Analysis of urinary tobacco-specific nitrosamine 4- (methylnitrosamino)1-(3-pyridyl)-1- butanol (NNAL) and HPV infection in American women: National health and nutrition examination survey.

Tobacco-specific nitrosamines (TSNAs) are a group of toxic substances specific to tobacco. 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) is a tobacco-specific nitrosamine measurable in urine with a much longer half-life than cotinine. We aimed to examine the association between urinary tobacco-specific NNAL and HPV infection among American women. We used cross-sectional data from the National Health and Nutrition Examination Survey (NHANES) between 2007 and 2014 to collect details on their urinary NNAL, HPV infection status, and other essential variables. The association between dietary urinary NNAL and HPV infection status was analyzed by using a weighted multivariate logistic regression model, and stratified subgroup analysis. In total, 5197 participants aged 18-59 years were identified, with overall prevalence of high-risk and low-risk HPV infection of 22.0% and 19.1%, respectively. The highest quartile of NNAL(Q4) was more positively associated with low-risk HPV infection than the lowest quartile of NNAL(Q1) (OR = 1.83 (1.35,2.50), p<0.001). the highest quartile of NNAL(Q4) was more positively associated with high-risk HPV infection than the lowest quartile of NNAL(Q1) (OR = 2.20 (1.57,3.08), p < 0.001). In subgroup analyses, the positive correlation between urinary NNAL levels and low-risk HPV infection status was inconsistent in marital status and BMI (interaction p < 0.05). The positive association of urinary NNAL levels with high-risk HPV infection status was inconsistent in smoking and BMI. (interaction p < 0.05). Tobacco-specific NNAL levels positively correlate with high- and low-risk HPV. Future well-designed longitudinal studies are still needed to validate the effect of tobacco exposure on HPV infection by NNAL.

Mass Spectrometric Quantitation of N'-Nitrosonornicotine-1N-oxide in the Urine of Cigarette Smokers and Smokeless Tobacco Users.

N'-Nitrosonornicotine (NNN) and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), which always occur together and are present exclusively in tobacco products, are classified as "carcinogenic to humans" (Group 1) by the International Agency for Research on Cancer. While 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) serves as an excellent biomarker for NNK exposure, the currently available biomarker for NNN exposure is urinary "total NNN" (free NNN plus its N-glucuronide). Quantitation of urinary NNN requires extensive precautions to prevent artifactual formation of NNN resulting from nitrosation of nornicotine during analysis. NNN itself can also be formed endogenously by the same nitrosation reaction, which may sometimes cause an overestimation of exposure to preformed NNN. It is thus important to develop an alternative biomarker to specifically reflect NNN metabolic fate and facilitate relevant cancer etiology studies. In this study, we report the first detection of N'-nitrosonornicotine-1N-oxide (NNN-N-oxide) in human urine. Using a highly specific and sensitive MS3 transition-based method, NNN-N-oxide was quantified with a mean level of 8.40 ± 6.04 fmol/mL in the urine of 10 out of 32 cigarette smokers. It occurred in a substantially higher level in the urine of 13 out of 14 smokeless tobacco users, amounting to a mean concentration of 85.2 ± 96.3 fmol/mL urine. No NNN-N-oxide was detected in any of the nonsmoker urine samples analyzed (n = 20). The possible artifactual formation of NNN-N-oxide during sample preparation steps was excluded by experiments using added ammonium sulfamate. The low levels of NNN-N-oxide in the urine of tobacco users indicate that the pyridine N-oxidation pathway represents a minor detoxification pathway of NNN, which further supports the importance of the α-hydroxylation pathway of NNN metabolic activation in humans.

Urinary concentrations of neonicotinoid insecticides were related to renal tubular dysfunction and neuropsychological complaints in Dry-zone of Sri Lanka.

Neonicotinoids are systemic insecticides used since the 1990's , that possess renal tubular toxicity. We conducted a field-based descriptive study in the North Central Dry-zone of Sri Lanka, where chronic kidney disease (CKD) of unknown etiology has been increasing since the 1990's. To elucidate the relationship between renal tubular dysfunctions and urinary neonicotinoids concentrations, we collected spot urine samples from15 CKD patients, 15 family members, and 62 neighbors in 2015, analyzed two renal tubular biomarkers, Cystatin-C and L-FABP, quantified seven neonicotinoids and a metabolite N-desmethyl-acetamiprid by LC-MS/MS; and we investigated their symptoms using a questionnaire. Cystatin-C and L-FABP had a positive correlation (p < 0.001). N-Desmethyl-acetamiprid was detected in 92.4% of the urine samples, followed by dinotefuran (17.4%), thiamethoxam (17.4%), clothianidin (9.8%), thiacloprid and imidacloprid. Dinotefuran and thiacloprid have never been registered in Sri Lanka. In High Cystatin-C group (> 70 µg/gCre, n = 7), higher urinary concentration of dinotefuran (p = 0.009), and in Zero Cystatin-C group (< LOQ, n = 7), higher N-desmethyl-acetamiprid (p = 0.013), dinotefuran (p = 0.049), and thiacloprid (p = 0.035), and more complaints of chest pains, stomachache, skin eruption and diarrhea (p < 0.05) were found than in Normal Cystatin-C group (n = 78). Urinary neonicotinoids may be one of the potential risk factors for renal tubular dysfunction in this area.

3-Ethenylpyridine Measured in Urine of Active and Passive Smokers: A Promising Biomarker and Toxicological Implications.

In studies of tobacco toxicology, including comparisons of different tobacco products and exposure to secondhand or thirdhand smoke, exposure assessment using biomarkers is often useful. Some studies have indicated that most of the toxicity of tobacco smoke is due to gas-phase compounds. 3-Ethenylpyridine (3-EP) is a major nicotine pyrolysis product occurring in the gas phase of tobacco smoke. It has been used extensively as an environmental tracer for tobacco smoke. 3-EP would be expected to be a useful tobacco smoke biomarker as well, but nothing has been published about its metabolism and excretion in humans. In this Article we describe a solid-phase microextraction (SPME) GC-MS/MS method for determination of 3-EP in human urine and its application to the determination of 3-EP in the urine of smokers and people exposed to secondhand smoke. We conclude that 3-EP is a promising biomarker that could be useful in studies of tobacco smoke exposure and toxicology. We also point out the paucity of data on 3-EP toxicity and suggest that additional studies are needed.

Absorption, Pharmacokinetics, and Urinary Excretion of Pyridines After Consumption of Coffee and Cocoa-Based Products Containing Coffee in a Repeated Dose, Crossover Human Intervention Study.

SCOPE: The present study assesses the absorption, pharmacokinetics, and urinary excretion of coffee pyridines and their metabolites after daily regular exposure to specific dosages of coffee or cocoa-based products containing coffee (CBPCC), considering different patterns of consumption. METHODS AND RESULTS: In a three-arm, crossover, randomized trial, 21 volunteers are requested to randomly consume for 1 month: one cup of espresso coffee per day, three cups of espresso coffee per day, or one cup of espresso coffee plus two CBPCC twice per day. The last day of the one-month treatment, blood and urine samples are collected for 24 h. Trigonelline, N-methylpyridinium, N-methylnicotinamide, and N-methyl-4-pyridone-5-carboxamide are quantified. Trigonelline and N-methylpyridinium absorption curves and 24-h urinary excretion reflect the daily consumption of different servings of coffee or CBPCC, showing also significant differences in main pharmacokinetic parameters. Moreover, inter-subject variability due to sex and smoking is assessed, showing sex-related differences in the metabolism of trigonelline and smoking-related ones for N-methylpyridinium. CONCLUSION: The daily exposure to coffee pyridines after consumption of different coffee dosages in a real-life setting is established. This data will be useful for future studies aiming at evaluating the bioactivity of coffee-derived circulating metabolites in cell experiments, mimicking more realistic experimental conditions.

Anabasine-based measurement of cigarette consumption using wastewater analysis.

Community tobacco use can be monitored over time using wastewater-based epidemiological approaches by estimating the mass loads of nicotine and its metabolites, cotinine, or hydroxycotinine, in wastewater. However, due to the use of nicotine in smoking cessation products, other sources of nicotine contribute to cotinine and hydroxycotinine loads. The use of nicotine replacement therapies could vary in space and time and mask the true rates of tobacco consumption. Therefore, this work evaluated the content of tobacco specific markers, anatabine and anabasine, in cigarettes, in urine of smokers, and in wastewater. The results indicated that the anabasine content in both licit and illicit cigarettes in Australia is less variable than anatabine and is therefore considered a better measure of tobacco consumption. A study determining the excretion of tobacco-specific alkaloids of smoking and non-smoking volunteers gave an average urinary mass load of anabasine of 4.38 µg/L/person and a daily mass load of 1.13 µg/day/person. Finally, this was compared with the mass loads of anabasine from wastewater-based epidemiology data of 3 µg/day/person to estimate cigarette rates in a South Australian city: equivalent to 2.6 cigarettes/person/day. The rate of decline of cigarette use was greater when using anabasine as a measure of consumption compared with cotinine. This is the first study to estimate the rate of anabasine excretion, which can be used to estimate tobacco use independent of therapeutically prescribed nicotine.

A Study of Opiate, Opiate Metabolites and Antihistamines in Urine after Consumption of Cold Syrups by LC-MS/MS.

Studying the origin of opiate and/or opiate metabolites in individual urine specimens after consumption of cold syrups is vital for patients, doctors, and law enforcement. A rapid liquid chromatography-tandem mass spectrometry method using "dilute-and-shoot" analysis without the need for extraction, hydrolysis and/or derivatization has been developed and validated. The approach provides linear ranges of 2.5-1000 ng mL-1 for 6-acetylmorphine, codeine, chlorpheniramine, and carbinoxamine, 2.5-800 ng mL-1 for morphine and morphine-3-ß-d-glucuronide, and 2.5-600 ng mL-1 for morphine-6-ß-d-glucuronide and codeine-6-ß-d-glucuronide, with excellent correlation coefficients (R2 > 0.995) and matrix effects (< 5%). Urine samples collected from the ten participants orally administered cold syrups were analyzed. The results concluded that participants consuming codeine-containing cold syrups did not routinely pass urine tests for opiates, and their morphine-codeine concentration ratios (M/C) were not always < 1. In addition, the distribution map of the clinical total concentration of the sum of morphine and codeine against the antihistamines (chlorpheniramine or carbinoxamine) were plotted for discrimination of people who used cold syrups. The 15 real cases have been studied by using M/C rule, cutoff value, and distribution map, further revealing a potential approach to determine opiate metabolite in urine originating from cold syrups.

Biomonitoring method for neonicotinoid insecticides in urine of non-toilet-trained children using LC-MS/MS.

There is a growing appreciation of the importance of determining chemical exposure levels in early childhood, as well as in embryonic and foetal life, which are now widely believed to be essential for gaining insight into potential health risks associated with these chemicals. To facilitate the assessment of exposure to neonicotinoid insecticides (NEOs) in non-toilet-trained children, a new method using disposable diapers (nappies) was developed for the simultaneous determination of the NEOs acetamiprid and its metabolite N-desmethylacetamiprid, clothianidin, dinotefuran, imidacloprid, thiacloprid, and thiamethoxam (NEO biomarkers). The urine absorbed in disposable diapers was extracted with acetone (diaper urine) and was cleaned using a solid-phase extraction column, before analysis with LC-MS/MS. The absolute recoveries of NEO biomarkers were 19-50%. Good results were observed for the linearity of the matrix-matched calibration curves (r2 = 0.983-0.996; concentration range LOQ-20 µg L-1) and the precision of intra-day (% relative standard deviation (%RSD): 3.3-12.7%) and inter-day (%RSD: 4.3-19.5%) analyses. The lowest and highest limits of detection of the developed method were 0.07 µg L-1 for acetamiprid and 0.75 µg L-1 for clothianidin. The developed method was applied for the evaluation of fifty diapered three-year-old children in Japan. Importantly, the study revealed relatively high detection rates for dinotefuran and N-desmethylacetamiprid; 84% and 78% respectively. The highest geometric mean of dinotefuran urinary concentration was 2.01 µg L-1. Thus, a method for determining NEO biomarkers in urine extracted from disposable diapers was established. This is the first report on the simultaneous quantitative analysis of NEO biomarkers of diaper-absorbed urine samples.

Accuracy of a Rapid Diagnostic Test for the Presence of Direct Oral Factor Xa or Thrombin Inhibitors in Urine-A Multicenter Trial.

The rapid determination of the presence of direct oral anticoagulants (DOACs) in a patient remains a major challenge in emergency medicine and for rapid medical treatment decisions. All DOACs are excreted into urine. A sensitive and specific point-of-care test has been developed to determine whether they are present in patient urine samples. This prospective multicenter study aimed to demonstrate at least 95% correct positive and negative predictive results for factor Xa and thrombin inhibitors in urine samples using DOAC Dipstick pads compared with liquid chromatography-tandem mass spectrometry (LC-MS/MS) (NCT03182829). Nine hundred and fourteen subjects were included and 880 were evaluated per protocol (factor Xa inhibitors apixaban, edoxaban, and rivaroxaban: n = 451, thrombin inhibitor dabigatran: n = 429) at 18 centers. The sensitivity, specificity, accuracy, and predictive values and agreement between methods for determination of factor Xa inhibitors were at least noninferior to 95% with a 0.5% margin and of thrombin inhibitor superior to 97.5%. These results were compared with LC-MS/MS results in the intention-to-analyze cohort (all p < 0.05). The receiver operating curve showed c-values of 0.989 (factor Xa inhibitors) and 0.995 (thrombin inhibitor). Visual evaluation of the factor Xa and thrombin inhibitor pads was not different between centers. Qualitative determination of both types of DOACs was accurate using the DOAC Dipstick compared with using LC-MS/MS. The high predictive values may impact laboratory and clinical decision-making processes.

LC-ESI/MS/MS analysis of neonicotinoids in urine of very low birth weight infants at birth.

OBJECTIVES: Neonicotinoid insecticides are widely used systemic pesticides with nicotinic acetylcholine receptor agonist activity that are a concern as environmental pollutants. Neonicotinoids in humans and the environment have been widely reported, but few studies have examined their presence in fetuses and newborns. The objective of this study is to determine exposure to neonicotinoids and metabolites in very low birth weight (VLBW) infants. METHODS: An analytical method for seven neonicotinoids and one neonicotinoid metabolite, N-desmethylacetamiprid (DMAP), in human urine using LC-ESI/MS/MS was developed. This method was used for analysis of 57 urine samples collected within 48 hours after birth from VLBW infants of gestational age 23-34 weeks (male/female = 36/21, small for gestational age (SGA)/appropriate gestational age (AGA) = 6/51) who were admitted to the neonatal intensive care unit of Dokkyo Hospital from January 2009 to December 2010. Sixty-five samples collected on postnatal day 14 (M/F = 37/22, SGA/AGA = 7/52) were also analyzed. RESULTS: DMAP, a metabolite of acetamiprid, was detected in 14 urine samples collected at birth (24.6%, median level 0.048 ppb) and in 7 samples collected on postnatal day 14 (11.9%, median level 0.09 ppb). The urinary DMAP detection rate and level were higher in SGA than in AGA infants (both p<0.05). There were no correlations between the DMAP level and infant physique indexes (length, height, and head circumference SD scores). CONCLUSION: These results provide the first evidence worldwide of neonicotinoid exposure in newborn babies in the early phase after birth. The findings suggest a need to examine potential neurodevelopmental toxicity of neonicotinoids and metabolites in human fetuses.

An available strategy based on accurate mass by ultra high performance liquid chromatography coupled to Fourier transform ion cyclotron resonance mass spectrometry technology to characterization of metabolic profile of palbociclib in rat urine, feces and bile.

Palbociclib (named PD 0332991) is a novel highly selective cyclin-dependent kinase 4 and 6 (CDK 4/6) inhibitor, which has been approved by the Food and Drug Administration (FDA) for the treatment of hormone-receptor-positive advanced breast cancer. This present study developed a comprehensive strategy to investigate the metabolic profile of palbociclib in rat urine, feces and bile samples based on an ultra high performance liquid chromatography coupled to Fourier transform ion cyclotron resonance mass spectrometry (UHPLC-FT-ICR MS). A total of 29 metabolites, including 18 phase I metabolites and 11 phase II metabolites, were detected and identified. The metabolic pathways included hydroxylation, oxidation, dehydrogenation, N-dealkylation, carbonylation, oxidative deamination, acetylation, glucuronidation, sulphate conjugation as well as the crossover of multiple metabolic pathways in vivo, and 16 of these metabolites were proposed for the first time. This study showed an insight into the metabolism of palbociclib in vivo, which may provide relevant chemical information for subsequent studies in the future.

Microdosed Cocktail of Three Oral Factor Xa Inhibitors to Evaluate Drug-Drug Interactions with Potential Perpetrator Drugs.

OBJECTIVES: The aim of this study was to prove the suitability of simultaneously administered microdoses of the factor Xa inhibitors (FXaIs) rivaroxaban, apixaban and edoxaban (100 µg in total). To evaluate drug-drug interactions, the impact of ketoconazole, a known strong inhibitor of cytochrome P450 3A4 and P-glycoprotein, was studied. METHODS: In a crossover clinical trial, 18 healthy volunteers were randomized to the two treatments using microdoses of rivaroxaban, apixaban and edoxaban alone and when coadministered with ketoconazole. Plasma and urine concentrations of microdosed apixaban, edoxaban and rivaroxaban were quantified using a validated ultra-performance liquid chromatography-tandem mass spectrometry assay with a lower limit of quantification of 2.5 pg/ml. RESULTS: The microdosed FXaI cocktail showed similar pharmacokinetic parameters compared with published data, using normal therapeutic doses of each FXaI. Ketoconazole significantly increased exposure, with geometric mean AUC ratios of 1.90 (apixaban), 2.35 (edoxaban) and 2.27 (rivaroxaban). CONCLUSION: The microdosed FXaI cocktail approach was able to precisely predict the drug interaction with ketoconazole. This is the first study that has been conducted to evaluate drug-drug interactions with a drug class, and the low administered doses also allow evaluation in vulnerable target populations. STUDY PROTOCOL: EudraCT 2016-003024-23.

Pharmacokinetics, absorption, metabolism, and excretion of [14C]ivosidenib (AG-120) in healthy male subjects.

PURPOSE: Pharmacokinetics, absorption, metabolism, and excretion of ivosidenib, a mutant isocitrate dehydrogenase-1 inhibitor, were determined in healthy male subjects. METHODS: In this open-label phase I study, a single dose of [14C]ivosidenib (500 mg, 200 µCi/subject) was orally administered to eight subjects (CYP2D6 extensive, intermediate, or poor metabolizers) under fasted conditions. Blood, plasma, urine, and fecal samples were assayed for radioactivity and profiled for metabolites. Ivosidenib plasma concentrations were determined using LC-MS/MS. Metabolites were separated using reverse-phase HPLC and analyzed using high-resolution LC-MS and LC-MS/MS. RESULTS: Ivosidenib was readily absorbed and slowly eliminated from plasma. Median Tmax of both unchanged ivosidenib and radioactivity in plasma was 4 h. Plasma t½ values for total radioactivity and ivosidenib were 71.7 and 53.4 h, respectively. The mean AUC0-72 blood-to-plasma total radioactivity concentration ratio was 0.565, indicating minimal partitioning to red blood cells. CYP2D6 genotype had no effect on ivosidenib exposure. The mean recovery of radioactivity in excreta was 94.3% over 360 h post-dose; the majority was excreted in feces (77.4 ± 9.62%) with a low percentage recovered in urine (16.9 ± 5.62%), suggesting fecal excretion is the primary route of elimination. Unchanged [14C]ivosidenib accounted for 67.4% of the administered radioactivity in feces. Only [14C]ivosidenib was detected in plasma, representing 92.4% of the total plasma radioactivity. Thirteen metabolites were structurally identified in excreta. CONCLUSION: Ivosidenib was well-absorbed, slowly metabolized to multiple oxidative metabolites, and eliminated by fecal excretion, with no CYP2D6 effect observed. Unchanged ivosidenib was the only circulating species in plasma.

19F-NMR-based determination of the absorption, metabolism and excretion of the oral phosphatidylinositol-3-kinase (PI3K) delta inhibitor leniolisib (CDZ173) in healthy volunteers.

1. Leniolisib is a novel oral phosphatidylinositol-3-kinase (PI3K) delta inhibitor, currently in clinical development for the treatment of inflammatory and autoimmune diseases. 2. We investigated the absorption, metabolism, and excretion of leniolisib in healthy subjects after a single oral 400 mg dose as part of a first-in-human clinical study. The parent drug and metabolites were quantified by 19F-NMR in plasma, urine and faeces after liquid chromatography separation, and structures were determined by liquid chromatography coupled to tandem mass spectrometry. 3. Drug-related material was mainly excreted as oxidative metabolites in urine and faeces, providing evidence that elimination occurs mainly by metabolism. No metabolites were abundant in plasma relative to the parent drug. An average mass balance of 66% was obtained, demonstrating that relatively extensive elimination/excretion data can be obtained by 19F-NMR in a first in human clinical study without the use of a radiolabeled drug.

Metabolic profiling of the anti-tumor drug regorafenib in mice.

Regorafenib is a novel tyrosine kinase inhibitor, which has been approved by the United States Food and Drug Administration for the treatment of various tumors. The purpose of the present study was to describe the metabolic map of regorafenib, and investigate its effect on liver function. Mass spectrometry-based metabolomics approach integrated with multiple mass defect filter was used to determine the metabolites of regorafenib in vitro incubation mixtures (human liver microsomes and mouse liver microsomes), serum, urine and feces samples from mice treated with 80 mg/kg regorafenib. Eleven metabolites including four novel metabolites were identified in the present investigation. As halogen substituted drug, reductive defluorination and oxidative dechlorination metabolites of regorafenib were firstly report in present study. By screening using recombinant cytochrome P450 s (CYPs), CYP3A4 was found to be the principal isoforms involved in regorafenib metabolism. The predication with a molecular docking model confirmed that regorafenib had potential to interact with the active sites of CYP3A4, CYP3A5 and CYP2D6. Serum chemistry analysis revealed no evidence of hepatic damage from regorafenib exposure. This study provided a global view of regorafenib metabolism and its potential side-effects.

A high-performance liquid chromatography-tandem mass spectrometry method for simultaneous determination of imigliptin, its five metabolites and alogliptin in human plasma and urine and its application to a multiple-dose pharmacokinetic study.

Imigliptin is a novel DPP-4 inhibitor, designed to treat type 2 diabetes mellitus (T2DM). A selective and sensitive method was developed using high performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS) to simultaneously quantify imigliptin, its five metabolites, and alogliptin in human plasma and urine. Solid-phase extraction (SPE) and direct dilution were used to extract imigliptin, its five metabolites, alogliptin from plasma and urine, respectively. The extracts were injected onto a SymmetryShield RP8 column with a gradient elution of methanol and water containing 10 mM ammonium formate (pH = 7). Ionization of all analytes was performed using an electrospray ionization (ESI) source in positive mode and detection was carried out with multiple reaction monitoring (MRM) mode. The results revealed that the method had excellent selectivity and linearity. Inter- and intra-batch precisions of all analytes were less than 15% and the accuracies were within 85%-115% for both plasma and urine. The sensitivity, matrix effect, extraction recovery, linearity, and stabilities were validated for all analytes in human plasma and urine. In conclusion, the validation results showed that this method was robust, specific, and sensitive and it can successfully applied to a pharmacokinetic study of Chinese T2DM subjects after oral dose of imigliptin and alogliptin.

Metabolites characterization of a novel DPP-4 inhibitor, imigliptin in humans and rats using ultra-high performance liquid chromatography coupled with synapt high-resolution mass spectrometry.

Imigliptin has been reported as a novel dipeptidyl-peptidase-IV (DPP-4) inhibitor to treat type 2 Diabetes Mellitus (T2DM), and is currently being tested in clinical trials. In the first human clinical study, imigliptin was well tolerated and proved to be a potent DPP-4 inhibitor. Considering its potential therapeutic benefits and promising future, it is of great importance to study the metabolite profiles in the early stage of drug development. In the present study, a robust and reliable analytical method based on the ultra-high performance liquid chromatography/quadrupole time-of-flight mass spectrometry (UHPLC/Q-TOF MS) method combined with MassLynx software was established to investigate the characterization of metabolites of imigliptin in human and rat plasma, urine and feces after oral administration. As a result, a total of 9 metabolites were identified in humans, including 6, 9 and 8 metabolites in human plasma, urine, and feces, respectively. A total of 11 metabolites were identified in rats, including 7, 10 and 8 metabolites in rat plasma, urine, and feces, respectively. In addition, 6 of the metabolites detected in humans and rats were phase I metabolites, including demethylation, carboxylation, hydroxylation and dehydrogenation metabolites, and 5 of the metabolites were phase II metabolites, including acetylation and glucuronidation. There was no human metabolite detected compared to those in rats. The major metabolites detected in human plasma (M1 and M2) were products resulting from acetylation, and hydroxylation followed by dehydrogenation. M1 was the major metabolite in rat plasma. M2 and the parent drug were the major drug-related substances in human urine. The parent drug was the major drug-related substances in rat urine. M2, M5 (hydroxylation product) and M6 (2 × hydroxylation and acetylation product) were the predominant metabolites in human feces. M2 and M5 were the major metabolites in rat feces. In addition, renal clearance was the major route of excretion for imigliptin.

Zolpidem and Zolpidem Carboxylic Acid Results from Medication Monitoring.

Zolpidem (Ambien®) is one of the "Z" drugs often used to improve sleep in older patients and those suffering from insomnia. Schwope, D.M., DePriest, A., Black, D.L., Caplan, Y.H., Cone, E.J., Heltsley, R. (2014) Determing zolpidem compliance: urinary metabolite detection and prevalence in chronic pain patients . Journal of Analytical Toxicology, 38, 513-518 reported that zolpidem in urine is not very prevalent being present <23% of the time in patient urine while the major metabolite, zolpidem 4-phenyl carboxylic acid (ZCA), is much more prevalent in urine with positive rates as high as 50% of the patient samples reviewed. Results from patient testing over a year's time are in agreement with the reported zolpidem results. However, the data observed herein for ZCA are not consistent with the earlier report. These data suggest that monitoring ZCA may result in even higher levels of positivity. Further, while the Food and Drug Administration has pointed out that female dosing should be half that given to males, results of this population testing indicate that the majority of patients (83% male and 73% female) receive 10 mg/day or 12.5 mg/day for Ambien CR® with females demonstrating statistically significantly higher levels of ZCA albeit zolpidem levels are not statistically significantly different between men and women. Estimates of patient positivity are dependent upon the value of the limit of quantification (LOQ) as demonstrated by the zolpidem results herein (LOQ = 50 ng/mL vs. 4 ng/mL). However, even with a much higher LOQ of 50 ng/mL for ZCA in this work, the positivity from ZCA results is significantly higher (e.g., 64.8%) than reported earlier (50.3%). Nevertheless, these data support the addition of ZCA for monitoring zolpidem in urine.

Evaluation of cAMS for 14C microtracer ADME studies: opportunities to change the current drug development paradigm.

AIM: Although regulatory guidances require human metabolism information of drug candidates early in the development process, the human mass balance study (or hADME study), is performed relatively late. hADME studies typically involve the administration of a 14C-radiolabelled drug where biological samples are measured by conventional scintillation counting analysis. Another approach is the administration of therapeutic doses containing a 14C-microtracer followed by accelerator mass spectrometry (AMS) analysis, enabling hADME studies completion much earlier. Consequently, there is an opportunity to change the current drug development paradigm. MATERIALS & METHODS: To evaluate the applicability of the MICADAS-cAMS method, we successfully performed: the validation of MICADAS-cAMS for radioactivity quantification in biomatrices and, a rat ADME study, where the conventional methodology was assessed against a microtracer MICADAS-cAMS approach. RESULTS & DISCUSSION: Combustion AMS (cAMS) technology is applicable to microtracer studies. A favorable opinion from EMA to complete the hADME in a Phase I setting was received, opening the possibilities to change drug development.

Comparison of metabolic pathways of different α-N-heterocyclic thiosemicarbazones.

Clinical failure of novel drugs is often related to their rapid metabolism and excretion. This highlights the importance of elucidation of their pharmacokinetic profile already at the preclinical stage of drug development. Triapine, the most prominent representative of α-N-heterocyclic thiosemicarbazones, was investigated in more than 30 clinical phase I/II trials, but the results against solid tumors were disappointing. Recent investigations from our group suggested that this is, at least partially, based on the fast metabolism and excretion. In order to establish more detailed structure/activity/metabolism relationships, herein a panel of 10 different Triapine derivatives was investigated for their metabolic pathways. From the biological point of view, the panel consists of terminally dimethylated thiosemicarbazones with nanomolar IC50 values, derivatives with micromolar cytotoxicities comparable to Triapine and a completely inactive representative. To study the oxidative metabolism, a purely instrumental approach based on electrochemistry/mass spectrometry was applied and the results were compared to the data obtained from microsomal incubations. Overall, the investigated thiosemicarbazones underwent the phase I metabolic reactions dehydrogenation, hydroxylation, oxidative desulfuration (to semicarbazone and amidrazone) and demethylation. Notably, dehydrogenation resulted in a ring-closure reaction with formation of thiadiazoles. Although strong differences between the metabolic pathways of the different thiosemicarbazones were observed, they could not be directly correlated to their cytotoxicities. Finally, the metabolic pathways for the most cytotoxic compound were elucidated also in tissues collected from drug-treated mice, confirming the data obtained by electrochemical oxidation and microsomes. In addition, the in vivo experiments revealed a very fast metabolism and excretion of the compound. Graphical abstract Structure/activity/metabolisation relationships for 10 anticancer thiosemicarbazones were established using electrochemical oxidation coupled to mass spectrometry (EC-MS) and human liver microsomes analyzed by LC-MS.