Substrate to, and inhibitor of CYP 3A4. Administered in ug dose. Several references consider it safe for use.

(To be edited, initial data ST OCT 04) Opioid analgesic used (509-100 ug / dose) intravenously in general anesthesia during long and moderatly long surgery. Used together with droperidol in neuroleptanalgesia typ II. Probably metabolized by CYP3A4. MFM James, RJ Hift. Porphyrias. Br J Anaesth 2000; 85, 143-53: use EPI-list: safe. Australian list: safe. South African list: use. French list: use. Austarlian list: safe.

Uneventful use reported in 5 patients with acute porphyria.