Tracking problems and possible solutions in the quantitative determination of small molecule drugs and metabolites in biological fluids using liquid chromatography-mass spectrometry.

During the last decade, quantification of low molecular weight molecules using liquid chromatography-tandem mass spectrometry in biological fluids has become a common procedure in many preclinical and clinical laboratories. This overview highlights a number of issues involving "small molecule drugs", bioanalytical liquid chromatography-tandem mass spectrometry, which are frequently encountered during assay development. In addition, possible solutions to these issues are proposed with examples in some of the case studies. Topics such as chromatographic peak shape, carry-over, cross-talk, standard curve non-linearity, internal standard selection, matrix effect, and metabolite interference are presented. Since plasma is one of the most widely adopted biological fluid in drug discovery and development, the focus of this discussion will be limited to plasma analysis. This article is not intended to be a comprehensive overview and readers are encouraged to refer to the citations herein.

High-throughput determination of ultra-low concentrations of LAG078, a lipid modulator, in human plasma.

A high throughput method with ultra-low level quantification limit (10 pg/ml) was developed and validated for the quantitative determination of LAG078, a lipid modulator, in human plasma to support clinical studies employing low doses of the compound. The method consisted of reverse phase chromatographic separation of the analyte from plasma extract followed by electrospray ionization (ESI) in the negative ion mode and tandem mass spectrometry in the multiple reaction monitoring mode (MRM). Extraction was performed using a combination of protein precipitation and liquid-liquid extraction in the 96-well plate format to increase the throughput of the method. Optimised chromatographic separation in a short and high-resolution column (50 mm x 2.0 mm i.d., 3 microm particle size) coupled with MRM mode of detection yielded clean chromatograms with minimal signal suppression. The standard curve was linear (r=0.996) within the concentration range of 0.01 (lower limit of quantification) to 50 ng/ml using 0.5 ml of human plasma. The accuracy of the method varied from 95-101% with a precision (CV) of 5.29-13.2% over the concentration range. The method was simple and rapid.

Determination of LAG078, a lipid-lowering compound, in dog plasma using liquid chromatography-tandem mass spectrometry: application in a toxicokinetic study.

A high throughput method was developed and validated for the quantitative determination of LAG078, a lipid-lowering compound, in dog plasma obtained during toxicokinetic studies. The method was based on reverse phase liquid chromatographic separation of the analyte from plasma extract followed by turbo-ionspray (TIS) in the negative ion mode and tandem mass spectrometry in the multiple reaction monitoring (MRM) mode. Extraction was performed using a combination of protein precipitation and liquid-liquid extraction in the 96-well plate format to increase the throughput of the method. Optimized chromatographic separation under basic condition (pH approximately 10) in a short polymer based column (50 mm x 2.0 mm i.d.) coupled with MRM mode of detection yielded clean chromatograms with minimal signal suppression. The standard curve was linear (r = 0.997) within the concentration range of 0.05 (lower limit of quantification; LLOQ) to 50 ng/ml using only 0.1 ml of dog plasma. The accuracy of the method varied from 95 to 100% with a precision (CV) of 3.04-10.8% over the concentration range. The method was simple, rapid, and robust.

Rapid analysis of MMI270B, an inhibitor of matrix metalloproteases in human plasma by liquid chromatography-tandem mass spectrometry: matrix interference in patient samples.

A high-throughput method was developed and validated for the quantitative determination of MMI270B, an inhibitor of matrix metalloprotease (MMP) enzymes, in human plasma. The method was based on reverse-phase chromatographic separation of the analyte from plasma extract followed by atmospheric pressure chemical ionization (APCI) and tandem mass spectrometry in the selected reaction monitoring mode (SRM). Extraction was performed using simple protein fi ltration in the 96-well plate format to increase the throughput of the method. Optimised chromatographic separation in a short column (30 x 4.6 mm i.d.) coupled with positive APCI mode of ionization followed by selective SRM mode of detection yielded clean chromatograms with minimal signal suppression. The chromatographic conditions resolved isobaric interference peaks observed in samples from patients dosed with MMI270B. The standard curve was linear (r = 0.997) within the concentration range of 1.04 (lower limit of quanti fi cation) to 1040 ng/mL using 0.1 mL of human plasma. The accuracy of the method varied from 93.6 to 103% with a precision of 2.17-6.71% over the concentration range. The method was simple, rapid, and robust with an analyte recovery of >98%.