title: The dispersion behaviour of dry powder inhalation formulations cannot be assessed at a single inhalation flow rate.
abstract: The dispersion performances of inhalation powders are often tested at only one inhalation flow rate in mechanistic formulation studies. This limited approach is challenged by studies showing that interactions exist between inhalation flow rate and the effects on dispersion performance of several formulation variables. In this note we explain that such interactions with inhalation flow rate are, in fact, always to be expected. Because these interactions may greatly affect conclusions concerning the effects of formulation variables and their underlying mechanisms, the utility of future dry powder inhalation formulation studies may benefit from an approach in which dispersion performance is by default tested over a range of inhalation flow rates.
authors.affiliation: Department of Pharmaceutical Technology and Biopharmacy, University of Groningen, Groningen, The Netherlands. Electronic address: f.grasmeijer@rug.nl.
authors.forename: Floris
authors.initials: F
authors.lastname: Grasmeijer
authors.affiliation: Department of Pharmaceutical Technology and Biopharmacy, University of Groningen, Groningen, The Netherlands. Electronic address: a.h.de.boer@rug.nl.
authors.forename: Anne H
authors.initials: AH
authors.lastname: de Boer
mesh_terms: D000280:Administration, Inhalation; D000336:Aerosols; D002626:Chemistry, Pharmaceutical; D016503:Drug Delivery Systems / Q000295:instrumentation*; D058995:Dry Powder Inhalers; D008956:Models, Chemical; D004364:Pharmaceutical Preparations / Q000008:administration & dosage / Q000737:chemistry*; D011208:Powders; D012212:Rheology; D013678:Technology, Pharmaceutical / Q000379:methods; D013997:Time Factors
chemical_list: D000336:Aerosols; D004364:Pharmaceutical Preparations; D011208:Powders
keywords: Adhesive mixture; Cohesive mixture; Dispersibility; Energy ratio; Energy ratio distribution