The synthesis and pharmacological activity of a new series of 4-alkyl-1-oxa-4,9-diazaspiro[5.5]undecane derivatives as potent dual ligands for the σ₁ receptor (σ₁R) and the μ-opioid receptor (MOR) are reported. A lead optimization program over the initial 4-aryl analogues provided 4-alkyl derivatives with the desired functionality and good selectivity and ADME profiles. Compound 14u (EST73502) showed MOR agonism and σ₁R antagonism and a potent analgesic activity, comparable to the MOR agonist oxycodone in animal models of acute and chronic pain after single and repeated administration. Contrary to oxycodone, 14u produces analgesic activity with reduced opioid-induced relevant adverse events, like intestinal transit inhibition and naloxone-precipitated behavioral signs of opiate withdrawal. These results provide evidence that dual MOR agonism and σ₁R antagonism may be a useful strategy for obtaining potent and safer analgesics and were the basis for the selection of 14u as a clinical candidate for the treatment of pain.

中文翻译：

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EST73502 的发现，一种双 μ-阿片受体激动剂和 σ1 受体拮抗剂，用于治疗疼痛的临床候选药物


一系列新的 4-烷基-1-氧杂-4,9-二氮杂螺[5.5]十一烷衍生物的合成和药理活性，作为 σ ₁受体 (σ ₁ R) 和 μ-阿片受体 (MOR) 的有效双配体）被报道。对初始 4-芳基类似物的先导优化程序提供了具有所需功能性和良好选择性和 ADME 特性的 4-烷基衍生物。化合物14u (EST73502) 在单次和重复给药后在急性和慢性疼痛动物模型中显示出 MOR 激动作用和 σ ₁ R 拮抗作用以及有效的镇痛活性，与 MOR 激动剂羟考酮相当。与羟考酮相反， 14u产生镇痛活性，并减少阿片类药物引起的相关不良事件，如肠道运输抑制和纳洛酮诱发的阿片戒断行为症状。这些结果证明，MOR 的双重激动和 σ ₁ R 拮抗可能是获得有效且更安全的镇痛药的有用策略，并且是选择14u作为治疗疼痛的临床候选药物的基础。