Hanks G W, Forbes K
University of Bristol, Department of Palliative Medicine Bristol Oncology Centre, UK.
Acta Anaesthesiol Scand. 1997 Jan;41(1 Pt 2):154-8. doi: 10.1111/j.1399-6576.1997.tb04630.x.
Cancer pain generally responds in a predictable way to analgesic drugs and drug therapy is the mainstay of treatment. A small proportion of patients, of the order of 20%, have pain that does not respond well to conventional analgesic management. Because opioid analgesics are the most important part of this pharmacological approach, a terminology has developed which centres around whether or not pain will respond to opioid analgesics. The terms opioid-responsive-pain and opioid-non-responsive pain, or opioid-resistant-pain, have been used to differentiate between patients whose pain falls into these two broad groups. This terminology is not satisfactory because it implies an all or none phenomenon, that is that pain either does or does not respond to opioid analgesics. Rarely is there such a clear distinction in practice. This is because the end point when titrating dose against pain with strong opioid analgesics is not simply pain relief or lack of relief: adverse effects may limit dose titration. It is preferable to describe patients with pain which is relatively less sensitive to opioids and/or patients where there is an inbalance between analgesia and unwanted effects as having "opioid-poorly-responsive pain". A pragmatic definition of opioid-poorly-responsive pain is pain that is inadequately relieved by opioid analgesics given in a dose that causes intolerable side effects despite routine measures to control them. Included in this definition is so called paradoxical pain which is not a distinct entity. Neuropathic pain is the most common form of opioid-poorly-responsive pain. The underlying pathophysiology remains unclear but abnormal metabolism of morphine is not the cause of a poor response to this drug. Patients with opioid-poorly-responsive-pain should be considered for treatment with the same opioid by an alternative (spinal) route or with an alternative opioid agonist administered by the same route (whether oral or parenteral), in conjunction with adjuvant analgesics such as tricyclic antidepressants. The most commonly used alternative oral opioids are phenazocine and methadone; transdermal fentanyl is an additional option.
癌症疼痛通常对镇痛药有可预测的反应，药物治疗是主要的治疗方法。约20%的一小部分患者的疼痛对传统镇痛管理反应不佳。由于阿片类镇痛药是这种药理学方法的最重要部分，因此形成了一种围绕疼痛是否会对阿片类镇痛药产生反应的术语。阿片类药物反应性疼痛和阿片类药物无反应性疼痛或阿片类药物抵抗性疼痛这两个术语已被用于区分疼痛属于这两大类的患者。这个术语并不令人满意，因为它意味着一种全有或全无的现象，即疼痛要么对阿片类镇痛药有反应，要么没有反应。在实践中很少有如此明确的区分。这是因为在用强效阿片类镇痛药根据疼痛滴定剂量时，终点不仅仅是疼痛缓解或未缓解：不良反应可能会限制剂量滴定。将对阿片类药物相对不敏感的疼痛患者和/或镇痛与不良反应之间存在失衡的患者描述为“阿片类药物反应欠佳性疼痛”更为合适。阿片类药物反应欠佳性疼痛的一个实用定义是，尽管采取了常规措施来控制，但给予导致无法耐受副作用的剂量的阿片类镇痛药仍无法充分缓解的疼痛。这个定义包括所谓的矛盾性疼痛，它并非一个独特的实体。神经病理性疼痛是阿片类药物反应欠佳性疼痛最常见的形式。其潜在的病理生理学仍不清楚，但吗啡代谢异常并非对该药物反应不佳的原因。对于阿片类药物反应欠佳性疼痛的患者，应考虑通过替代（脊髓）途径使用相同的阿片类药物进行治疗，或通过相同途径（无论是口服还是胃肠外途径）给予替代阿片类激动剂，并联合使用辅助镇痛药，如三环类抗抑郁药。最常用的替代口服阿片类药物是非那佐辛和美沙酮；透皮芬太尼是另一种选择。
