Potential of measured relative shifts in collision cross section values for biotransformation studies.

Ion mobility spectrometry-mass spectrometry (IMS-MS) separates gas phase ions due to differences in drift time from which reproducible and analyte-specific collision cross section (CCS) values can be derived. Internally conducted in vitro and in vivo metabolism (biotransformation) studies indicated repetitive shifts in measured CCS values (CCSmeas) between parent drugs and their metabolites. Hence, the purpose of the present article was (i) to investigate if such relative shifts in CCSmeas were biotransformation-specific and (ii) to highlight their potential benefits for biotransformation studies. First, mean CCSmeas values of 165 compounds were determined (up to n = 3) using a travelling wave IMS-MS device with nitrogen as drift gas (TWCCSN2, meas). Further comparison with their predicted values (TWCCSN2, pred, Waters CCSonDemand) resulted in a mean absolute error of 5.1%. Second, a reduced data set (n = 139) was utilized to create compound pairs (n = 86) covering eight common types of phase I and II biotransformations. Constant, discriminative, and almost non-overlapping relative shifts in mean TWCCSN2, meas were obtained for demethylation (- 6.5 ± 2.1 Å2), oxygenation (hydroxylation + 3.8 ± 1.4 Å2, N-oxidation + 3.4 ± 3.3 Å2), acetylation (+ 13.5 ± 1.9 Å2), sulfation (+ 17.9 ± 4.4 Å2), glucuronidation (N-linked: + 41.7 ± 7.5 Å2, O-linked: + 38.1 ± 8.9 Å2), and glutathione conjugation (+ 49.2 ± 13.2 Å2). Consequently, we propose to consider such relative shifts in TWCCSN2, meas (rather than absolute values) as well for metabolite assignment/confirmation complementing the conventional approach to associate changes in mass-to-charge (m/z) values between a parent drug and its metabolite(s). Moreover, the comparison of relative shifts in TWCCSN2, meas significantly simplifies the mapping of metabolites into metabolic pathways as demonstrated.

Double Trap Interface: A novel gas interface for high throughput analysis of biomedical samples by AMS.

Although Accelerator Mass Spectrometry (AMS) offers unparalleled sensitivity by investigating the fate of 14C-labeled compounds within the organism, its widespread use in ADME (absorption, distribution, metabolism, excretion) studies is limited. Conventional approaches based on Liquid Scintillation Counting (LSC) are still preferred, in particular because of complexity and costs associated with AMS measurements. Progress made over the last decade towards more compact AMS systems increased the interest in a combustion-based AMS approach allowing the analysis of samples in gaseous form. Thus, a novel gas Double Trap Interface (DTI) was designed, providing high sample throughput for the analysis of biomedical samples. DTI allows the coupling of an Elemental Analyzer (EA) for sample combustion to the hybrid ion source of a MICADAS (MIni CArbon DAting System) AMS system. The performance was evaluated in two studies through the analysis of more than 1000 samples from 14C-labeled biomatrices and fractions collected after liquid chromatography (LC). The covered activity ranged from 1 to 1000 mBq/g for labeled biomatrices and from 1 to 10000 mBq/g(C) for LC fractions. The implemented routine allows automated measurements requiring less than 5 min per sample (12-13 analyses per hour) without the need for sample conversion to graphite.

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.

The impact of early human data on clinical development: there is time to win.

Modern accelerator mass spectrometry (AMS) methods enable the routine application of this technology in drug development. By the administration of a (14)C-labelled microdose or microtrace, pharmacokinetic (PK) data, such as mass balance, metabolite profiling, and absolute bioavailability (AB) data, can be generated easier, faster, and at lower costs. Here, we emphasize the advances and impact of this technology for pharmaceutical companies. The availability of accurate intravenous (iv) PK and human absorption, distribution, metabolism, and excretion (ADME) information, even before or during Phase I trials, can improve the clinical development plan. Moreover, applying the microtrace approach during early clinical development might impact the number of clinical pharmacology and preclinical safety pharmacology studies required, and shorten the overall drug discovery program.

ADME studies of [5-(3)H]-2'-O-methyluridine nucleoside in mice: a building block in siRNA therapeutics.

The chemical modification 2'-O-methyl of nucleosides is often used to increase siRNA stability towards nuclease activities. However, the metabolic fate of modified nucleosides remains unclear. Therefore, the aim of this study was to determine the mass balance, pharmacokinetic, and absorption, distribution, metabolism, and excretion (ADME)-properties of tritium-labeled 2'-O-methyluridine, following a single intravenous dose to male CD-1 mice. The single intravenous administration of [5-(3)H]-2'-O-methyluridine was well tolerated in mice. Radioactivity was rapidly and widely distributed throughout the body and remained detectable in all tissues investigated throughout the observation period of 48 h. After an initial rapid decline, blood concentrations of total radiolabeled components declined at a much slower rate. [(3)H]-2'-O-Methyluridine represented a minor component of the radioactivity in plasma (5.89% of [(3)H]-AUC 0-48 h). Three [(3)H]-2'-O-methyluridine metabolites namely uridine (M1), cytidine (M2), and uracil (M3) were the major circulating components representing 32.8%, 8.11%, and 23.6% of radioactivity area under the curve, respectively. The highest concentrations of total radiolabeled components and exposures were observed in kidney, spleen, pineal body, and lymph nodes. The mass balance, which is the sum of external recovery of radioactivity in excreta and remaining radioactivity in carcass and cage wash, was complete. Renal excretion accounted for about 52.7% of the dose with direct renal excretion of the parent in combination with metabolism to the endogenous compounds cytidine, uracil, cytosine, and cytidine.

Absorption, distribution, metabolism, and excretion (ADME) of ¹4C-sonidegib (LDE225) in healthy volunteers.

PURPOSE: The absorption, distribution, metabolism, and excretion of the hedgehog pathway inhibitor sonidegib (LDE225) were determined in healthy male subjects. METHODS: Six subjects received a single oral dose of 800 mg ¹4C-sonidegib (74 kBq, 2.0 µCi) under fasting conditions. Blood, plasma, urine, and fecal samples were collected predose, postdose in-house (days 1-22), and during 24-h visits (weekly, days 29-43; biweekly, days 57-99). Radioactivity was determined in all samples using accelerator mass spectrometry (AMS). Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used to determine concentrations of sonidegib and its main circulating metabolite in plasma. Metabolite profiles and structures were determined in pooled plasma, urine, and fecal samples using high-performance LC-AMS and LC-MS/MS, respectively. RESULTS: A single dose of ¹4C-sonidegib was well tolerated in healthy subjects. Unchanged sonidegib and total radioactivity reached peak concentration in plasma by 2 and 3 h, respectively, and demonstrated similarly long half-lives of 319 and 331 h, respectively. Absorbed sonidegib (estimated 6-7 %) was extensively distributed, and the approximate terminal volume of distribution was 2,500 L. Unchanged sonidegib and a metabolite resulting from amide hydrolysis were the major circulating components (36.4 and 15.4 % of radioactivity area under the curve, respectively). Absorbed sonidegib was eliminated predominantly through oxidative metabolism of the morpholine part and amide hydrolysis. Unabsorbed sonidegib was excreted through the feces. Metabolites in excreta accounted for 4.49 % of the dose (1.20 % in urine, 3.29 % in feces). The recovery of radioactivity in urine and feces was essentially complete (95.3 ± 1.93 % of the dose in five subjects; 56.9 % of the dose in one subject with incomplete feces collection suspected). CONCLUSIONS: Sonidegib exhibited low absorption, was extensively distributed, and was slowly metabolized. Elimination of absorbed sonidegib occurred largely by oxidative and hydrolytic metabolism.

Metabolism of patupilone in patients with advanced solid tumor malignancies.

A phase 1, open-label, non-randomized, single center study was conducted to determine the pharmacokinetics, distribution, metabolism, elimination, and mass balance of patupilone in patients with advanced solid tumors. Five patients with advanced solid tumors received 10 mg/m(2) (1.1 MBq) of (14) C-radiolabeled patupilone at cycle 1 as a 20-minute intravenous infusion every 3 weeks until disease progression. Sequential samples of blood/plasma were taken for 3 weeks and urine and fecal samples were collected for seven days after the first dose of patupilone. Patupilone blood levels decreased rapidly after the infusion. The compound showed a large volume of distribution (Vss: 2242 L). The main radiolabeled component in blood was patupilone itself, accompanied by the lactone hydrolysis products that are unlikely to contribute to the pharmacological effect of patupilone. The blood clearance of patupilone was relatively low at 14 L/h. The administered radioactivity dose was excreted slowly (46 % of dose up to 168 h) but ultimately accounted for 91 % of the dose by extrapolation. The fecal excretion of radioactivity was 2-3 times higher than the urinary excretion consistent with hepato-biliary elimination. Three patients had progressive disease and two patients had stable disease as their best response. Patupilone was generally well tolerated in patients with advanced solid tumors with no newly occurring safety events compared to previous clinical studies. In adult solid tumor patients, intravenous radiolabeled patupilone undergoes extensive metabolism with fecal excretion of radioactive metabolites predominating over renal excretion.

Maximum capacities for adsorption of phenanthrene in the slowly and very slowly desorbing domains in nineteen soils and sediments.

The maximum amounts of phenanthrene that can be taken up in both the slowly desorbing domain and the very slowly desorbing domain of 19 soils and sediments were determined by measuring the desorption of phenanthrene added at high loadings associated with equilibrium concentrations in water close to the aqueous solubility of phenanthrene. For two soils and one sediment, literature values for Langmuir phenanthrene adsorption capacities were available. These values were almost equal to the sum of the maximum amounts taken up in the slowly and in the very slowly desorbing domain. For the other soils, the range of the sum of the maximum amounts in the slowly and very slowly desorbing domains was comparable to the range for literature values of Langmuir phenanthrene adsorption capacities for soils and sediments. Results suggested that the maximum amounts determined from the desorption studies were Langmuir adsorption capacities. The correlation of maximum capacities for adsorption in both the slow desorption domain as well as the very slow desorption domain with soot content was virtually absent. In contrast, the variation of maximum amounts of phenanthrene adsorbed in either the slowly or the very slowly desorbing domains was substantially reduced by normalization to the total organic carbon content of the soils and sediments. It is suggested that adsorption in the slowly and very slowly desorbing domain took place in organic matter derived material such as kerogen, charcoal, or char.