Animal experiment:

Rats[1] Maximum single doses administered orally are 2 g/kg body weight to 10 male and 10 female Biorex Wistar rats and 4 g/kg to 10 male and 10 female Swiss albino mice. The animals are observed for 7 days, any mortalities are recorded, and a full postmortem performed.

Ipsalazide is a novel sulfasalazine analog designed to release 5-aminosalicylic acid and a nontoxic carrier molecule in the gastrointestinal tract.

Sulfasalazine exerts beneficial effects in colitis by releasing 5-aminosalicylic acid in the colon, but its use can be limited by side effects. Ipsalazide is designed which the sulfapyridine of sulfasalazine has been replaced by carrier molecules[1].

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

[1]. Chan RP, et al. Studies of two novel sulfasalazine analogs, ipsalazide and balsalazide. Dig Dis Sci. 1983 Jul;28(7):609-15.