After oral administration of sulfasalazine, the majority of the administered dose reaches the colon, where it is split into 5‐aminosalicylic acid (5‐ASA) and sulfapyridine. 5‐ASA is believed to be the effective component in the treatment of inflammatory bowel disease. After intraduodenal administration of 5‐ASA (20 mg) in rats, 91% of the drug was absorbed in the proximal small intestine. Peak serum 5‐ASA concentration (55 μg/ml) was reached in 1 h. Approximately 61 and 6% of the administered dose were excreted in the urine and bile, respectively, in 24 h, almost exclusively in the acetylated form. When sulfapyridine (20 mg) was administered in addition to 5‐ASA, 70% of the sulfapyridine was absorbed in the small intestine, peak serum concentration (50 jug/ml) was reached in 1 b, and 30% of the administered dose was excreted in the urine in 24 b. The results indicate that after oral administration of 5‐ASA, a therapeutically significant concentration of the drug is not expected in the terminal ileum which is a common site of involvement in Crohn's disease. The therapeutic implications of these findings are discussed herein.
|Original language||English (US)|
|Number of pages||3|
|Journal||The American Journal of Gastroenterology|
|State||Published - May 1982|
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