Pimavanserin (ACP-103)(ACP-103) is an effective and specific 5-HT2A receptor inverse agonist (mean pIC50: 8.7, in the cell-based functional assay). Pimavanserin is an atypical antipsychotic used in the treatment of hallucinations and psychosis in patients with Parkinson disease.

5-HT2A:8.7(pIC50)

Pimavanserin (ACP-103) 在异源表达的人类5-HT2A受体上与[3H]ketanserin的结合发生竞争性拮抗作用，其平均pKi值在膜中为9.3，在整个细胞中为9.70。 Pimavanserin 对人类5-HT2C受体显示出较低的亲和力（膜中平均pKi为8.80，整个细胞中为8.00，通过放射配体结合测定）和作为反向激动剂的效力较低（R-SAT中平均pIC50为7.1），并且在5-HT2B受体、多巴胺D2受体和其他人类单胺受体上缺乏亲和力和功能活性[1]。 Pimavanserin (ACP-103) 对5-HT2A受体具有高度选择性，对其他受体缺乏亲和力，这些受体在包括65种不同分子靶标的广泛筛选中；Pimavanserin 唯一显示出亲和力的其他受体是5-HT2C，根据测验，Pimavanserin 对5-HT2A受体的选择性大约是对5-HT2C受体的30倍[2]。

Pimavanserin（ACP-103）是一种强效、有效、口服活性的5-HT2A受体逆向激动剂，具有与抗精神病化合物效用一致的行为药理学特征。Pimavanserin 减轻由5-HT2A受体激动剂（±）-2,5-二甲氧基-4-碘苯丙胺 hydrochloride 在大鼠中诱发的头摆行为（3 mg/kg p.o.）和预脉冲抑制缺损（1-10 mg/kg s.c.），并减轻由N-甲基-D-天冬氨酸受体非竞争性拮抗剂5H-二苯并[a,d]环庚烯-5,10-亚胺（dizocilpine maleate; MK-801）在小鼠中诱发的过动行为（0.1 和 0.3 mg/kg s.c.; 3 mg/kg p.o.），这与5-HT2A受体作用机制在体内和类似抗精神病化合物的效用一致。Pimavanserin 在大鼠中展示出>42.6%的口服生物利用度[1]。

For the membrane binding, NIH-3T3 cells are grown to 70% confluence in 15 cm2 dishes and transfected with 10 μg of receptor plasmid DNA using Polyfect transfection reagent. Two days after transfection, cells expressing the desired serotonin receptor are homogenized in 20 mM HEPES/10 mM EDTA and spun down at 11,000 g at 4°C for 30 min. The supernatant is discarded, and the pellet is resuspended in 20 mM HEPES/1 mM EDTA and spun down at the same setting. The pellet is then resuspended in 20 mM HEPES/0.5 mM EDTA, and membranes are used for binding assays. Bradford analysis is used to determine total membrane protein. Kd and Bmax values are derived from 12-point concentration experiments using 1 nM [3H]ketanserin for the 5-HT2A receptor and 3 nM [3H]mesulergine for the 5-HT2B and 5-HT2C receptors. Membranes are incubated at room temperature for 3 h with various concentrations of test ligand in the presence of a fixed concentration of radioligand. The suspension is filtered as explained below for whole-cell binding, washed with ice-cold buffer, and dried, and radioactivity is determined using TopCount[1].

Pimavanserin (ACP-103) is dissolved in DMSO and stored, and then diluted with appropriate media before use[1]. For the whole-cell binding, 6 million human embryonic kidney 293T cells are plated in 10-cm dishes and transfected with 5 μg of plasmid DNA using Polyfect. Two days after transfection, cells are harvested with 10 mM EDTA, washed, and resuspended in binding buffer (1× DMEM with 0.1% bovine serum albumin). Then, 60,000 cells transfected with the 5-HT2A receptor or 20,000 cells transfected with the 5-HT2C-INI receptor are incubated at 37°C for 3 h in the presence of 5 nM radioligand ([3H]ketanserin for 5-HT2A receptors and [3H]mesulergine for 5-HT2C-INI receptors) and varying concentrations of ligands (total volume 100 μL in a 96-well plate). Cells are filtered onto a 96-well GF/B filter plate and washed with 300 mL of wash buffer (25 mM HEPES, 1 mM CaCl2, 5 mM MgCl2, and 0.25 M NaCl) using a Filtermate 196 harvester. The filter plates are dried under a heat lamp before addition of 50 μL of scintillation fluid to each well. Plates are counted on a TopCount. Separately, the hydrochloride salt form of Pimavanserin (10 μM) is evaluated at MDS Pharma Services for activity in a broad screen of radioligand binding assays at 65 different receptors[1].