Chimeric mouse model for MRI contrast agent evaluation.

PURPOSE: While rodents are the primary animal models for contrast agent evaluation, rodents can potentially misrepresent human organ clearance of newly developed contrast agents. For example, gadolinium (Gd)-BOPTA has ~50% hepatic clearance in rodents, but ~5% in humans. This study demonstrates the benefit of chimeric mice expressing human hepatic OATPs (organic anion-transporting polypeptides) to improve evaluation of novel contrast agents for clinical use. METHODS: FVB (wild-type) and OATP1B1/1B3 knock-in mice were injected with hepatospecific MRI contrast agents (Gd-EOB-DTPA, Gd-BOPTA) and nonspecific Gd-DTPA. T1 -weighted dynamic contrast-enhanced MRI was performed on mice injected intravenously. Hepatic MRI signal enhancement was calculated per time point. Mass of gadolinium cleared per time point and percentage elimination by means of feces and urine were also measured. RESULTS: Following intravenous injection of Gd-BOPTA in chimeric OATP1B1/1B3 knock-in mice, hepatic MRI signal enhancement and elimination by liver was more reflective of human hepatic clearance than that measured in wild-type mice. Gd-BOPTA hepatic MRI signal enhancement was reduced to 22% relative to wild-type mice. Gd-BOPTA elimination in wild-type mice was 83% fecal compared with 32% fecal in chimeric mice. Hepatic MRI signal enhancement and elimination for Gd-EOB-DTPA and Gd-DTPA were similar between wild-type and chimeric cohorts. CONCLUSION: Hepatic MRI signal enhancement and elimination of Gd-EOB-DTPA, Gd-BOPTA, and Gd-DTPA in chimeric OATP1B1/1B3 knock-in mice closely mimics that seen in humans. This study provides evidence that the chimeric knock-in mouse is a more useful screening tool for novel MRI contrast agents destined for clinical use as compared to the traditionally used wild-type models.

Applying risk management to analytical methods for the desorbing process of ginkgo diterpene lactone meglumine injection.

Analysis errors can occur in the desorbing process of ginkgo diterpene lactone meglumine injection (GDMI) by a conventional analysis method, due to several factors, such as easily crystallized samples, solvent volatility, time-consuming sample pre-processing, fixed method, and offline analysis. Based on risk management, near-infrared (NIR) and mid-infrared (MIR) spectroscopy techniques were introduced to solve the above problems with the advantage of timely analysis and non-destructive nature towards samples. The objective of the present study was to identify the feasibility of using NIR or MIR spectroscopy techniques to increase the analysis accuracy of samples from the desorbing process of GDMI. Quantitative models of NIR and MIR were established based on partial least square method and the performances were calculated. Compared to NIR model, MIR model showed greater accuracy and applicability for the analysis of the GDMI desorbing solutions. The relative errors of the concentrations of Ginkgolide A (GA) and Ginkgolide B (GB) were 2.40% and 2.89%, respectively, which were less than 5.00%. The research demonstrated the potential of the MIR spectroscopy technique for the rapid and non-destructive quantitative analysis of the concentrations of GA and GB.

Development and validation of a new HPLC-MS method for meglumine impurity profiling.

We report a new High Performance Liquid Chromatography-Mass Spectrometry (HPLC-MS) method to rapidly detect and quantify meglumine by-products (specifically reducing sugar(s) and nitrogen impurities) that could be present in the meglumine samples. Meglumine is a secondary amine obtained from glucose and it is an excipient used as counter-ion in several pharmaceutical formulations, especially when the concentration of the active pharmaceutical ingredient (API) is so high that the sodium is not a suitable option. Moreover, the increased use of meglumine is related to its ability to improve solubility in aqueous solutions due to the presence of a large number of hydroxyl groups. Thus, even if meglumine is widely used as excipient in pharmaceutical formulations, its impurity profile has never been fully evaluated. Here, we propose the use of a commercial agent that specifically reacts with carbonyl compounds, 1-(4-aminobenzyl)-1,2,4-triazole, with the aim of improving the detection of reducing sugars, such as glucose, after an easy derivatization procedure. Finally, we describe the method validation and the analysis of the impurity profile of meglumine samples from different manufacturers.

How transfer rates generate Gd-BOPTA concentrations in rat liver compartments: implications for clinical liver imaging with hepatobiliary contrast agents.

Following the injection of hepatobiliary contrast agents, MRI detects all molecules included in a region of interest but cannot estimate true concentrations in sinusoids, interstitium, hepatocytes or bile canaliculi. The aim of the study was to measure true concentrations in hepatocytes and to show how transfer rates across sinusoidal and canalicular membranes generate these concentrations. We perfused livers isolated from normal rats with 200 µM Gd-DTPA and Gd-BOPTA and measured clearances from sinusoids to liver and from hepatocytes to bile canaliculi or back to interstitium. We detected Gd-BOPTA with a gamma probe and determined true concentrations in each liver compartment knowing their liver volumes. No pharmacokinetic modelling was applied. Gd-BOPTA clearance from sinusoids to liver (2.5 ± 0.4 mL/min) was 50 times higher than that of Gd-DTPA (0.05 ± 0.02 mL/min) when portal flow rate was 30 mL/min (p < 0.0001). Gd-BOPTA clearance from sinusoids to liver was always superior to hepatocyte clearance, and hepatocyte Gd-BOPTA concentrations measured by the probe increased over time. Gd-BOPTA concentrations reached 439 ± 83 µM in hepatocytes and 15 × 700 ± 3100 µM in bile canaliculi, while concentrations in sinusoids were 200 µM. Gd-BOPTA true concentrations in hepatocytes depend on the simultaneous clearances from sinusoids to hepatocytes and from hepatocytes to bile canaliculi and back to sinusoids. The study better defines how signal intensities are generated when hepatobiliary contrast agents are injected in clinical imaging. Copyright © 2016 John Wiley & Sons, Ltd.

Speciation of antimony in injectable drugs used for leishmaniasis treatment (Glucantime®) by HPLC-ICP-MS and DPP.

Meglumine antimonate is the active of Glucantime® used for the treatment of leishmaniasis, a tropical disease caused by parasitic protozoa, and it is estimated that 12 million people worldwide are affected. This drug mainly contains Sb(V) under the form of an organic complex with N-methylglucamine (NMG). During the synthesis of this molecule, traces of Sb(III) may be present, also probably complexed. Due to the fact that Sb(III) is considered more toxic than Sb(V), it is important to evaluate the Sb(III) concentration in the drug samples. In the literature, very different concentrations for residual concentrations of Sb(III) in the drug ampoules are found. Therefore, to have a true insight of antimony speciation, two independent analytical methods were developed in this work. We used an anion exchange method coupled with inductively coupled plasma mass spectrometry (ICP-MS) which was cross-referenced with an electrochemistry method (differential pulse polarography (DPP)) that could be used for routine analysis on the production site. To obtain Sb species in detectable forms, the complexes between Sb species and NMG need to be broken. This was obtained by diluting samples in hydrochloric acid in deaerated conditions to avoid Sb redox reactions. For the two analytical methods, the HCl concentration was optimized to obtain simultaneously a complete destruction of the complexes as well as limited redox reactions for Sb(V) and Sb(III) released species. For high-performance liquid chromatography (HPLC)-ICP-MS, a dilution with 5 M HCl gives the better results. The side reaction is an oxidation of Sb(III) which can be limited by the removal of oxygen. When DPP is used, the major problem is the reduction of Sb(V) which is present in high amount in the samples. Working with 0.6 M HCl allows this problem to be minimized. When applied to different lots of Glucantime®, Sb(III) concentration values are in good agreement for the two analytical methods, with, for HPLC-ICP-MS, the advantage of the simultaneous detection of both Sb redox species.

Trace detection of meglumine and diatrizoate from Bacillus spore samples using liquid chromatography/mass spectrometry.

Following the September 11, 2001 terrorist attacks, letters containing Bacillus anthracis were distributed through the United States postal system killing five people. A complex forensic investigation commenced to identify the perpetrator of these mailings. A novel liquid chromatography/mass spectrometry protocol for the qualitative detection of trace levels of meglumine and diatrizoate in dried spore preparations of B. anthracis was developed. Meglumine and diatrizoate are components of radiographic imaging products that have been used to purify bacterial spores. Two separate chromatographic assays using multiple mass spectrometric analyses were developed for the detection of meglumine and diatrizoate. The assays achieved limits of detection for meglumine and diatrizoate of 1.00 and 10.0 ng/mL, respectively. Bacillus cereus T strain spores were effectively used as a surrogate for B. anthracis spores during method development and validation. This protocol was successfully applied to limited evidentiary B. anthracis spore material, providing probative information to the investigators.

Determination of meglumine in pharmaceutical formulations using high performance liquid chromatography.

Four different approaches were followed for the development of a HPLC method for the determination of meglumine in solid dosage formulations: derivatization of meglumine prior to HPLC analysis, the use of an ion-pairing reagent in the mobile phase, the use of charged surface hybrid stationary phase and the use of a column designed for carbohydrate separations. The method using anionic pairing reagent in the mobile phase was shown to be suitable for the quantitative determination of meglumine in solid dosage forms. The HPLC separation was achieved on an Agilent Eclipse XDB-C18 column (150 mm x 4.6 mm, 3.5 microm particle size) using a mobile phase with octane-1-sulfonic acid. The method was validated and validation included the following studies: selectivity, precision (repeatability), linearity and accuracy. During validation experiments RID and DAD detectors were used.

Hair and fingernail gadolinium ICP-MS contents in an overdose case associated with nephrogenic systemic fibrosis.

Nephrogenic systemic fibrosis (NSF) is a rare acquired disorder affecting renal insufficiency patients. There is a growing recognition of the association between the rapid rise in the use of gadolinium (Gd)-containing contrast agents for magnetic resonance imaging (MRI), and the occurrence of acute nephrogenic systemic fibrosis. This case report concerns a 62-year-old woman with chronic renal insufficiency who underwent numerous MRI examinations using Gd-based contrast agents. For the first time, to our knowledge, Gd was performed in the NSF patient's blood, as well as in hair and in fingernails by inductively plasma coupled mass spectrometry. Gd contents in blood, hair and in fingernails were initially 300 to 1000 times higher compared to controls. These results are a new illustration of the strong association between the frequent use of Gd-based contrast media and NSF in patients with kidney diseases. Gd quantitative determination could be of major interest for patients with renal failure who are required to undergo repeated gadolinium-enhanced MRI examinations.

Inefficacy of the association N-methyl glucamine and topical miltefosine in the treatment of experimental cutaneous leishmaniasis by Leishmania (Leishmania) amazonensis

Pentavalent antimonial (SbV) is the first treatment for cutaneous leishmaniasis (CL). Other drugs present similar side effects and higher cost. Oral miltefosine is effective to treat kala-azar. The aim of the present study was to compare the efficacy of glucamine (SbV) plus topical miltefosine with glucamine in the treatment of CL. Eighty isogenic C57BL/6 mice were inoculated with Leishmania (Leishmania) amazonensis and divided into two groups: one group was treated with SbV associated with miltefosine, and the other group received SbV plus saline solution. Groups were evaluated according to the diameter of the inoculated foot pad, the culture, and the parasite count using the limiting dilution assay. There was not statistical difference. The efficacy of glucamine in CL treatment did not increase when associated with topical miltefosine.(AU)

Ternary amorphous composites of celecoxib, poly(vinyl pyrrolidone) and meglumine with enhanced solubility.

The present study highlights the development of ternary amorphous composites to enhance the solubility of a poorly soluble crystalline drug, celecoxib (CEL). These systems comprised of an 'amorphous drug,' and its 'stabilizer' and 'solubilizer.' The ternary amorphous system of CEL, poly(vinyl pyrrolidone) (PVP) and meglumine (MEG) (7:2:1 w/w) enhanced CEL solubility by approximately equal to 10.2-fold over that for the crystalline drug, and maintained the thermodynamic stability of the amorphous drug. However, MEG alone was unable to stabilize the amorphous CEL against thermally-induced crystallization, and so gave no solubility advantage. The PVP-MEG combination provided a 'synergistic' enhancement of CEL solubility, as compared to their use alone in the amorphous systems. Phase-solubility studies provided greater insight into molecular mechanisms underlying stability and solubility of these amorphous systems. MEG exhibited phase-specific interaction with CEL molecules, when stabilized by PVP in the amorphous state. The higher solubility of CEL from ternary amorphous systems was also thermodynamically favored, as analyzed by van't Hoff plots. A possible molecular level interaction of MEG with PVP-stabilized amorphous CEL seems to be responsible for the solubility advantage of the CEL-PVP-MEG ternary amorphous system.

Analysis of gadobenate dimeglumine by capillary zone electrophoresis coupled with electrospray-mass spectrometry.

Highly reliable and accurate analytical methods are needed for the determination of magnetic resonance imaging (MRI) contrast agents in complex matrices of clinical interest. We demonstrate the reliability of capillary zone electrophoresis (CZE) coupled with electrospray ionization-mass spectrometry (ESI-MS) for the analysis of MultiHance (gadobenate dimeglumine), a gadolinium-based MRI agent. A sheath liquid interface connected the CE system with an electrospray mass spectrometer equipped with an ion-trap analyzer. CZE with ultraviolet (CZE-UV) and with mass detection (CZE-MS) were compared by analyzing gadobenate dimeglumine and the free ligand diluted in water and in biological fluids (i.e., human serum and urine). The optimization of some relevant CZE-MS parameters was accomplished, like CE buffer composition, sheath liquid composition and flow, and type and length of the separation capillary. CZE-UV was highly influenced by the biological sample components, which hindered a reliable quantification of both gadobenate and free ligand in serum and urine. In CZE-MS, on the other hand, the electrophoretic runs turned out to be independent of the clinical matrices, due to the informative potential and to the selectivity of MS detection.

Pharmacokinetics and tissue distribution in animals of gadobenate ion, the magnetic resonance imaging contrast enhancing component of gadobenate dimeglumine 0.5 M solution for injection (MultiHance).

OBJECTIVE: Evaluation of the pharmacokinetic behavior of gadobenate dimeglumine, a new multipurpose parenteral contrast agent for magnetic resonance imaging. METHODS: The pharmacokinetics were evaluated in rats, rabbits, dogs and monkeys after intravenous injections of non-labelled gadobenate dimeglumine and, for biodistribution studies, 153Gd-labelled gadobenate dimeglumine. Assays were performed by high performance liquid chromatography, X-ray fluorescence and gamma spectrometry. The binding of gadobenate ion to animal and human serum albumin was studied by equilibrium dialysis. RESULTS: After intravenous injection gadobenate dimeglumine distributes into plasma and extracellular fluid as well as into the intrahepatocytic space. Gadobenate ion is cleared from plasma by renal and biliary excretion. It does not accumulate in specific tissues, except temporarily in tissues related to its elimination. Gadobenate ion is not metabolized. Its binding to plasma proteins is too weak to be detected by equilibrium dialysis. CONCLUSIONS: Gadobenate dimeglumine combines the properties of an extracellular-fluid agent with those of a hepatobiliary agent. Its complete elimination and biological stability satisfy the requirements for its safe use in humans.

High-performance liquid chromatographic determination of the magnetic resonance imaging contrast agent gadobenate ion in plasma, urine, faeces, bile and tissues.

The gadobenate ion is an intravascular paramagnetic contrast agent for magnetic resonance imaging. An HPLC method for assaying gadobenate ion in plasma, urine, faeces, bile and tissue samples is described. The analysis is based on the reversed-phase chromatographic separation of gadobenate ion from the endogenous components of biological matrices and detection by UV absorption at 210 nm. The selectivity of the method was satisfactory. The mean absolute recovery was greater than 95%. The precision and accuracy of the analytical methods were in the range 0.1-6.5% and -12 to +9.3%, respectively. The detection limits in plasma (0.1 ml), urine (0.05 ml), dried faeces (200 mg suspended in 4 ml water), bile (0.5 ml), and dried liver tissue (100 mg suspended in 1 ml water) were, respectively, 0.24, 0.47, 2.6, 0.63 and 2.8 nmol ml(-1) (corresponding to 0.16, 0.31, 1.7, 0.42 and 1.9 microg ml(-1)).

On-line HPLC-electrospray ionization mass spectrometry: a pharmacological tool for identifying and studying the stability of Gd3+ complexes used as magnetic resonance imaging contrast agents.

The identification of MRI contrast agents (CAg) as gadolinium complexes often used at very low concentrations in Pharmacology was carried out by ESI-MS or HPLC-ESI-MS. Firstly, Omniscan, Dotarem and Magnevist were tested. In these compounds, the Gd3+ ion must be solidly chelated by linear or macrocyclic ligands because of the severe toxicity of the free Gd3+. Spectra were obtained at low voltage, preserving the non-covalent binding integrity of the complexes, and at various higher voltages showing the progressive destruction of the complexes. Secondly, a direct reaction of these drugs with the oxidative human neutrophil production, induced in vitro by Phorbol 12-myristate 13-acetate enhancing the respiratory burst, was investigated. This was done to mimic what happens in the case of inflammatory diseases, or infection, or when people are likely to develop anaphylactoid reactions, as the i.v. injection of CAg causes contact between the complexes and neutrophils in the blood. Analysis by HPLC-ESI-MS coupling did not show any direct reaction between Gd complexes and the chemical compounds in the neutrophil oxidative metabolism, even if uncertainty remains as regards meglumine salt. HPLC-ESI-MS is a good way of visualizing characteristic, Gd isotopic distribution and of following its associations in biological samples.

Simple 1H NMR spectroscopic method for assay of salts of the contrast agent diatrizoate in commercial solutions.

A simple, accurate, and specific 1H NMR spectroscopic method was developed for the assay of diatrizoate meglumine or the combination diatrizoate meglumine and diatrizoate sodium in commercial solutions for injection. A mixture of injectable solution and sodium acetate, the internal standard, was diluted with D2O and the 1H NMR spectrum of the solution was obtained. Two approaches were used to calculate the drug content, based on the integral values for the -N-CO-CH3 protons of diatrizoic acid at 2.23 ppm, and -N-CH3 protons of meglumine at 2.73 ppm, and the CH3-CO-protons of sodium acetate at 1.9 ppm. Recoveries (mean +/- standard deviation) of diatrizoic acid and meglumine from 10 synthetic mixtures of various amounts of these compounds with a fixed amount of internal standard were 100.3 +/- 0.55% and 100.1 +/- 0.98%, respectively. In addition to providing a direct means of simultaneously assaying diatrizoic acid and meglumine, the proposed NMR method can also be used to identify diatrizoate meglumine and each of its molecular components.

High-performance liquid chromatographic assay of the magnetic resonance imaging contrast agent gadobenate in plasma, urine and bile.

Gadobenate dimeglumine (Gd-BOPTA-Dimeg) is currently under evaluation as an intravascular paramagnetic contrast agent for magnetic resonance imaging. The anion Gd-BOPTA2- is the moiety of Gd-BOPTA-Dimeg responsible for contrast enhancement. An HPLC method for assaying gadobenate (Gd-BOPTA2-) in plasma, urine and bile samples is described. The analysis is based on the reversed-phase chromatographic separation of the ion pair Gd-BOPTA(2-)-tetrabutylammonium from the endogenous components of biological fluids and its detection by UV absorption at 210 nm. The mean accuracy and precision of the method were in the range -3.4 to +5.0% and 0.2-3.5%, respectively. The method detection limits for Gd-BOPTA2- in plasma (0.8 ml), urine (0.2 ml) and bile (1.0 ml) were 1.1, 7.6 and 1.7 microM (corresponding to 0.73, 5.1 and 1.1 micrograms/ml), respectively.

[Analysis of meglumine in pharmaceutical products by means of high pressure liquid chromatography]. / Analisi della meglumina nelle forme farmaceutiche mediante cromatografia liquida ad alta pressione.

A method for the quantitative analysis of methylglucamine in pharmaceutical products by high pressure liquid chromatography is described. The suggested procedure overcomes every preliminary treatments of the sample and does not suffer of interferences due to excipients and other active substances.