Effect of food coadministration on 5-aminosalicylic acid oral suspension bioavailability

Clin Pharmacol Ther. 1990 Jul;48(1):26-33. doi: 10.1038/clpt.1990.113.


Single doses of 1 gm 5-aminosalicylic acid (5-ASA) suspension was administered to 24 healthy volunteers during both fasting and fed conditions. For subjects in a fasting state, plasma 5-ASA and acetyl 5-ASA concentrations peaked rapidly 1 hour after dosing to 14.72 micrograms/ml and 11.4 micrograms/ml, respectively. The elimination half-life of 5-ASA was 51.9 minutes, whereas the acetyl 5-ASA half-life could not be determined. A mean of 78.3% of the dose was excreted in the urine, with 5-ASA accounting for 21.2% of the dose and acetyl 5-ASA accounting for the balance. Only 11.3% of the dose was eliminated in the feces, consisting mostly of acetyl 5-ASA. Food coadministration reduced 5-ASA and acetyl 5-ASA systemic relative bioavailability to 44% and 76%, respectively, compared with the fasting treatment. Urinary excretion of the salicylates was reduced to 46.8%, and fecal salicylate elimination increased almost 100%--to 24.2% of the total dose.

MeSH terms

  • Administration, Oral
  • Adult
  • Aminosalicylic Acids / administration & dosage
  • Aminosalicylic Acids / blood
  • Aminosalicylic Acids / pharmacokinetics*
  • Aminosalicylic Acids / urine
  • Biological Availability
  • Feces / analysis
  • Food*
  • Humans
  • Male
  • Mesalamine


  • Aminosalicylic Acids
  • Mesalamine
  • N-acetyl-5-aminosalicylic acid