Determination Of Fosfomycin Research Articles

Concepts for New Rapid Simple HPLC Method for Quantification of Fosfomycin Trometamol in Pharmaceutical Dosage Forms with Direct UV Detection

Two different concepts for developing direct HPLC-UV methods for quantifying fosfomycin trometamol were developed without any derivatization and modification of the analyte. In the first concept, without the use of alkylamines as ion-pairs in the mobile phase, by using cyanopropyl CN and a strong anion-exchanger column, we investigated the possibility of their highly polar and anion-exchanging forces and mechanisms to retain, separate and detect trometamol without the help of additional agents or modifiers. In the second concept, the most frequent reversed-phase C18 columns with different characteristics and vendors were tested in combination with different length-based alkylamines with 3–10 C atoms in their chains. In our research, we found that the ion-pairing of fosfomycin with 6–10 C-atom-based alkyl-length of aliphatic chains manifested the most appropriate strength of interactions between alkyl-paired trometamol molecules and octadecylsilane or C18 bonded RP column to achieve optimal retention, selectivity and peak shape on chromatograms, with the possibility for the fine-tuning of elution time. The simplicity of our method concept omits the need for expensive and sophisticated columns like HILIC, C30 graphite carbon, and mixed-mode-based columns for easier retaining, separation, and determination of fosfomycin, and for its quantification purposes, especially in high-throughput analyses in regular quality-control laboratories.

Quantitative 31P-NMR spectroscopy for the determination of fosfomycin and impurity A in pharmaceutical products of fosfomycin sodium or calcium.

A quantitative 31P-NMR method for the determination of fosfomycin and impurity A in pharmaceutical products of fosfomycin sodium or calcium has been developed. In this method, coaxial inserts containing trimethyl phosphate are used as external standard. The method is convenient and robust, and gives both high accuracy and precision. It is shown that an accurate determination is possible using different probes and coaxial inserts.

DETERMINATION OF ANTIBIOTIC FOSFOMYCIN IN CHICKEN SERUM BY LIQUID CHROMATOGRAPHY-TANDEM MASS SPECTROMETRY

A high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was developed for the determination of fosfomycin in chicken serum using fudosteine as the internal standard. Serum samples were treated with methanol to precipitate proteins. A subsequent clean up using liquid-liquid extraction followed by dilution was performed to eliminate phospholipids which are prone to produce unwanted matrix effects. The HPLC-MS/MS system involved the use of an isocratic mobile phase on a cyano stationary phase column and electrospray ion source operating in negative ion mode. Single reaction monitoring of transitions m/z 137 →79 and 178 →91 was performed on a triple quadrupole mass spectrometer to quantify fosfomycin and fudosteine, respectively. Response was linear over the range of 0.1 to 50 μg mL−1. Recovery ranged from 95 to 108%. Accuracy determined for spiked samples at 5, 10, and 20 μg mL−1 was −7.8, 1 and −0.7%, respectively, expressed as relative error. Within day and between days precision, in terms of coefficient of variation, were less than 10% for all concentrations. The developed method was successfully used in a pharmacokinetic study after oral administration of calcium fosfomycin to broiler chickens.

Determination of Fosfomycin Trometamol and its Related Substances in the Bulk Drug by Ion‐Pair HPLC with Evaporative Light Scattering Detection

Ion‐pair high performance liquid chromatography (HPLC) with an evaporative light scattering detector was used to develop a method for the determination of fosfomycin trometamol and its related substances in the bulk drug. Utilizing a Luna 5 µm C18 column at 35°C, evaporation temperature of 45°C, and nebulizing gas pressure of 3.5 bar, the optimized mobile phase was a 15 mM octylamine solution (adjusted to pH 5.2 with glacial acetic acid) with acetonitrile (92∶8), and the flow rate was maintained at 1.5 mL/min. Validation of the method was performed, and specificity, reproducibility, precision, and accuracy were confirmed. The linear range for fosfomycin trometamol and fosfomycin trometamol impurity A was 48.7–292 µg/mL and 10.5–84 µg/mL, respectively. The limit of quantitation was 16.3 µg/mL for fosfomycin trometamol and 10.7 µg/mL for fosfomycin trometamol impurity A. Due to its simplicity and accuracy, this method is particularly suitable for routine quality control of fosfomycin trometamol, and can probably be applied to the determination of fosfomycin and related substances in fosfomycin sodium and fosfomycin calcium.

Determination of fosfomycin in chicken plasma samples by gas chromatography: application to pharmacokinetic studies

A sensitive gas chromatographic method is described for the analysis of fosfomycin (FOS) in chicken plasma using phenylphosphonic acid (PPA) as the internal standard. Plasma samples were ultrafiltered, and the ultrafiltrate was then evaporated to dryness. The residue was reconstituted with a silylation reagent for the derivatization of FOS and PPA. The methodology involves the use of a HP-5 capillary column and a flame ionisation detector (FID). The retention times of FOS and PPA were 4.63 and 8.68 minutes, respectively. Response was linear in the range of 1–150 μ mL−1. The detection and quantitation limits were 1 and 2.1 μ mL−1, respectively. Recovery was determined as 109% for FOS. The method was applied to the determination of FOS in chicken plasma samples collected during pharmacokinetic studies.

Determination of fosfomycin by indirect spectrophotometric method

2-(5-Bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP) is a sensitive photometric reagent for determination of zirconium, when fosfomycin is added, it can quantitatively replace 5-Br-PADAP by complexing with zirconium, thus, an indirect spectrophotometric method based on ligand exchange has been established. The detection wavelength is at 605 nm, and the apparent molar absorption coefficient was found to be 4.59×10 4 l mol −1 cm −1. Beer’s law is obeyed in the range of 0–28×10 −6 M. The composition and stability constant of zirconium with 5-Br-PADAP and with fosfomycin has also been estimated. The proposed method is simple and reproducible, it was applicable to the analysis of fosfomycin from pharmaceutical manufacture.

Determination of fosfomycin in human urine by capillary gas chromatography: Application to clinical pharmacokinetic studies

A capillary gas chromatographic method for the determination of fosfomycin in human urine is described. After dilution of the sample and derivatization, analysis was on a HP-1 capillary column and a flame ionization detector was used to determine the bistrimethylsilyl derivative of fosfomycin. Response was linear in the range 50–5000 μg mL−1. The detection limit was about 10 μg mL−1. The within and between day coefficients of variation did not exceed 6%. The method was applied to the determination of fosfomycin in urine samples collected during clinical pharmacokinetic studies.

Determination of fosfomycin in biological fluids by capillary electrophoresis

A capillary electrophoresis method was developed for the determination of the antibiotic fosfomycin in serum, cerebrospinal fluid and aqueous humor. The technique uses indirect UV detection and the working buffer includes an organic cation to improve fosfomycin mobility. The electrophoretic time of migration is less than 7 min in both fluids. The limit of quantification is 2.5 and 1 μg/ml in serum and aqueous fluids, respectively (signal-to-noise ratio = 3). The method was validated in serum and water over the concentration range 2.5–200 μg/ml. The calibration graph for serum was linear with a correlation coefficient r = 0.999. At a fosfomycin concentration of 2.5 μg/ml in serum, the intra- and inter-day precisions (coefficients of variation) were 5 and 5.2%, respectively. The mean recovery in serum was 94.5% (S.D. = 2.4%).

Chromatographic analysis of some alkylphosphonic acids using a conductimetric detection. Application to fosfomycin determination

This paper describes an ion chromatographic technique with conductimetric detection for the rapid quantitative analysis of alkylphosphonic acids. The choice of the mixture of acetonitrile/borategluconate buffer (12∶88 v/v) as the mobile phase is discussed: acetonitrile was added to decrease the retention time of phenylphosphonic acid and fosfomycin. Simultaneously the background conductivity was smaller. Borate/gluconate buffer showed the good buffer capacity at pH=8.5 required for the injection of strong acids. The pH was set at 8.5 to obtain the fully dissociated species since their monoionic forms are poorly retained. No eluent suppression process was necessary since the mobile phase led to a low background conductivity. The validation of the method has been studied. Linearity was determined over a concentration range of from 10 to 80 μg·ml−1. Intra- and inter-day reproducibilities were satisfactory with relative standard deviations respectively less than 1.0 and 4.8%. The lowest detectable limits were from 0.2 to 1.0 μg depending on the analysed compound. The method has been successfully applied to the determination of fosfomycin in biological samples.