Introduction: An active metabolite of buprenorphine (BUP), called norbuprenorphine (NorBUP), is implicated in neonatal opioid withdrawal syndrome when BUP is taken during pregnancy. Therefore, reducing or eliminating metabolism of BUP to NorBUP is a novel strategy that will likely lower total fetal exposure to opioids and thus improve offspring outcomes. Precision deuteration alters pharmacokinetics of drugs without altering pharmacodynamics. Here, we report the synthesis and testing of deuterated buprenorphine (BUP-D2).
Methods: We determined opioid receptor affinities of BUP-D2 relative to BUP with radioligand competition receptor binding assays, and the potency and efficacy of BUP-D2 relative to BUP to activate G-proteins via opioid receptors with [35S]GTPγS binding assays in homogenates containing the human mu, delta, or kappa opioid receptors. The antinociceptive effects of BUP-D2 and BUP were compared using the warm-water tail withdrawal assay in rats. Blood concentration versus time profiles of BUP, BUP-D2, and NorBUP were measured in rats following intravenous BUP-D2 or BUP injection.
Results: The synthesis provided a 48% yield and the product was ≥99% deuterated. Like BUP, BUP-D2 had sub-nanomolar affinity for opioid receptors. BUP-D2 also activated opioid receptors and induced antinociception with equal potency and efficacy as BUP. The maximum concentration and the area under the curve of NorBUP in the blood of rats that received BUP-D2 were over 19- and 10-fold lower, respectively, than in rats that received BUP.
Discussion: These results indicate that BUP-D2 retains key pharmacodynamic properties of BUP and resists metabolism to NorBUP and therefore holds promise as an alternative to BUP.
简介:丁丙诺啡(BUP)的一种活性代谢物--诺丁诺啡(Norbuprenorphine,NorBUP)与孕期服用 BUP 的新生儿阿片类药物戒断综合征有关。因此,减少或消除 BUP 对 NorBUP 的代谢是一种新策略,有可能降低胎儿对阿片类药物的总暴露量,从而改善后代的预后。精确氘化可在不改变药效学的情况下改变药物的药代动力学。在此,我们报告了氘代丁丙诺啡(BUP-D2)的合成和测试:方法:我们通过放射性竞争受体结合试验确定了 BUP-D2 相对于 BUP 的阿片受体亲和力,并通过[35S]GTPγS 结合试验确定了 BUP-D2 相对于 BUP 通过阿片受体激活 G 蛋白的效力和功效。利用大鼠温水断尾试验比较了 BUP-D2 和 BUP 的抗痛觉作用。在大鼠静脉注射 BUP-D2 或 BUP 后,测量了 BUP、BUP-D2 和 NorBUP 的血药浓度随时间变化的曲线:合成收率为 48%,产品氚化率≥99%。与 BUP 一样,BUP-D2 对阿片受体的亲和力也在纳摩尔以下。BUP-D2 也能激活阿片受体并诱导抗痛觉,其效力和疗效与 BUP 相当。接受 BUP-D2 治疗的大鼠血液中 NorBUP 的最大浓度和曲线下面积分别比接受 BUP 治疗的大鼠低 19 倍和 10 倍以上:这些结果表明,BUP-D2 保留了 BUP 的主要药效学特性,并能抵抗代谢为 NorBUP,因此有望成为 BUP 的替代品。