title: Pharmacokinetics of Der p 2 allergen and derived monomeric allergoid in allergic volunteers.
abstract: BACKGROUND
  Presently, sublingual immunotherapy is widely used as an alternative to the injection route for respiratory allergy, but its pharmacokinetics in humans is poorly known, and data are available only for Par j 1 allergen. We aimed at assessing the biodistribution of iodine-123-radiolabelled Der p 2 in allergic volunteers.
  
  
  METHODS
  Purified Der p 2 and its monomeric allergoid were radiolabelled with iodine-123 and administered sublingually to 7 allergic volunteers. The subjects were allowed to swallow 6 min after administration. Dynamic (up to 10 min) and static scintigraphic images (30 min, 1, 2, 3 and 20 h) were recorded, and blood samples were obtained at different time points to measure the plasma radioactivity and to assess the presence of circulating radiolabelled species by gel chromatography.
  
  
  RESULTS
  The local pharmacokinetics did not differ between allergen and allergoid. Plasma radioactivity began to increase only after swallowing and peaked at 1-2 h. Both the allergen and the allergoid persisted in the mouth for several hours, and traces could be detectable up to 20 h. At radioactivity plasma peak, gel chromatography showed that a fraction of the allergoid, but not the allergen, was absorbed as an intact molecule.
  
  
  CONCLUSIONS
  These results indicate that the pharmacokinetics of sublingual administration is independent of the allergen used and characterized by the long persistence in the mouth. The contribution of enteric absorption of the allergoid in the mechanism of action of sublingual immunotherapy remains to be defined.
authors.affiliation: Medical and Radiometabolic Therapy, University of Genoa, Genoa, Italy.
authors.forename: Marcello
authors.initials: M
authors.lastname: Bagnasco
authors.forename: Vania
authors.initials: V
authors.lastname: Altrinetti
authors.forename: Giampaola
authors.initials: G
authors.lastname: Pesce
authors.forename: Mauro
authors.initials: M
authors.lastname: Caputo
authors.forename: Gianni
authors.initials: G
authors.lastname: Mistrello
authors.forename: Paolo
authors.initials: P
authors.lastname: Falagiani
authors.forename: Giorgio Walter
authors.initials: GW
authors.lastname: Canonica
authors.forename: Giovanni
authors.initials: G
authors.lastname: Passalacqua
mesh_terms: D000286:Administration, Sublingual; D000328:Adult; D000485:Allergens / Q000008:administration & dosage / Q000737:chemistry / Q000378:metabolism*; D039741:Antigens, Dermatophagoides / Q000008:administration & dosage / Q000737:chemistry / Q000378:metabolism*; D060829:Arthropod Proteins; D006801:Humans; D006967:Hypersensitivity / Q000378:metabolism*; D007457:Iodine Radioisotopes; D008297:Male; D011877:Radionuclide Imaging; D014018:Tissue Distribution
chemical_list: D000485:Allergens; D039741:Antigens, Dermatophagoides; D060829:Arthropod Proteins; C451163:Dermatophagoides pteronyssinus antigen p 2; D007457:Iodine Radioisotopes