The identification of new sleep drugs poses particular challenges in drug discovery owing to disease-specific requirements such as rapid onset of action, sleep maintenance throughout major parts of the night, and absence of residual next-day effects. Robust tools to estimate drug levels in human brain are therefore key for a successful discovery program. Animal models constitute an appropriate choice for drugs without species differences in receptor pharmacology or pharmacokinetics. Translation to man becomes more challenging when interspecies differences are prominent. This report describes the discovery of the dual orexin receptor 1 and 2 (OX1 and OX2) antagonist ACT-541468 out of a class of structurally related compounds, by use of physiology-based pharmacokinetic and pharmacodynamic (PBPK-PD) modeling applied early in drug discovery. Although all drug candidates exhibited similar target receptor potencies and efficacy in a rat sleep model, they exhibited large interspecies differences in key factors determining their pharmacokinetic profile. Human PK models were built on the basis of in vitro metabolism and physicochemical data and were then used to predict the time course of OX2 receptor occupancy in brain. An active ACT-541468 dose of 25 mg was estimated on the basis of OX2 receptor occupancy thresholds of about 65% derived from clinical data for two other orexin antagonists, almorexant and suvorexant. Modeling predictions for ACT-541468 in man were largely confirmed in a single-ascending dose trial in healthy subjects. PBPK-PD modeling applied early in drug discovery, therefore, has great potential to assist in the identification of drug molecules when specific pharmacokinetic and pharmacodynamic requirements need to be met.
由于特定疾病的要求,如快速起效、在整个夜间的主要时间段保持睡眠状态以及次日无残留影响等,确定新的睡眠药物给药物发现带来了特殊的挑战。因此,估算药物在人脑中含量的可靠工具是成功发现药物的关键。对于在受体药理学或药代动力学方面没有物种差异的药物,动物模型是一个合适的选择。当种间差异突出时,向人体转化就变得更具挑战性。本报告介绍了通过在药物发现早期应用基于生理学的药代动力学和药效学(PBPK-PD)模型,从一类结构相关的化合物中发现了
奥曲肽受体 1 和 2(OX1 和 OX2)双重拮抗剂 ACT-541468。虽然所有候选药物在大鼠睡眠模型中都表现出相似的靶受体效力和疗效,但在决定药代动力学特征的关键因素上却表现出巨大的种间差异。根据体外代谢和理化数据建立了人体 PK 模型,然后用于预测 OX2 受体在大脑中的占据时间过程。根据另外两种
奥曲肽拮抗剂(almorexant 和 suvorexant)的临床数据得出的约 65% 的 OX2 受体占据阈值,估算出 ACT-541468 的有效剂量为 25 毫克。在对健康受试者进行的单次升剂量试验中,ACT-541468 的人体模型预测结果基本得到了证实。因此,当需要满足特定的药代动力学和药效学要求时,在药物发现的早期应用 PBPK-PD 建模在协助确定药物分子方面具有巨大的潜力。