Determination of cephalosporins in raw bovine milk by high-performance liquid chromatography

Effects of temporary cessation of milking following intramammary cefazolin sodium infusion on residual antibiotic in lactating dairy cows

The aims of studies were to estimate the withdrawal period of antibiotic from milk after the intramammary infusion of cefazolin sodium (CEZ) in cows with difficulties in frequent milk discharge due to disease such as teat injury. The period was compared among cows milked twice a day after 150 or 450 mg of CEZ were administered to all quarters (Study 1, 2) and the cows in which milking of front-right quarter was ceased for five days after administration of these infusions to only that quarter (Study 3). In Studies 1 and 2, the median of 17.66 µg/ml and 83.18 µg/ml of CEZ were detected in the samples of first milking after intramammary administration, respectively; however, there was no residual antibiotic by 72 hr in all cows. In Study 3, the median of 1.96 µg/ml of CEZ was detected in the sample after the resumption of milking at 120 hr, and the residual was eliminated by 174 hr. The withdrawal period may be prolonged by the cessation of milking after administration, and the period is the total time from cessation to 72 hr after the resumption of milking.

Improving the chromatographic selectivity of β-lactam residue analysis in milk using phenyl-column chemistry prior to detection by tandem mass spectrometry

Analyte isobaric interferences can limit the development of a comprehensive analytical method for the quantitative liquid chromatography-tandem mass spectrometry profiling of an important cohort of veterinary drugs. In this work, a selective chromatographic separation was developed for the analysis of 32 β-lactam antibiotic residues (12 penicillins, 14 cephalosporins, five carbapenems and faropenem) in milk samples. A range of analytical columns with different stationary phases and mobile phases were evaluated for retention and separation of the β-lactam compounds. Results showed that, among the columns tested, only phenyl-hexyl could adequately separate ampicillin from cephalexin and amoxicillin from cefadroxil, which had shown isobaric interferences on a number of stationary phases. Chromatography was performed using a water/acetonitrile binary gradient with formic acid and ammonium acetate. The β-lactam residues were extracted from the milk samples using a water:acetonitrile solution and purified by C₁₈ dispersive solid-phase extraction (d-SPE) clean-up, followed by concentration under nitrogen and ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) determination. Analytes were monitored in positive electrospray ionisation mode (ESI(+)). Possible interfering matrix effects were overcome by using 13 internal standards. The method was fully validated according to 2002/657/EC guidelines, showing satisfactory performance characteristics. Under within-laboratory reproducibility conditions, trueness and precision ranged from 91 to 130% and from 1.4 to 38.6%, respectively. Decision limits (CCα) were in the range 2.1-133 μg kg^-1. Limits of detection (LODs) and quantitation (LOQs) ranged between 0.0090 and 1.5 μg kg^-1 and from 0.030 to 5.0 μg kg^-1, respectively.

Efficacy of Cefquinome against Escherichia coli Environmental Mastitis Assessed by Pharmacokinetic and Pharmacodynamic Integration in Lactating Mouse Model

This work investigates the pharmacodynamic effectiveness of cefquinome against environmental Escherichia coli mastitis infection, following an intramammary administration. We established the pharmacokinetic and pharmacodynamic (PK/PD) model in lactating mice. The PK/PD parameters were identified to achieve an antibacterial efficacy as indicated by PD activity, cytokine expression and PK/PD simulation. From our findings, given an 200 μg/gland dose once daily can achieve a considerable therapeutic effectiveness in experimental circumstance.

Dose Assessment of Cefquinome by Pharmacokinetic/Pharmacodynamic Modeling in Mouse Model of Staphylococcus aureus Mastitis

This work aimed to characterize the mammary gland pharmacokinetics of cefquinome after an intramammary administration and integrate pharmacokinetic/pharmacodynamic model. The pharmacokinetic profiles of cefquinome in gland tissue were measured using high performance liquid chromatograph. Therapeutic regimens covered various dosages ranging from 25 to 800 μg/gland and multiple dosing intervals of 8, 12, and 24 h. The in vivo bacterial killing activity elevated when dosage increased or when dosing intervals were shortened. The best antibacterial effect was demonstrated by a mean 1.5 log₁₀CFU/gland visible count reduction. On the other hand, the results showed that the percentage of time duration of drug concentration exceeding the MIC during a dose interval (%T > MIC) was generally 100% because of the influence of drug distribution caused by the blood-milk barrier. Therefore, pharmacokinetic/pharmacodynamic parameter of the ratio of area under the concentration-time curve over 24 h to the MIC (AUC_0-24/MIC) was used to describe the efficacy of cefquinome instead of %T > MIC. When the magnitude of AUC_0-24/MIC exceeding 16571.55 h⋅mL/g, considerable activity of about 1.5 log₁₀CFU/g gland bacterial count reduction was observed in vivo. Based on the Monte Carlo simulation, the clinical recommended regimen of three infusions of 75 mg per quarter every 12 h can achieve a 76.67% cure rate in clinical treatment of bovine mastitis caused by Staphylococcus aureus infection.

Determination of Cefalothin and Cefazolin in Human Plasma, Urine and Peritoneal Dialysate by UHPLC-MS/MS: application to a pilot pharmacokinetic study in humans

An ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method for the analysis of cefazolin and cefalothin in human plasma (total and unbound), urine and peritoneal dialysate has been developed and validated. Total plasma concentrations are measured following protein precipitation and are suitable for the concentration range of 1-500 µg/mL. Unbound concentrations are measured from ultra-filtered plasma acquired using Centrifree(®) devices and are suitable for the concentration range of 0.1-500 µg/mL for cefazolin and 1-500 µg/mL for cefalothin. The urine method is suitable for a concentration range of 0.1-20 mg/mL for cefazolin and 0.2-20 mg/mL for cefalothin. Peritoneal dialysate concentrations are measured using direct injection, and are suitable for the concentration range of 0.2-100 µg/mL for both cefazolin and cefalothin. The cefazolin and cefalothin plasma (total and unbound), urine and peritoneal dialysate results are reported for recovery, inter-assay precision and accuracy, and the lower limit of quantification, linearity, stability and matrix effects, with all results meeting acceptance criteria. The method was used successfully in a pilot pharmacokinetic study with patients with peritoneal dialysis-associated peritonitis, receiving either intraperitoneal cefazolin or cefalothin. Copyright © 2015 John Wiley & Sons, Ltd.

A gold immunochromatographic assay for the rapid and simultaneous detection of fifteen β-lactams

A novel gold immunochromatographic assay (GICA) based on anti-β-lactam receptors was innovatively developed that successfully allowed rapid and simultaneous detection of fifteen β-lactams in milk samples in 5-10 minutes. By replacing the antibodies used in traditional GICA with anti-β-lactam receptors, the difficulty in producing broad specific antibodies against β-lactams was overcome. Conjugates of ampicillin with BSA and goat anti-mouse immunoglobulin (IgG) were immobilized onto the test and control lines on the nitrocellulose membrane, respectively. Since goat anti-mouse IgG does not combine with receptors, negative serum from mice labelled with gold nanoparticles (GNP) was mixed with GNP-labelled receptors. Results were obtained within 20 min using a paper-based sensor. The utility of the assay was confirmed by the analysis of milk samples. The limits of detection (LOD) for amoxicillin, ampicillin, penicillin G, penicillin V, cloxacillin, dicloxacillin, nafcillin, oxacillin, cefaclor, ceftezole, cefotaxime, ceftiofur, cefoperazone, cefathiamidine, and cefepime were 0.25, 0.5, 0.5, 0.5, 1, 5, 5, 10, 25, 10, 100, 10, 5, 5, and 2 ng mL(-1), respectively, which satisfies the maximum residue limits (MRL) set by the European Union (EU). In conclusion, our newly developed GICA-based anti-β-lactam receptor assay provides a rapid and effective method for one-site detection of multiple β-lactams in milk samples.

A Rapid, Validated RP-HPLC Method for the Simultaneous Determination of Cleaning Validation and Cross-Contamination of 12 Beta-Lactam Compounds

The present work reports a rapid reversed-phase high-performance liquid chromatography (RP-HPLC) method for the simultaneous determination of 12 beta-lactam components for cleaning validation and cross-contamination. A strategic experimental approach was implemented for the method development. The desired chromatographic separation was achieved on a Symmetry C18 (4.6 X 75 mm, 3.5 μm) column using gradient elution. The optimized mobile phase consisted of the buffer tetrabutylammonium hydroxide pH-6.8 and acetonitrile. The eluted compounds were monitored at 215 nm and 254 nm wavelength using a photodiode array detector. The developed method separated 12-beta-lactam compounds from each other within a run time of 50 min. The method is effective for the determination of cross-contamination of penicillin and cephalosporin production blocks. The present method is specific and a lower limit of quantification was determined on the basis of the signal-to-noise ratio method; it is 1 μg/mL for all components. The developed RP-HPLC method was validated according to the International Conference on Harmonization (ICH) guidelines.

New spectrofluorimetric method for determination of cephalosporins in pharmaceutical formulations

A simple, accurate, precise spectrofluorimetric method has been proposed for the determination of three cephalosporins, namely, cefixime (cefi), cephalexine (ceph), and cefotaxime sodium (cefo) in pharmaceutical formulations. This method is based on a reaction between cephalosporins with 8-hydroxy-1,3,6-pyrenetrisulfonic acid trisodium salt (HPTS) in alkaline medium, at pH 12.0 for cefi and 13.0 for ceph and cefo to give highly fluorescent derivatives extracted with chloroform and subsequent measurements of the formed fluorescent products at 520, 500 and 510 nm after excitation at 480, 470 and 480 nm for cefi, ceph and cefo respectively. The optimum experimental conditions have been studied. Beer's law is obeyed over concentrations of 10-60 ng/mL, 5-35 ng/mL and 10-60 ng/mL for cefi, ceph and cefo, respectively. The detection limits were 4.20 ng/mL, 2.54 ng/mL and 4.09 ng/mL for cefi, ceph and cefo, respectively, with a linear regression correlation coefficient of 0.99783, 0.99705 and 0.9978 and recoveries in ranges 96.96-105.77, 96.13-102.55 and 95.45-105.39% for cefi, ceph and cefo, respectively. This method is simple and can be applied for the determination of cefi, ceph and cefo in pharmaceutical formulations in quality control laboratories.

Development and validation of a high-performance liquid chromatography method for determination of cefquinome concentrations in sheep plasma and its application to pharmacokinetic studies

Cefquinome has a broad spectrum of antibacterial activity and was developed especially for use in animals. A simple and sensitive high-performance liquid chromatography (HPLC) method with UV-visible detection for quantification of cefquinome concentrations in sheep plasma was developed and validated. Separation of cefquinome from plasma components was achieved on a Phenomenex Gemini C(18) column (250 mm by 4.6 mm; internal diameter [i.d.], 5 μm). The mobile phase consisted of acetonitrile and 0.1% trifluoroacetic acid in water and was delivered at a rate of 0.9 ml/min. A simple and rapid sample preparation involved the addition of methanol to 200 μl of plasma to precipitate plasma proteins followed by direct injection of 50 μl of supernatant into the high-performance liquid chromatography system. The linearity range of the proposed method was 0.02 to 12 μg/ml. The intraday and interday coefficients of variation obtained from cefquinome were less than 5%, and biases ranged from -3.76% to 1.24%. Mean recovery based on low-, medium-, and high-quality control standards ranged between 92.0 and 93.9%. Plasma samples were found to be stable in various storage conditions (freeze-thaw, postpreparative, short-term, and long-term stability). The method described was found to be readily available, practicable, cheap, rapid, sensitive, precise, and accurate. It was successfully applied to the study of the pharmacokinetics of cefquinome in sheep. This method can be very useful and an alternate to performing pharmacokinetic studies in the determination of cefquinome for clinical use.

Flow injection analysis-solid phase extraction (FIA-SPE) method for preconcentration and determination of trace amounts of penicillins using methylene blue grafted polyurethane foam

A simple, fast, and fully automated FIA-SPE method with UV detection for the preconcentration and determination of the investigated penicillins has been developed. This paper provides adequate procedure for the preconcentration and determination of the studied compounds in pharmaceuticals and milk samples. Penicillins (penicillin G, amoxicillin, and ampicillin) are extracted in a mincolumn packed with methylene blue grafted polyurethane foam (MBGPUF) material. The antibiotics are eluted by hydrochloric acid solution to the flow cell of UV-vis spectrophotometer at 230 nm. The analytes are preconcentrated on the sorbent at pH 8.0-9.5 and sample flow rate 3.0 mL/min. Elution was performed with 200 microL 0.2 mol L(-1) hydrochloric acid at 2 mL min(-1). Sample throughput is 12h(-1) at 120 s preconcentration time. High selectivity of the sorbent for the analytes was achieved at the specified pH range. The enrichment factors achieved are 14, 16, and 11 with 3 sigma detection limits of 12, 15, and 19 ng mL(-1) for penicillin G, amoxicillin and ampicillin, respectively. The method was successfully applied to the determination of these antibiotics in pharmaceutical control and contaminated milk samples with RSD<or=8.8%.

Kinetic spectrophotometric determination of certain cephalosporins using oxidized quercetin reagent

A simple, precise and accurate kinetic spectrophotometric method for determination of cefoperazone sodium, cefazolin sodium and ceftriaxone sodium in bulk and in pharmaceutical formulations has been developed. The method is based upon a kinetic investigation of the reaction of the drug with oxidized quercetin reagent at room temperature for a fixed time of 30 min. The decrease in absorbance after the addition of the drug was measured at 510 nm. The absorbance concentration plot was rectilinear over the range 80-400 microg mL(-1) for all studied drugs. The concentration of the studied drugs was calculated using the corresponding calibration equation for the fixed time method. The determination of the studied drugs by initial rate, variable time and rate-constant methods was feasible with the calibration equations obtained but the fixed time method has been found to be more applicable. The analytical performance of the method, in terms of accuracy and precision, was statistically validated; the results were satisfactory. The method has been successfully applied to the determination of the studied drugs in commercial pharmaceutical formulations. Statistical comparison of the results with a well established reported method showed excellent agreement and proved that there is no significant difference in the accuracy and precision.

Residue depletion of cefquinome in swine tissues after intramuscular administration

A high-performance liquid chromatography (HPLC) method with ultraviolet (UV) detection was developed for the detection of cefquinome (CEQ) residues in swine tissues. The limit of detection (LOD) of the method was 5 ng g(-1) for muscle and 10 ng g(-1) for fat, liver, and kidney. Mean recoveries of CEQ in all fortified samples at a concentration range of 20-500 ng g(-1) were 80.5-86.0% with coefficient of variation (CV) below 10.3%. Residue depletion study of CEQ in swine was conducted after five intramuscular injections at a dose of 2 mg kg(-1) of body weight with 24 h intervals. CEQ residue concentrations were detected in muscle, fat, liver, and kidney using the HPLC-UV method at 265 nm. The highest CEQ concentration was measured in kidney tissue during the study period, indicating that kidney was the target tissue for CEQ. CEQ concentrations in all examined tissues were below the accepted maximum residue limit (MRL) recommended by the Committee for Veterinary Medical Products of European Medical Evaluation Agency (EMEA) at 3 days post-treatment.

Use of SDS micelles for improving sensitivity, resolution, and speed in the analysis of β-lactam antibiotics in environmental waters by SPE and CE

This study dealt with the potential of MEKC with LIF detection involving derivatization with sulfoindocyanine succinimidyl ester (Cy5) for the separation and determination of beta-lactam antibiotics (ampicillin, amoxicillin, cephradine, and cephalexin) in environmental water samples. Water samples of 50 mL were enriched by SPE by passage through a weak base-cation Amberlite(R) IRA-93 exchange column. SDS micelles play important roles in the whole analytical process by improving the yield (sensitivity) and the kinetics of the labeling reaction, the elution of the retained antibiotics from the SPE preconcentration system and the electrophoretic resolution of their Cy5-derivatives. The optimum procedure includes a derivatization step of the antibiotics at 25 degrees C for 10 min and direct injection for MEKC analysis, which is conducted within about 15 min using 15 mM SDS in the running buffer (35 mM sodium borate at pH 9.3). LODs from 30 to 45 ng/L and RSDs (within-day precision) from 3.5 to 5.9% were obtained for the antibiotics in water samples with average recoveries ranging from 96.4 to 99.4%. These results indicate that the method proposed is a straightforward and sensitive tool for the determination of these antibiotics in environmental water samples providing similar quantitative results to those using more expensive equipment like LC-electrospray MS/MS.

Analysis of cephalosporin antibiotics

A comprehensive review with 276 references for the analysis of members of an important class of drugs, cephalosporin antibiotics, is presented. The review covers most of the methods described for the analysis of these drugs in pure forms, in different pharmaceutical dosage forms and in biological fluids.

Determination of cefquinome in pig plasma and bronchoalveolar lavage fluid by high-performance liquid chromatography combined with electrospray ionization mass spectrometry

The aim of this study was to develop a rapid and sensitive method for the quantification of cefquinome in animal plasma and bronchoalveolar lavage (BAL) fluid using high-performance liquid chromatography combined with electrospray tandem mass spectrometry (LC-ESI-MS/MS). Cefadroxil is used as internal standard. For plasma, the sample preparation includes a simple deproteinization step with a Microcon filter. This allows detecting the unbound cefquinome concentration, which is correlated with the concentration in other body fluids, such as BAL fluid. To be able to detect the total plasma concentration, deproteinization with acetonitrile, followed by a back-extraction of actonitrile with dichloromethane was performed. The BAL fluid is centrifuged to precipitate floating particles. Chromatographic separation is achieved on a PLRP-S column using 0.005% formic acid and methanol as mobile phase. For plasma, good linearity was observed in the range of 5-2500 ng ml(-1) for both the unbound and total concentration. The response in BAL fluid was linear in the range of 4-1000 ng ml(-1). The limit of quantification (LOQ) was set at 5.00 ng ml(-1) for plasma and at 4.00 ng ml(-1) for BAL fluid. The limit of detection (LOD) was 3.12 ng ml(-1) and 0.41 ng ml(-1) for the unbound and total concentration in plasma, respectively, and was 1.43 ng ml(-1) for BAL fluid. The method was shown to be of use in a pharmacokinetic study in pigs, where the correlation between cefquinome concentrations in plasma and BAL fluid of pigs was studied.