Shir Y, Eimerl D, Magora F, Damm D, Schulte-Monting J, Chrubasik J
Department of Anaesthesiology, Hadassah University Hospital, Jerusalem, Israel.
Br J Anaesth. 1990 Aug;65(2):204-9. doi: 10.1093/bja/65.2.204.
Plasma concentrations of methadone were measured by gas chromatography in 16 patients receiving extradural methadone by continuous infusion for relief of postoperative pain. Venous blood samples were taken after a loading dose of extradural methadone 2 mg and during infusion of 0.46 mg h-1 plus patient-controlled increments of 0.2-1 mg. Mean (SD) plasma concentration of methadone was 9.8 (2.1) ng ml-1 at 15 min; this did not change significantly during the first 2 h, after which it increased gradually to 32.2 (4.6) ng ml-1 (P less than 0.001) at the end of 24 h. The mean quantity of extradural methadone required to produce effective analgesia was 10.3 (1.8) mg during the first 12 h after operation and 6 (1.0) mg for the subsequent 12 h. The mean amount of methadone for effective analgesia on the second day was 7.6 (1.1) mg. No adverse effects were detected during the 2-3 days of methadone therapy. Plasma concentration of methadone increased significantly during patient-controlled infusion of extradural methadone in the first 24 h after operation, suggesting rapid vascular uptake. Systemic activity of the drug contributes to the analgesic effect of extradural methadone.
采用气相色谱法测定了16例接受硬膜外持续输注美沙酮以缓解术后疼痛患者的血浆美沙酮浓度。在给予2mg硬膜外美沙酮负荷剂量后以及在以0.46mg h-1输注并由患者自控追加0.2 - 1mg的过程中采集静脉血样。美沙酮的平均（标准差）血浆浓度在15分钟时为9.8（2.1）ng/ml；在最初2小时内无显著变化，此后在24小时末逐渐升高至32.2（4.6）ng/ml（P<0.001）。术后前12小时产生有效镇痛所需的硬膜外美沙酮平均量为10.3（1.8）mg，随后12小时为6（1.0）mg。第二天有效镇痛所需的美沙酮平均量为7.6（1.1）mg。在美沙酮治疗的2 - 3天内未检测到不良反应。术后头24小时内患者自控硬膜外输注美沙酮期间，美沙酮血浆浓度显著升高，提示血管快速摄取。该药物的全身活性有助于硬膜外美沙酮的镇痛效果。
