• DOI: 10.1016/j.ces.2011.07.029

The purpose of this study was to understand the kinetics of emptying of micronised salbutamol sulphate (SS) and lactohale 300 (LH300) under varying air flow rates (30–180
L
min
−1) from three dry powder inhaler devices, Rotahaler
® (RH), Monodose Inhaler
® (MI) and Handihaler
® (HH). Aerosol concentration
vs. time profiles, determined through real-time laser diffraction particle sizing, demonstrated that the majority of the powder from RH was emitted within one second while a more prolonged aerosolisation was observed from MI and HH. Peak aerosol concentrations were achieved more rapidly from RH compared to MI for both SS and LH300. Calculated cumulative emitted mass (CCEM)
vs. time profiles were obtained from the aerosol concentration
vs. time profiles and the emitted mass and the rate of CCEM (
k
CCEM
), estimated from a modelling approach, increased with increasing air flow rates. The
k
CCEM
vs. air flow rate profiles of SS and LH300 were significantly different at high air flow rates. The
k
CCEM
was highest from RH and lowest from MI. Differences in
k
CCEM
between the devices were related to capsule aperture size while the differences between the materials were due to the powder bed structure. This approach provided an understanding of the rate at which powder mass emptied from dry powder inhaler devices and was proposed to be a powerful development tool for the future powder inhalers.
► Novel laser diffraction approach to study powder emptying from inhalation devices. ► Non-linear least squares modelling and estimation of powder emptying rate constants. ► Comparative emptying rate constants and variability consistent with device mechanism. ► Emptying rate constants influenced by air flow rate within devices.