Not metabolised. Two references consider it (probably) safe. Porphyrinogenic in rat model.

(To be edited, initial data ST OCT 04) Aminosteroide muscle relaxant used under general anaesthesia. Excreted unchanged in bile and to a small extent in urine. South African list: use with care. French list: authorized. Famewo (6 mg i.v.) PMID 3986654: safe

Uneventful use reported in 1 patient with acute porphyria.