在二十年前的药理学课堂上，阿片和非类固醇类抗炎剂（NSAIDs）的作用部位这样直接讲述的：“阿片是中枢药物，NSAIDs是外周药物，因此阿片能产生困倦而NSAIDs不能。”当时人们刚刚发现脑和脑干中阿片的立体特异性结合位点，因而假定阿片在这些中枢受体上发挥其镇痛作用。就在 In the Pharmacology Class two decades ago opioids and non-steroidal anti-inflammatory drugs (NSAIDs) were directly elucidated as follows: “Opioids are central drugs and NSAIDs are peripheral drugs, so opioids are drowsy and NSAIDs can not. ”At the time, people had just discovered the stereospecific binding sites for opiates in the brain and brainstem, and it is assumed that opioids exert their analgesic effect on these central receptors. at