Olsalazine-¹³C₆is intended for use as an internal standard for the quantification of olsalazine by GC- or LC-MS. Olsalazine is an orally bioavailable prodrug form of the anti-inflammatory agent 5-aminosalicylic acid that is cleaved by bacterial azo reductases in the gut to generate active 5-ASA.¹In vitro, olsalazine increases ion transport in isolated rabbit distal ileum when applied to the luminal side (ED₅₀= 0.3 mM) and stimulates fluid transport in rat jejunum when used at a concentration of 5 mM.^2,3Olsalazine (150 mg/kg for 8 days) improves stool consistency and decreases occult and gross bleeding as well as myeloperoxidase (MPO) activity and leukotriene B₄levels in colon tissue in a mouse model of acute colitis induced by dextran sulfate .⁴Olsalazine also inhibits bovine xanthine oxidasein vitro(IC₅₀= 3.4 mg/L) and lowers serum uric acid levels in a mouse model of hyperuricemia induced by oxonic acid when administered at a dose of 20 mg/kg.⁵Formulations containing olsalazine have been used in the treatment of inflammatory bowel disease (IBD) and ulcerative colitis.

1.Nugent, S.G., Kumar, D., Rampton, D.S., et al.Intestinal luminal pH in inflammatory bowel disease: Possible determinants and implications for therapy with aminosalicylates and other drugsGut48(4)571-577(2001) 2.Pamukcu, R., Hanauer, S.B., and Chang, E.B.Effect of disodium azodisalicylate on electrolyte transport in rabbit ileum and colon in vitro. Comparison with sulfasalazine and 5-aminosalicylic acidGastroenterology95(4)975-981(1988) 3.Mohsen, A.Q.M., Mulvey, D., Priddle, J.D., et al.Effects of olsalazine in the jejunum of the ratGut28(3)346-352(1987) 4.Murthy, S., Murthy, N.S., Coppola, D., et al.The efficacy of BAY y 1015 in dextran sulfate model of mouse colitisInflamm. Res.46(6)224-233(1997) 5.Niu, Y., Li, H., Gao, L., et al.Old drug, new indication: Olsalazine sodium reduced serum uric acid levels in mice via inhibiting xanthine oxidoreductase activityJ. Pharmacol. Sci.135(3)114-120(2017)