Design, optimization, and in vivo evaluation of a series of pyridine derivatives with dual NK1 antagonism and SERT inhibition for the treatment of depression.

A series of substituted pyridines, ether linked to a phenylpiperidine core were optimized for dual NK(1)/SERT affinity. Optimization based on NK(1)/SERT binding affinities, and minimization of off-target ion channel activity lead to the discovery of compound 44. In vivo evaluation of 44 in the gerbil forced swim test (a depression model), and ex-vivo NK(1)/SERT receptor occupancy data support the potential of a dual acting compound for the treatment of depression.

Ex vivo assessment of binding site occupancy of monoamine reuptake inhibitors: methodology and biological significance.

The goal of this study was to develop and validate ex vivo binding assays for serotonin (SERT), norepinephrine (NET) and dopamine (DAT) transporters, and to use these assays to evaluate the binding site occupancy of triple and double monoamine reuptake inhibitors in rat brains. This study demonstrated that while autoradiographic methods provided anatomic precision and regional resolution, the homogenate binding method for site occupancy assessment yielded comparable sensitivity with markedly improved throughput. For ex vivo binding assays, the reduction of temperature and time during the in vitro process (primarily incubation with a radioligand) markedly decreased the dissociation of test agents from binding sites in brain tissues. This reduction, in turn, minimized the potential for underestimation of site occupancy in vivo especially for test compounds with affinity >10nM. The ratios of measured occupancy ED(50) values (doses at which 50% occupancy occurs) among SERT, NET and DAT sites for duloxetine, venlafaxine, nomifensine, indatraline, DOV 21,947 and DOV 216,303 were consistent with the ratios of the in vitro affinities between these target binding sites. The biological relevance of the monoamine transporter occupancy for these compounds is discussed.