Determination of brain and plasma drug concentrations by liquid chromatography/tandem mass spectrometry

Abstract

A method is described for the evaluation of drug concentrations in plasma and brain from treated rats. The analyte is recovered from plasma or brain homogenate by liquid‐liquid extraction and subsequently analyzed by liquid chromatography/tandem mass spectrometry (LC/MS/MS). A simple experimental protocol renders the procedure valuable for obtaining information rapidly on brain penetration and plasma exposure of specific classes of compounds. This methodology has been applied to evaluate brain penetration with 30 different compounds from the same discovery program. In an attempt to increase throughput in our screening efforts, mixture dosing was evaluated. Results from single compound administration were compared with results following administration of a mixture of four compounds. Preliminary results, with specific classes of compounds, show no major differences (ranking order) in brain or plasma concentrations between mixture dosing and single compound administration, suggesting that mixture dosing could be applicable to brain penetration studies in the drug discovery phase. Copyright © 2000 John Wiley & Sons, Ltd.

LC/MS/MS in Drug Development: Targeting the Brain

“…Verification of applicability with individual compound administration suggested no major differences (ranking order) in brain or plasma concentrations between mixture dosing and single compound administration (31). Frick et al (32) showed for 89 triazines that concentrations of compounds at one hour post-dose in the brains of mice following cassette dosing (n=9) were correlated with those observed after dosing with discrete compounds.…”

“…Analyzed with LC/MS/MS, a brain homogenate was used by Tamvakopoulos et al (31) to determine brain penetration of a group of compounds following cassette dosing. Verification of applicability with individual compound administration suggested no major differences (ranking order) in brain or plasma concentrations between mixture dosing and single compound administration (31).…”

The application of cassette dosing for pharmacokinetic screening in small-molecule cancer drug discovery

“…However, in some of the published studies, there was no attempt to validate the approach in this manner and only cassette dosing pharmacokinetic data are presented. Some groups have extended the cassette dosing approach to assess brain uptake in addition to plasma exposure (39,45,46). Very few publications have described the experience of the implementation of cassette dosing in the context of a particular drug discovery project or explored the problems associated with this approach.…”

Automated sample preparation and purification of homogenized brain tissues

“…Standard curve and QCs were prepared by adding aliquots of 25 L working standard solutions, which were made from serial dilution of a 40 g/mL stock solution at concentrations of 2,4,8,20,40,80,200, 400, 800, 2000, 4000 ng/mL. 100 L aliquots of dosed brain tissue homogenates were transferred from their respective 14-mL sample tubes to the source plate.…”

“…Recently, automated 96-well sample preparations using robotics have been reported in numerous studies [4][5][6][7][8]. In these applications, robotic liquid handling, liquid sample preparation for plasma or urine analysis, as well as liquid-liquid extractions (LLE) and solid phase extraction (SPE) have facilitated high throughput quantitative analysis in drug discovery.…”