Slow-onset long-acting dopamine transport inhibitors for treating drug addiction

我们之前已经证明，我们的主要概念证明慢效长效多巴胺转运体（DAT）抑制剂- CTDP-30640 -增强脑电刺激奖励，增强大脑中与奖励相关的伏隔核位点的细胞外多巴胺，刺激运动活动，并显着减少实验室大鼠静脉注射可卡因的自我给药-所有这些都具有非常明显的慢效长效作用。在同一时期，我们扩展了我们在该领域的研究，包括我们使用计算机辅助分子药物设计和我们自己开发的药效团DAT模型重新设计和合成的另外三种化合物- CTDP-31345， CTDP-31346和CTDP-32476。由于CTDP-31345和CTDP-31346的化学结构高度相似，我们决定只运行这两种化合物中的一种，即CTDP-31345，通过全面的临床前动物筛选模式。我们发现CTDP-31345增强脑电刺激奖励，增强大脑中与奖励相关的伏隔核的细胞外多巴胺，刺激运动活动，并显着减少实验室大鼠静脉注射可卡因的自我给药-所有这些都具有非常明显的慢效长效作用。在一个不太乐观的情况下，我们发现CTDP-31345在药物识别动物行为范式中推广到可卡因，产生戏剧性的运动致敏，并在药理学上解毒并从先前静脉注射可卡因的习惯中行为消失的实验室大鼠中引发可卡因寻求行为的复发。我们进一步发现CTDP-31345本身支持静脉自我给药，尽管比可卡因低得多。正如我们之前在化合物CTDP-30640中看到的那样，化合物CTDP-31345的作用与可卡因的作用是叠加的。这促使我们探索快效短效阿片类药物海洛因与慢效长效阿片类药物美沙酮之间的关系，后者作为阿片类药物成瘾患者的抗成瘾药物具有众所周知的临床疗效。我们认为，在我们的临床前动物模型中研究海洛因和美沙酮的关系可能会为可卡因和其他精神兴奋剂的药物开发策略提供启示。我们发现，与可卡因与CTDP-30640或CTDP-31345 -美沙酮预处理的关系相反：1)剂量依赖性地抑制静脉注射海洛因自我给药，具有明显的行为消失模式；2)剂量依赖性地抑制海洛因增强的脑刺激奖励；3)剂量依赖性地抑制海洛因增强的伏隔核奖励相关和复发相关的神经递质多巴胺水平，通过体内脑微透析测量。这表明美沙酮对海洛因的作用具有功能性拮抗作用，这可以用美沙酮产生细胞内化mu阿片受体的能力来解释。这些数据表明，为了完全成功，潜在的抗可卡因药物应该更充分地模仿美沙酮的作用，即，在功能上对抗可卡因的作用（可能是通过诱导多巴胺转运体的构象变化），同时以类似可卡因的方式阻断转运体（但具有缓慢的持久药代动力学），以替代可卡因，并纠正被认为是导致可卡因“饥饿”和可卡因渴望的大脑化学物质缺乏。此外，我们相信，我们的化合物CTDP-30640和CTDP-31345比其他作为潜在抗成瘾药物治疗（如GBR-12909）开发的DAT抑制剂表现出更慢的起效和更长的作用持续时间（例如，单次注射后96小时），这一事实证明了我们的药效团药物设计模型，我们的分子药物设计程序和我们的前药物开发策略的有效性。在纯分子药物设计水平上，在报告期间，我们还成功地设计和合成了新的慢效长效哌醋甲酯类似物，增加了多巴胺转运体的选择性，从而产生了新的测试化合物- CTDP-32476。CTDP-32476的初步实验表明，它可能作为一种有效的抗成瘾药物治疗精神兴奋剂成瘾的潜在效用。

We had previosuly shown that our lead proof-of-concept slow-onset long-acting dopamine transporter (DAT) inhibitor - CTDP-30640 - enhances electrical brain-stimulation reward, enhances extracellular dopamine in the reward-related nucleus accumbens locus in the brain, stimulates locomotor activity, and significantly reduces intravenous cocaine self-administration in laboratory rats - all with a very pronounced slow-onset long-acting profile of action. During this same period, we extended our research in this area to include three additional compounds that we designed and synthesized de novo using computer-assisted molecular drug design and a pharmacophore DAT model that we ourselves developed - CTDP-31345, CTDP-31346, and CTDP-32476. Because of the high degree of similarity between the chemical structures of CTDP-31345 and CTDP-31346, a decision was made to run only one of those two compounds through a full range of preclinical animal screening paradigms - CTDP-31345. We found that CTDP-31345 enhances electrical brain-stimulation reward, enhances extracellular dopamine in the reward-related nucleus accumbens locus in the brain, stimulates locomotor activity, and significantly reduces intravenous cocaine self-administration in laboratory rats - all with a very pronounced slow-onset long-acting profile of action. On a less promising note, we found that CTDP-31345 generalizes to cocaine in the drug-discrimination animal behavioral paradigm, produces dramatic locomotor sensitization, and triggers relapse to cocaine-seeking behavior in laboratory rats who has been pharmacologically detoxified and behaviorally extinguished from their prior intravenous cocaine-taking habits. We further found that CTDP-31345 itself supports intravenous self-administration, albeit at a much lower rate than cocaine. As we had previously seen with compound CTDP-30640, the effects of compound CTDP-31345 are additive with those of cocaine. This prompted us to explore the relationship between the fast-onset short-acting opiate heroin and the slow-onset long-acting opiate methadone, the latter of which is well-known to have clinical efficacy as an anti-addiction medication for patients addicted to opiates. We reasoned that investigating the heroin-methadone relationship in our preclinical animal models might shed light on medication development stratgies for cocaine and other psychostimulants. We found that - in contrast to the relationship between cocaine and CTDP-30640 or CTDP-31345 - methadone pretreatment: 1) dose-dependently inhibited intravenous heroin self-administration with a clear behavioral extinction pattern, 2) dose-dependently inhibited heroin-enhanced brain-stimulation reward, and 3) dose-dependently inhibited heroin-enhanced nucleus accumbens levels of the reward-related and relapse-related neurotransmitter dopamine as measured by in vivo brain microdialysis. This suggests a functional antagonism by methadone of heroin's actions, which may be explained by methadone's ability to produce cellular internalization of the mu opioid receptor. These data suggest that in order to be fully successful, potential anti-cocaine medications should more fully emulate methadone's action - i.e., functionally antagonizing cocaine's actions (perhaps by inducing conformational changes in the dopamine transporter) while at the same time blocking the transporter in a cocaine-like manner (but with slow-onset long-lasting pharmacokinetics) so as to substitute for cocaine and remediate the brain chemical deficiency believed to underlie cocaine "hunger" and cocaine craving. In addition, we believe that the facts that our compounds CTDP-30640 and CTDP-31345 show much slower onsets and much longer durations of action (e.g., 96 hours following a single injection) than other DAT inhibitors developed as potential anti-addiction pharmacotherapies (e.g., GBR-12909) demonstrate the validity of our pharmacophore drug design model, our molecular drug design procedures, and our pro-drug medication development strategy. On a purely molecular drug design level, during the reporting period we also successfully designed and synthesized new slow-onset long-duration methylphenidate analogs with increased selectivity for the dopamine transporter, resulting in a new test compound - CTDP-32476. Preliminary experiments with CTDP-32476 suggest that it may have potential utility as an effective anti-addiction pharmacotherapy for psychostimulant addiction.