Dextromethorphan在急性術後疼痛的處置－－綜說

Dextromethorphan in the Management of Acute Postoperative Pain, Areview

Dextromethorphan (DM) is a well known N-methyl-D-aspartate (NMDA) receptor antagonist and has a long history of clinical safety as an antititussive drug for 5 decades. The discovery of the N-methyl-D-aspartate (NMDA) receptor and its links to pain processing and spinal neural hyper-excitability provoked renewed interest in DM as a potential post-operative analgesic drug. This paper reviews the use and results of DM in the management of acute postoperative pain. Animal studies show that NMDA receptor antagonists may prevent induction of spinal hyper-excitability and development of central excitability. The previous review article by McCartney et al. showed that DM can produce significant preventive analgesia in 67% of DM studies reviewed. A preventive analgesia may reduce central sensitization induced by perioperative inputs. The efficacy of preventive analgesia is demonstrated as a reduction in postoperative pain intensity and/or analgesic use exceeds the expected clinical duration of action of the target preventive drug. Studies show that oral route or low doses of DM correlated with poor analgesia. In addition, DM administered parenteral routes (IM or IV) provided superior analgesia postoperatively with reduction of acute postoperative pain and analgesic consumption. The literature reviews suggest that postoperative pain control can be improved with the perioperative proper usage of DM as an adjunct to opioids, NSAIDs and local anesthetics in patients receiving various surgeries. The enhanced perioperatively analgesic effects of DM with negligible side effects appear to depend on the route of administration (oral, IV. or IM) as well as proper dosages (oral 90 mg, IM 40 mg, IV 0.5 mg/kg).

Dextro methophan（DM）是個N-methyl-D-aspartate（NMDA）受體拮抗劑，也是個有臨床安全記錄使用近五十年的止咳藥。而近年來發現N-methyl-D-aspartate（NMDA）受體和疼痛訊息傳遍及脊髓神經的過度激活（hyper-excitability）有闕，對於DM是否具有潛在性成為術後止痛的藥物，引起新的興趣。此篇即是對DM在處置急性疼痛效果上做一系統性回顧。動物模型指出NMDA受體拮抗劑有預防引起脊髓神經的過度激活進及進展成中樞過度興奮的作用。在之前McCartney所做的系統性回顧，其發現DM臨床研究中有67%顯著產生了預防性止痛的好處。而預防性止痛是強調”中樞神經過敏化”是由於手術周期刺激引起：而且預防性止痛的效果彰顯於術後病患疼痛強度的減輕、止痛藥之使用遠超過臨床所測試藥物的藥效。我們發現所有無法呈現DM預防性止痛的效果的研究，DM皆是從口途徑或小劑量給予：此外DM經由非腸道吸收技與（不論是肌肉注射或是靜脈注射），提供病人術後較好的急性疼痛處置，包括降低術後疼痛及止痛藥的使用量。曲目前文獻回顧建議DM或許能應用於各種手術及麻醉方式。在手術問期，適當的將DM與嗎啡類止痛劑、非類固醇藥物及局部麻醉劑搭配使用於接受各種手術病患，在術後病患疼痛控制上能獲得改進。而為獲得DM的止痛效果而且幾乎無副作用，則端賴給予之途徑（口服、靜脈或肌肉路徑）、適切的劑量（口服近90毫克、IM40毫克或IV0.5mg／kg）及給予的時間點。