Study of long-term side effects of morphine intrathecal administration in cancer pain model

镇痛剂量的吗啡和苯乙酮输注均产生耐受性。低剂量itdex与it吗啡合用有明显的镇痛作用，无耐受性。在吗啡输注动物中，脊髓沿导管形成严重的印象，表明肉芽肿形成。添加低剂量的IT DEX可抑制IT吗啡输注引起的肉芽肿的形成并引起运动障碍。然而，IT DEX和吗啡对大鼠癌性骨痛模型的镇痛作用很小。添加DEX可抑制慢性吗啡致小鼠的耐受性和肉芽肿形成。联用吗啡和DEX可能有助于缓解慢性癌症患者的疼痛，避免副作用。

Analgesic doses of IT morphine and IT DEX infusion produce tolerance. Co-administration of low doses of IT DEX with IT morphine has significant analgesia without tolerance. Severe impression of the spinal cord along the course of the catheter indicating granuloma formation could be seen in morphine infusion animals. Addition of low dose of IT DEX inhibits IT morphine infusion-induced granuloma formation followed by motor impairment. However, IT DEX and morphine provided a littleanalgesic effects in a rat model of cancer induced bone pain. Development of tolerance and granuloma formation followed by motor impairment induced by chronic IT morphine were inhibited by addition of DEX. Combination of IT morphine and DEX may contribute to patients with chronic cancer pain to avoid side effects.