Mesalazine release from coated tablets: effect of dietary fibre.

Delayed-release mesalazine formulations relay on pH-dependent coat dissolution to ensure delivery of 5-aminosalicylic acid (5-ASA) to the colon. As dietary fibre acidifies the colonic lumen we have studied the effect of fibre supplementation in 10 patients with quiescent colitis. Greater intake of dietary fibre was associated with a decrease in stool pH and an increase in stool frequency and faecal mass. However, the 24 h faecal and urinary excretion of 5-ASA and N-acetyl-5-ASA was unchanged. The percentage of total faecal ASA excreted as N-acetyl-5-ASA correlated with whole-gut transit time, suggesting that prolonged transit may be disadvantageous to patients with colitis as N-acetyl-5-ASA appears to be inactive.