COMPARATIVE PHARMACOKINETICS OF INTRAVENOUS AND INTRATHECAL SUFENTANIL FOR MAJOR ABDOMINAL-SURGERY

The absorption and distribution of a single bolus of sufentanil 150 mu g for abdominal surgery were studied in 20 patients randomly injected either intravenously or intrathecally. Samples of plasma and cerebros pinal fluid (CSF) were taken at regular intervals from time zero to 18 0 minutes after injection and at the time of tracheal extubation. Sufe ntanil was analysed by radioimmunoassay. The plasma sufentanil concent ration (C-p) after intravenous injection was significantly higher duri ng 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 rea ched the central circulation at the time of tracheal extubation follow ing intrathecal administration was 78%. In the intravenous group, sufe ntanil could be found in the CSF in only 3 patients, suggesting that t he analgesic effect in this group is produced mostly by the supraspina l distribution of sufentanil. After intrathecal administration, sufent anil 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 sh orter than is the case with intrathecal morphine. Sufentanil produces both surgical supraspinal and spinal analgesia after intrathecal injec tion.