Pharmacocinétique de la péthidine après rachianesthésie. Implications cliniques

Abstract

Eleven male patients undergoing endoscopic resection for prostatic adenoma and bladder tumours under spinal anaesthesia received intrathecal pathidine 1 mg · kg −1. Plasma concentration and its evolution with time were assessed; pethidine plasma concentrations were determined by high performance liquid chromatography. Pethidine was rapidly and extensively absorbed. The peak plasma concentration of pethidine was 176±66 ng · ml −1 (range : 84–208) and the time to peak concentration was 2.3±1.4 h (range : 0.5–6 h). The terminal elimination half-life was 7.2±2.2 h (range : 4–11.5 h). The plasma concentrations of pethidine remained below 500–700 ng · ml −1, the minimum concentration necessary to obtain a systemic analgesic effect. Two patients required noramidopyrine as a complement at the 8th and 12th h respectively. No respiratory depression was observed. Intrathecal pethidine (1 mg · kg −1) was an effective agent for spinal anaesthesia : the prolonged postoperative analgesia was due to the drug acting on opioid receptors in the spinal cord. This led to the necessity of postoperative monitoring during 24 h after intrathecal pethidine administration.