Derivative constant wavelength synchronous fluorescence spectrometry for the simultaneous detection of cefadrine and cefadroxil in water samples.

A sensitive accurate spectrofluorimetric technique was developed to detect cefadroxil and cefradine traces in water samples simultaneously, by applying a procedure based on the formation of hydrolysis products corresponding to these compounds by sodium hydroxide (1 N NaOH) treatment. The conventional and the synchronous fluorescence spectra of these hydrolyzed products were totally overlapped making resolving of this mixture impossible. The second-derivative constant-wavelength synchronous fluorescence spectra allowed their detection simultaneously in a single scan after experimental conditions optimization, which was measured at 390 nm and 379 nm for cefadroxil and cefradine, respectively at Δλ = 30.0. The calibration curves between derivative synchronous fluorescence intensity and drugs concentration showed suitable linear correlation in the range of 0.1 to 5 µg.mL-1 for cefadroxil and 0.5-10 µg.mL-1 for cefradine. The proposed fluorimetric method is superior in being simple, environmental friendly and cost effective in comparison to the previously published reported methods.

Optimized Photoelectrochemical Detection of Essential Drugs Bearing Phenolic Groups.

The World Health Organization (WHO) model "List of Essential Medicines" includes among indispensable medicines antibacterials and pain and migraine relievers. Monitoring their concentration in the environment, while challenging, is important in the context of antibiotic resistance as well as their production of highly toxic compounds via hydrolysis. Traditional detection methods such as high-performance liquid chromatography (HPLC) or LC combined with tandem mass spectrometry or UV-vis spectroscopy are time-consuming, have a high cost, require skilled operators and are difficult to adapt for field operations. In contrast, (electrochemical) sensors have elicited interest because of their rapid response, high selectivity, and sensitivity as well as potential for on-site detection. Previously, we reported a novel sensor system based on a type II photosensitizer, which combines the advantages of enzymatic sensors (high sensitivity) and photoelectrochemical sensors (easy baseline subtraction). Under red-light illumination, the photosensitizer produces singlet oxygen which oxidizes phenolic compounds present in the sample. The subsequent reduction of the oxidized phenolic compounds at the electrode surface gives rise to a quantifiable photocurrent and leads to the generation of a redox cycle. Herein we report the optimization in terms of pH and applied potential of the photoelectrochemical detection of the hydrolysis product of paracetamol, i.e., 4-aminophenol (4-AP), and two antibacterials, namely, cefadroxil (CFD, ß-lactam antibiotic) and doxycycline (DXC, tetracycline antibiotic). The optimized conditions resulted in a detection limit of 0.2 µmol L-1 for DXC, but in a 10 times higher sensitivity, 20 nmol L-1, for CFD. An even higher sensitivity, 7 nmol L-1, was noted for 4-AP.

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.

Characteristics, Properties and Analytical Methods of Cefadroxil: A Review.

Infections are the second leading cause of mortality worldwide and there are many reasons justifying the need for further studies of antimicrobial agents. Cefadroxil is a drug that has bactericidal activity and broad spectrum of action. Quantitative analyzes about cefadroxil are essential for the understanding of bioavailability, bioequivalence, and therapeutic control, which will ensure the product's characteristics and patients' safety. Thus, this study highlights a brief literature review about the drug and the existing methods developed for the determination of cefadroxil found in official and scientific papers. According to the methods found in literature, liquid chromatography and spectrophotometry of absorption in the ultraviolet region prevailed over the others. Importantly, most of the solvents used for the development of the described analytical methods are toxic to the environment, making it necessary to educate researchers and pharmaceutical companies to use nontoxic solvents to provide environmental-friendly methods and better benefits to equipments and mainly to analysts.

Determination of Cefadroxil in Tablet/Capsule formulations by a validated Reverse Phase High Performance Liquid Chromatographic method.

An innovative, selective and rapid reversed phase High Performance Liquid Chromatographic (RP-HPLC) method for the analysis of cefadroxil in bulk material and oral solid dosage forms has been developed and validated. The chromatographic system consisted of Sil-20A auto sampler, LC-20A pump and SPD-20A UV/visible detector. The separation was achieved by C18 column at ambient temperature with a mobile phase consisting of methanol: Phosphate buffer (10: 90) at a flow rate of 1.5 ml/min. The method is reproducible, repeatable (%RSD for intra-day and inter-day ranged between 1.75-5.33% and 0.58-2.69%) and linear (R2=0.9935). The LOD and LOQ of the method were 0.5 and 1.0 µg/ml, respectively. The present RP-HPLC method was found to be sensitive, accurate, precise, rapid and cost effective that can be efficiently used in QC/QA laboratories for routine analysis of the raw materials as well as oral dosage formulations of cefadroxil.

A comparative study of capillary zone electrophoresis and pH-potentiometry for determination of dissociation constants.

Acidity constants of six cephalosporin antibiotics, cefalexin, cefaclor, cefadroxil, cefotaxim, cefoperazon and cefoxitin are determined using capillary zone electrophoresis (CZE) and pH-potentiometric titrations. Since CZE is a separation method, it is not necessary for the samples to be of high purity and known concentration because only mobilities are measured. The effect on determination of dissociation constants of different matrices (serum, 0.9% NaCl, fermentation matrix) was examined. The advantages of CZE can be utilized in those fields where potentiometry has limitations (sample quantity, solubility, purity, simultaneous determinations), although pK(a) values that are close to each other can be determined by potentiometry with more accuracy.

Flow injection chemiluminescence determination of cefadroxil using potassium permanganate and formaldehyde system.

A simple, rapid and precise flow injection chemiluminescence (FI-CL) method is proposed for the determination of cefadroxil and is suitable for application to other antibiotics containing phenolic hydroxyl groups. A possible mechanism for this selectivity is suggested. The method is based on the CL-emitting reaction between cefadroxil and potassium permanganate in sulfuric acid medium, enhanced by formaldehyde (HCHO). Under the optimum conditions, calibration graphs over the ranges of 0.05-0.8 and 1.0-10.0 microg ml(-1) were obtained. The proposed method was successfully applied to the determination of cefadroxil in pharmaceutical formulations with no evidence of interference from common excipients. The detection limit (3sigma) of this method is 25 ng ml(-1) (6.9 x 10(-8) mol l(-1)). The relative standard deviation was less than 2% for 0.4 and 4.0 microg ml(-1) cefadroxil (n = 20). The sample throughput was found to be 120 h(-1).

Determination of cefadroxil by sequential injection with spectrophotometric detector.

A sequential injection analysis (SIA) spectrophotometric procedure for cefadroxil determination has been developed. The SIA instrumentation was modified to achieve the desired function and operations by using the software developed to interface the PC with the conventional SIA system. The method is based on the measurement of a red, water-soluble product formed by the reaction between cefadroxil and 4-aminoantipyrine in the presence of alkaline potassium hexacyanoferrate(III) at 510 nm. Optimum conditions for determining the drug were investigated. Beer's law was obeyed over the concentration ranges of 1 - 10 mg L(-1) and 10 - 50 mg L(-1) with a detection limit (3 sigma) of 0.17 mg L(-1) and a limit of quantification (10 sigma) of 0.56 mg L(-1). The relative standard deviations of 1.98% and 1.93% for 5 mg L(-1) and 30 mg L(-1) of the drug, respectively (n = 11) are obtained. The proposed method has been applied satisfactorily to the determination of cefadroxil in commercial pharmaceutical formulations with a sampling rate of 100 h(-1). Results obtained were in good agreement with those obtained by the official HPLC method at the 95% confidence level.

Chemiluminescence flow-injection analysis of beta-lactam antibiotics using the luminol-permanganate reaction.

A new flow injection chemiluminescence (CL) method has been developed for the determination of six beta-lactam antibiotics, including amoxicillin, cefadroxil, cefoperazone sodium, cefazolin sodium, cefradine and ceftriaxone sodium. When the antibiotic was injected into a stream of KMnO4 with alkaline luminol, a strong CL signal was produced. The method allows the measurements of 0.1-50.0 mg/L amoxicillin, 0.1-80.0 mg/L cefadroxil, 1.0-30.0 mg/L cefoperazone sodium, 1.0-30.0 mg/L cefazolin sodium, 3.0-50.0 mg/L cefradine and 3.0-50.0 mg/L ceftriaxone sodium. The detection limits are 0.05 mg/L for amoxycillin, 0.05 mg/L for cefadroxil, 0.4 mg/L for cefoperazonum sodium, 0.4 mg/L for cefazolin sodium, 0.8 mg/L for cefradine and 0.8 mg/L for ceftriaxone sodium. The relative standard deviations in 11 repeated measurements are 0.6%, 0.8%, 1.5%, 1.2%, 0.4% and 0.3% for 3.0 mg/L amoxicillin, 1.0 mg/L cefadroxil, 10.0 mg/L cefoperazone sodium, 10.0 mg/L cefazolin sodium, 10.0 mg/L cefradine and 10.0 mg/L ceftriaxone sodium, respectively. The method was successfully applied to the determination of amoxicillin in pharmaceutical preparations. A possible CL reaction mechanism is also discussed.

A sensitive assay of amoxicillin in mouse serum and broncho-alveolar lavage fluid by liquid-liquid extraction and reversed-phase HPLC.

A sensitive and simple high-performance liquid chromatography (HPLC) method was developed and validated for the analysis of amoxicillin in mouse serum and broncho-alveolar lavage (BAL) fluid. One hundred microlitres of sample were needed for the assay. Sample processing was carried out with liquid-liquid extraction. Cefadroxil was used as an internal standard. The chromatographic separation was achieved on a C18 reversed-phase column with a mobile phase consisting of phosphate buffer, 1-octanesulphonic acid sodium salt and acetonitrile. The detection was conducted at 210 nm. The ranges of the standard curves were 0.2-20 and 0.05-5 microg/ml for serum and BAL samples, respectively. The recoveries of amoxicillin from serum and normal saline were 87 and 88%, respectively. The coefficients of variation were 1.78-6.13% for intra-day and 0.82-6.42% for inter-day analyses. The accuracy was within 100+/-6%. This method was successfully applied to analyze amoxicillin in mouse serum and BAL samples from a pharmacokinetic study.

Derivative spectrophotometry in the analysis of mixtures of cefotaxime sodium and cefadroxil monohydrate.

Derivative spectrophotometry (ratio-spectra 1st- and 2nd-derivative and zero-crossing 2nd-derivative techniques) was applied for the determination of some cephalosporins in two component mixtures. Cefotaxime sodium salt (C(16)H(16)O(7)N(5)S(2)Na) and cefadroxil monohydrate (C(16)H(17)N(3)O(5)S.H(2)O) were examined. In all procedures, the calibration plots are linear up to 43 microg/ml of each antibiotic, with r ranging from 0.9997 to 0.9999. In the ratio-spectra method, the measurements were taken at 239.5 and 291.5 nm (cefotaxime, 1st-derivative), 238 and 283 nm (cefadroxil, 1st-derivative), 284 and 303 nm (cefotaxime, 2nd-derivative), and 229.5 and 245.5 nm (cefadroxil, 2nd-derivative). Detection limits at P=0.05 level of significance, calculated by a statistical treatment of calibration data, ranged from 0.15 to 0.58 microg/ml. LOD and LOQ ranged, respectively, from 0.19 to 0.51 and from 0.63 to 1.70 microg/ml. By the zero-crossing 2nd-derivative method, lines of regression are linear at 257 and 279 nm (cefotaxime) and 242 and 296 nm (cefadroxil). Detection limits from 0.28 to 0.51 microg/ml. LOD and LOQ from 0.27 to 0.41 and from 0.90 to 1.37 microg/ml, respectively. All the samples were tested for stability in solution and in the course of actual analysis, up to 80 h from their preparation. The developed derivative spectrophotometric methods were applied to synthetic mixtures and the RSD values ranged between 0.05 and 1.35% (ratio-spectra technique) and 0.01 and 1.07% (zero-crossing technique). The methods were also applied to vials and tablets for these drugs. The recoveries obtained were between 100.9 and 102.4% (ratio-spectra) and between 99.8 and 102.0% (zero-crossing). The procedures are simple, rapid, and did not require any preliminary separation or treatment of the samples. Instrumentation commonly available was utilised. The cephalosporins analysed are frequently used antibiotics of relevant clinical and pharmacological importance; hence this work would be of interest for the readers of journals devoted to pharmaceutical and biomedical analysis.

Flow-injection spectrophotometric determination of certain cephalosporins based on the formation of dyes.

A flow-injection spectrophotometric method is described for the determination of cefadroxil (I) and cefotaxime (II). The method is based on the hydrolysis of the cephalosporin with sodium hydroxide whereby the sulfide ion is produced. The latter is allowed to react with N,N-diethyl-p-phenylenediamine sulfate (N,N-DPPD) and Fe (III), and the blue color produced is measured at 670 nm (method A). Linear calibration graphs are obtained in the range 36.34-109.2 and 95.48-477.4 microgml(-1) for I and II, respectively. The experimental limits of detection (three times the noise signal) are 0.036 and 0.048 microgml(-1) for I and II, respectively. The total flow-rate is 5.3 ml min(-1) for both drugs. Alternately, the sulfide ion produced is allowed to react with p-phenylenediamine dihydrochloride (PPDD) and Fe (III), and the violet color produced is measured at 597 nm (method B). Linear calibration graphs are obtained in the range 0.5-400 and 0.5-450 microg ml(-1) for I and II, respectively. The limits of detection are 0.4 and 0.2 microg ml(-1) for I and II, respectively. The total flow-rate is 3 ml min(-1) for both drugs. The methods have been successfully applied to the analysis of some pharmaceutical formulations, particularly of the injection and capsule types. The relative standard deviation (RSD) (n = 10) at the 50 and 100 microg ml(-1) levels of I and II were 0.83-0.77 and 0.9-0.8% with N,N-DPPD and PPDD as reagents, respectively. Recoveries were quantitative; the results obtained agreed with those obtained by other reported methods.

Study on electrooxidation of cefadroxil monohydrate and its determination by differential pulse voltammetry.

In this work electrooxidation of cefadroxil monohydrate was investigated using a glassy carbon electrode depending on pH and supporting electrolyte. It was shown that the direct determination of the substance from capsules and in oral suspension could be made by differential pulse voltammetry (DPV). UV and first derivative UV spectrophotometric methods are also proposed as comparative methods.

Spectrofluorometric determination of alpha-aminocephalosporins in biological fluids and pharmaceutical preparations.

A selective and highly sensitive fluorometric method was developed for the determination of four alpha-aminocephalosporins, namely cefaclor, cefadroxil, cephalexin and cephradine. The method involves the reaction of the target compounds with fluorescamine at a specific pH, ranging from 7.8 to 8.4. The produced derivatives exhibit maximum fluorescence intensities at 472-478 nm after excitation at 370-372 nm. The method is highly specific because other alpha-aminocephalosporins whose alpha amino group was blocked do not react similarly and hence do not interfere. At the specific pH range of the reaction where no degradation may occur with that medium the proposed method can be utilised as a stability-indicating assay. The different experimental parameters affecting the derivatisation reaction were carefully studied and incorporated into the procedure. Under the described conditions, the proposed method is linear over the concentration range of 0.05(-1) microg/ml(-1) for both cefaclor and cephalexin, and 0.05-0.65 and 0.025-0.5 microg/ml(-1) for cefadroxil and cepharadine, respectively and the coefficients of determination were greater than 0.999 (n = 3). The recoveries of the title compounds from spiked serum ranged from 88.6 to 89.7% and from spiked urine from 92.2 to 93.3% with a limit of quantitation (LOQ) of 25-50 ng/ml(-1) and limit of detection (LOD) of 5 ng/ml(-1) (S/N = 2) for all drugs. The mechanism of the fluorometric reaction is proposed and the advantages of the proposed method are discussed.

Selective spectrofluorimetric determination of phenolic beta-lactam antibiotics through the formation of their coumarin derivatives.

A simple, sensitive and selective spectrofluorimetric procedure was developed for the determination of amoxycillin, cefadroxil and cefoperazone. The method is based on the reaction between these drugs and ethyl acetoacetate, in acidic medium, to give yellow fluorescent products with excitation wavelengths ranging from 401 to 467 nm and emission wavelengths ranging from 465 to 503 nm. The reaction conditions were studied and optimized. The reaction obeyed Beer's law over the range of 10.0-20.0, 1.5-1.0 and 50.0-100.0 microg ml(-1) for amoxycillin, cefadroxil and cefoperazone, respectively. Interference's from other antibiotics, drugs and dosage forms additives, in capsules and vials dosage forms, were investigated. The proposed method was applied to the analysis of pharmaceutical formulations (capsules and vials) containing the above antibiotics, either alone or in combination with other antibiotics or drugs. The validity of the method was tested by the recovery studies of standard addition which were found to be satisfactory. The results of the proposed method demonstrated that the method is equally accurate, precise and reproducible as the official methods (USP XXIII) and those published for the non-official binary mixtures.

[Studies on the simultaneous measurement of several cephalosporins by RP-HPLC (I)].

This paper reported the research on the simultaneous separation and determination of six cephalosporins by RP-HPLC. Six cephalosporins are cefalcor, cefalexin, cefradine, cefadroxil, cefominox and cefoxitin. The analytical conditions for this method were as follows: a Hypersil ODS C18(200 mm x 4.6 mm i.d., 5 microns), detection wavelength: 254 nm; a mobile phase solution of 50 mmol/L monopotassium phosphate (pH 3.4)-acetonitrile (87.5:12.5) and DAD detector. The flow rate was 1.0 mL/min. The calibration curves of the six compounds were linear, the correlation coefficients were 0.9951 for cefominox, 0.9999 for the others, the range were 164 ng-16.4 micrograms for cefominox, 99 ng-9.934 micrograms for cefadroxil, 104 ng-10.358 micrograms for cefalcor, 122 ng-12.224 micrograms for cefalexin, 107 ng-10.702 micrograms for cefradine and 115 ng-11.506 micrograms for cefoxitin. The recovery rates were 103.5% for cefominox, 99.3% for cefadroxil, 101.4% for cefalcor, 101.5% for cefalexin, 98.7% for cefradine and 97.6% for cefoxitin. Six cephalosporins were all stable in 50 mmol/L monopotassium phosphate (pH 3.4-4.6). When preparations of these cephalosporins were determined, it is indicated there were no difference between the results by using this method and the pharmacopoeia methods. The total separation time of these cephalosporins was within fifteen minutes. This method is simple, sensitive, rapid and accurate.

Analysis of cefadroxil by micellar electrokinetic capillary chromatography: development and validation.

A method is developed and validated for analysis of the antibiotic cefadroxil using micellar electrokinetic capillary chromatography. It permits cefadroxil to be completely separated from ten of its known related substances within 15 min (including the washing procedure). The separation is performed in an acetate buffer (50 mM, pH 5.25) containing sodium dodecyl sulfate (SDS; 110 mM). The fused-silica capillary was 44 cm long (36 cm effective length), 50 microm ID; the voltage, 18 kV; temperature, 15 degrees C; and the detection wavelength; 254 nm. The influence of the type of buffer, buffer pH and concentration, and of the SDS concentration was investigated. The robustness of the method was examined by means of a full-fraction factorial design. The parameters for validation such as linearity, precision, limit of detection and limit of quantitation are also reported.

Predictive strategy for the rapid structure elucidation of drug degradants.

Structural information on drug degradants and impurities can serve to accelerate the drug discovery and development cycle. Traditional structure elucidation methodologies for obtaining this information are often slow and resource-consuming; therefore, LC/MS profiling and LC/MS/MS substructural analysis methodologies have been developed to rapidly and accurately elucidate structures of impurities and degradants. This work is a further development of methodologies used for the elucidation of degradation products of paclitaxel [K.J. Volk et al., Proc. 9th AAPS Ann. Meeting, 1994, p.29]. In this study cefadroxil was used as a model compound for the evaluation of a predictive strategy for the production and elucidation of impurities and degradants induced by acid, base, and heat, using LC/MS and LC/MS/MS profiling methodology, resulting in an LC/MS degradant database which includes information on molecular structures, chromatographic behavior, molecular weight, UV data, and MS/MS substructural information. Furthermore, libraries such as this can provide a predictive foundation for pre-clinical development work involving drug stability, synthesis, and monitoring.

Sensitive assay for measuring amoxicillin in human plasma and middle ear fluid using solid-phase extraction and reversed-phase high-performance liquid chromatography.

We developed a sensitive assay to measure amoxicillin in human plasma and middle ear fluid (MEF) using solid-phase extraction and reversed-phase HPLC. Amoxicillin and cefadroxil, the internal standard, were extracted from 50-200 microliters of sample with Bond Elut C18 cartridges. The extract was analyzed on a 15 cm x 2 mm, 5 micron Keystone MOS Hypersil-1 (C8) column with UV detection at 210 nm. The mobile phase was 6% acetonitrile in 5 mM phosphate buffer (pH = 6.5) and 5 mM tetrabutylammonium. The average absolute recovery of amoxicillin and cefadroxil were 91.2 +/- 16.6% and 91.0 +/- 6.8%, respectively. The limit of quantitation was 0.125 microgram/ml with 200 microliters sample size. The linear range was from 0.125 to 35.0 micrograms/ml with correlation coefficients greater than 0.999. These analytic conditions produced a highly sensitive amoxicillin assay in human body fluids without derivatization.

Automated column liquid chromatographic determination of amoxicillin and cefadroxil in bovine serum and muscle tissue using on-line dialysis for sample preparation.

A fully automated method is described for the determination of amoxicillin and cefadroxil in bovine serum and muscle tissue. The method is based on the on-line combination of dialysis and solid-phase extraction for sample preparation, and column liquid chromatography with ultraviolet detection. In order to enhance the UV detectability of the analytes, post-column addition of 0.1 M sodium hydroxide is performed. The method shows good linearity and repeatability for both analytes in serum as well as in muscle tissue; the limits of detection in these samples are 0.05 microgram/ml and 0.2 microgram/g, respectively. The method has a sample throughput of 30 samples per 24 h.