Distribution and concentrations of 5-aminosalicylic acid in rectosigmoid biopsy specimens after rectal administration

Abstract
Ecimens 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. CONCLUSION: 5-ASA penetrates into the rectal mucosa after local application. Local availability, assessed by means of fluorescence microscopy, correlates well with serum concentrations. © The ASCRS 1996...