5-aminosalicylic acid in a slow-release preparation: bioavailability, plasma level, and excretion in humans.

The release pattern, bioavailability, and kinetics of a 5-aminosalicylic acid tablet with sustained release were studied in humans. Six ileostomy patients received a single dose (500 mg). Eight and 48 h later, respectively, 58% and 65% of the dose was recovered in the ileostomy effluents, either as 5-aminosalicylic acid still retained in the preparation, free 5-aminosalicylic acid or acetyl-5-aminosalicylic acid. Fourteen healthy volunteers took 1500 mg of 5-aminosalicylic acid per day for 6 days and a steady state plasma acetyl-5-aminosalicylic acid concentration was reached on day 5 (1.1-2.9 microgram/ml). 5-Aminosalicylic acid was not detected in the plasma. At steady state, 40% of the 24-h dose was recovered from feces, and 53% from the urine. The sustained-release preparation studied provides sufficient amounts of 5-aminosalicylic acid to all parts of the gut and its curative effect in ulcerative colitis and Crohn's disease should be examined in controlled trials.