Furthermore our sample preparation uses
Furthermore, our sample preparation uses a simple isolation procedure. Numerous CYP450 phenotyping methods employed extensive extraction procedures for sample preparation such as dual liquid extraction or solid phase extraction which are costly and time consuming , , , , , , , , . A new method was recently reported by Tanaka et al.  for probe drug extraction i.e. “the Ostro Pass-Through Sample preparation” which showed a significant improvement in bioanalysis compared to the use of protein precipitation solely. Extraction recoveries obtained using their method ranged between 66.4% and 116% which are quite comparable to the recoveries attained using our methods i.e. 81.7% and 115.3%. In addition, their method showed lower correlation coefficients (between 0.946 and 0.992). Therefore there is no added benefit in adding an extra step (filtration through a sorbent) with extra cost to the sample preparation process. Finally, the CYP450 phenotyping method reported by Stewart et al.  using UPLC–MS/MS raised many advantages compared to previous published methods in term of sensitivity, low doses of probe drugs, low blood volume and the rapidity and the simplicity of their extraction methods. Their assay allows the determination of five probe drugs to GTP-Binding Protein Fragment, G alpha for CYP1A2, 2C9, 2C19, 2D6 and 2E1 in human plasma or urine. However, this cocktail approach displays two major limitations, i.e. the utilization of mephenytoin and debrisoquin as probes drugs to phenotype for CYP2C19 and 2D6 respectively, and it did not contain any probe drug to measure CYP3A4 activity which metabolizes approximately 30–50% of drugs used in clinic .
Our methods demonstrate many advantages compared to previously published methods for the evaluation of CYP450 activities by LC–MS/MS. These current assays offer an improvement in sensitivity allowing the detection of seven probe drugs and their respective metabolites in plasma and urine in polymedicated patients , , , .The methods presented in this manuscript have been applied to a clinical study in 30 polymedicated patients to identify properly phenotypic CYP450 activities without induction of any drug side effects.
Conclusion Funding This work was supported by the Canadian Institutes of Health Research (CIHR; grant #299309). Sophie Gravel is recipient of a studentship from the Fonds de la Recherche du Québec en Santé (FRQS). Veronique Michaud is the recipient of a research scholarship from FRQS in partnership with the Institut national d’excellence en santé et en services sociaux (INESSS).
Introduction Widespread application of chiral compounds results in their ubiquitous occurrence in environment and accumulation in organisms as well as subsequently toxic effects on organisms (Lewis et al., 1999). In general, the enantiomers of chiral compounds possess enantioselective biological activities and toxicity due to their different structural properties (Sekhon, 2009). However, chiral compounds have been treated as racemic mixtures in their environmental fate and ecotoxicity for a long time. In recent years, the stereoselectivity-related environmental safety of chiral compounds has become a popular focus of attention (Liu et al., 2005, Wang et al., 2014). The enantiomeric ratio (ER) of chiral compounds accumulated in organisms has been found to be different among species (Borga and Bidleman, 2005, Harner et al., 1999, Warner et al., 2005, Wiberg et al., 2000), indicating enantioselective accumulation of chiral compounds are species-specific. The ER of α-HCH was detected to vary along the polar bear food chain and increase from ≈1.0 in cod to 2.3 in polar bear (Wiberg et al., 2000). In arctic marine invertebrates, depletion of the (+)-α-HCH enantiomer increased from ice fauna to zooplankton, and to benthos (Borga and Bidleman, 2005, Harner et al., 1999). Compared to α-HCH, chlordane and o,p'-DDT showed stronger enantioselective bioaccumulation in benthic amphipods than in zooplankton and ice fauna (Borga and Bidleman, 2005). In the similar area, enantioselective species-specific biotransformation of individual PCB stereoisomers has also been reported in marine food web. Greater nonracemic enantiomeric fractions (EFs) of PCBs were observed in several seabird species and ringed seals, but racemic EFs were found in the prey such as zooplankton and fish (Warner et al., 2005). Besides in animals, the accumulation of chiral compounds has also been found to be enantioselective species-specific in plants (Wang et al., 2014, Schneiderheinze et al., 1999). However, the mechanisms of enantioselective species-specific biotransformation of chiral compounds have received little attention and remain unclear so far.