title: Distribution and concentrations of 5-aminosalicylic acid in rectosigmoid biopsy specimens after rectal administration.
abstract: OBJECTIVE
  Using the autofluorescent properties of 5-aminosalicylic acid (5-ASA), we studied the penetration and distribution of this molecule in human colonic biopsies at different time intervals after administration of 5-ASA enemas.
  
  
  METHODS
  Fluorescence scores of rectosigmoidal biopsy specimens were compared with 5-ASA and acetyl-5-aminosalicylic (Ac-5-ASA) concentrations, determined by high-performance liquid chromatography, in adjacent biopsies and in serum samples.
  
  
  RESULTS
  5-ASA penetrates into the rectal mucosa and into the epithelial cells after local application by means of an enema. We found a characteristic 5-ASA staining of two intramucosal structures that need further identification: intraepithelial triangular configurations and "5-ASA scavengers" in the lamina propria. Fluorescence scores correlate well with 5-ASA concentrations in adjacent biopsies (r = 0.67; P < 0.005) and correlate even better with serum concentrations of 5-ASA (r = 0.84; P < 0.005) and Ac-5-ASA (r = 0.80; P < 0.005), hence reflecting the amount of systemically absorbed and metabolized 5-ASA.
  
  
  CONCLUSIONS
  5-ASA penetrates into the rectal mucosa after local application. Local availability, assessed by means of fluorescence microscopy, correlates well with serum concentrations.
authors.affiliation: University Hospital Gent, Department of Gastroenterology, Belgium.
authors.forename: R
authors.initials: R
authors.lastname: Schoonjans
authors.forename: M
authors.initials: M
authors.lastname: De Vos
authors.forename: A M
authors.initials: AM
authors.lastname: Schelfhout
authors.forename: M
authors.initials: M
authors.lastname: Praet
authors.forename: A
authors.initials: A
authors.lastname: Elewaut
mesh_terms: D000285:Administration, Rectal; D000636:Aminosalicylic Acids / Q000008:administration & dosage / Q000032:analysis / Q000493:pharmacokinetics*; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000008:administration & dosage / Q000032:analysis / Q000493:pharmacokinetics*; D001706:Biopsy; D002851:Chromatography, High Pressure Liquid; D012809:Colon, Sigmoid / Q000378:metabolism* / Q000473:pathology; D005453:Fluorescence; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism / Q000473:pathology; D019804:Mesalamine; D012007:Rectum / Q000378:metabolism* / Q000473:pathology
chemical_list: D000636:Aminosalicylic Acids; D000894:Anti-Inflammatory Agents, Non-Steroidal; D019804:Mesalamine