Distribution and concentrations of 5-aminosalicylic acid in rectosigmoid biopsy specimens after rectal administration.
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.
Schoonjans
R
R
University Hospital Gent, Department of Gastroenterology, Belgium.
De Vos
M
M
Schelfhout
A M
AM
Praet
M
M
Elewaut
A
A
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
D000636:Aminosalicylic Acids; D000894:Anti-Inflammatory Agents, Non-Steroidal; D019804:Mesalamine