Famotidine: Partly unmetabolized. No clinical observations pointing to CYP inducing properties. Combined with two inorganic salts without CYP interactive properties.

Famotidine: Used in gastric hyperacidity (H2-receptor antagonist). About 70% excreted in urine in unmetabolised form. Partly metabolised in the liver to inactive sulfoxide metabolite. Impaired liver function does not seem to change the kinetics.

Uneventful use reported in 1 patient with acute porphyria.