title: Rational design of a dry powder inhaler: device design and optimisation.
abstract: OBJECTIVE
  As part of the development of a dry powder inhalation system for the treatment of asthma and chronic obstructive pulmonary disease, this work specifically aimed at the systematic, however, cost-effective and efficient development of an inhalation device.
  
  
  METHODS
  Based on theoretical design considerations and an initial inhaler prototype, the concept of a modular inhaler was developed. The modular inhaler was used for the systematic evaluation of the influence of the inhaler's inner dimensions on the resistance to the air flow and the in-vitro deposition characteristics of the inhalation system by using statistical design of experiments and cascade impaction analysis.
  
  
  RESULTS
  A reliable statistical model enabled the accurate prediction of the device resistance of any combination of inner dimensions of the inhaler. In conjunction with results from in-vitro deposition studies, this allowed for the definition of optimised inner dimensions of the inhaler to maximise the fine particle fraction and minimise oropharyngeal deposition within the desired range of the inhaler's resistance to air flow.
  
  
  CONCLUSIONS
  The concept of the modular inhaler and statistical design and evaluation of experiments proved to be important tools for an efficient and successful product development. Eventually, the approaches described and the knowledge obtained enabled the cost-effective development and design of a technically feasible and competitive dry powder inhaler.
authors.affiliation: Welding GmbH & Co. KG, Hamburg, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Friebel
authors.forename: Hartwig
authors.initials: H
authors.lastname: Steckel
authors.forename: Bernd W
authors.initials: BW
authors.lastname: Müller
mesh_terms: D000280:Administration, Inhalation; D001993:Bronchodilator Agents / Q000008:administration & dosage / Q000737:chemistry; D019819:Budesonide / Q000008:administration & dosage / Q000737:chemistry; D002214:Capsules; D017046:Cost Savings; D016503:Drug Delivery Systems / Q000295:instrumentation; D058995:Dry Powder Inhalers / Q000191:economics; D004867:Equipment Design; D005240:Feasibility Studies; D006801:Humans; D008422:Materials Testing; D015233:Models, Statistical; D013678:Technology, Pharmaceutical
chemical_list: D001993:Bronchodilator Agents; D002214:Capsules; D019819:Budesonide