ABSTRACT:The pharmacokinetics and metabolism of the direct thrombin inhibitor dabigatran ( Antithrombotic therapy plays an important role in the prevention and treatment of thromboembolic disorders. However, currently available agents are subject to certain limitations. Oral vitamin K antagonists, such as warfarin, have unpredictable pharmacokinetics and show numerous drug and food interactions (Ansell et al., 2004), whereas unfractionated and low molecular weight heparins and fondaparinux require parenteral administration. An orally active direct thrombin inhibitor would offer a number of potential advantages over these agents (Weitz and Bates, 2005).Dabigatran is a reversible, competitive, direct thrombin inhibitor that has been shown to be an effective antithrombotic agent in animal models (Stassen et al., 2001; Wienen et al., 2001a,b) and to be efficacious and safe in the prevention of deep vein thrombosis in patients undergoing elective total hip or knee replacement (Eriksson et al., 2005). Dabigatran etexilate is currently in Phase III development for primary prevention of venous thromboembolism (VTE) in patients undergoing major orthopedic surgery, acute VTE treatment, and VTE secondary prevention, as well as stroke prevention in patients with atrial fibrillation. Pharmacokinetic studies in healthy volunteers and orthopedic surgery patients showed that dose-dependent concentrations of dabigatran are achieved after p.o. administration of dabigatran etexilate, with peak concentrations reached after approximately 2 h and with a slight delay up to 6 h on the day of surgery (Eriksson et al., 2004(Eriksson et al., , 2005Stangier et al., 2005).This article describes a series of in vivo and in vitro studies performed to investigate the pharmacokinetics and metabolism of dabigatran in humans. ABBREVIATIONS: Dabigatran, -alanine, N-[[2-[[[4-[[[(hexyloxy) Materials and Methods Reference

ABSTRACT:The pharmacokinetics and metabolism of linagliptin (BI1356, 8-(3R-amino-piperidin-1-yl)-7-but-2-ynyl-3-methyl-1-(4-methylquinazolin-2-ylmethyl)-3,7-dihydro-purine-2,6-dione) were investigated in healthy volunteers. Type 2 diabetes mellitus (T2DM) accounts for 90 to 95% of all diabetes cases and its incidence is increasing (Wild et al., 2004). The high frequency of complications associated with the disease leads to a significant reduction in life expectancy. One relatively new therapeutic option is the inhibition of the enzyme dipeptidyl peptidase-4 (DPP-4), which is responsible for the rapid degradation of the incretin hormones glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide. After food intake, both hormones augment the action of insulin (Holst and Gromada, 2004;Mari et al., 2005;Drucker and Nauck, 2006;Drucker, 2007). The plasma half-life of GLP-1 is limited to a few minutes because of its rapid proteolytic degradation by DPP-4 (Graefe-Mody et al., 2009). Inhibitors of DPP-4 prolong the half-life of GLP-1 and glucose-dependent insulinotropic polypeptide, which leads to increases in glucose-dependent insulin secretion, inhibition of endogenous glucose production, decreased blood glucose, and the induction of feelings of satiety (Drucker, 2002;Nauck et al., 2003;Holst and Gromada, 2004).Linagliptin is a novel, orally active, highly specific, and potent inhibitor of DPP-4 that is currently in clinical development for the treatment of T2DM (Eckhardt et al., 2007;Fuchs et al., 2009b). Early clinical studies with linagliptin suggested a reduction in the glycated hemoglobin levels in patients with T2DM while maintaining a placebo-like safety and tolerability profile (Heise et al., 2009;Retlich et al., 2009). The pharmacokinetics of linagliptin were previously shown to be nonlinear due to target-mediated, concentrationdependent changes in binding to DPP-4 (Hüttner et al., 2008; Thomas et al., 2008a,b;Fuchs et al., 2009a;Heise et al., 2009).We report here a series of in vivo and in vitro studies performed to further establish the pharmacokinetics and metabolism of linagliptin in humans after intravenous and oral administration.Article, publication date, and citation information can be found at http://dmd.aspetjournals.org. doi:10.1124/dmd.109.031476.ABBREVIATIONS: T2DM, type 2 diabetes mellitus; DPP-4, dipeptidyl peptidase-4; GLP-1, glucagon-like peptide-1; BI1355, 8-(3S-amino-piperidin-1-yl)-7-but-2-ynyl-3-methyl-1-(4-methyl-quinazolin-2-ylmethyl)-3,7-dihydro-purine-2,6-dione; CD1790, 7-but-2-ynyl-8-(3S-hydroxy-piperidin-1-yl)-3-methyl-1-(4-methyl-quinazolin-2-ylmethyl)-3,7-dihydro-purine-2,6-dione; CD1789, 7-but-2-ynyl-8-(3R-hydroxy-piperidin-1-yl)-3-methyl-1-(4-methyl-quinazolin-2-ylmethyl)-3,7-dihydro-purine-2,6-dione; CD10604, 7-but-2-yn-1-yl-3-methyl-1-[(4-methylquinazolin-2-yl)methyl]-8-(3-oxopiperidin-1-yl)-3, 7-dihydro-1H-purine-2,6-dione; LOQ, lower limit of quantification; LC-MS/MS, liquid chromatography-tandem mass spectrometry; HPLC, high-performance liquid chromat...

Metabolite quantification and profiling continues to grow in importance in today's drug development. The guidance provided by the 2008 FDA Metabolites in Safety Testing Guidance and the subsequent ICH M3(R2) Guidance (2009) has led to a more streamlined process to assess metabolite exposures in preclinical and clinical studies in industry. In addition, the European Bioanalysis Forum (EBF) identified an opportunity to refine the strategies on metabolite quantification considering the experience to date with their recommendation paper on the subject dating from 2010 and integrating the recent discussions on the tiered approach to bioanalytical method validation with focus on metabolite quantification. The current manuscript summarizes the discussion and recommendations from a recent EBF Focus Workshop into an updated recommendation for metabolite quantification in drug development.

In vivo drug metabolism studies with low concentrations of analytes and high matrix burden are challenging. Of special interest are 'first-in-man' studies in early stages of pharmaceutical development that do not use 14 C labeled drug candidates. Beside conventional MS-fishing techniques which are biased towards known/expected metabolites and mass defect filtration procedures, this paper focuses on the untargeted/unbiased analysis of drug related compounds in complex matrices using two orthogonal separation techniques: UPLC and TWIMS. Standard sample material after oral administration of a drug compound to rats was investigated by UPLC/ TWIMS in MS E acquisition mode using interlaced collision energies for the parallel detection of [M+H] + parent ions and fragments. Due to the fragmentation after ion mobility separation in the transfer region of the Synapt G2-triwave device, [M+H] + ion species are aligned with their related fragments by virtue of possessing the same retention time and drift time profile. Four dimensional data analysis of the continuum raw data was performed by automated peak picking and alignment within the MS E viewer software. As result, completely purified MS-and MS/MS-data of metabolites were extracted from raw mass data with high matrix burden and were used without compromise for structure elucidation. This analytical methodology is universally applicable for the unbiased/untargeted and robust analysis of any analyte of interest in complex matrices, including small molecules, peptides and proteins. The high quality data files can be used as data repositories for the purpose of retrospective analysis which is of particular interest for the long term process in drug development.

The human absorption, distribution, metabolism, and excretion (hADME) study is the cornerstone of the clinical pharmacology package for small molecule drugs, providing comprehensive information on the rates and routes of disposition and elimination of drug-related material in humans through the use of 14 C-labeled drug. Significant changes have already been made in the design of the hADME study for many companies, but opportunity exists to continue to re-think both the design and timing of the hADME study in light of the potential offered by newer technologies, that enable flexibility in particular to reducing the magnitude of the radioactive dose used. This paper provides considerations on the variety of current strategies that exist across a number of pharmaceutical companies and on some of the ongoing debates around a potential move to the so called "human first/human only" approach, already adopted by at least one company. The paper also provides a framework for continuing the discussion in the application of further shifts in the paradigm.