title: The kinetics of cohesive powder de-agglomeration from three inhaler devices.
abstract: OBJECTIVE
  The purpose of the current investigation is to understand the kinetics of de-agglomeration (k(d)) of micronised salbutamol sulphate (SS) and lactohale 300 (LH300) under varying air flow rates (30-180l min(-1)) from three dry powder inhaler devices (DPIs), Rotahaler (RH), Monodose Inhaler (MI) and Handihaler (HH).
  
  
  RESULTS
  Cumulative fine particle mass vs. time profiles were obtained from the powder concentration, emitted mass and volume percent <5.4 μm, embedded in the particle size distributions of the aerosol at specific times. The rate of de-agglomeration (k(d)), estimated from non-linear least squares modelling, increased with increasing air flow rates. The k(d)vs. air flow rate profiles of SS and LH300 were significantly different at high air flow rates. The k(d) was highest from RH and lowest from MI. Differences in k(d) between the devices were related to device mode of operation while the differences between the materials were due to the powder bed structure.
  
  
  CONCLUSIONS
  This approach provided a methodology to measure the rate constant for cohesive powder de-agglomeration following aerosolisation from commercial devices and an initial understanding of the influence of device, air flow rate and material on these rate constants.
authors.affiliation: Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, Victoria 3052, Australia.
authors.forename: Srinivas Ravindra Babu
authors.initials: SR
authors.lastname: Behara
authors.forename: Ian
authors.initials: I
authors.lastname: Larson
authors.forename: Paul
authors.initials: P
authors.lastname: Kippax
authors.forename: David A V
authors.initials: DA
authors.lastname: Morton
authors.forename: Peter
authors.initials: P
authors.lastname: Stewart
mesh_terms: D000336:Aerosols; D000392:Air Movements; D000420:Albuterol / Q000737:chemistry; D007700:Kinetics; D009330:Nebulizers and Vaporizers; D010316:Particle Size; D011208:Powders / Q000737:chemistry*
chemical_list: D000336:Aerosols; D011208:Powders; D000420:Albuterol