Partly unmetabolized. No clinical observations pointing to CYP inducing properties.

Used in peptic ulcer and gastro-oesophageal reflux (H2-receptor antagonist). About 70% excreted in urine in unmetabolized form. Partly metabolized in the liver to inactive sulfoxide metabolite. Impaired liver function does not seem to change the kinetics.

Uneventful use reported in 8 patients with acute porphyria.