Antibacterial effect of fosfomycin tromethamine on the bacteria inside urinary infection stones

OBJECTIVE

This study sought to evaluate the antibacterial effect of fosfomycin tromethamine (FT) on the bacteria inside urinary infection stones.

METHODS

The internal structures of urinary stones were observed via scanning electron microscopy to verify the presence of internal bacteria. We randomly assigned equal numbers of patients with kidney stones who met the inclusion criteria into two groups in a prospective study and treated them with different perioperative antibiotics. One group (experimental group) was treated with FT, and the other (control group) was treated with cefuroxime sodium. All stone specimens were collected via percutaneous nephrolithotomy (PCNL). The primary infection stones were screened via a stone component analysis, 30 cases in the experimental group and 31 cases in the control group. High-performance liquid chromatography (HPLC)-mass spectrometry was used to measure the drug concentration inside the stones, the bacterial count was calculated via stone culture, and the clinical infection index were monitored for between-group comparisons.

RESULTS

Compared with the control group, the experimental group had a higher internal drug concentration, a higher drug sensitivity against various pathogenic bacteria, a lower bacterial colony count in the stone culture, and a lower incidence of postoperative clinical infection.

CONCLUSIONS

FT is more effective than cefuroxime, which is commonly used during the perioperative period of urinary stones, and exerts a high antibacterial effect on these internal bacteria, and effectively reduces the probability of infection and sepsis after urinary stone surgery. FT can be used as an antibiotic during the perioperative period of urinary stones.

Synthesis and characterization of triazole based supramolecule for interaction with cefuroxime in tap water and blood plasma

In this study a new calix[4]arene triazole 5 was successfully synthesized using click reaction and characterized through UV-visible, FT-IR, ¹H NMR spectroscopes and Mass Spectrometry. The supramolecular interaction of compound 5 towards commonly used drugs has been carried out using UV-Visible spectroscopy. The supramolecule 5 showed characteristic enhancement in the absorbance intensity after mixing with Cefuroxime at pH (2-12). Compound 5 displayed considerably good interactions with cefuroxime in the presence of other drugs. Compound 5 exhibits linear relationship with cefuroxime concentration in the range of (10-80µM) with regression value of 0.9954. The standard deviation for 50µM Cefuroxime was found to be 0.01 and the limit of detection for cefuroxime was calculated to be 2µM. Job's plot experiments showed 1:1 (5: cefuroxime) binding stoichiometry between compound 5 and cefuroxime. Supramolecule 5 displayed fairly good spectrophotometric recognition of Cefuroxime in human blood plasma and tap water thus showing that the ingredients of tap water and plasma sample was inert in the recognition of cefuroxime.

Diagnostic Accuracy of Global Pharma Health Fund Minilab™ in Assessing Pharmacopoeial Quality of Antimicrobials

Global Pharma Health Fund (GPHF) Minilab™, a semi-quantitative thin-layer chromatography (TLC)-based commercially available test kit, is widely used in drug quality surveillance globally, but its diagnostic accuracy is unclear. We investigated the diagnostic accuracy of Minilab system for antimicrobials, using high-performance liquid chromatography (HPLC) as reference standard. Following the Minilab protocols and the Pharmacopoeia of the People's Republic of China protocols, Minilab-TLC and HPLC were used to test five common antimicrobials (506 batches) for relative concentration of active pharmaceutical ingredients. The prevalence of poor-quality antimicrobials determined, respectively, by Minilab TLC and HPLC was amoxicillin (0% versus 14.9%), azithromycin (0% versus 17.4%), cefuroxime axetil (14.3% versus 0%), levofloxacin (0% versus 3.0%), and metronidazole (0% versus 38.0%). The Minilab TLC had false-positive and false-negative detection rates of 2.6% (13/506) and 15.2% (77/506) accordingly, resulting in the following test characteristics: sensitivity 0%, specificity 97.0%, positive predictive value 0, negative predictive value 0.8, positive likelihood ratio 0, negative likelihood ratio 1.0, diagnostic odds ratio 0, and adjusted diagnostic odds ratio 0.2. This study demonstrates unsatisfying diagnostic accuracy of Minilab system in screening poor-quality antimicrobials of common use. Using Minilab as a stand-alone system for monitoring drug quality should be reconsidered.

Consumption-based approach for predicting environmental risk in Greece due to the presence of antimicrobials in domestic wastewater

The main objective of the current study was to estimate the potential environmental risks associated with human consumption of antimicrobials in Greece. Consumption data was collected for the 24 most often used antimicrobials for the years 2008-2010, and their predicted environmental concentrations (PECs) in raw and treated wastewater were calculated using mass balances and literature data on human excretion and elimination efficiency during wastewater treatment. The ecotoxicological risk was estimated by calculating the ratio of PEC to predicted no-effect concentration (PNEC) for three categories of aquatic organisms (algae, daphnids, and fish). PNEC values were calculated based on experimental ecotoxicity data and data originated from the Ecological Structure Activity Relationship (ECOSAR). PEC values in raw sewage ranged between 0.02 μg L(-1) (erythromycin) and 27 μg L(-1) (amoxicillin), while in treated wastewater, the highest concentration was predicted for cefuroxime axetil (6.6 μg L(-1)). Based on acute toxicity data for algae, risk quotient (RQ) values higher than 1 were obtained for 7 out of the 24 target antimicrobials in raw and treated wastewater, while no significant risk was estimated for daphnids and fish. Regarding the possible risk due to the chronic toxicity of antimicrobials, RQ values higher than 80 were obtained for amoxicillin and clarithromycin in algae. The use of baseline toxicity data from ECOSAR showed that the environmental risk from exposure to mixtures of antimicrobials was low for all three aquatic species. However, further studies on toxicity of mixtures should be performed as calculation of toxicity ratio (TR) values showed that 90 % of the target antimicrobials seem to exhibit a specific mode of toxic action when present in mixtures rather than baseline toxicity. As a result, an underestimation of toxicity based on the ECOSAR model is possible for the mixture of target antimicrobials. For Greek rivers where low (dilution factor, D<10) and medium (D=10-100) dilution of wastewater occurs, moderate to high risk is expected due to the existence of individual antimicrobials such as amoxicillin, clarithromycin, ciprofloxacin, azithromycin, erythromycin, and levofloxacin in discharged treated wastewater.

Environmental risk assessment of selected pharmaceuticals in Turkey

In this study, environmental risks of selected pharmaceuticals were investigated to assess potential hazards. Ciprofloxacin, Clarithromycin, Cefuroxime axetil, antibiotics, Benzalkoniuman antiseptic, Paracetamol, an analgesic, and Naproxen, an anti-inflammatory, were selected due to their high rate of usage in Turkey. Ciprofloxacin was found to have the highest risk due to its high PEC/PNEC ratio (28.636). Benzalkonium, Paracetamol and Clarithromycin have a potential to cause environmental hazards. The biodegradation and biological concentration factors (BCF) of the drugs were also determined using EPA/STWIN and EPA/BCFWIN programs. The results illustrated that these pharmaceuticals are nonbiodegradable in wastewater treatment plants. The BCFs of Benzalkonium and Clarithromycin were found to be very high, 70.790 L/kg and 56.490 L/kg, respectively. It was suggested that alternative treatment methods other than biological ones should be investigated for these pharmaceuticals because of their low biodegradability. Also, unnecessary use of antibiotics is supposed to be discouraged to reduce environmental hazards.

Spectrophotometric complexation of cephalosporins with palladium (II) chloride in aqueous and non-aqueous solvents

The complexation reaction of cephalosporins namely cefotaxime (CTX), cefuroxime (CRX), and cefazolin (CEFAZ) with palladium (II) ions have been studied in water and DMF in 25 °C by the spectrophotometric methods. The method is based on the formation of yellow to yellowish brown complex between palladium (II) chloride and the investigated cephalosporins in the presence of sodium lauryl sulfate (SLS) as surfactant. The complexation process was optimized in terms of pH, temperature and contact time. The stoichiometry of all the complexes was found to be 2:1 (metal ion/ligand) for CTX, CRX, and 1:2 for CEFAZ. The stoichiometry of palladium (II)-cephalosporins was estimated by mole ratio and continuous variation methods and emphasized by the KINFIT program. These drugs could be determined by measuring the absorbance of each complex at its specific λmax. The results obtained are in good agreement with those obtained using the official methods. The proposed method was successfully applied for the determination of these compounds in their dosage forms.

Biotic and abiotic degradation of four cephalosporin antibiotics in a lake surface water and sediment

Cephalosporins are widely used veterinary and human antibiotics, but their environmental fate and impacts are still unclear. We studied degradation of four cephalosporins (cefradine, cefuroxime, ceftriaxone, and cefepime) from each generation in the surface water and sediment of Lake Xuanwu, China. The four cephalosporins degraded abiotically in the surface water in the dark with half-lives of 2.7-18.7d, which were almost the same as that in sterilized surface water. Under exposure to simulated sunlight, the half-lives of the cephalosporins decreased significantly to 2.2-5.0d, with the maximal decrease for ceftriaxone from 18.7d in the dark to 4.1d under the light exposure. Effects of dissolved organic matter (DOM) and nitrate on photodegradation of the cephalosporins were compound-specific. While DOM (5 mg L(-1)) stimulated the photodegradation of only cefradine (by 9%) and cefepime (by 34%), nitrate (10 microM) had effects only on cefepime (stimulation by 13%). Elimination rates of the cephalosporins in oxic sediment (half-lives of 0.8-3.1d) were higher than in anoxic sediment (half-lives of 1.1-4.1d), mainly attributed to biodegradation. The data indicate that abiotic hydrolysis (for cefradine, cefuroxime, and cefepime) and direct photolysis (for ceftriaxone) were the primary processes for elimination of the cephalosporins in the surface water of the lake, whereas biodegradation was responsible for the elimination of the cephalosporins in the sediment. Further studies are needed on chemical structure, toxicity, and persistence of transformation products of the cephalosporins in the environment.

Chiral separation of diastereoisomers of cefuroxime axetil by high-performance thin-layer chromatography

Conditions for separation and determination of diastereoisomers of cefuroxime axetil by HPTLC on cellulose layers with densitometry were developed. A good separation of the constituents was achieved using a mobile phase composed of 1% aqueous beta-cyclodextrin-methanol (15 + 1, v/v). For detecting spots on the chromatograms, densitometric measurements were used at 285 nm. The method is characterized by high sensitivity; the LOD was 0.04 microg/spot and LOQ was 0.11 microg/spot for both forms of the cefuroxime axetil diastereoisomers. For the individual diastereoisomers, high recovery values from 96.63 to 104.16% were obtained. Identification of the diastereoisomers was performed by 1H-NMR spectrometric analysis.

[Determination of 9 cephalosporin drug residues in beef by ultra performance liquid chromatography-tandem mass spectrometry]

A confirmative method to determine 9 cephalosporin residues in beef by ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was developed. The sample was homogenized and extracted with acetonitrile and water for 1 min at 14,000 r/min, centrifuged at 10,000 r/min and 4 degrees C for 10 min. A total of 2 mL saturated sodium chloride solution was added to avoid foaming during the acetonitrile evaporation, the acetonitrile was evaporated below 37 degrees C using a rotary evaporator, and then cleaned up on an Oasis HLB (500 mg, 6 mL) SPE column by washing with 5 mL water and eluting with acetonitrile-water (7:3, v/v). The eluate was blown to dryness under a stream of nitrogen and adjusted to 3.0 mL with water. The separation was carried out on an ACQUITY UPLC BEH C18 column within 5 min, analyzed by UPLC-MS/MS system with external standard method. The limits of quantification (LOQs) of cefuroxime, ceftiofur and cefalonium were 10, 0.5 and 0.5 microg/kg, respectively; the LOQs of other cephalosporins were 1.0 microg/kg. The recoveries of cephalosporins ranged from 74.2% to 119% and the relative standard deviations (RSDs) ranged from 2.9% to 15% for the spiked beef sample. The method is quick, easy, very sensitive and suitable for the determination of cephalosporin residues in beef.

[Studies on the action features between cefuroxime axetil and bovine serum albumin]

Under different temperatures and physiological conditions, with cefuroxime axetil concentrations in the range of 1.959 X 10(-6) to 13.71 X 10(-6) mol x L(-1), and bovine serum albumin (BSA) concentrations at 2.0 X 10(-6) mol x L(-1), the interaction between cefuroxime axetil and BSA was studied by fluorescence spectroscopy, three-dimensional fluorescence spectrum, synchronous fluorescence spectrum and UV-Vis absorption spectroscopy. After analyzing and processing the fluorescence quenching data at different temperatures according to Sterm-Volmer equation, Lineweaver-Burk equation and thermodynamic equation, the average value of the apparent binding constant (K(LB): 3.907 X 10(6) L x mol(-1)), and thermodynamics parameters (enthalpy change delta H: -13.43 kJ x mol(-1), entropy change delta S: 81.90 J x K(-1) and standard Gibbs free energy change delta G0: -38.34 kJ x mol(-1)) were calculated, and the amounts of binding sites (n: 1.042)were measured. The fluorescence quenching mechanism of BSA after cefuroxime axetil was added was discussed. BSA was bound with cefuroxime axetil and formed a new compound. The quenching belonged to static fluorescence quenching. The thermodynamic parameters agree with delta H approximately 0, delta S > 0 and delta G0 < 0, and the binding reaction is mainly entropy-driven and electro-static interaction force plays a major role in the reaction. The maximum emission wavelength of Tyr and Trp had an obvious red shift in the synchronous fluorescence spectra, the fluorescence emission wavelength of two peaks had a blue shift in the three-dimensional fluorescence spectrum of BSA in the presence of cefuroxime axetil and the maximum absorbtion wavelenghs of three systems in the UV-Vis absorption spectra were obviously different. These showed that the changes in the micro-environment of Tyr and Trp and demonstrated that the conformation of BSA changed as cefuroxime axetil had been added. This provides important information for discussing the configuration modification of BSA because of the added cefuroxime axetil, and for elucidating the pharmacological effects of cefuroxime axetil and biological effects in the organism.

Column and thin-layer chromatographic methods for the simultaneous determination of acediasulfone in the presence of cinchocaine, and cefuroxime in the presence of its hydrolytic degradation products

Column liquid chromatography (LC) and thin-layer chromatography (TLC)-densitometry methods are described for simultaneous determination of acediasulfone (Ace) and cinchocaine (Cinco). In the LC method, the separation and quantitation of the 2 drugs was achieved on a Zorbax C8 column (5 microm, 150 x 4.6 mm id) using a mobile phase composed of methanol-phosphate buffer, pH 2.5 (66 + 34, v/v), at a flow rate of 1 mL/min and ultraviolet detection at 300 and 327 nm for Ace and Cinco, respectively. The method showed linearity over concentration ranges of 20-200 and 45-685 microg/mL, respectively. In the TLC-densitometry method, a mobile phase composed of methanol-tetrahydrofuran-acetic acid (45 + 5 + 0.5, v/v/v) was used for the separation of the 2 drugs. The linearity range was 0.5-4 and 2-9 microg/spot, respectively. In addition, stability indicating TLC-densitometry method has been developed for determination of cefuroxime sodium in the presence of 5-70% of its known hydrolytic degradation products. The mobile phase butanol-methanol-tetrahydrofuran-concentrated ammonium hydroxide (50 + 50 + 50' + 5, v/v/v/v) was used. The concentration range was 2-10 microg/spot. The optimized methods proved to be specific and accurate for the analysis of the cited drugs in laboratory-prepared mixtures and dosage forms. The obtained results agreed statistically with those obtained by the reference methods.

A stability indicating assay method for cefuroxime axetil and its application to analysis of tablets exposed to accelerated stability test conditions

Cefuroxime axetil is the esterified form of cefuroxime, injectable second generation cephalosporine antibiotic that can be given orally. Stereo and structural isomers of cefuroxime axetil (CA), anti-cefuroxime axetil (ACA) and Delta(3)-cefuroxime axetil (DCA), can be present in cefuroxime dosage forms as the process related impurities as well as possible degradation product. Sensitive and precise reversed-phase high-performance liquid chromatography (RP-HPLC) method was developed and validated for the determination of cefuroxime axetil in the presence of its degradation products in solid dosage forms. The RSD values for cefuroxime axetil, anti-cefuroxime axetil and Delta(3)-cefuroxime axetil of 1.80, 1.99 and 2.48%, respectively, indicated a good precision of the RP-HPLC method. Developed RP-HPLC method was sensitive with LOD = 0.08 microg mL(-1) and LOQ = 0.60 microg mL(-1) for anti-cefuroxime axetil and LOD = 0.06 microg mL(-1) and LOQ = 0.45 microg mL(-1) for Delta(3)-cefuroxime axetil. Holding studies were carried out on Ceroxim tablets, according to ICH regulation at 30 degrees C/60% relative humidity (RH) and 40 degrees C/75% RH for 1, 2, 3 and 6 months. The review data from the stability studies conducted, show the significant content change of Delta(3)-cefuroxime axetil.

The stability of Cefuroxime axetil in tablets

The stability of cefuroxime axetil in BIORACEF tablets was studied by means of long term (298 K/60% RH), intermediate (303 K/65% RH), accelerated (313 K/75% RH) and stress stability tests. Changes in the concentration of cefuroxime axetil diastereoisomers A and B and their total was determined using the RP-HPLC method, as described in a monograph of Cefuroxime axetil tablets in the British Pharmacopoeia 2003. After 2 years of storage under long term, 1 year under intermediate and 6 months under accelerated storage conditions, the preparation of BIORACEF meets the quality requirements as regards both. the active substance content and chromatographic purity. Under stress conditions the decomposition of cefuroxime axetil diastereoisomers follows the first-order reversible autocatalytic reaction with delta3-isomers of cefuroxime axetil as the main product. The kinetic parameters of the decomposition reaction were calculated and compared with analogical parameters obtained for ZINNAT tablets stored in the same conditions.

Spectrophotometric determination of certain cephalosporins in pure form and in pharmaceutical formulations

A simple and reproducible spectrophotometeric method for the assay of cefotaxime sodium, cefuroxime sodium, and ceftriaxone disodium with metol-chromium(VI) reagent has been developed. The procedure is based on direct oxidation of metol by potassium dichromate in presence of drug in acidic medium and subsequent formation of ternary complex. Beer's law is obeyed in the range 0.2-28 microg ml(-1) at lambdamax 520 nm. For more accurate analysis, Ringbom optimum concentration range is found to be 0.8-26.5 microg ml(-1). The molar absorptivity and Sandell sensitivity were calculated. Six replicate analysis of solutions containing seven different concentrations of the examined drugs were carried out and gave a mean correlation coefficient < or =0.9996; the factors of the regression line equation for the three cephalosporins were calculated. The proposed method was applied to the determination of the examined drugs in pharmaceutical formulations and the results demonstrated that the method is equally accurate, precise, and reproducible as the official methods.

Simultaneous measurement of cefuroxime in rat blood and brain by microdialysis and microbore liquid chromatography. Application to pharmacokinetics

To characterize the pharmacokinetics of cefuroxime in rat blood and brain, microdialysis probes were inserted into the jugular vein and brain striatum, respectively. Cefuroxime (20 mg/kg, i.v.) was administered via the femoral vein. Blood microdialysates were automatic injected onto microbore liquid chromatography via an on-line injectors. The mobile phase consisted of methanol-100 mM monosodium phosphoric acid (25:75, v/v, pH 5.0) with a flow-rate of 0.05 ml/min. Ultraviolet detector was set at a wavelength of 280 nm for cefuroxime. The present assay enhanced the detection sensitivity and enabled the determination of cefuroxime down to 5 ng/ml. The pharmacokinetic data demonstrated that the area under the concentration curve (AUC) ratio of unbound cefuroxime in rat brain and blood was about 4.2% after cefuroxime (20 mg/kg, i.v.) administration. These results provided further evidence that cefuroxime could penetrate the blood-brain barrier.

Spectrophotometric and atomic absorption spectrometric determination of certain cephalosporins

Two sensitive spectrophotometric and atomic absorption spectrometric procedures are developed for the determination of certain cephalosporins (cefotaxime sodium and cefuroxime sodium). The spectrophotometric methods are based on the charge-transfer complex formation between these drugs as n-donors and 7,7,8,8-tetracyanoquinodimethane (TCNQ) or p-chloranilic acid (p-CA) as pi-acceptors to give highly coloured complex species. The coloured products are measured spectrophotometrically at 838 and 529 nm for TCNQ and p-CA, respectively. Beer's law is obeyed in a concentration range of 7.6-15.2 and 7.1-20.0 microg x ml(-1) with TCNQ, 95.0-427.5 and 89.0-400.5 microg x ml-1 with p-CA for cefotaxime sodium and cefuroxime sodium, respectively. The atomic absorption spectrometric methods are based on the reaction of the above cited drugs after their alkali-hydrolysis with silver nitrate or lead acetate in neutral aqueous medium. The formed precipitates are quantitatively determined directly or indirectly through the silver or lead content of the precipitate formed or the residual unreacted metal in the filtrate by atomic absorption spectroscopy. The optimum conditions for hydrolysis and precipitation have been carefully studied. Beer's law is obeyed in a concentration range of 1.9-11.4 and 1.78-8.90 microg x ml(-1) with Ag(I), 14.2-57.0 and 13.3-53.4 microg x ml-1 with Pb(II) for cefotaxime sodium and cefuroxime sodium, respectively (for both direct and indirect procedures). The spectrophotometric and the atomic absorption spectrometric procedures hold well their accuracy and precision when applied to the analysis of cefotaxime sodium and cefuroxime sodium dosage forms.

Cefuroxime selective electrodes for batch and FIA determinations in pharmaceutical preparations

Different cefuroxime selective electrodes, without internal reference solution and comprising PVC membranes, were constructed and evaluated. Membranes were prepared with cefuroxime tetraoctylammonium (A) or cefuroxime bis(triphenylphosphoranylidene)ammonium (B) as ion-exchanger, 2-nitrophenyl octyl ether (X) or bis(2-ethylhexyl)sebacate (Y) as plasticizing mediator solvent and 4-tert-otcylphenol (TOP) as additive. From the comparative evaluation of the described electrodes, membranes comprising 2-nitrophenyl octyl ether, cefuroxime tetraoctylammonium and 4-tert-otcylphenol presented better working characteristics. For these electrodes (type XA-TOP), with a lifetime > 5 months, a lower limit of linear range of 2.8 x 10(-4) M, a practical detection limit of 1.3 x 10(-4) M, a reproducibility of approximately +/-0.6 mV day(-1) and a slope of -50.4 mV decade(-1), under H3PO4/NaH2PO4 solutions (pH 3.5; I =0.1 M), were found. The presence of the additive on the membranes was of crucial importance for the electrodes good characteristics. Interference from sulphate, chloride, nitrate, iodide, cefaclor, cefadroxil, cefazolin and cephradine, on the electrodes behaviour was evaluated. Only a slight interference from nitrate and iodide was recorded, being type XA-TOP electrodes the most selective units. Electrodes with a tubular configuration prepared with type XA-TOP membranes, aiming flow injection analysis, were also constructed. When these tubular potentiometric detectors were evaluated in a double-channel flow injection manifold, with 3.5 pH and 0.1 M ionic strength conditions, significantly better working characteristics than those of the corresponding conventional electrodes, namely higher slopes (-54.6 mV decade(-1)) and better reproducibilities (+/-0.2 mV day(-1)), were found. Both conventional and tubular type XA-TOP electrodes were used for injections analyses by batch and FIA, respectively, presenting low consumption of samples and reagents. Relative error deviations to the reference procedures <3.0% were found.

Application of capillary zone electrophoresis in cephalosporin analysis

Cephalosporins have structures and antibiotic activity similar to those of penicillins which represent a class of compounds with closely related structures. Most of the cephalosporins contain aromatic groups and show distinctive UV spectra. Separating the different types of cephalosporins is a challenging task for HPLC. but the resolving power of capillary zone electrophoresis (CZE) makes this separation fast and simple. The present study reports the application of CZE for cephalosporin analysis and the separation of cephalosporins from plasma. Both field strength and temperature were shown to influence the plate number. The influence of injection time on the peak height was studied. Furthermore, the influence of pH value on the separation of cephalosporins by CZE was investigated. The low sample amount required and the relatively short analysis time are the main advantages of this method.

Measurement of cefuroxime in human bronchoalveolar lavage fluid by high-performance liquid chromatography after solid-phase extraction

A sensitive and selective method for the determination of cefuroxime in bronchoalveolar lavage (BAL) fluid using high-performance liquid chromatography (HPLC) with UV detection at 280 nm after solid-phase extraction with C18 cartridges was developed. A Waters symmetry C18 column was used and the mobile phase was acetonitrile-0.05 M ammonium phosphate buffer (pH 3.2) (15:85, v/v). The method enabled the determination of cefuroxime at concentrations below 100 ng/ml, with a linear calibration curve at concentrations of 5-100 ng/ml for 400 microliters of BAL. The intra- and inter-assay coefficient of variations for 10, 40 and 80 ng/ml were between 5.3 and 8.9%. Analytical recoveries were between 92.7 and 106.2%. The detection limit was 1 ng/ml at a signal-to-noise ratio of 3:1 using 400 microliters of BAL. The method was successfully used for the analysis of BAL fluid from patients after oral administration of 500 mg cefuroxime axetil twice daily.

The myth of the second prophylactic antibiotic dose in aortoiliac reconstructions

OBJECTIVES

To determine whether a prophylactic second dose of antibiotics is justified when severe blood loss and/or prolonged operation time occurs during aortoiliac reconstructions.

METHODS

We measured the cefuroxime concentration in venous blood serum and subcutaneous fat tissue of 30 patients who underwent elective aortoiliac reconstruction after a single intravenous dose of 1500 mg cefuroxime.

RESULTS

The mean blood loss was 1912 ml (range 200-7000). The mean operation time was 212 min (range 70-330). The cefuroxime concentration in blood serum 30 min after the gift varied from 53.7-561.6 mg/l and during closure of the abdominal incision from 13.2-90.0 mg/l. Taking the minimum inhibitory concentration for Staphylococcus species as 1.0 mg/l, we found an adequate prophylactic serum cefuroxime concentration in all patients. There was a statistically significant correlation between serum cefuroxime concentration and blood loss (p = 0.01) and operation time (p = 0.0001).

CONCLUSIONS

Although serum concentration of cefuroxime is greatly influenced by blood loss and operation time, a second dose of cefuroxime in aortoiliac reconstructions is not necessary if the operation is completed within 5.5 h and if perioperative blood loss does not exceed 7000 ml.

Analytical investigation of beta-lactam antibiotics in pharmaceutical preparations. IX. Colorimetric determination of six cephalosporins of second and third generation in the range of micromolar concentrations

A sensitive, accurate, precise and the same time simple and rapid method for the colorimetric determination of some cephalosporins of the second and third generations, such as: cefoxitin sodium (CFXT), cefaclor (CFCL), cefamandole nafate (CFMD), ceforanide l-lysine (CFRN), cefotaxime sodium (CFTX), and cefurozime sodium (CFRX) was described. The new method proposed is based: a) On the reduction of Fe(III) to Fe(II) by the drug analysed and b) On complexation of Fe(II) formed with o-Phenanthroline (O-Phen) consistently the formation of the well known highly stable orange-red coloured chelate complex [Fe(II)-(o-Phen)3]2+ which exhibits an absorption maximum at lambda = 510 nm (pH 4.50 +/- 0.2). Beer's law is obeyed for: 1.0 - 37.5 microgram mL-1 for CFX, 1.0 - 25.0 microgram mL-1 for CFMD, CFRN, and CFTX and 2.0 - 37.5 microgram mL-1 for CFTX and CFCL, while the apparent molar absorptivity ( epsilon in L mol-1cm-1) and the Sandell's sensitivity in (ngcm-2) both referred to the drug analyzed, are 1.29 x 10(4); 34.7 (CFXT), 7.61 x 10(3); 50.7 (CFCL), 3.33 x 10(4); 15.4 (CFMD), 2.60 x 10(4); 17.6 (CFRN) respectively. The regression line equation for each one of the above studied cephalosporins were calculated with a correlation coefficient 0.9997 < r < 1.0000; the accuracy and the precision of the method was considered as very satisfactory, while the results of a statistical analysis by means of the Student's t-test and the variance ratio F-test prove that no significant difference was observed between the results of the proposed method and those of official one.

Perioperative antibiotic prophylaxis with cefuroxime in oral-maxillofacial surgical procedures

A study was carried out to investigate the suitability of cefuroxime for perioperative antibiotic prophylaxis in maxillofacial surgical procedures. Serum and tissue samples were taken, to determine the intraoperative cefuroxime concentration, from 40 patients who had been given 1.5 g cefuroxime (Zinacef) i.v. during maxillofacial surgery. The time between i.v. administration and taking the blood and tissue samples varied between 10 and 260 min. The serum tissue kinetics were determined using an HPLC method in the jaw area, particular emphasis being given to the concentrations measured in bone. It was demonstrated that concentrations of cefuroxime were reached which are above the MIC values for many of the pathogens in the maxillofacial area and therefore adequate protection during intraoperative bacterial contamination is guaranteed. Maximum serum levels averaging 80 mg/l were measured within 30 min of administration. An average of 15 mg/l could still be demonstrated after 4 h. The bone samples gave maximum levels of 8-9 mg/kg 90 min after administration. Average levels of 1-3 mg/kg were still measurable after 4 h. It is only possible to describe trends due to the wide variation in the values, particularly of the bone samples. No postoperative wound infection was seen under prophylaxis with cefuroxime. Cefuroxime is suitable for perioperative prophylaxis during maxillofacial surgery procedures because of its favourable kinetics and broad spectrum of action.

Spectrofluorimetric analysis of cefuroxime in pharmaceutical dosage forms

A fluorimetric method has been developed for the quantitative analysis of cefuroxime, based upon the formation of a fluorescent derivative formed by alkaline hydrolysis with 1.0 M sodium hydroxide and heating at 100 degrees C for 60 min. The fluorescent product gave excitation and emission maxima at 380 and 436 nm, respectively. The method was performed in aqueous solution adjusted to pH 10.5 by addition of phosphate buffer solution. The calibration curve was found to be linear in the range of concentrations 0.050-1.70 micrograms ml-1. The lower limit of detection was 1.0 x 10(-2) micrograms ml-1. The method was applied to authentic pharmaceutical preparations containing cefuroxime sodium or cefuroxime axetil, the 1-(acetyloxy) ethyl ester of the drug, and was found to be satisfactory. Cefuroxime sodium was also determined in physiological solutions used to prepare intravenous infusions of this antibiotic.

Transplacental transfer of cefuroxime in uncomplicated pregnancies and those complicated by hydrops or changes in amniotic fluid volume

The transplacental transfer of cefuroxime was determined at antenatal fetal blood sampling in a cross sectional study of 78 patients between 15-35 weeks' gestation, 8-138 minutes after a maternal intravenous dose of 750 mg. Mean serum cefuroxime concentration, measured by high performance liquid chromatography, was 7.4 (95% confidence interval (CI) 6.8 to 8.1) mg/l in control fetuses; concentrations in hydropic fetuses were similar (6.2 mg/l, CI 4.7 to 7.7) but in fetuses with oligohydramnios they were significantly lower, (4.9 mg/l, CI 3.6 to 6.2). Antibiotic concentration did not correlate with gestational age and remained unchanged by transfusion of packed red cells. We conclude that (i) fetal serum concentrations of cefuroxime obtained after a maternal dose of 750 mg are only adequate for prophylaxis against organisms with a minimum inhibitory concentration of < 4 mg/l and (ii) transplacental passage of cefuroxime is significantly reduced in the presence of oligohydramnios.

Concentration of cefuroxime in mandibular alveolar bone following a single preoperative dose

A pilot study was undertaken on 12 patients undergoing the bilateral removal of impacted mandibular wisdom teeth to determine the level of cefuroxime sodium within the alveolar bone adjacent to the third molar teeth following a single preoperative intravenous administration. The results indicated that a single 1.5 g intravenous bolus injection provided satisfactory alveolar bone concentrations for routine antibiotic prophylaxis at the time of wisdom tooth removal.

Effects of carbon dioxide and sub-lethal levels of antibiotics on adherence of coagulase-negative staphylococci to polystyrene and silicone rubber

Fifty coagulase-negative staphylococci (CNS) strains were investigated for adherence to both silicone rubber and polystyrene using a microtitre tray system. Culture in an atmosphere containing a physiological level of carbon dioxide (5% CO2) profoundly affected adherent growth to both surfaces. Most strains adhered less well in this atmosphere compared to in air alone, with mean reductions in adherence of 84% and 86% to silicone rubber and polystyrene respectively. Occasional strains adhered better in 5% CO2. The effects of antibiotic concentrations equivalent to 1/4 MIC of cefuroxime, ciprofloxacin, vancomycin and teicoplanin on the adherence of 10 CNS strains were also studied. Vancomycin and teicoplanin frequently increased adherence to silicone rubber and polystyrene compared to controls. The effects of antibiotics on adherence were not only strain dependent but also sometimes atmosphere or surface specific. Antibiotic-induced changes in adherence did not appear to correlate with changes in strain protein profiles or surface hydrophobicities.

Concentration of cefuroxime in serum and middle ear effusion after single dose treatment with cefuroxime axetil

Antimicrobial agents play an important role in the treatment of patients with acute otitis media and otitis media with effusion (OME). The study was undertaken to determine the concentrations of cefuroxime in the blood and middle ear effusions (MEE) of children between 6 and 12 years of age with acute otitis media and chronic OME after a single oral dose administration of cefuroxime axetil, the ester prodrug of cefuroxime. Cefuroxime axetil (250 mg) was administered 2 to 6 hours before either myringotomy for acute otitis media or myringotomy and tube insertion for chronic OME. Blood samples and middle ear aspirates were obtained from 31 children and the samples were analyzed by high performance liquid chromatography. Cefuroxime was recovered in measurable concentrations in all serum samples and in 15 (79%) of the 19 MEE specimens analyzed. No correlation was seen between cefuroxime MEE concentrations and effusion type, bacteriology or serum concentrations. This study shows that cefuroxime does penetrate into MEE when OME is present and that therapeutic concentrations can be achieved in some patients.

Determination of bone and fat concentrations following systemic cefamandole and regional cefuroxime administration in patients undergoing knee arthroplasty

Five patients undergoing routine total knee replacement received standard antibiotic prophylaxis of 1000 mg of iv cefamandole and also regional administration of 750 mg of cefuroxime. Regional dosing was carried out at the start of the operation, following the application of a mid-thigh tourniquet, by administration into a foot vein. Samples of bone and fat were collected during the operation and assayed for cefuroxime and cefamandole by HPLC analysis. The mean cefuroxime bone (133.1 mg/l) and fat (88.4 mg/l) levels following regional administration were significantly higher (P less than 0.001) than the mean cefamandole bone (9.1 mg/l) and fat (9.8 mg/l) levels following systemic dosing. The possibility of administration of prophylaxis by the regional route is suggested.

Chemical stabilities of cefuroxime sodium and metronidazole in an admixture for intravenous infusion

The chemical stabilities of cefuroxime sodium and metronidazole, when mixed together for intravenous infusion, were studied by high-performance liquid chromatography (HPLC). The critical factor in the stability of the admixture was the degradation of cefuroxime sodium. At 25 degrees C, cefuroxime degraded by first-order kinetics with a rate constant of 7.04 x 10(-2)/day and a t90 (time to reach 90% of the original concentration) of 36 h. At 4 degrees C the rate constant was 5.23 x 10(-3)/day with a t90 of 20 days, however, over the time-scale studied, the kinetics approximated to zero-order at this temperature. The mixture was also stable with respect to metronidazole, nitrite ion and appearance. A 7-day storage life at 4 degrees C can be given to the mixture.

Spectrophotometric determination of certain cephalosporins using molybdophosphoric acid. Part II. Determination of cefadroxil, cefapirin, ceforanide and cefuroxime

The use of molybdophosphoric acid as an oxidising agent for the spectrophotometric determination of four cephalosporin derivatives, viz., cefadroxil monohydrate (I), cefapirin sodium (II), ceforanide L-lysine (III) and cefuroxime sodium (IV), either in the pure form or in pharmaceutical formulations is described. Beer's law is obeyed up to 100 micrograms ml-1 for I, up to 60 micrograms ml-1 for II and IV and up to 80 micrograms ml-1 for III. The molar absorptivities were 4.58 X 10(3), 11.3 X 10(3), 9.8 X 10(3) and 10.9 X 10(3) l mol-1 cm-1 and the Sandell sensitivities were 83.3, 39.3, 53.0 and 41.0 ng cm-2 for I, II, III and IV, respectively. The slopes and intercepts of the equations of the regression line were calculated for each of these drugs with the following correlation coefficients: I, 0.9993; II, 0.9999; III, 1.000; and IV, 0.9999. These antibiotics were determined successfully both in the pure form and in pharmaceutical preparations. The results demonstrated that the proposed procedure is at least as accurate, precise and reproducible as the official methods, while being simpler and less time consuming. A statistical analysis indicated that there was no significant difference between the results obtained by the proposed procedure and those of the official methods.

Kinetics of cefuroxime in the groin wound after vascular prosthetic implantation

The kinetics of cefuroxime in serum and wound fluid were investigated in the period after vascular prosthetic implantation. Cefuroxime was administered as intravenous bolus injections in doses of 0.75 gm (five patients) or 1.5 gm (five patients). The concentration of cefuroxime in wound fluid increased after the injection and reached a maximal level corresponding to serum concentration levels with 1.5 hours. The subsequent elimination of cefuroxime from the wound fluid closely paralleled the elimination from the serum. The wound fluid concentrations were found to be greater than the minimum inhibitory concentration for Staphylococcus aureus and Escherichia coli in 8 and 5 hours, respectively, after injection of 0.75 gm of cefuroxime, and in 11 and 7 hours, respectively, after injection of 1.5 gm of cefuroxime.

Serum and bone concentrations of cefuroxime in patients undergoing knee arthroplasty

Concentrations of cefuroxime were measured in the serum and femoral and tibial bone of 12 patients undergoing knee arthroplasty, following cefuroxime 1.5 g iv. The mean serum cefuroxime concentration was 112.4 mg/l at the time of application of the mid thigh tourniquet. The mean femoral bone concentration was 18.6 mg/kg and tibial bone was 15.5 mg/kg. These concentrations of cefuroxime appear adequate for prophylaxis against post-operative infection in knee arthroplasty.

Syn/anti isomerization of cefuroxime by ultraviolet light

Cefuroxime, like all the oximino cephalosporins on the market, has the methoxyimino group in the syn (Z) configuration. By U.V. light irradiation of cefuroxime, a syn/anti isomerization occurs until equilibration of the two isomers is reached. Measurement of the 1H-N.M.R. chemical shift differences of the two isomers allows the assignment of methoxyimine stereochemistry.

Concentration of cefuroxime in the bones of albino white rats: a comparative study of femur, humerus, and mandible

The levels of cefuroxime in rat bones with a different morphology, function, blood supply, and proportion between lamellar and cancellous bone were studied, after a 24-h administration of 750mg/kg X 3. The concentrations in the right and left femora, humeri, and mandibles of the same animal were measured 2 h after the last administration. The result indicate statistically significant differences between femur and humerus (P less than 0.001), femur and mandible (P less than 0.05), and humerus and mandible (P less than 0.05).

Stability of cefuroxime sodium in some aqueous buffered solutions and intravenous admixtures

Cefuroxime sodium (Zinacef) is a new semisynthetic, broad spectrum cephalosporin antibiotic for parenteral administration which is stable to most of the beta-lactamases. The stability of cefuroxime sodium in aqueous solutions, with or without phosphate buffer, and in 5% dextrose and 0.9% sodium chloride injections was studied using a stability-indicating high-pressure liquid chromatographic method developed in our laboratory. The optimum pH range of stability was determined to be approximately 4.5-7.3. Both buffered and unbuffered solutions followed first-order decomposition. In 5% dextrose and 0.9% sodium chloride injections, cefuroxime was stable for 1 day (more than 90% potent) at 25 degrees C and for at least 30 days at 5 degrees C. At -10 degrees C, there was negligible decomposition after 30 days. The pH values of the solutions stored at 5 degrees C and -10 degrees C remained in the maximum stability range and the solutions were clear even after 30 days of storage. Thawing the frozen solutions in a microwave oven adversely affected the stability.

Fluorimetric determination of cefuroxime in body fluids

A simple and accurate fluorimetric procedure for measuring cefuroxime in body fluids is described. A fluorescent product was produced by addition of hydrochloric acid, heating, and cooling, followed by addition of sodium hydroxide and further heating at 100 degree C. The fluorescence intensity of the final solution was measured in a fluorimeter at an excitation wavelength of 375 nm and an emission wavelength of 440 nm and related to the antibiotic concentration. Thin-layer chromatography of the final solution showed a single fluorescent spot (Rf value, 0.6). Freedom from interference from other therapeutic agents and endogenous substances, as well as the close correlation between this method and the standard microbiological assay method, was demonstrated. The simplicity and reliability of the fluorimetric assay method make it particularly suitable for clinical use.

Antibiotic assays in muscle: are conventional tissue levels misleading as indicator of the antibacterial activity?

Concentrations of ampicillin and cefuroxime in serum and muscle were studied in rabbits following a single intramuscular injection of 25 mg/kg. Simultaneous measurements were performed in whole muscle tissue pieces and in muscle tissue fluid obtained by implantation of cotton threads under the muscle fascia. The concentrations in the tissue fluid showed only a short time lag to thea serum levels. However, levels in whole muscle were substantially lower than the corresponding concentrations in muscle tissue fluid, indicating that the antibiotics were not evenly distributed within the tissue. The whole muscle tissue levels seriously underestimated, by a factor of approximately 5 times, the actual antibiotic concentrations in the extracellular fluid, where the microorganisms causing soft tissue infections are most likely to be found.

[Diffusion of cefuroxime into the prostatic and other tissues of the urogenital region (author's transl)]

From 33 patients with prostatic adenoma with an average age of 68.4 years, serum and prostatic tissue concentrations after a single bolus-dose of 1.5 grams of cefuroxime were estimated. The mean serum concentrations 30 to 35 minutes after the injection were measured with 132.6 and after 55 to 60 minutes with 99.6 micrograms/ml. The corresponding concentrations in the prostata tissue were 29.2 after 30 to 35 minutes and 20.1 micrograms/g after 55 to 60 minutes respectively. After 145 to 155 minutes the concentrations in the serum were still at 23 micrograms/ml and 9.2 micrograms/g in the prostatic tissue. In other organ tissues of the urogenital region (renal tissue, testicle, fat, muscle) the concentrations were different depending on the state of the tissue. The estimated concentrations of cefuroxime in serum and tissue are suited for the treatment of infections caused by cefuroxime sensitive microorganisms.

Measurements of cefuroxime concentration in bone in dogs and man

Measurements of Cefuroxime levels performed in dogs show a decrease against time in well perfused tissue similar to that in serum, while in bradytrophic tissue--such as bone and articular capsule--there is a distinct rise of these values in the time scale assessed. In similar investigations in man the higher levels in bradytrophic tissue are attributable to delayed elimination from the compact and spongy bone as compared to the serum. The effect on osteomyelitis, to be derived from this, is discussed.