Relatively low systemic exposure of substance with probably non-CYP metabolism. Acetylsalicylic acid is an inducer of CYP2C19. Two references state non-porphyrinogenicity.

Antiinflammatory agent perorally used 1 g/d, in ulcerating colitis. Composed of two mesalazine (5-amino-salicylic acid) molecules joined by azo-bonding. Only insignificantly (1-2%) absorbed, split by colon bacteria into two 5-ASA, which is acetylated in the gut and the liver.