Yamamura H
Masui. 1989 Feb;38(2):152-6.
The mechanism of action of aspirin as an analgesic is an inhibition of biosynthesis of prostaglandins. Thus the site of action has been believed to be peripheral. However, when aspirin is injected intra- thecally, it produces an analgesic effect. Aspirin has a membrane-stabilizing effect and it is used locally for the treatment of post- herpetic neuralgia. Epidural opioids are frequently used for the management of post-operative pain or cancer pain. Pharmacokinetic studies have shown that delayed respiratory depression results from migration of morphine in the cerebrospinal fluid to the brain. Peak concentrations of morphine near the brain stem occur about 3 hours after lumbar epidural injection, whereas lipophilic opioids such as meperidine, peak concentration occur within 30 to 60 minutes. The clearance from cerebrospinal fluid of lipophilic opioids is more rapid than that of morphine. Besides opioids, alpha 2 receptor agonists such as clonidine also have analgesic action when administered into the epidural space. Somatostatin is one of many neuropeptides found in the spinal cord. It has dual action: a mediation of thermal nociception and a general antinociceptive action. When somatostatin is administered intrathecally or epidurally, it produces analgesic effect and its efficacy appears to be equal to that of morphine.
阿司匹林作为镇痛药的作用机制是抑制前列腺素的生物合成。因此，其作用部位一直被认为是外周。然而，当阿司匹林鞘内注射时，它会产生镇痛作用。阿司匹林具有膜稳定作用，局部用于治疗带状疱疹后神经痛。硬膜外使用阿片类药物常用于术后疼痛或癌痛的管理。药代动力学研究表明，延迟性呼吸抑制是由于吗啡在脑脊液中向脑内迁移所致。腰段硬膜外注射后约3小时，脑干附近出现吗啡的峰值浓度，而亲脂性阿片类药物如哌替啶，峰值浓度在30至60分钟内出现。亲脂性阿片类药物从脑脊液中的清除比吗啡更快。除了阿片类药物外，α2受体激动剂如可乐定硬膜外给药时也具有镇痛作用。生长抑素是在脊髓中发现的众多神经肽之一。它具有双重作用：介导热痛觉和一般的抗伤害感受作用。当生长抑素鞘内或硬膜外给药时，它会产生镇痛作用，其疗效似乎与吗啡相当。
