Opioid. Possibly CYP-mediated metabolism. In several references considered safe. Significant clinical experience of non-porphyrinogenicity.

(To be edited, initial data ST OCT 04) Phenylpiperidine opioid analgesic used in severe pain conditions. Possibly CYP-mediated metabolism by hydrolysis or demetylation followed by glucuronidation. MFM James, RJ Hift. Porphyrias. Br J Anaesth 2000; 85, 143-53: safe. EPI-list: safe. Australian list: safe. South African list: use. French list: use. Anderson KE: Effects of antihypertensive drugs on hepatic heme biosynthesis,...Biochem Biophys Acta 543:313, 1978: safe Moore MR, Hift RJ: Drugs in the acute porphyrias. Cell Mol Biol 43:89, 1997: probably safe. Schoenfeld: observed to be safe. Thunell, patient inquiry: tolerated (n=2) In Sweden routinely used as analgesic agent in acute attacks of porphyria .

Uneventful use reported in 11 patients with acute porphyria.