Epidural and intramuscular pethidine--a pharmacokinetic study.

Epidural preservative-free pethidine hydrochloride 0,75 mg/kg is rapidly absorbed into the blood. At 1,5 mg/kg the plasma levels reached are similar to those achieved by intramuscular preservative-free pethidine hydrochloride, as is the time course. Plasma levels fall more rapidly after epidural pethidine. Since the plasma levels lag behind the analgesic effects, they are unlikely to be of importance as regards clinical analgesia.