Substrate of CYP 3A4. Inhibitor os CYPs 3A4, 2D6, 1A1, 1A2, 2B6, 2C19, 2C8, 2C9, 2E1. Several references consider it safe. Significant clinical experience points to non-porphyrinogenicity.

(To be edited, initial data ST OCT 04) Partial opioid antagonist used in postoperative pain and in Sweden also repeatedly in acute porphyric crises. Metabolized by CYP 3A4. 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 Without adverse reaction frequently used during acute porphyric crises (Sweden).

Uneventful use reported in 6 patients with acute porphyria.