Fabrication, physical characterizations and in vitro antibacterial activity of cefadroxil-loaded chitosan/poly(vinyl alcohol) nanofibers against Staphylococcus aureus clinical isolates.

Particular attention is devoting to the design of electrospun nanofibers (NFs) as new drug delivery nanosystems to overcome bacterial resistance and toxicological issues. Their advantages include high encapsulation efficiency, great drug-loading capacity, easiness in production, cost-effectiveness, and controlled targeted drug delivery. We aim to characterize electrospun chitosan (CS)/poly(vinyl alcohol) (PVA) NFs (CPNFs) loaded with cefadroxil monohydrate (CFX), a broad spectrum antibiotic. The biodegradable and biocompatible carrier system was greenly fabricated by electrospinning at various CS/PVA ratios. CPNFs were characterized using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and UV-spectrometry. Their potential toxicity was evaluated in human epidermal keratinocytes by 3-[4,5-dimethylthiazole-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay. Their antibacterial activity was tested by agar well diffusion method and MTT assay against clinical isolates of Staphylococcus aureus, a Gram-positive bacterium involved in serious skin infections. The thermostable CFX-loaded CPNFs at optimized 30:70 ratio revealed a burst and sustained release profile that occurred predominantly by diffusion following non-Fickian (anomalous) transport mechanism, as well as a more potent and safe antibacterial than free CFX. Thus, electrospun CFX-loaded CPNFs could be a new promising transdermal drug delivery system to activate the wound healing process and cost-effectively treat S. aureus-induced (resistant) skin infections.

Pushing the Limits of Molecular Crystal Structure Determination From Powder Diffraction Data in High-Throughput Chemical Environments.

Crystal structure determination from powder diffraction data (SDPD) using the DASH software package is evaluated for data recorded using transmission capillary, transmission flat plate, and reflection flat plate geometries on a selection of pharmaceutical compounds. We show that transmission capillary geometry remains the best option when crystal structure determination is the primary consideration and, as expected, reflection flat plate geometry is not recommended for SDPD because of preferred orientation effects. However, the quality of crystal structures obtained from transmission plate instruments can be excellent, and the convenience factor for sample preparation, throughput, and retrieval is higher than that of transmission capillary instruments. Indeed, it is possible to solve crystal structures within an hour of a polycrystalline sample arriving in the laboratory, which has clear implications for making small-molecule crystal structures more routinely available to the practicing laboratory medicinal chemist. With appropriate modifications to crystal structure determination software, it can be imagined that SDPD could become a rapid turn-around walk-up analytical service in high-throughput chemical environments.

A potential antibacterial wound dressing of cefadroxil chitosan nanoparticles in situ gel: Fabrication, in vitro optimization and in vivo evaluation.

Wound healing following skin injury is a natural phenomenon that usually lacks quality, rapidity, and aesthetics. Thus, the purpose of this study was to fabricate a new easily applied in situ gel of cefadroxil (CDX) loaded chitosan nanoparticles (CDX-CSNPs) that could promote wound healing, capable of inhibiting the possible accompanying bacterial infection. The nanoparticles were prepared by double emulsion technique and the influence of formulation parameters on drug entrapment efficiency (EE%), particle size (PS), polydispersity index (PDI) and zeta potential (ZP) were investigated using a full factorial design. The results show that the optimized CDX-CSNP1 composed of low molecular weight chitosan (0.2%w/v) was spherical with EE%, PS, PDI and ZP of 84.25 ±â€¯0.02, 408.30 ±â€¯53.17 nm, 0.458 ±â€¯0.048 and 22.80 ±â€¯0.57 mV, respectively. DSC and XRD studies confirmed the amorphous nature of the drug. After ensuring the safety and non toxicity of CDX-CSNP1 in situ gel through cytotoxic study, the antibacterial activity was evaluated using a rat skin infection model against Staphylococcus aureus. Compared to the rats treated with free CDX, the CDX-CSNP1 treated group revealed a remarkable accelerated wound healing process and bacterial clearance which was further confirmed by the histopathological examination of skin biopsies.

Rapid preparation of molecularly imprinted polymers by microwave-assisted emulsion polymerization for the extraction of florfenicol in milk.

In this study, we proposed a rapid and simple method for the preparation of molecularly imprinted polymers (MIPs) by emulsion polymerization. The polymerization process was accelerated by microwave heating, and the reaction time was greatly shortened. The obtained MIPs were spherical in shape and exhibited a uniform morphology. The MIPs with selectivity and high affinity to florfenicol were successfully applied as solid-phase extraction materials to extract and clean up the florfenicol in milk, followed by liquid chromatography-tandem mass spectrometry (LC-MS) analysis. The parameters affecting the performance of extraction and LC-MS analysis were evaluated. The detection limit of the method was 4.1ngmL(-1). The relative standard deviations of intra- and inter-day were in the range of 3.5-4.7% and 3.9-7.5%, respectively.

Disintegrants combination: development and optimization of a cefadroxil fast disintegrating tablet.

Fast Disintegrating Tablets (FDTs) is a rapidly growing dosage form preferred for special population (pediatric, geriatric and psychotic patients). It is also developed with the aim of improving bioavailability and patient compliance. During the present study, cefadroxil fast disintegrating tablets formulations (n=9) were designed and optimized by central composite design with two independent variables (croscarmellose and crospovidone) using design expert® software. The effects of independent variables on formulation properties such as friability, hardness, in vitro dispersion and disintegration were assessed by drawing response surface graphs with design expert® software. Tablets were assessed for pharmacopeial and non-pharmacopeial parameters to ensure the quality of compressed tablets. Among all formulations, F3, F8 and F9 have shown better results. The formulation F9 containing 15mg croscarmellose and 33.075mg crospovidone showed good pharmacotechnical attributes as well as shelf life. F 9 showed improved dissolution with t90% of> 2 min and will lead to better bioavailability.

Solubility-pH profiles of some acidic, basic and amphoteric drugs.

The solubility vs. pH profiles of five ionizable drugs of different nature (a monoprotic acid, a monoprotic base, a diprotic base and two amphoteric compounds showing a zwitterionic species each one) have been determined through two different methodologies: the classical shake-flask (S-F) and the potentiometric Cheqsol methods using in both instances the appropriate Henderson-Hasselbalch (H-H) or derived relationships. The results obtained independently from both approaches are consistent. A critical revision about the influence of the electrolyte used as buffering agent in the S-F method on the obtained solubility values is also performed. Thus, some deviations of the experimental points with respect the H-H profiles can be attributed to specific interactions between the buffering electrolyte and the drug due to the hydrotrophic character of citric and lactic acids. In other cases, the observed deviations are independent of the buffers used since they are caused by the formation of new species such as drug aggregates (cefadroxil) or the precipitation of a salt from a cationic species of the analyzed compound (quetiapine).

Phase transited and vapor-induced dual capsular system (DCS) for achieving delayed and osmotic release of cefadroxil.

In the present study, an intestinal pH, disintegrating and non-disintegrating dual capsular system using formaldehyde vapor and phase transition technique, respectively, was developed to achieve delayed as well as improved osmotic flow for the model drug cefadroxil. Formaldehyde vapor was used to attain gastric resistance to the outer gelatin capsule, which disintegrated at the intestinal pH to give a non-disintegrating asymmetric membrane capsule (AMC). The AMC was prepared via dry phase inversion process. The effects of different formulation variables were studied based on 2³ factorial design, namely, level of osmogen, ethylcellulose, and pore former, apart from studying the effects of varying osmotic pressure, agitation intensity, and intentional defect on drug release. Scanning electron microscopy showed an outer dense non-porous and an inner lighter porous region for the prepared asymmetric membrane. Statistical test was applied for in-vitro drug release at P > 0.05. The best formulation in the design closely corresponded to the extra design checkpoint formulation by a similarity (f2) value of 95.28. The drug release was independent of the agitation intensity and intentional defect of the film but dependent on the osmotic pressure of the dissolution medium. The release kinetics followed zero-order, and mechanism of release was Fickian diffusion.

Study on the binding behavior of bovine serum albumin with cephalosporin analogues by chemiluminescence method.

The luminol-bovine serum albumin chemiluminescence system was proposed for the first time. It was found that the hydrophilic luminol bound to the hydrophilic domain at Trp(134) of BSA with accelerating the electrons transferring rate of excited 3-aminophthalate, which led to the enhancement CL intensity of luminol at 425 nm. The increment of chemiluminescence intensity was proportional to the concentrations of bovine serum albumin from 5.0 × 10(-11) to 1.0 × 10(-8)mol L(-1) with the linear equation of ΔI=7.47 C(BSA)+4.89 (R(2)=0.9950). Based on the remarkable quenching effect of cephalosporin on the luminol-bovine serum albumin chemiluminescence system, the interaction of bovine serum albumin-cephalosporin was studied by flow injection-chemiluminescence method. A valuable model for studying the interaction of bovine serum albumin-cephalosporin was constructed and the formula lg[(I(0)-I)/I]=lg K(D)+n lg[D] was obtained. The binding parameters calculated by the model did agree very well with the results obtained by fluorescence quenching method. The major binding force of bovine serum albumin with cephalosporins was the hydrophobic effect. The binding ability of cephalosporin analogues to bovine serum albumin followed the pattern: cefoperazone, ceftriaxone and cefotaxime>cefuroxime and cefaclor>cefadroxil, cefradine and cefazolin, which was close to the order of their antibacterial ability. Using flow injection chemiluminescence method also obtained the stoichiometric ratio, the average of association constant K(P) and dissociation degree α of luminol-bovine serum albumin were 1:1, 1.12 × 10(7)L mol(-1) and 0.086, respectively.

Phase Transited Asymmetric Membrane Capsule: A Means for Achieving Delayed and Controlled Osmotic Flow.

In the present study, a phase transited nondisintegrating polymeric capsular system in achieving delayed as well as improved osmotic flow for the model drug cefadroxil was developed. Asymmetric membrane capsule (AMC) was prepared by precipitation of asymmetric membrane (AM) on the fabricated glass mold pins via wet phase inversion process. Effect of different formulation variables were studied based on 23 factorial design, namely, level of osmogen, ethylcellulose, pore former, apart from studying the effect of varying osmotic pressure on drug release. Scanning electron microscopy showed an outer dense non-porous region and an inner lighter porous region for the prepared AMC. Statistical test (Dunnett multiple comparison test) was applied for in vitro drug release (n=6) at P < 0.05. The best formulation in the design closely corresponded to the extra design checkpoint formulation by a similarity factor (f2) of 98.91, and a difference factor (f1) of 2.17. The drug release was independent of agitation intensity but dependent on the osmotic pressure of the dissolution medium. The release kinetics followed Higuchi model, and mechanism of release was Fickian diffusion.

Characterization of the interaction of cefadroxil with different metal ions using CE.

The present study describes the application of CE to investigate the interaction between a cephalosporin, cefadroxil and different metal ions. This study aims at quantifying the interaction of cefadroxil with Zn(2+), Al(3+), Fe(3+), Cu(2+) and Co(2+) ions using the effective electrophoretic mobility as a parameter for calculation of the reaction association constant (K). For this purpose, the electrophoretic mobilities of cefadroxil at different metal ion concentrations in citrate buffer pH 3.6 were determined. A mathematical model to calculate the association constant between cefadroxil and metal ions was used. The results showed that a strong change in the cefadroxil electrophoretic mobility was observed by increasing the metal ion concentrations. The results revealed that by increasing the concentration of metal ions in the running buffer the degree of complexation increases too. On the basis of the results, the strength of the interaction of cefadroxil with the investigated metal ions follows the order Zn(2+)>Cu(2+)>Co(2+)>Fe(3+)>Al(3+). The association constant of the investigated reactions ranged from 451.57 to 1546.52 L/mmol. The results indicate that it is possible to characterize the interaction between cefadroxil and metal ions quantitatively using CE.

Asymmetric membrane in membrane capsules: a means for achieving delayed and osmotic flow of cefadroxil.

In the present study, both disintegrating and non-disintegrating polymeric capsular system in achieving delayed as well as improved osmotic flow for the model drug cefadroxil was developed. Asymmetric membrane in membrane capsule (AMMC) was prepared on a glass mold pin via phase inversion process in two steps. Step 1 included formation of a non-disintegrating, asymmetric membrane capsule (AMC) and step 2 involved formation of a pH sensitive, disintegrating, asymmetric membrane (AM) formed over the non-disintegrating membrane. The effects of different formulation variables were studied namely, level of osmogen, membrane thickness, and level of pore former. Effects of varying osmotic pressure, agitational intensity and intentional defect in the inner membrane on drug release were also studied. Membrane characterization by scanning electron microscopy showed dense regions with less pores on the outer surface of the disintegrating membrane and porous regions on the inner surface of the non-disintegrating asymmetric membrane. In vitro release studies for all the prepared formulations were done (n=6). The drug release was independent of pH, agitational intensity and intentional defect on the membrane but dependent on the osmotic pressure of the dissolution medium. The release kinetics followed the zero order and the mechanism of release was Fickian diffusion.

Fluorescence studies of the dehydration of cefadroxil monohydrate.

Although cefadroxil does not exhibit the phenomenon of photoluminescence when dissolved in a fluid medium, the compound has been found to exhibit fluorescence in its solid-state monohydrate crystal form. The monohydrate was found to exhibit complicated photoluminescence, where two different sets of emission spectra could be obtained upon irradiation with an appropriate excitation wavelength. One of these photophysical systems became strongly suppressed when the monohydrate was half-dehydrated, and only one of the photophysical systems could be observed in this hemihydrate. In the fully dehydrated state, both photophysical pathways became almost totally suppressed, so that the nonsolvated cefadroxil became effectively nonfluorescent.

In vitro activity of cefadroxil, cephalexin, cefatrizine and cefpirome in presence of essential and trace elements.

Evidences supporting the introduction of metallic elements in several biological processes are rapidly accumulating. Likewise, many drugs possess modified toxicological and pharmacological properties when in the form of metal complexes. In order to ascertain the role of various essential and trace element complexation on the antibacterial activity of various cephalosporins, the synergistic or antagonistic behavior of cefadroxil, cephalexin, cefatrizine and cefpirome in presence of essential and trace elements has been studied and compared with the parent drug. The essential and trace elements comprised of magnesium, calcium, chromium, manganese, ferric, cobalt, nickel, copper, zinc and cadmium in the form of their chloride. These studies were carried out by observing the minimum inhibitory concentration (MIC) using agar dilution method and compared with the MIC'S of the standard cephalosporins against various species of Gram (+) and Gram (-) microorganisms such as Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus faecalis, Escherichia coli, Proteus vulgaris, Pseudomonas aeruginosa, Salmonella typhi and Shigella dysenteriae. Different dilutions of cephalosporins and salts of essential and trace elements were used in these studies. The ratio of the drug and metal salts was 1:1 and the reactions were carried out at two different temperatures as 37 degrees C and 60 degrees C in order to study the complex formation. The aim of our study was on one hand to evaluate the changes in microbiological activity of the standard cephalosporins after in vitro metal interactions to study the synergetic or antagonistic behavior of the later through the difference in MICs values of these cephalosporins and on the other hand to access the bioassay directed extent of drug metal complexations. Our investigation reveal that interaction of above cephalosporins with essential and trace elements cause antagonistic effect in many cases which was shown by decrease in antimicrobial activity of cephalosporins and MIC values were increased.

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.

Hydrates and solid-state reactivity: a survey of beta-lactam antibiotics.

Crystalline hydrates of hydrolytically susceptible pharmaceuticals are commonly encountered, and are particularly prevalent in the beta-lactam class of antibiotics. In order to rationalize how the apparent chemical incompatibility between water and beta-lactams is reduced through crystallization, a review of the published literature and available structural information on the solid state stability was undertaken. A search in the CSD yielded a total of 32 crystal structures of water-containing beta-lactams which were examined and classified in terms of hydrogen-bonded networks. In most cases the waters of hydration in the single crystal structures were found to fulfill structural roles and were not sufficiently close in proximity to react with the beta-lactam ring. Published data for the solid-state of several hydrates were also considered. In general, the stability data indicate high thermal stability for the crystalline hydrates. Moreover, even when water molecules are in appropriate proximity and orientation with respect to the beta-lactam moiety for a reaction to occur, the crystalline solids remain stable. The use of the crystal structure information along with computational modeling suggests that a combination of proximal relationships, steric and mechanistic arguments can explain the observed solid-state stability of crystalline beta-lactam hydrates.

Quantitative structure/activity relationship modelling of pharmacokinetic properties using genetic algorithm-combined partial least squares method.

Quantitative structure/activity relationship (QSAR) approaches have widely been applied to gain deeper understandings of the relationships between ADME parameters and molecular structure and properties. QSAR models for predicting ADME properties are required to cover structurally diverse compounds. In the present investigation, we describe application of genetic algorithm-combined partial least squares (GA-PLS) method to QSAR modelling of various ADME properties. By selecting an appropriate set of molecular descriptors automatically by the use of genetic algorithm, many ADME properties could be well-explained by simple molecular descriptors derived from 2-dimensional chemical structure.

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.

Synthesis, characterization and electronic spectra of cefadroxil complexes of d-block elements.

Cefadroxil (CD) is an essential pharmaceutical drug used in curing many diseases. Due to its popular use in many pharmaceutical forms, attention is paid in this research to the synthesis and stereochemistry of new iron, cobalt, nickel, copper, and zinc complexes of this drug both in solution and the solid states. The spectra of these complexes in solution and the study of their stoichiometry refer to the formation of 1:1 and 1:2 ratios of metal (M) to ligand (L). The calculated stability constants (Kf) of these complexes (1.5x10(7) to 5x10(13)) and the change in free energy of formation (deltaGf=2.5-12.5 kcal mol(-1) degree(-1)) are indicative of their high stability. The stereo chemical structure of the solid complexes was studied on the basis of their analytical, spectroscopic, magnetic, and thermal data. Infrared spectra proved the presence of M-N and M-O bonds. Magnetic susceptibility and solid reflectance spectral measurements were used to infer the structure. The prepared complexes were found to have the general formulae [ML(OH)x(H2O)y](H2O)z-M: Fe(II), x=0, y=2, z=1; M: Fe(III) and Co(III), x=1, y=2, z=1; M: Co(II) and Zn(II), x=0, y=1, z=0; M: Ni(II) and Cu(II), x=1, y=0, z=1; L: CD. Octahedral and tetrahedral structures were proposed for these complexes depending upon the magnetic and reflectance data and were confirmed by detailed mass and thermal analyses comparative studies.

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.