Alimentary pharmacology & therapeutics

Systemic availability of 5-aminosalicylic acid: comparison of delayed release and an azo-bond preparation.

PMID 8853765


To determine the systemic uptake of 5-aminosalicylic acid (5-ASA) and acetyl-5-ASA (Ac-5-ASA) at steady state during treatment with either an azo-bond preparation, olsalazine, or a delayed-release mesalazine. In an open cross-over trial with randomized sequence, 15 patients with ulcerative colitis in remission were given 7-day courses of olsalazine (Dipentum 1.0 g daily) and of mesalazine (Asacol 1.6 g daily). Plasma and urine were collected on days 6 and 7 of each course and concentrations of 5-ASA and Ac-5-ASA were determined by high-performance liquid chromatography (HPLC). Mean steady-state plasma concentrations of 5-ASA and Ac-5-ASA were significantly higher after treatment with mesalazine than with olsalazine (P < 0.0001). Total urinary excretion of 5-ASA and Ac-5-ASA as a percentage of the given dose was significantly higher on mesalazine than on olsalazine (P < 0.01). Only two patients experienced, during the first 3 days of treatment with olsalazine, transient watery diarrhoea which resolved spontaneously. No unexpected or major changes in haematology or biochemistry were detected during the study. As 5-ASA acts locally, the lower systemic load provided by olsalazine may increase efficacy and reduce the potential risk of nephrotoxicity during long-term maintenance treatment of ulcerative colitis.

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5-(Acetylamino)-2-hydroxybenzoic acid, AldrichCPR