Title: Opioid Induced Hyperalgesia
题目：鸦片类镇痛药导致的疼痛敏感性增加
Author 作者: Ellen Lemkin
 
Opioid analgesia can actually INCREASE sensitivity to pain in some cases
在某些情况下，鸦片类镇痛药实际上可以增加对疼痛的敏感性
The exact cause is unclear, but may be due to up-regulation of NDMA receptors in spinal cord dorsal horn neurons
虽然确切原因尚不清楚，但可能是由于脊髓背角神经元NDMA受体上调
Pain tends to be DIFFERENT and DIFFUSE from the underlying condition for which the narcotics were prescribed
疼痛往往是与用吗啡药治疗的疼痛性质不同并弥漫
Switching from shorter acting opiates to methadone may be effective, as it is a weak NDMA antagonist and has only partial cross tolerance with other opioids
从短效鸦片类转成美沙酮可能会是有效的，因为它是一个弱的NDMA阻断剂，对其他类鸦片药物只有部分交叉耐药性

References 参考文献：
Gussow, L. Toxicology Rounds. When Opioids Increase Pain. Emergency Medicine News Feb 2013. 35(2):6.