title: Systemic bioavailability and potency of high-dose inhaled corticosteroids: a comparison of four inhaler devices and three drugs in healthy adult volunteers.
abstract: OBJECTIVE
  To compare the systemic bioavailability (assessed by cortisol suppression) of high-dose budesonide when given by four inhaler devices and orally. Also studied are the relative systemic potencies of three inhaled steroids (budesonide, fluticasone propionate, and beclomethasone dipropionate) when given by metered-dose inhaler (MDI) with a large volume spacer.
  
  
  METHODS
  Double-blind, crossover, placebo-controlled trial.
  
  
  METHODS
  Sixteen healthy, steroid-naive adult volunteers.
  
  
  METHODS
  On separate occasions, each subjects took 4 mg of budesonide through the following devices: MDI alone, MDI with 750-mL. spacer, dry-powder inhaler and nebulizer; 4 mg of budesonide was also taken orally to assess the effects of GI absorption. For the drug comparison, each subject took 4 mg of budesonide, fluticasone, and beclomethasone, and 2 mg of budesonide and fluticasone by MDI and spacer.
  
  
  RESULTS
  Greatest percent suppression (95% confidence interval) of 9:00 AM cortisol with budesonide was observed with MDI alone (73% [57 to 90]) and turbohaler (72% [58 to 86]) compared with MDI spacer (42% [22 to 64]) and oral administration (14% [+6- to -34]). Nebulized budesonide produced an insignificant rise in 9:00 AM cortisol level. The most suppressive drug (given by MDI spacer) was fluticasone at 4 mg (86% [82 to 91]) and at 2 mg (72% [59 to 85]). The least suppressive drug was budesonide at 4 mg (43% [22 to 64]) and at 2 mg (25% [3 to 47]). The effects of 4 mg of beclomethasone were intermediate (66% [49 to 82%]).
  
  
  CONCLUSIONS
  The choice of delivery device for administration of budesonide can lead to important differences in systemic bioavailability. Fluticasone has greater systemic potency than budesonide or beclomethasone when given at microgram equivalent dosage. The systemic potency ratio of fluticasone propionate to budesonide in normal human volunteers in the present study is similar to the therapeutic potency ratio of the drug in asthmatic patients (approximately 2:1).
authors.affiliation: Hope Hospital, Salford, UK.
authors.forename: D
authors.initials: D
authors.lastname: Wales
authors.forename: H
authors.initials: H
authors.lastname: Makker
authors.forename: J
authors.initials: J
authors.lastname: Kane
authors.forename: P
authors.initials: P
authors.lastname: McDowell
authors.forename: B R
authors.initials: BR
authors.lastname: O'Driscoll
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000730:Androstadienes / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000494:pharmacology; D018927:Anti-Asthmatic Agents / Q000008:administration & dosage* / Q000493:pharmacokinetics / Q000494:pharmacology; D001507:Beclomethasone / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000494:pharmacology; D001682:Biological Availability; D019819:Budesonide / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000494:pharmacology; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005260:Female; D000068298:Fluticasone; D005938:Glucocorticoids / Q000008:administration & dosage* / Q000493:pharmacokinetics / Q000494:pharmacology; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D008297:Male; D009330:Nebulizers and Vaporizers
chemical_list: D000730:Androstadienes; D018927:Anti-Asthmatic Agents; D005938:Glucocorticoids; D019819:Budesonide; D000068298:Fluticasone; D001507:Beclomethasone; D006854:Hydrocortisone