Comparative Pharmacokinetics of Intravenous and Intrathecal Sufentanil for Major Abdominal Surgery

Summary

The absorption and distribution of a single bolus of sufentanil 150µg for abdominal surgery were studied in 20 patients randomly injected either intravenously or intrathecally. Samples of plasma and cerebrospinal fluid (CSF) were taken at regular intervals from time zero to 180 minutes after injection and at the time of tracheal extubation. Sufentanil was analysed by radioimmunoassay. The plasma sufentanil concentration (C_p) after intravenous injection was significantly higher during the first 30 minutes than after intrathecal administration. The C_p at 180 minutes after intrathecal sufentanil injection was higher than after intravenous administration. The fraction of sufentanil that reached the central circulation at the time of tracheal extubation following intrathecal administration was 78%. In the intravenous group, sufentanil could be found in the CSF in only 3 patients, suggesting that the analgesic effect in this group is produced mostly by the supraspinal distribution of sufentanil. After intrathecal administration, sufentanil reached the systemic circulation rapidly and remained detectable for many hours. Owing to the physicochemical properties of sufentanil, the CSF compartment acts as a reservoir of sufentanil for a period shorter than is the case with intrathecal morphine. Sufentanil produces both surgical supraspinal and spinal analgesia after intrathecal injection.