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

我们之前已经证明，我们的主要概念验证缓慢起效的长效多巴胺转运蛋白（DAT）抑制剂- CTDP-30640 -增强了脑电刺激奖励，增强了大脑中与奖励相关的丘脑核位点的细胞外多巴胺，刺激运动活动，并显著减少了实验室大鼠的静脉内可卡因自我给药-所有这些都具有非常显著的缓慢起效的长效作用特征。在同一时期，我们扩展了我们在这一领域的研究，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，因此决定仅通过全范围的临床前动物筛选模式运行这两种化合物中的一种- CTDP-31345。我们发现，CTDP-31345增强了脑电刺激奖励，增强了大脑中奖励相关的丘脑核位点的细胞外多巴胺，刺激了运动活动，并显著减少了实验室大鼠的静脉内可卡因自我给药-所有这些都具有非常明显的缓慢起效的长效作用特征。在一个不太有希望的注意，我们发现CTDP-31345在药物歧视动物行为范例中推广到可卡因，产生显著的运动敏化，并触发实验室大鼠的可卡因寻求行为复发，这些大鼠已经被脱毒并从先前的静脉注射可卡因习惯中行为消失。我们进一步发现CTDP-31345本身支持静脉内自我给药，尽管速率比可卡因低得多。 正如我们之前在化合物CTDP-30640中所见，化合物CTDP-31345的作用与可卡因的作用是相加的。 这促使我们探讨快速起效的短效阿片类药物海洛因和缓慢起效的长效阿片类药物美沙酮之间的关系，后者是众所周知的，作为阿片类药物成瘾患者的抗成瘾药物。 我们推断，在我们的临床前动物模型中研究海洛因-美沙酮的关系可能有助于可卡因和其他精神兴奋剂的药物开发策略。 我们发现，与可卡因和CTDP-30640或CTDP-31345 -美沙酮预处理之间的关系相反：1）剂量依赖性地抑制静脉注射海洛因自我给药，具有明确的行为消退模式，2）剂量依赖性地抑制海洛因增强的脑刺激奖励，和3）通过体内脑微透析测量的剂量依赖性抑制海洛因增强的奖赏相关和复发相关神经递质多巴胺的脑桥核水平。 这表明美沙酮对海洛因的作用具有功能性拮抗作用，这可以通过美沙酮产生μ阿片受体的细胞内化的能力来解释。 这些数据表明，为了取得完全成功，潜在的抗可卡因药物应该更充分地模仿美沙酮的作用-即，在功能上拮抗可卡因的作用（可能通过诱导多巴胺转运蛋白的构象变化），同时以类似可卡因的方式阻断转运蛋白（但具有缓慢起效的持久药代动力学），以便替代可卡因并补救被认为是可卡因“饥饿”和可卡因渴望的基础的脑化学物质缺乏。 此外，我们认为我们的化合物CTDP-30640和CTDP-31345显示出慢得多的起效和长得多的作用持续时间（例如，单次注射后96小时）比作为潜在抗成瘾药物疗法开发的其他DAT抑制剂（例如，GBR-12909）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药物开发策略的有效性。 在纯分子药物设计水平上，在本报告期间，我们还成功设计并合成了新的缓慢起效的长效哌甲酯类似物，其对多巴胺转运蛋白的选择性增加，从而产生了新的供试化合物- CTDP-32476。 CTDP-32476的初步实验表明，它可能具有作为精神兴奋剂成瘾的有效抗成瘾药物治疗的潜在效用。

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.