Amantadine, a N-methyl-D-aspartate receptor antagonist, does not enhance postoperative analgesia in women undergoing abdominal hysterectomy

N-methyl-D-aspartate (NMDA) antagonists administered before surgery will im prove postoperative analgesia, presumably by inhibiting spinal sensitizatio n processes. However, current clinical formulations of NMDA antagonists eit her enable only an oral application (i.e., dextromethorphan) or are associa ted with psychotropic side effects, as with the IV delivery of ketamine. Be cause of its noncompetitive NMDA receptor antagonist characteristics, amant adine may improve postoperative analgesia when administered before surgical ly induced trauma. in this prospective, randomized clinical study, we exami ned whether female patients undergoing elective abdominal hysterectomy expe rienced less postoperative pain when IV amantadine was applied in compariso n with placebo before the start of surgery. Thirty patients were randomly a ssigned to receive 500mL saline IV before the induction of standardized gen eral anesthesia in Group 1 (Control group) or, in a double-blinded manner, 200 mg amantadine IV in 500 mL saline in Group 2 (Treatment group). Postope rative pain control was provided via TV patient-controlled analgesia with p iritramide. During the first 48 h after tracheal extubation, pain perceptio n was assessed by visual analog scales, and all analgesic requirements were documented. There were no significant differences between the two groups w ith respect to pain scores, postoperative analgesic requirements, and the i ncidence of side effects. Because of no differences in postoperative pain o r opioid consumption, we conclude that a preoperative dose of 200 mg amanta dine TV fails to enhance postoperative analgesia in patients undergoing ele ctive abdominal hysterectomy.