title: Clinical effect of Diskus dry-powder inhaler at low and high inspiratory flow-rates in asthmatic children.
abstract: In vitro studies with the Diskus inhaler at low and high flow rates show consistent doses of drug as fine particles <4.7 microm. The present study was designed to ascertain whether this in vitro flow independency translates into flow-independent clinical effect when the device is used by patients at low (30 L x min[-1]) and high (90 L x min[-1]) flow rates. A pilot study in 129 children aged 3-10 yrs demonstrated that 99% of children of 3 yrs and above can generate a flow > or = 30 L x min(-1) through the device, while 26% performed > or = 90 L x min(-1). Eighteen children aged 8-15 yrs with exercise induced asthma inhaled placebo or salmeterol 50 microg at either 30 L x min(-1) or 90 L x min(-1). Exercise challenges were carried out 1 h and 12 h after dosing. The maximum percentage fall in forced expiratory volume in one second (FEVI) after exercise 12 h after treatment was significantly less after salmeterol at either flow rates as compared to placebo. There was no significant difference in the protection from salmeterol on the day of low-flow inhalation versus the day of high-flow inhalation. Consistent in vitro fine particle dosing from the Diskus inhaler translates into a consistent clinical effect at low and high flow rates in children.
authors.affiliation: Dept of Paediatrics, National University Hospital, Copenhagen, Denmark.
authors.forename: K G
authors.initials: KG
authors.lastname: Nielsen
authors.forename: I L
authors.initials: IL
authors.lastname: Auk
authors.forename: K
authors.initials: K
authors.lastname: Bojsen
authors.forename: M
authors.initials: M
authors.lastname: Ifversen
authors.forename: B
authors.initials: B
authors.lastname: Klug
authors.forename: H
authors.initials: H
authors.lastname: Bisgaard
mesh_terms: D000293:Adolescent; D000420:Albuterol / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000627:therapeutic use; D001250:Asthma, Exercise-Induced / Q000188:drug therapy* / Q000503:physiopathology*; D016084:Bronchoconstriction / Q000187:drug effects / Q000502:physiology; D001993:Bronchodilator Agents / Q000008:administration & dosage / Q000627:therapeutic use; D002648:Child; D018592:Cross-Over Studies; D004311:Double-Blind Method; D015444:Exercise; D005260:Female; D005541:Forced Expiratory Volume / Q000502:physiology; D006801:Humans; D008297:Male; D009330:Nebulizers and Vaporizers; D011208:Powders; D012123:Pulmonary Ventilation / Q000502:physiology*; D000068299:Salmeterol Xinafoate
chemical_list: D001993:Bronchodilator Agents; D011208:Powders; D000068299:Salmeterol Xinafoate; D000420:Albuterol