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.

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]

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.