Administered in ug dose. Non-oxidative, non-hepatic metabolism.

(To be edited, initial data ST OCT 04) Opioid analgesic administered (30-50 ug) as epidural injection. Used in induction and maintainace of assisted ventilation. Short duration of effect. Metabolized by unspecific blood- and tissue esterases to carboxylic acid metabolite. Liver is not engaged in its biotransformation.