A definite measure of occupancy exposures, seeking with non-radiolabeled in vivo 5-HT2A receptor occupancy and in vitro free fractions.

Unbound drug concentration in the brain would be the true exposure responsible for specific target occupancy. Drug exposures from preclinical are total concentrations of those over/underestimate the clinical dose projection. With the application of mass spectrometry, the current work proposes a definite measure of test drug exposures at serotonin-2A occupancy.

Assessment of sigma-1 receptor occupancy in mice with non-radiolabelled FTC-146 as a tracer.

The use of liquid chromatography coupled with mass spectrometry (LC-MS/MS) is advantageous in in-vivo receptor occupancy assays at pre-clinical drug developmental stages. Relatively, its application is effective in terms of high throughput, data reproducibility, sensitivity, and sample processing. In this perspective, we have evaluated the use of FTC-146 as a non-radiolabelled tracer to determine the sigma-1 receptor occupancy of test drugs in mice brain.

Simultaneous in-vivo receptor occupancy assays for serotonin 1A, 2A, and dopamine 2 receptors with the use of non-radiolabelled tracers: Proposed method in screening antipsychotics.

Introduction: Conventionally, receptor occupancy assays employ radiolabelled tracer. However, recent advances with non-radiolabelled tracers brought a revolution in target engagement assays. Non-radiolabelled tracer based receptor occupancy uses LC-MS/MS based quantification.

In-vivo rat striatal 5-HT4 receptor occupancy using non-radiolabelled SB207145.

Objectives: The objective of the current investigation was to develop a simple, rapid method for determining in-vivo 5-hydroxytryptamine type 4 receptor (5-HT4 R) occupancy in rat brain using non-radiolabelled SB207145 as a tracer for accelerating the drug discovery process.

Methods: In-vivo tracer optimization studies for tracer dose, survival intervals and brain distribution profile were carried out in rats. The tracer was pharmacologically validated using potent well-characterized 5-HT4 R ligands.