1例76岁转移癌患者因疼痛入院。住院后给予口服美散痛(methadone)5mg,每日3次;必要时皮下注射吗啡8mg。住院第6天,为了预防消化性溃疡给予静脉注射甲腈咪胍300mg,每日4次。第12天,在注吗啡后3小时,病者变得无反应,呼吸率2/min,脉搏54/min,瞳孔缩小但有反应。即给予静注纳洛酮(naloxone,吗啡拮抗剂)0.4mg,病者清醒,呼吸转为20/min。但6小时后再次无反应,再予以纳洛酮后又马上清醒。因此停用所有麻醉剂及甲腈咪胍24小时,该段时间病者无疼痛。甲腈咪胍抑制肝内微粒体酶,减少肝血流,因此那些依靠肝内清除的药物的清除率降低。本病例合用 A 76-year-old patient with metastatic cancer was hospitalized for pain. After hospitalization, oral methadone (5 mg) was given orally 3 times a day, and morphine 8 mg was injected subcutaneously when necessary. The sixth day of hospitalization, in order to prevent peptic ulcer given cimetidine 300mg, 4 times a day. On the 12th day, 3 hours after the injection of morphine, the patient became nonresponsive with a respiration rate of 2 / min and a pulse of 54 / min, with pupil constriction but response. That is given intravenous naloxone (naloxone, morphine antagonist) 0.4mg, the patient awake, breathing to 20 / min. However, no response after 6 hours, and then immediately after naloxone awake. Therefore, all anesthetics and acetylimidate were discontinued for 24 hours, during which time the patient had no pain. Cimetidine inhibits microsomal enzymes in the liver and reduces hepatic blood flow, so the clearance rate of those drugs that depend on intrahepatic clearance is reduced. This case combined