Exploring in vivo metabolism and excretion of QO-58L using ultra-high-performance liquid chromatography coupled with tandem mass spectrometry.

QO-58 lysine (QO-58L) as a new potassium channel opener, reported to have a potential activity to cure neuropathic pain. The aim of this research is to develop and validate a high-performance liquid chromatography with tandem spectrometry (LC-MS/MS) method for the quantification of QO-58L in rat urine, feces and bile. In addition, analyze and identify the metabolites in urine and bile. The assay for this compound in samples detected with multiple reaction monitoring mode (MRM), and take nimodipine as internal standards (IS). To better understand the biotransformation of QO-58L, metabolites in urine and bile were identified by using ultra high performance liquid chromatography tandem quadrupole/time of flight mass spectrometry (UHPLC-Q-TOF-MS) in the positive and negative ion mode. Urine, feces and bile were quantified by three new methods. The results showed that: QO-58L was mainly eliminated through fecal route (92.94%), a small amount of it via biliary excretion (2.05%), and rarely through urinary excretion (0.024%). As a result, there are 11 metabolites were identified, including 8 phase I metabolites resulting from elimination, hydroxylation and dihydroxylation, and 3 phase II metabolites originating from sulfation, N-acetylcysteine conjugation and glucuronidation. Furthermore, the newly discoveries of excretion and metabolism significantly expanded our understanding and was going to be greatly helpful for QO-58L's further pharmacokinetic study in vivo.

In vitro characterization and pharmacokinetics of dapagliflozin (BMS-512148), a potent sodium-glucose cotransporter type II inhibitor, in animals and humans.

(2S,3R,4R,5S,6R)-2-(3-(4-Ethoxybenzyl)-4-chlorophenyl)-6-hydroxymethyl-tetrahydro-2H-pyran-3,4,5-triol (dapagliflozin; BMS-512148) is a potent sodium-glucose cotransporter type II inhibitor in animals and humans and is currently under development for the treatment of type 2 diabetes. The preclinical characterization of dapagliflozin, to allow compound selection and prediction of pharmacological and dispositional behavior in the clinic, involved Caco-2 cell permeability studies, cytochrome P450 (P450) inhibition and induction studies, P450 reaction phenotyping, metabolite identification in hepatocytes, and pharmacokinetics in rats, dogs, and monkeys. Dapagliflozin was found to have good permeability across Caco-2 cell membranes. It was found to be a substrate for P-glycoprotein (P-gp) but not a significant P-gp inhibitor. Dapagliflozin was not found to be an inhibitor or an inducer of human P450 enzymes. The in vitro metabolic profiles of dapagliflozin after incubation with hepatocytes from mice, rats, dogs, monkeys, and humans were qualitatively similar. Rat hepatocyte incubations showed the highest turnover, and dapagliflozin was most stable in human hepatocytes. Prominent in vitro metabolic pathways observed were glucuronidation, hydroxylation, and O-deethylation. Pharmacokinetic parameters for dapagliflozin in preclinical species revealed a compound with adequate oral exposure, clearance, and elimination half-life, consistent with the potential for single daily dosing in humans. The pharmacokinetics in humans after a single dose of 50 mg of [(14)C]dapagliflozin showed good exposure, low clearance, adequate half-life, and no metabolites with significant pharmacological activity or toxicological concern.

Identification of human metabolites of (-)-N-{2-[(R)-3-(6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline-2-carbonyl)piperidino]ethyl}-4-fluorobenzamide (YM758), a novel If channel inhibitor, and investigation of the transporter-mediated renal and hepatic excretion of these metabolites.

(-)-N-{2-[(R)-3-(6,7-Dimethoxy-1,2,3,4-tetrahydroisoquinoline-2-carbonyl)piperidino]ethyl}-4-fluorobenzamide (YM758) is a novel inhibitor of the "funny" If current channel (If channel) that is expressed in the sinus node of heart and is being developed as a treatment for stable angina and atrial fibrillation. Its metabolites were identified in human urine, plasma, and feces by radio-high-performance liquid chromatography and liquid chromatography-tandem mass spectrometry analyses after oral administration of [(14)C]YM758. 6,7-Dimethoxy-2-[(3R)-piperidin-3-ylcarbonyl]-1,2,3,4-tetrahydroisoquinoline (YM-252124), (5R)-5-[(6,7-dimethoxy-3,4-dihydroisoquinolin-2(1H)-yl)carbonyl]piperidin-2-one (YM-385459), 2-{[(3R)-1-{2-[(4-fluorobenzoyl)amino]ethyl}piperidin-3-yl]carbonyl}-7-methoxy-1,2,3,4-tetrahydroisonolin-6-yl beta-D-glucopyranosiduronic acid (AS2036329), and the unchanged drug were detected as major constituents in both urine and plasma, whereas N-(4-fluorobenzoyl)glycine (YM-385461) was detected in plasma, but not in urine. The renal and hepatic uptake transporters for these metabolites were investigated by assessing their inhibitory effect on uptake activity in human (h) organic cation transporter (OCT) 1-3/rat (r) Oct1-3, human organic anion transporter (OAT) 1/rOat1, hOAT3/rOat3, and organic anion-transporting protein 1B1/1B3-expressing HEK293 cells. IC(50) values of YM-252124 for 1-methyl-4-phenylpyridinium uptake via hOCT2 and rOct2 were 93.9 and 1700 microM, respectively, suggesting that this metabolite is secreted into urine via hOCT2/rOct2 and that the large difference in the inhibitory potentials between hOCT2 and rOct2 explains the species difference in the urinary excretion ratio of the radioactivity. The renal secretion of YM-385461, one derivative of p-aminohippuric acid, via hOAT1/rOat1, and hepatic uptake of YM-252124 via hOCT1/rOct1 was also expected. This kind of study was useful in investigating the relationship between the urinary/hepatic elimination and the transport activity for metabolites.