Ipsalazide is a novel salicylazosulfapyridine analog for the treatment of inflammatory bowel disease.

Ipsalazide is designed with the replacement of the sulfapyridine of sulfasalazine by carrier molecules, aiming to mitigate side effects. Sulfasalazine exerts beneficial effects in colitis by releasing 5-aminosalicylic acid in the colon, but its use can be limited by side effects[1].

Within 7 days of a single oral dose of ipsalazide (4 g/kg in mice or 2 g/kg in rats), no deaths or visible abnormalities occurred. At postmortem, no abnormalities were observed. The carrier molecule of ipsalazide (ABG) is readily absorbed, with nearly half of the dose appearing in the urine. However, approximately 40% of the ABG was not recovered, and it is possible that this has undergone further metabolism, resulting in the loss of the aromatic amine function, which is the basis for the colorimetric measurement of ABG[1].