Relatively low systemic exposure of substance with probably non-CYP metabolism. Acetyl salicylic acid is an inducer of CYP 2C19. Two references state non-porphyrinogenicity.

5-aminosalicylic acid (5-ASA). Antiinflammatory agent in suppositorium or foam for local rectal use, 1 g/d. Low systemic exposure, only about 20 % of the given dose recovered in urine after acetylation in the intestinal mucosa and the liver. South African list: use. EPI-list: use

Uneventful use reported in 6 patients with acute porphyria.