Simultaneous determination of ceftazidime and pyridine in human plasma by LC-UV.

A sensitive, accurate and precise liquid chromatography (LC) method for the simultaneous determination of ceftazidime and pyridine in human plasma has been developed and validated. Acetonitrile (ACN) was employed to precipitate the proteins in the plasma samples. Chromatographic separation was performed with a Kinetex® C18 (150 mm × 3 mm, 2.6 µm) column with gradient elution. Ammonium formate 20 mM and ACN were mixed in a ratio of 98:2 (v/v) for mobile phase A and 85:15 (v/v) for mobile phase B. Both were adjusted to pH 4.5 with formic acid. The flow rate was 0.4 mL/min. UV detection was performed at 254 nm. Calibration curves were linear in the range from 0.3 to 225 µg/mL for ceftazidime and from 0.2 to 10 µg/mL for pyridine with correlation coefficients ≥ 0.999. Within- and between-run precision and accuracy were satisfactory with coefficients of variation (CV) ≤ 8.0% and deviations ≤ 7.0%, respectively. The method fulfilled all validation criteria prescribed by the European Medicines Agency guidelines. Next, it has been used successfully to analyze plasma samples of patients who received ceftazidime under intermittent and continuous administration. With intermittent administration, the concentration of the antibiotics reached a peak and then dropped quickly, which may be below the minimal inhibitory concentration (MIC). With continuous administration, the concentration of the antibiotics remained stable over 24 h, certainly above the MIC. Although the same tendency in ceftazidime concentration changes over time was observed, a difference in concentration amongst the patients was noticeable. The concentration of pyridine in plasma was negligible.

Liquid chromatographic method to follow-up ceftazidime and pyridine in portable elastomeric infusion pumps over 24 h.

Portable infusion pumps are an interesting solution to continue outpatient parenteral antimicrobial therapy (OPAT) at the patient's home. However, the use of ceftazidime for such applications is challenging in view of its relatively poor stability in solution. In this study, elastomeric infusion pumps with 6 or 7 g of ceftazidime were deflated over 24 h in an oven at 33°C while ceftazidime and its degradation product, pyridine, were regularly monitored. Hereto, a fast and sensitive liquid chromatographic (LC) method has been developed using a Kinetex® C18 (150 × 3 mm, 2.6 µm) column with gradient elution. Ammonium formate 20 mM and acetonitrile (ACN) were mixed in a ratio of 98:2 v/v for mobile phase A and 85:15 v/v for mobile phase B. Both were adjusted to pH 4.5 with formic acid. The flow rate was set at 0.4 mL/min. The solution with a starting dose of 6 g ceftazidime was found to be degraded 10% after an average of 19 h 11 min so that an administration of 6 g to the patient was not reached. For the solution with a starting dose of 7 g of ceftazidime, 10% degradation was observed after an average of 18 h 42 min. However, by starting from a higher dose, an average of 6.56 g of ceftazidime could be administered over 24 h. In addition, 1.0% of pyridine versus ceftazidime pentahydrate with sodium carbonate (=mixture for injection) was formed over 24 h.

Antibiotic therapeutic drug monitoring in intensive care patients treated with different modalities of extracorporeal membrane oxygenation (ECMO) and renal replacement therapy: a prospective, observational single-center study.

BACKGROUND: Effective antimicrobial treatment is key to reduce mortality associated with bacterial sepsis in patients on intensive care units (ICUs). Dose adjustments are often necessary to account for pathophysiological changes or renal replacement therapy. Extracorporeal membrane oxygenation (ECMO) is increasingly being used for the treatment of respiratory and/or cardiac failure. However, it remains unclear whether dose adjustments are necessary to avoid subtherapeutic drug levels in septic patients on ECMO support. Here, we aimed to evaluate and comparatively assess serum concentrations of continuously applied antibiotics in intensive care patients being treated with and without ECMO. METHODS: Between October 2018 and December 2019, we prospectively enrolled patients on a pneumological ICU in southwest Germany who received antibiotic treatment with piperacillin/tazobactam, ceftazidime, meropenem, or linezolid. All antibiotics were applied using continuous infusion, and therapeutic drug monitoring of serum concentrations (expressed as mg/L) was carried out using high-performance liquid chromatography. Target concentrations were defined as fourfold above the minimal inhibitory concentration (MIC) of susceptible bacterial isolates, according to EUCAST breakpoints. RESULTS: The final cohort comprised 105 ICU patients, of whom 30 were treated with ECMO. ECMO patients were significantly younger (mean age: 47.7 vs. 61.2 years; p < 0.001), required renal replacement therapy more frequently (53.3% vs. 32.0%; p = 0.048) and had an elevated ICU mortality (60.0% vs. 22.7%; p < 0.001). Data on antibiotic serum concentrations derived from 112 measurements among ECMO and 186 measurements from non-ECMO patients showed significantly lower median serum concentrations for piperacillin (32.3 vs. 52.9; p = 0.029) and standard-dose meropenem (15.0 vs. 17.8; p = 0.020) in the ECMO group. We found high rates of insufficient antibiotic serum concentrations below the pre-specified MIC target among ECMO patients (piperacillin: 48% vs. 13% in non-ECMO; linezolid: 35% vs. 15% in non-ECMO), whereas no such difference was observed for ceftazidime and meropenem. CONCLUSIONS: ECMO treatment was associated with significantly reduced serum concentrations of specific antibiotics. Future studies are needed to assess the pharmacokinetic characteristics of antibiotics in ICU patients on ECMO support.

Stability and Sterility of Extemporaneously Prepared Nonpreserved Cefazolin, Ceftazidime, Vancomycin, Amphotericin B, and Methylprednisolone Eye Drops.

PURPOSE: To determine in-use stability and sterility of fortified cefazolin, ceftazidime, vancomycin, amphotericin B, and methylprednisolone eye drops in a simulated inpatient setting with and without a mobile refrigerated container (MR). METHODS: Each drug was prepared and divided into 4 groups: 1) simulated patient use with the MR group: stored at 4°C and kept in the MR during drug administration, 2) simulated patient use without the MR (NoMR) group: stored at 4°C and no MR, 3) refrigerated control group: stored at 4°C, and 4) room temperature control group: stored at room temperature. Stability and sterility data were evaluated at days 0, 4, 7, 14, 21, and 28. Linear mixed-effects model and survival analysis were performed. RESULTS: Median time to 10% loss of concentration for in-use medications (MR/NoMR groups) was >28/27.9, 22.2/22.2, 19.4/19.4, 10.18/<4, and >28/>28 days for cefazolin, ceftazidime, vancomycin, amphotericin B, and methylprednisolone, respectively. There was no significant difference in the predicted concentration loss per day among all groups for vancomycin and methylprednisolone (all P > 0.05). For the other study medications, all room temperature control groups, the cefazolin NoMR group, and the ceftazidime NoMR group had significantly greater predicted concentration loss per day compared with the refrigerated control groups (all P ≤ 0.02). Culture results were negative for all drugs throughout the study. CONCLUSIONS: The NoMR group showed that the drug significantly degraded rapidly for cefazolin, ceftazidime, and amphotericin B. Implementation of MR could decrease the predicted loss of concentration per day for cefazolin and ceftazidime. In vitro antimicrobial activity and sterility were retained for 28 days.

Development and validation of an LC tandem MS assay for the quantification of ß-lactam antibiotics in the sputum of cystic fibrosis patients.

OBJECTIVES: Antibiotic therapy is of vital importance for the control of infectious exacerbations in cystic fibrosis (CF) patients. However, very little is known regarding the fraction of systemically administered antibiotics reaching the lower respiratory tract secretions. We developed and validated a method to measure the concentrations of piperacillin, ceftazidime, meropenem and aztreonam in CF sputum, and present the validation data. METHODS: Ultra-performance LC coupled to tandem MS was used. A single sample can be measured in 2.5 min with multiple reaction monitoring in positive electrospray ionization mode. Deuterated internal standards were used and a concentration range of 0.7-160 mg/L was covered. The method was validated according to the EMA guideline on analytical method validation. RESULTS: The boundaries within which a reliable measurement in CF sputum can be performed were determined. A few constraints are linked to the instability of the antibiotics in sputum. Piperacillin showed limited stability at room temperature and during freeze-thaw cycles. Autosampler instability was observed after 15 h for aztreonam at low concentrations. CONCLUSIONS: The method allows a reliable measurement of the selected antibiotics, if precautions are taken regarding the limited stability of piperacillin at room temperature. Due to freeze-thaw instability, piperacillin should always be analysed on the day of sampling. Quick review of the analytical data and reanalysis are needed as low concentrations of aztreonam are not stable in the autosampler.

Determination of cefotaxime, cefoperazone, ceftazidime and cefadroxil using surface plasmon resonance band of silver nanoparticles

The aim of this work is to evaluate simple, sensitive, effective and validated procedures for the determination of cefotaxime, cefoperazone, ceftazidime and cefadroxil. In this study, the methods based on the ability of the cited drugs to reduce Ag+ ions to silver nanoparticles (Ag-NPs) in the presence of Polyvinyl Pyrrolidone (PVP) as a stabilizing agent producing very intense surface plasmon resonance peak of Ag-NPs (λmax. = 410-430 nm). The plasmon absorbance of the Ag-NPs allows the quantitative spectrophotometric determination of the cited drugs. The calibration curves are linear with concentration ranges of 0.4-3.2, 1-8, 0.5-4.0 and 1.5-9.0 µg/mL for cefotaxime, cefoperazone, ceftazidime and cefadroxil, respectively. Apparent molar absorptivity, detection and quantitative limits are calculated. Applications of the proposed methods to representative pharmaceutical formulations are successfully presented. The extracellular synthesis of nanoparticles is fast, and the method doesn't require various elaborate treatments and tedious extraction procedures.

Espectro y actividad in vitro de ceftazidima/avibactam / Spectrum and in vitro activity of ceftazidime/avibactam

Ceftazidima es una cefalosporina de tercera generación con buena actividad frente a enterobacterias y Pseudomonas spp., que es estable frente a betalactamasas de amplio espectro como TEM, SHV y OXA, y es inactivada por betalactamasas de espectro extendido, cefamicinasas y carbepenemasas. Avibactam es un nuevo inhibidor sintético de betalactamasas, no betalactámico, perteneciente a la clase de los diazabiciclooctanos, que tiene una potente actividad inhibidora sobre betalactamasas de clase A, incluyendo betalactamasas de espectro extendido y carbapenemasas, como las KPC, betalactamasas de clase C y algunas de clase D, entre las que se halla OXA-48, pero no OXA-24. No tiene actividad frente a las carbapenemasas de clase B (metalobetalactamasas). La combinación de ambos restablece la actividad amenazada del betalactámico ocasionada por la emergencia y expansión, en diferentes especies de Enterobacteriaceae, de serinabetalactamasas que hidrolizan la ceftazidima. La excelente actividad in vitro frente a enterobacterias productoras de betalactamasas de espectro extendido, betalactamasas de clase C o carbapenemasas tipos KPC y OXA-48, hace de ceftazidima/avibactam una herramienta con elevado potencial para el tratamiento de infecciones por enterobacterias multirresistentes. De igual forma, la actividad de ceftazidima/avibactam frente a Pseudomonas aeruginosa es muy superior a la de la mayoría de los betalactámicos disponibles, siendo solo comparable a la de ceftolozano/tazobactam. La existencia de cepas resistentes por producción de metalobetalactamasas y otros mecanismos poco frecuentes obliga a la prudencia en su posicionamiento para uso clínico (AU)

Ceftazidime is a third-generation cephalosporin active against Enterobacteriaceae and Pseudomonas spp. It is stable against broad spectrum beta-lactamases such as TEM, SHV or OXA, and is inactivated by the extended spectrum beta-lactamases (ESBLs), class C enzymes (AmpC) and carbapenemases. Avibactam is a new non-beta-lactam synthetic beta-lactamase inhibitor belonging to the diazabicyclooctane class. It shows potent inhibitory activity against class A beta-lactamases, including the ESBLs, AmpC and KPC carbapenemases, and some class D beta-lactamases including the carbapenemase OXA-48 but not OXA-24. On the other hand, avibactam is not active against class B carbapenemases (metallo-beta-lactamases, MBLs). The combination of avibactam with ceftazidime restores the activity of the beta-lactam compromised by the emergence and dissemination in distinct Enterobacteriaceae species of serin-betalactamases that hydrolyse ceftazidime. The excellent in vitro activity against Enterobacteriaceae isolates producing ESBLs, AmpC and carbapenemases from classes A (KPC) and D (OXA-48) makes ceftazidime/ avibactam a highly useful tool for the management of infections by multidrug-resistant strains. Likewise, the activity of ceftazidime/avibactam against P. aeruginosa is higher than that of most other available betalactams, with only ceftolozane/tazobactam showing similar activity. The isolation of resistant strains due to the production of MBLs and other infrequent mechanisms calls for prudent therapeutic use of this valuable combination (AU)

Desarrollo y validación de un procedimiento de medida para la medición simultánea de la concentración de masa de ceftazidima, meropenem y piperacilina en el plasma mediante UHPLC-MS/MS / Development and validation of a procedure for the simultaneous measurement of ceftazidime, meropenem and piperacillin mass concentration in plasma using UHPLC-MS/MS

Introducción. La ceftazidima, el meropenem y la piperacilina son antibióticos ¿-lactámicos de amplio espectro empleados en el tratamiento empírico de pacientes críticos con sepsis. Estos fármacos presentan una actividad antimicrobiana dependiente del tiempo por lo que sus concentraciones de masa en el plasma deberían medirse y mantenerse por encima de la concentración mínima inhibitoria. El objetivo de este estudio es desarrollar y validar un procedimiento de medida basado en la cromatografía de alta y rápida resolución acoplada a la espectrometría de masas en tándem para la medición simultánea de la concentración de masa de ceftazidima, meropenem y piperacilina en el plasma. Material y métodos. Después de una precipitación de proteínas de las muestras con acetonitrilo y posterior dilución con agua, los eluatos son introducidos en una columna C18 de fase inversa usando un gradiente de agua/acetonitrilo que contiene ácido fórmico. Los antibióticos son detectados mediante un espectrómetro de masas de triple cuadrupolo trabajando en las modalidades de ionización por electroespray y monitorización de reacción múltiple. Resultados. Los límites de cuantificación son cercanos a 0,50mg/l. Los coeficientes de variación y sesgos relativos son inferiores a 10,8 y 12,0%, respectivamente. Los valores de recuperación están comprendidos entre 55,7 y 77,4%. La evaluación del efecto matriz muestra una sobreexpresión iónica para todos los antibióticos. No se observan interferencias ni contaminación por arrastre. Conclusiones. El procedimiento de medida validado podría ser empleado en la práctica diaria del laboratorio clínico para la medición de estas magnitudes farmacológicas, principalmente en pacientes críticos con sepsis (AU)

Introduction. Ceftazidime, meropenem and piperacillin are broad spectrum antibiotics often used for the empirical treatment of infections in critically ill patients with sepsis. These antibiotics show time-dependent antimicrobial activity, meaning that the antibiotic mass concentration in plasma should be measured and maintained above the minimal inhibitory concentration. The aim of this study was to develop and to validate an ultra-performance liquid chromatography-tandem mass spectrometry procedure for the simultaneous measurement of ceftazidime, meropenem, and piperacillin mass concentration in plasma. Material and methods. After protein precipitation with acetonitrile and subsequent dilution of the supernatant with water, eluates were introduced into a reverse-phase C18 column using a water/methanol gradient containing formic acid. Antibiotics were detected by electrospray ionisation mass spectrometry in multiple reaction monitoring mode. Results. The lower limits of quantification were close to 0.50mg/l. Coefficients of variation and absolute relative biases were less than 10.8 and 12.0%, respectively. Recovery values ranged from 55.7 to 77.4%. Evaluation of the matrix effect showed ion enhancement for all antibiotics. No interferences or carry-over were observed. Conclusions. The validated measurement procedure could be used in daily clinical laboratory practice to measure the mass concentration of these antibiotics in plasma, and in critically ill patients with sepsis (AU)

Electrophoretic stacking for sensitive determination of antibiotic ceftazidime in human blood and microdialysates from diabetic foot.

An electrophoretic stacking method has been developed for monitoring the therapeutic level of the antibiotic ceftazidime in blood plasma and microdialysates taken from peripheral soft tissues of the lower limbs of patients with diabetic foot syndrome. The biological samples are treated by addition of acetonitrile in an amount of 75% v/v and injected into a capillary in a large volume; after turning on the separation voltage, the residual acetonitrile is forced out of the capillary by the application of hydrodynamic pressure. The clinical samples were separated in an optimised background electrolyte composed of 50 mM chloroacetic acid +20% v/v methanol +0.5% v/v INST coating solution. The attained LOD for ceftazidime equalled 0.42 µg mL-1 (0.8 µM) and the migration time equalled 3.75 min when using a 25 µm capillary with minimum length of 31.5 cm. The separation was controlled by a maximum voltage of +30 kV and the movement of the analyte was accelerated by a pressure of 50 mbar. The RSD values for intra-day repeatability of the migration time and peak area are 0.14% and 3.8%, respectively; the inter-day values equalled 0.25% for the migration time and 7.3% for peak area, respectively. Pharmacological studies revealed that ceftazidime passes from the blood circulation to the peripheral tissues of the lower limbs with an efficiency of 20%. The introduction of CE control of ceftazidime level in diabetic foot represents a very important improvement in achieving the targeted therapeutic effect.

Preconcentration and determination of ceftazidime in real samples using dispersive liquid-liquid microextraction and high-performance liquid chromatography with the aid of experimental design.

A rapid and simple method for the extraction and preconcentration of ceftazidime in aqueous samples has been developed using dispersive liquid-liquid microextraction followed by high-performance liquid chromatography analysis. The extraction parameters, such as the volume of extraction solvent and disperser solvent, salt effect, sample volume, centrifuge rate, centrifuge time, extraction time, and temperature in the dispersive liquid-liquid microextraction process, were studied and optimized with the experimental design methods. Firstly, for the preliminary screening of the parameters the taguchi design was used and then, the fractional factorial design was used for significant factors optimization. At the optimum conditions, the calibration curves for ceftazidime indicated good linearity over the range of 0.001-10 µg/mL with correlation coefficients higher than the 0.98, and the limits of detection were 0.13 and 0.17 ng/mL, for water and urine samples, respectively. The proposed method successfully employed to determine ceftazidime in water and urine samples and good agreement between the experimental data and predictive values has been achieved.

Assay of ceftazidime and cefepime based on fluorescence quenching of carbon quantum dots.

A novel and sensitive method for the determination of ceftazidime and cefepime in an active pharmaceutical ingredient (API) has been developed based on the fluorescence quenching of poly(ethylene glycol) (PEG)2000-capped carbon quantum dots (CQDs) prepared using a chemical oxidation method. The quenching of fluorescence intensity is proportional to the concentration of ceftazidime and cefepime over the range of 0.33-3.30 and 0.24-2.40 µg/mL, respectively. The mode of interaction between PEG2000-capped CQDs and ceftazidime/cefepime in aqueous solutions was investigated using a fluorescence, UV/Vis and Fourier transform infrared spectrometry (FTIR) at physiological pH. UV/Vis and FTIR spectra demonstrated that ground state compounds were formed through hydrophobic interaction the fluorescence quenching of CQDs caused by ceftazidime and cefepime. The quenching constants decreased with increases in temperature, which was consistent with static quenching.

[Update of near-infrared models for testing ceftazidime, water and arginine in ceftazidime for injection].

UNLABELLED: To find a more reasonable index to decide whether the universal quantitative NIR model needs to be updated and to develop a general method to update universal quantitative NIR models, the quantitative models for testing ceftazidime, water and arginine contents in ceftazidime for injection were taken as example. The study was performed by analyzing the similarity between new sample spectra and the training set spectra of the original models. At first, new samples of ceftazidime for injection were divided into five groups by cluster analysis. Then representative samples of each group were selected by sample selection strategy. Spectra of those samples were used to update the original quantitative models. The prediction deviation of the new ceftazidime powder injection samples by the models before and after updating was calculated. Decreasing the prediction deviation was regarded as the standard to decide if the updating was effective. At the same time, the correlation coefficient of new sample spectra and reference sample spectra was defined as the index to study the general method for model updating. (Reference sample refers to training set sample) Finally, the proposed method was validated by updating universal models for testing ceftazidime, water and arginine contents in ceftazidime powder injections. Results show that the correlation coefficient of new sample spectra and training set sample spectra of the original model was calculated within modeling wavelength range. It was proved that when correlation coefficient rT < 96.5%, the model needs to be updated. Accordingly, rT = 96.5% was set as the threshold. The quantitative models were updated by the method mentioned above. As a result, when testing ceftazidime for injection containing sodium carbonate using newly updated models, the average predicting deviation of ceftazidime contents decreased from 8.1% to 2.3%. And the average predicting deviation of water contents decreased from 2.2% to 0.3%. Meanwhile, with regard to samples containing arginine using the updated models, the average predicting deviation of ceftazidime contents decreased from 7.0% to 1.9%. The average predicting deviation of water contents decreased from 0.6% to 0.3%. And that of arginine contents de- creased from 2.3% to 0.4%. CONCLUSION: The newly updated models can be used for testing ceftazidime, water and arginine contens in ceftazidime for injection samples of domestic market. It is reasonable to set rT as the index to decide whether the model needs updating. Moreover, it is necessary to take PCA scores graph of new sample spectra and training set spectra of the original model into account. The proposed method for updating models can be used as a usual approach. And rT = 96.5% can be set as the threshold to determine whether the model needs to be updated.

Pd-Au nanoparticle decorated carbon nanotube as a sensing layer on the surface of glassy carbon electrode for electrochemical determination of ceftazidime.

A simple electrodeposition method is employed to construct a thin film modifier of palladium-gold nanoparticles (Pd-AuNPs) decorated multi-walled carbon nanotube (MWCNT) on the surface of glassy carbon electrode (GCE). Morphology and property of Pd-AuNPs-MWCNT have been examined by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Electrochemical performance of Pd-AuNPs-MWCNT/GCE for detection of ceftazidime (CFZ) has been investigated by cyclic voltammetry (CV). This nanostructured film modified electrode effectively exhibited enhanced properties for detection of ceftazidime (CFZ). The effects of various experimental variables such as, the amount of casted MWCNT, time and potential of deposition of metal nanoparticles and the pH of the buffered solution on the electrode response are optimized. The proposed electrode showed a linear dynamic range of 0.05-50µM and the detection limit of 1nM for the CFZ. The modified electrode successfully supports the sensitive detection of trace amounts of the CFZ in pharmaceutical and clinical preparations.

Biological and physicochemical stability of ceftazidime and aminophylline on glucose parenteral solution

Ceftazidime is a broad spectrum antibiotic administered mainly by the parenteral route, and it is especially effective against Pseudomonas aeruginosa. The period of time in which serum levels exceed the Minimum Inhibitory Concentration (MIC) is an important pharmacodynamic parameter for its efficacy. One of the forms to extend this period is to administer the antibiotic by continuous infusion, after prior dilution in a Parenteral Solution (PS). The present work assessed the stability of ceftazidime in 5% glucose PS for 24 hours, combined or not with aminophylline, through High Performance Liquid Chromatography (HPLC). The physicochemical evaluation was accompanied by in vitro antimicrobial activity compared MIC test in the 24-hour period. Escherichia coli and Pseudomonas aeruginosa were the microorganisms chosen for the MIC comparison. The HPLC analysis confirmed ceftazidime and aminophylline individual stability on PS, while the MIC values were slightly higher than the mean described in the literature. When both drugs were associated in the same PS, the ceftazidime concentration by HPLC decreased 25% after 24 hours. Not only did the MIC values show high loss of antibiotic activity within the same period, but also altered MIC values immediately after the preparation, which was not detected by HPLC. Our results indicate that this drug combination is not compatible, even if used right away, and that PS might not be the best vehicle for ceftazidime, emphasizing the importance of the MIC evaluation for drug interactions.

Ceftazidima é um antimicrobiano administrado por via parenteral, que apresenta amplo espectro de ação, principalmente contra Pseudomonas aeruginosa. O tempo em que a concentração sérica de ceftazidima permanece acima da concentração mínima inibitória (MIC) é um importante parâmetro farmacodinâmico para a determinação da eficácia antimicrobiana e pode ser potencializado através da utilização de infusão contínua em soluções parenterais (PS). Este artigo visa a avaliar a estabilidade da ceftazidima em solução de glicose 5%, na presença e na ausência do fármaco aminofilina, através de cromatografia líquida de alta eficiência HPLC e MIC durante o período de 24 horas. Os microorganismos selecionados para a determinação do MIC foram Escherichia coli e Pseudomonas aeruginosa. Os ensaios em cromatógrafo líquido confirmaram a estabilidade dos fármacos ceftazidima e aminofilina quando são individualmente associados em PS, enquanto os valores de MIC ficaram maiores que os valores encontrados na literatura. Quando ambos os fármacos foram associados na mesma solução parenteral a concentração de ceftazidima obtida por HPLC diminuiu 25% depois de 24 horas. Os valores de MIC mostraram maior decaimento da atividade antimicrobiana neste mesmo período e também valores de MIC alterados nas soluções preparadas no tempo zero, decaimento este que não foi detectado em HPLC. Os resultados indicaram incompatibilidade na associação dos fármacos em PS, enfatizando a importância dos resultados de MIC para interações de fármacos.

Detection of extended spectrum beta lactamases, ampc beta lactamases and metallobetalactamases in clinical isolates of ceftazidime resistant Pseudomonas Aeruginosa

We studied the prevalence of ceftazidime resistance in Pseudomonas aeruginosa and the rates of extended-spectrum β-lactamase (ESBL), AmpC β-lactamase (AmpC) and metallo-β-lactamase (MBL) production among the ceftazidime resistant Pseudomonas aeruginosa. A very high rate of MBL production was observed, which suggested it to be an important contributing factor for ceftazidime resistance among Pseudomonas aeruginosa.

Simultaneous multiresponse optimization of an HPLC method to separate seven cephalosporins in plasma and amniotic fluid: application to validation and quantification of cefepime, cefixime and cefoperazone.

An HPLC method for the separation of seven cephalosporins [Cefepime (CEP), ceftazidime (CTA), ceftizaxime (CTI), ceftriaxone (CTR), cefotaxime (COT), cefixime (CIX) and cefoperazone (COP)] in human plasma and amniotic fluid has been developed. Optimization of the chromatographic method was performed in three steps: a series of initial experiments followed by two sets of experiments based on different experimental designs. The initial experiments were performed to decide the basic analytical requirements of the method. Then screening experiment fractional factorial design was used in order to decrease the number of parameters by eliminating parameters which having insignificant effect on responses. The parameters having significant effect were further optimized through a full factorial design. Having studied two responses (retention times and resolutions), a desirability function that assess the responses together, was used to find experimental conditions where the system generated desirable results. The desirable results were obtained with XTerra C18 (250 mm x 4.6mm, 5 microm i.d.) column, 40 mM phosphate buffer, pH 3.2, 18% MeOH, 0.85 mL min(-1) flow rate and 32 degrees C column temperature. Gradient elution with MeOH was applied. A simple and efficient solid-phase extraction was applied for the preparation of plasma and amniotic fluid samples. The validation parameters of the method were evaluated in accordance with ICH guideline. The method validated was applied to the analysis of CEP and COP in maternal venous, fetal venous and fetal arterial plasma, and to the analysis of CIX in maternal venous plasma and amniotic fluid.

Rapid and selective UV spectrophotometric method for the analysis of ceftazidime.

A new UV spectrophotometric method was developed for quantitative evaluation of ceftazidime preparations. The UV detector was set at 255 nm. Beer's law is obeyed in the concentration range of 7.0-14.0 microg/mL. The method was found to be selective, linear, accurate, and precise in the specified ranges. Intra- and interday variability for the method were <2% relative standard deviation. Common excipients used as additives in pharmaceutical preparations do not interfere with the proposed method. This method was successfully used for quantification of ceftazidime in pure form and in pharmaceutical preparations.

Stability of tobramycin and ceftazidime in icodextrin peritoneal dialysis solution.

PURPOSE: The data describing the compatibility of tobramycin and ceftazidime in icodextrin-based peritoneal dialysis (PD) solution is limited. The objective of this study was to assess the chemical stability of tobramycin and ceftazidime in icodextrin PD solution in polyvinyl chloride containers. METHODS: Commercially available 2-L bags of icodextrin 7.5% PD solution were used for each sample. Nine tobramycin study samples were prepared by adding 80 mg tobramycin HCl to each bag. Nine ceftazidime samples were prepared by adding 1000 mg ceftazidime to each bag. Three bags of tobramycin-icodextrin solution were stored under each of the following conditions: refrigeration (4 degrees C), room temperature (25 degrees C), and body temperature (37 degrees C). Three bags of ceftazidime-icodextrin solution were also stored at each of the respective temperatures. Samples were withdrawn from each bag immediately after preparation and at predetermined intervals (1, 2, 4, 6, 8, 12, 24, 48, 72, 96, 120, 168, and 336 hours after preparation). Solutions were visually inspected for precipitation, cloudiness, and discoloration at each sampling interval. All samples were immediately frozen (-80 degrees C) after collection and stored prior to assay. Total concentrations of tobramycin and ceftazidime in dialysate fluid were determined by high-performance liquid chromatography. The last time point when tobramycin or ceftazidime concentration was >90% from baseline was used to denote stability. RESULTS: All solutions were clear in appearance and no color change or precipitation was observed during the study. For tobramycin, under refrigeration, a mean of 94.6%+/-2.3% of the initial concentration remained at 336 hours (14 days); at room temperature, 90.5%+/-4.3% remained at 168 hours (7 days); at body temperature, 90.0%+/-8.1% remained at 24 hours. For ceftazidime, under refrigeration, a mean of 98.0%+/-0.3% of the initial concentration remained at 168 hours (7 days); at room temperature, 91.6%+/-2.0% remained at 48 hours; at body temperature, 93.9%+/-1.1% remained at 8 hours. Stability was not assessed beyond these respective time points. CONCLUSION: Premixed tobramycin-icodextrin PD solution remains stable for 336 hours (14 days) when refrigerated (4 degrees C) and for 168 hours (7 days) at room temperature (25 degrees C). Ceftazidime-icodextrin PD solution is stable for 168 hours and 48 hours, respectively, when stored at 4 degrees C and 25 degrees C. It is recommended that the bags be kept refrigerated whenever possible. Tobramycin-icodextrin solution stored at body temperature was stable up to 24 hours, and ceftazidime-icodextrin solutions up to 8 hours, permitting the practice of pre-warming solutions prior to administration.

Development and validation of spectrophotometric methods for determination of ceftazidime in pharmaceutical dosage forms.

Two spectrophotometric methods for the determination of ceftazidime (CFZM) in either pure form or in its pharmaceutical formulations are described. The first method is based on the reaction of 3-methylbenzothiazolin-2-one hydrazone (MBTH) with ceftazidime in the presence of ferric chloride in acidic medium. The resulting blue complex absorbs at lambdamax 628 nm. The second method describes the reaction between the diazotized drug and N-(1-naphthyl)ethylenediamine dihydrochloride (NEDA) to yield a purple colored product with lambdamax at 567 nm. The reaction conditions were optimized to obtain maximum color intensity. The absorbance was found to increase linearly with increasing the concentration of CFZM; the systems obeyed the Beer's law in the range 2-10 and 10-50 microg mL-1 for MBTH and NEDA methods, resp. LOD, LOQ and correlation coefficient values were 0.15, 0.79 and 0.50, 2.61. No interference was observed from common excipients present in pharmaceutical formulations. The proposed methods are simple, sensitive, accurate and suitable for quality control applications.

Evaluation of ceftazidime contents in antibiotic discs by capillary electrophoresis.

Good quality of antibiotic discs is a fundamental prerequisite to accurate antibiotic susceptibility tests. Capillary electrophoresis (CE) is a widely used method for quantitative analysis. Here, using ceftazidime as an example, we report an easy-to-perform strategy to determine ceftazidime content in discs. First, a serial of ceftazidime standard solutions was prepared to determine the detection linearity. Utilizing the background buffer containing 50 mmol/L Na2HPO4, 0.045 mmol/L beta-cyclodextrin and 3.15 mmol/L Tris (hydroxymethyl) aminomethane, ceftazidime of concentrations ranging from 1.875 to 60 microg/ml showed a linear response to detected peak areas. Subsequently, four kinds of ceftazidime discs were selected from different manufacturers. The discs were homogenized using 1 ml deionized water, and then detected by CE after filtration. The results showed that one kind of discs were of poor quality as further confirmed by disc diffusion tests using standard strains. This study proved the potential of CE as an easy choice to perform disc quality control under appropriate conditions.