Background: 5-Aminosalicylate (5-ASA) formulations are approved for the treatment of ulcerative colitis (UC). Determination of the colonic pharmacokinetics of 5-ASA is challenging. A dynamic model of 5-ASA colonic amounts after oral delayed-release 5-ASA (Asacol), oral extended delayed-release 5-ASA (Lialda), 5-ASA enema (Rowasa), foam and suppositories (Canasa) was developed to determine the colonic kinetics of these agents.
Methods: We created a model with Stella software. Colonic 5-ASA in the right, transverse, descending, sigmoid colon, and rectum were estimated for adults after recommended doses of the above formulations. Simulations of active mild/moderate UC and in remission were performed and compared using Student's t-test for differences in means.
Results: For UC in remission, the highest amounts of 5-ASA were from Asacol in the right and transverse colon (P < 0.01), Lialda in the descending and sigmoid colon (P < 0.01), and Rowasa in the rectum (P < 0.01). For active UC, sigmoid amounts were highest with foam (P < 0.01), and rectal amounts highest with Rowasa (P < 0.01). Differences in rectosigmoid amounts of 5-ASA from enemas and suppositories for UC in remission occurred based on the relationship between the timing of administration relative to the daily bowel movement (P < 0.01).
Conclusions: Compared to Asacol, Lialda results in higher 5-ASA amounts in the left colon. Asacol with Rowasa provides highest 5-ASA amounts across the entire colon. Higher 5-ASA amounts from topical formulations occur when the insertion occurs soon after the daily bowel movement. This model provides a rationale for further investigation.
Article first published online 29 May 2012
*Gastroenterology Department, NorthShore University HealthSystem, Highland Park, Illinois
†Center for the Study of Complex Diseases, Research Institute, NorthShore University HealthSystem, Evanston, Illinois
‡Division of Nutritional Sciences, University of Illinois, Urbana, Illinois
§Department of Geography/NCSA, University of Illinois, Urbana, Illinois.
Reprints: Dr. E.D. Ehrenpreis, Medical Director, Center for the Study of Complex Diseases, Research Institute, NorthShore University HealthSystem, Evanston, IL (e-mail: email@example.com).
Supported by the Keyser Family Research Fund and the Center for the Study of Complex Diseases.
Received March 29, 2012
Accepted April 9, 2012