title: Systemic bioavailability of hydrofluoroalkane (HFA) formulations of fluticasone/salmeterol in healthy volunteers via pMDI alone and spacer.
abstract: OBJECTIVE
  To compare a test version of HFA fluticasone/salmeterol (FP/SM) combination inhaler (Neolab, UK) with the reference product Seretide (GlaxoSmithKline, UK).
  
  
  METHODS
  An in vitro Anderson cascade impactor was used to compare the fine particle dose (<4.7 microm). Two separate randomized cross-over studies were performed to compare the systemic bioavailability of test vs. reference (T vs. R) formulations of FP/SM 250/25 microg pMDI in healthy volunteers. In study 1 blood pharmacokinetic analysis using oral charcoal block was performed over 24 h following a single dose of four puffs via pMDI alone. In study 2 systemic bioactivity was measured following single doses of four and eight puffs via a spacer device: serum potassium (K(+)) to reflect SM, and overnight urinary cortisol : creatinine (OUCC) for FP. An early pharmacokinetic profile was also assessed over 120 min.
  
  
  RESULTS
  The in vitro fine particle dose was similar for test vs. reference pMDI alone and via spacer. The results of both studies were consistent: No significant differences between formulations were seen in terms of FP kinetics. Analysis of SM kinetics revealed superiority of the test product. No significant dose-response or difference in T : R ratio was noted for OUCC. Fall in K(+) revealed a significant dose-response with a non-significant T : R ratio.
  
  
  CONCLUSIONS
  The in vitro fine particle dose may not predict pharmacokinetic and systemic pharmacodynamic outcomes. Single dosing studies with fluticasone/salmeterol 250/25 microg via pMDI or with spacer showed pharmacokinetic equivalence with FP, but not SM. No significant difference between formulations was seen with either adrenal suppression or hypokalaemia.
authors.affiliation: Asthma and Allergy Research Group, Division of Medical Sciences, Ninewells Hospital & Medical School, University of Dundee, DD1 9SY, UK.
authors.forename: Karine L
authors.initials: KL
authors.lastname: Clearie
authors.forename: Peter A
authors.initials: PA
authors.lastname: Williamson
authors.forename: Sriram
authors.initials: S
authors.lastname: Vaidyanathan
authors.forename: Jeannine
authors.initials: J
authors.lastname: Du Bois
authors.forename: Haylene
authors.initials: H
authors.lastname: Nell
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Lipworth
mesh_terms: D000280:Administration, Inhalation; D000328:Adult; D000420:Albuterol / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D000730:Androstadienes / Q000008:administration & dosage / Q000493:pharmacokinetics*; D018927:Anti-Asthmatic Agents / Q000008:administration & dosage / Q000493:pharmacokinetics*; D019540:Area Under Curve; D001682:Biological Availability; D003404:Creatinine / Q000652:urine; D018592:Cross-Over Studies; D004338:Drug Combinations; D005260:Female; D000068297:Fluticasone-Salmeterol Drug Combination; D005938:Glucocorticoids / Q000008:administration & dosage / Q000493:pharmacokinetics*; D006801:Humans; D006845:Hydrocarbons, Fluorinated; D006854:Hydrocortisone / Q000652:urine; D008297:Male; D036501:Metered Dose Inhalers; D011188:Potassium / Q000097:blood; D055815:Young Adult
chemical_list: D000730:Androstadienes; D018927:Anti-Asthmatic Agents; D004338:Drug Combinations; D000068297:Fluticasone-Salmeterol Drug Combination; D005938:Glucocorticoids; D006845:Hydrocarbons, Fluorinated; D003404:Creatinine; D000420:Albuterol; D011188:Potassium; D006854:Hydrocortisone