title: Nasal absorption of hydroxocobalamin in healthy elderly adults.
abstract: OBJECTIVE
  To investigate the nasal absorption of hydroxocobalamin in 10 healthy elderly adults.
  
  
  METHODS
  In a cross-over study, blood samples were collected before administration of the drug and after 10, 20, 30, 40, 60, 120, 180 and 240 min. The plasma cobalamin concentration was determined by competitive radioisotope binding technique.
  
  
  RESULTS
  The maximal plasma cobalamin concentration (Cmax) after nasal administration of 750 microg hydroxocobalamin was 1900 +/- 900 pmol l(-1) (mean +/- s.d.). The maximal plasma cobalamin concentration was reached in 35 +/- 13 min (t[max]). The Cmax after nasal administration of 1500 microg hydroxocobalamin was 3500 +/- 2500 pmol l(-1) with a t(max) of 28 +/- 16 min. Both the AUC(0,240 min) and AUC(0,00) increased significantly with an increase of the dose from 750 microg to 1500 microg (P = 0.037 and P = 0.028, respectively). The nasal spray was well tolerated. No signs of irritation or local sensitivity were noted.
  
  
  CONCLUSIONS
  The nasal absorption of hydroxocobalamin in healthy elderly adults is rapid, high and well tolerated.
authors.affiliation: Department of Geriatric Medicine, University Hospital Nijmegen, The Netherlands.
authors.forename: D Z
authors.initials: DZ
authors.lastname: van Asselt
authors.forename: F W
authors.initials: FW
authors.lastname: Merkus
authors.forename: F G
authors.initials: FG
authors.lastname: Russel
authors.forename: W H
authors.initials: WH
authors.lastname: Hoefnagels
mesh_terms: D000042:Absorption; D000280:Administration, Inhalation; D000368:Aged; D018592:Cross-Over Studies; D005260:Female; D006397:Hematinics / Q000097:blood / Q000493:pharmacokinetics*; D006801:Humans; D006879:Hydroxocobalamin / Q000097:blood / Q000493:pharmacokinetics*; D008297:Male; D009297:Nasal Mucosa / Q000378:metabolism*
chemical_list: D006397:Hematinics; D006879:Hydroxocobalamin