Improving the treatment of Parkinson's disease: Structure-based development of novel 5-HT2A receptor antagonists/inverse agonists

Pimavanserin is a selective 5-HT2A receptor antagonist and inverse agonist approved by the FDA in 2016, which is used to treat patients with Parkinson's disease psychosis (PDP). But pimavanserin has potential risk with increasing mortality in elderly patients and also increasing the risk of QT interval prolongation in patients. Therefore, searching for new drugs with high efficacy and low toxicity is urgently needed. Based on the docking study of pimavanserin, a series of novel pimavanserin derivatives (7-1∼7-37) were designed and synthesized. The biological activities were evaluated by cell assays and compound 7-16 exhibited 50-fold higher 5-HT2A receptor antagonist activity (IC50 = 0.54 vs 27.3 nM) and 23-fold higher inverse agonist activity (IC50 = 2.1 vs 50 nM) than pimavanserin. Moreover, 7-16 showed increased potency window between the 5-HT2A and hERG activities than pimavanserin. Furthermore, compound 7-16 demonstrated excellent in vitro and in vivo pharmacokinetics, 4-fold more improvement in functional activity in vivo, and good safety profile. Therefore, compound 7-16 represents a potentially promising candidate as a novel anti-PDP agent that warrants further investigation.