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Composite blend microbeads of sodium alginate (NaAlg) with sodium carboxymethyl cellulose (NaCMC) containing magnesium aluminum silicate (MAS) particles and enteric coated with chitosan have been prepared to achieve controlled release (CR) of amoxicillin in stomach environment. The composite beads have been characterized by X-ray diffraction (XRD) to study drug distribution, DSC for understanding thermal stability and Fourier transform infrared (FTIR) spectroscopy to investigate chemical interactions as well as to assess the structure of the drug-loaded formulations. Surface morphology of the beads was investigated by scanning electron microscopy (SEM). The size distribution of beads loaded with drug as studied by particle size analyzer was in the range of 745-889 μm. The beads exhibited quite widely varying encapsulation efficiencies from 52 to 92%. Equilibrium swelling of the beads measured in water and in vitro release of amoxicillin in pH 1.2 medium suggests that drug release depends on polymer blend composition, concentration of MAS and extent of enteric coating., (Copyright © 2012 Elsevier B.V. All rights reserved.)

An artificial tris-catecolate siderophore with a tripodal backbone and its conjugates with ampicillin and amoxicillin were synthesized. Both conjugates exhibited significantly enhanced in vitro antibacterial activities against Gram-negative species compared to the parent drugs, especially against Pseudomonas aeruginosa . The conjugates appeared to be assimilated by an induced bacterial iron transport process as their activities were inversely related to iron concentration. The easily synthesized tris-catecolate siderophore has great potential for future development of various drug conjugates to target antibiotic-resistant Gram-negative bacteria.

The effect of solar radiation on the inactivation of multidrug resistant Escherichia coli (MDR) strains selected from an urban wastewater treatment plant (UWWTP) effluent and the change of their resistance to a mixture of three antibiotics (evaluated in terms of minimum inhibit concentration (MIC)) in wastewater polluted stream were investigated. The solar photodegradation of the mixture of the three target antibiotics (amoxicillin (AMX), ciprofloxacin (CPX), and sulfamethoxazole (SMZ)) was also evaluated. Additionally, since UWWTP effluents are possible sources of antibiotics and antibiotic resistant bacteria, the disinfection by conventional chlorination process of the UWWTP effluent inoculated with MDR strains was investigated too. Solar radiation poorly affected the inactivation of the two selected antibiotic resistant E. coli strains (40 and 60% after 180 min irradiation). Moreover, solar radiation did not affect strain resistance to AMX (MIC>256 μg/mL) and SMZ (MIC>1024 μg/mL), but affected resistance of the lower resistance strain to CPX (MIC decreased by 33% but only after 180 min of irradiation). Chlorination of wastewater sample strongly decreased the number of the two selected antibiotic resistant E. coli strains (99.667 and 99.999%), after 60 min of contact time at 2.0 mg/L initial chlorine concentration, but the resistance of survived colonies to antibiotics was unchanged. Finally, the solar photodegradation rate of the antibiotic mixture (1mg/L initial concentration respectively) resulted in the following order (half-life time): CPX (t(1/2)=24 min)

The UV-A/TiO(2) photocatalytic decomposition of amoxicillin (AMX) in aqueous suspensions was investigated. Experiments were performed at antibiotic concentrations between 2.5 and 30 mg/L, eight commercially available TiO(2) catalysts at loadings between 100 and 750 mg/L, acidic or near-neutral conditions (pH 5 or 7.5) and two different matrices (ultrapure water and secondary treated effluent) at a photon flux of 8 × 10(-4) E/(L min). Of the various catalysts tested, Degussa P25 was highly active, i.e. complete AMX degradation and 93% mineralization could be achieved after 25 and 90 min of reaction, respectively at 10 mg/L AMX and 250 mg/L titania. In general, mineralization was slower than degradation due to the formation of stable transformation by-products. For the range of concentrations studied, initial degradation rates can be approached by a Langmuir-Hinshelwood kinetic model, while the reaction order with respect to AMX shifts from first to zeroth as initial concentration increases from 2.5 to 5 mg/L to higher values. Degradation in treated effluent was partly impeded compared to pure water due to the inherent presence of organic and inorganic constituents that compete for hydroxyl radicals. Although increasing solution pH from 5 to 7.5 had no effect on degradation, it retarded mineralization. The antibiotic activity of AMX prior to and after photocatalytic degradation was tested to three reference bacterial strains, namely Escherichia coli (ATCC 23716), Klebsiella pneumoniae (NCTC 5056) and Enterococcus faecalis (ATCC 14506). The first two were found to be highly resistant at AMX concentrations up to 25 mg/L, while the latter could partly be inactivated at lower AMX concentrations (i.e. 10 mg/L) and/or in the presence of photocatalytic by-products., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Degradation of the antibiotics amoxicillin in aqueous solution using sulphate radicals under ultrasound irradiation was investigated. The preliminary studies of optimal degradation methodology were conducted with only oxone (2KHSO(5) · KHSO(4) · K(2)SO(4)), cobalt activated oxone (oxone/Co(2+)), oxone+ultrasonication (oxone/US) and cobalt activated oxone+ultrasonication (oxone/Co(2+)/US). The chemical oxygen demand (COD) removal efficiency were in the order of oxone

The degradation of the β-lactam antibiotic amoxicillin (AM) treated with direct UV-C and UV/H(2)O(2) photolytic processes was investigated in the present study. In addition, the antibacterial activity of the solution treated by UV/H(2)O(2) advanced oxidation was compared with AM solution treated with ozone. The degradation rate of amoxicillin in both processes fitted pseudo first-order kinetics, and the rates increased up to six fold with increasing H(2)O(2) addition at 10mM H(2)O(2) compared to direct photolysis. However, low mineralization was achieved in both processes, showing a maximum of 50% TOC removal with UV/H(2)O(2) after a reaction time of 80min (UV dose: 3.8×10(-3)EinsteinL(-1)) with the addition of 10mM H(2)O(2). The transformation products formed during the degradation of amoxicillin in the UV and UV/H(2)O(2) processes were identified by LC-IT-TOF analysis. In addition, microbial growth inhibition bioassays were performed to determine any residual antibacterial activity from potential photoproducts remaining in the treated solutions. An increase of the antibacterial activity in the UV/H(2)O(2) treated samples was observed compared to the untreated sample in a time-based comparison. However, the UV/H(2)O(2) process effectively eliminated any antibacterial activity from AM and its intermediate photoproducts at 20min of contact time with a 10mM H(2)O(2) dose after the complete elimination of AM, even though the UV/H(2)O(2) advanced oxidation process led to bioactive photoproducts., (Copyright © 2011 Elsevier B.V. All rights reserved.)

The aim of the present investigation was to develop and optimize gastroretentive floating system of amoxicillin for the efficient treatment of peptic ulcer induced by Helicobacter pylori infection. Floating microballoons were developed using central composite design (CCD), and optimization was done by employing response surface methodology. The selected independent variables were cellulose acetate phthalate, drug-Eudragit S100 ratio, and the ratio of dichloromethane/ethanol/isopropyl alcohol. The selected dependent variables were yield, mean particle size, buoyancy, encapsulation efficiency, and drug release within 8 h. A quadratic polynomial model was generated which had linear, interaction, and quadratic terms to predict and evaluate the independent variables with respect to the dependent variables. Results showed that selected independent variables significantly affect the yield (30.53-82.71%), particle size (31.62-47.03 μm), buoyancy (42.68-95.75%), encapsulation efficiency (56.96-93.13%), and cumulative drug release from the microballoons (34.01-74.65%). The interaction and quadratic terms were also found to affect the process variables. An excellent agreement was found between the actual value and predicted value. In conclusion, it can be said that CCD is a valuable second-degree design to develop and optimize GFS of amoxicillin which in turn provides a basis to localize the drug release in the gastric region for effective treatment of H. pylori-mediated infection.

The surgical repair of pelvic organ prolapse using synthetic mesh can fail because of slow or partial implant integration due to poor biocompatibility or infection. As systemic antibiotic prophylaxis has only limited success, we have developed a system that coats standard polypropylene mesh with clinically relevant antibiotics. Amoxicillin and ofloxacin are both released from the mesh in vitro at high levels over 3 days, preventing adhesion and biofilm formation by a clinical isolate of E. coli. In an in vivo incisional hernia repair model in rats, the antibiotic-coated mesh results in appropriate tissue integration with adequate vascularization and collagen formation. When implanted animals are infected with virulent E. coli, both antibiotic coatings provide full protection against infection (as assessed both clinically and microbiologically), thus demonstrating their bioavailability. This method is a specific approach for producing a therapeutic coating that could reduce postsurgical infections., (Copyright © 2011 Wiley Periodicals, Inc.)

Amoxicillin (Amx) and cephalexin (Cfx) are β-lactam antibiotics widely used in human and veterinary medicine. Two points of interest surrounding these molecules are the photodegradation of the molecules and their microbiological implications, as well as the persistence and bioaccumulation in the environment which may cause resistance to bacterial strains. The kinetic and mechanistic aspects of the photosensitized degradation of Amx and Cfx have been studied in water at pH 7.4 and 10 by stationary and time-resolved methods. Kinetic evidence indicates that the Rose Bengal-sensitized photooxidation of Amx at pH 7.4 proceeds via O(2)((1)Δ(g)) and O(2•-) mechanisms while at pH 10 the degradation path occurs, principally, via O(2)((1)Δ(g)). For Cfx, this process is attributed to O(2)((1)Δ(g)) and O(2•-). Photoproducts, which arise from the addition of oxygen atoms and subsequent oxidation of the groups -CH(3) to -COOH, were detected. For both antibiotics the bacteriostatic activity decreases in parallel to their photodegradation. The results of this study could potentially help scientists to better understand and predict the photodegradability of these antibiotics on living organisms and in different environmental compartments.

Three oxidation processes of UV-Fe3+(EDTA)/H2O2 (UV: ultraviolet light; EDTA: ethylenediaminetetraacetic acid), UV-Fe3+/H2O2 and Fe3+/H2O2 were simultaneously investigated for the degradation of amoxicillin at pH 7.0. The results indicated that, 100% amoxicillin degradation and 81.9% chemical oxygen demand (COD(Cr)) removal could be achieved in the UV-Fe3+ (EDTA)/H2O2 process. The treatment efficiency of amoxicillin and COD(Cr) removal were found to decrease to 59.0% and 43.0% in the UV-Fe3+/H2O2 process; 39.6% and 31.3% in the Fe3+/H2O2 process. Moreover, the results of biodegradability (biological oxygen demand (BOD5)/COD(Cr) ratio) revealed that the UV-Fe3+ (EDTA)/H2O2 process was a promising strategy to degrade amoxicillin as the biodegradability of the effluent was improved to 0.45, compared with the cases of UV-Fe3+/H2O2 (0.25) and Fe3+/H2O2 (0.10) processes. Therefore, it could be deduced that EDTA and UV light performed synergetic catalytic effect on the Fe3+/H2O2 process, enhancing the treatment efficiency. The degradation mechanisms were also investigated via UV-Vis spectra, and high performance liquid chromatography-mass spectra. The degradation pathway of amoxicillin was further proposed.

Background and Methods: A dual (immediate/sustained-release) oral amoxicillin suspension was developed as a new dosage form to eradicate Helicobacter pylori. Carbopol®-loaded amoxicillin nanospheres could bind with the mucosa after delivery to the stomach and could increase the efficiency of the drug, providing both an immediate and a sustained action., Results: The objective of this research was to develop amoxicillin nanospheres using a spray-drying technique and to investigate such features as their particle size, drug content, percentage yield, surface morphology, in vitro release, and stability. The nanospheres had a particle size range of 280-320 nm after optimizing the preparation method using a central composite design. The drug content and percentage yield was 85.3% ± 0.7% and 92.8% ± 0.9%, respectively. The in vitro release profile of the amoxicillin nanospheres was consistent with a Korsmeyer-Peppas pattern, and the release after one hour was 19%, while for the original drug, amoxicillin, under the same conditions, 90% was released in the first 30 minutes., Conclusion: The nanospheres used in this study enabled controlled release of amoxicillin over an extended period of time for up to 12 hours and the formulation was stable for 12 months.

In this study the anaerobic treatability of amoxycillin (AMX) was investigated in a laboratory-scale anaerobic multi-chamber bed reactor (AMCBR)/aerobic continuously stirred tank reactor (CSTR) system. The chemical oxygen demand (COD) and AMX removal efficiencies were around 94% in the AMCBR reactor at hydraulic retention times (HRTs) between 2.25 and 5.5 days. Decreasing the HRT appeared not to have a significant effect on the performance of the AMCBR up to a HRT of 1.13 days. The maximum methane production rate and methane percentage were around 1,100-1,200 mL/day and 55%, respectively, at HRTs between 2.25 and 5.5 days. The decrease in HRT to 1.5 days decreased slightly the gas productions (1,000 mL/day and 500 mL for total and methane gases) and methane percentage (45%). The AMCBR recovered back to its baseline performance within a couple of days. The acute toxicity of 150 mg/L AMX was monitored with Daphnia magna, Lepistes sp., and Vibrio fischeri acute toxicity tests. The acute toxicity removals were 98, 96 and 96% for V. fischeri, D. magna and Lepistes sp. in the effluent of the sequential system treating 150 mg/L AMX at HRTs of 2.25-5.5 days. Among the trophic organisms used in the acute toxicity tests the most sensitive organism was found to be bacteria (V. fischeri) while the most resistant organism was found to be fish (Lepistes sp.).

This communication reports facile one pot synthesis of amoxicillin and sodium salt of amoxicillin stabilized gold nanoparticles (Au-NPs). Primarily the cyclic thioether linkage i.e. the thiozolidine ring of amoxicillin is utilized for sequestering Au(III). Fluorescence quenching of these clusters makes it an efficient protocol for sensing Cu(2+) at nano scale levels., (This journal is © The Royal Society of Chemistry 2011)

The bromination of five selected pharmaceuticals (metoprolol, naproxen, amoxicillin, phenacetin, and hydrochlorothiazide) was studied with these compounds individually dissolved in ultra-pure water. The apparent rate constants for the bromination reaction were determined as a function of the pH, obtaining the sequence amoxicillin>naproxen>>hydrochlorothiazide≈phenacetin≈metoprolol. A kinetic mechanism specifying the dissociation reactions and the species formed for each compound according to its pK(a) value and the pH allowed the intrinsic rate constants to be determined for each elementary reaction. There was fairly good agreement between the experimental and calculated values of the apparent rate constants, confirming the goodness of the proposed reaction mechanism. In a second stage, the bromination of the selected pharmaceuticals simultaneously dissolved in three water matrices (a groundwater, a surface water from a public reservoir, and a secondary effluent from a WWTP) was investigated. The pharmaceutical elimination trend agreed with the previously determined rate constants. The influence of the main operating conditions (pH, initial bromine dose, and characteristics of the water matrix) on the degradation of the pharmaceuticals was established. An elimination concentration profile for each pharmaceutical in the water matrices was proposed based on the use of the previously evaluated apparent rate constants, and the theoretical results agreed satisfactorily with experiment. Finally, chlorination experiments performed in the presence of bromide showed that low bromide concentrations slightly accelerate the oxidation of the selected pharmaceuticals during chlorine disinfection., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Helicobacter pylori reside in the gastric mucus layer and at the mucus-epithelial cell interface wherein access of antimicrobial drug to the infection site is restricted both from the stomach and from the gastric blood supply. The aim of the present study was to develop pectin or gellan gum blended sodium alginate microspheres in order to eradicate gastric Helicobacter pylori. The percentage drug release and mucoadhesion were decrease on increasing the calcium chloride in the formulation dispersion. Curing time significantly effected encapsulation efficiency and was not affected % drug content, % buoyancy, and particle size and drug release. The efficacy of the optimized formulation was evidenced by absence of amplified bacterial gene in treated stomach tissue of Mongolian gerbils as observed using in polymerase chain reaction. The results demonstrate that the developed formulation of Am has potential to eradicate Helicobacter pylori by targeted and prolonged retention at gastric mucosa.

Bearing in mind the present scenario of the increasing biological tolerance of bacteria against antibiotics, a time controlled two pulse dosage form of amoxicillin was developed. The compression coating inlay tablet approach was used to deliver the drug in two pulses to different parts of the GIT after a well defined lag time between the two releases. This was made possible by formulating a core containing one of the two drug fractions (intended to be delivered as the second pulse), which was spray coated with a suspension of ethyl cellulose and a hydrophilic but water insoluble agent as a pore former (microcrystalline cellulose). Coating of up to 5% (m/m) was applied over the core tablet, giving a corresponding lag of 3, 5, 7 and 12 h. Increasing the level of coating led to retardation of the water uptake capacity of the core, leading to prolongation of the lag time. Microcrystalline cellulose was used as a hydrophilic but water insoluble porosity modifier in the barrier layer, varying the concentration of which had a significant effect on shortening or prolongation of the lag time. This coated system was further partially compression coated with the remaining drug fraction (to be released as the first immediate release pulse) with a disintegrant, giving a final tablet. The core tablet and the final two pulse inlay tablet were further investigated for their in vitro performance.

Local intravaginal drug therapy is preferred for treatment of ascending genital infections during pregnancy. In the present study, an in situ forming biodegradable hydrogel for sustained release of amoxicillin in the cervicovaginal region is described. A generation 4 poly(amidoamine) [G4-(NH(2))(64)] dendrimer with peripheral thiopyridyl terminations is cross-linked with 8-arm polyethylene glycol (PEG) bearing thiol terminations. The hydrogels were formulated and tested in vivo in a pregnant guinea pig model for volume, retention times, biodegradation, tolerability and transport across fetal membrane. The physicochemical characterization of the hydrogels was carried out using differential calorimetry, SEM, and confocal imaging. The hydrogels offer antibacterial activity arising from sustained release of amoxicillin from gels. The in vivo studies in guinea pig showed that 100-200 μL of gel sufficiently covered the cervicovaginal region with a residence time of at least 72 h and gel was primarily retained in the maternal tissues without crossing the fetal membranes into the fetus. The dendrimer gels were stable up to 72 h, and the in vivo biodegradation of gel occurred after 72 h; this correlated well with the in vitro degradation pattern. The pH of the vagina was not altered upon application of the gel, and none of the animals aborted up to 72 h after application of gel. The histological evaluation of the cervical tissues showed absence of edema in the epithelial cell layer, no sloughing of the epithelial or superficial mucous layer, and absence of necrosis and infiltration of inflammatory cells in the submucosal layers, confirming that tissues were tolerant to the gel. The immunohistofluorescence images showed the localization of the gel components on the superficial mucified epithelial layer. The cross-linking density and swelling of hydrogels was impacted by the polymer content, and the 10% hydrogels exhibited the highest cross-link density. The in vitro drug release studies carried out using Franz diffusion cells showed that amoxicillin release from 6 and 10% gels was sustained for 240 h as compared to 3% gels. As the polymer concentration increased to 10%, the release pattern from gels approached diffusion controlled mechanism with diffusional exponent n = 0.49. In conclusion, the biodegradable in situ forming hydrogels of the present study offer a therapeutic option to provide sustained localized delivery of amoxicillin intracervically to the pregnant woman for the treatment of ascending genital infections.

The present study was aimed at evaluating the effectiveness of amoxicillin-bearing HSA (human serum albumin) and PLGA [poly(lactic-co-glycolic acid)] microparticles in combating Listeria monocytogenes infection in Swiss albino mice. Amoxicillin-bearing HSA microspheres were prepared by chemical cross-linking of a drug/albumin mixture with glutaraldehyde, and PLGA microspheres were prepared by the W/O/W (water-in-oil-in-water) emulsion technique. The microspheres were characterized for their size, ζ potential and entrapment efficiency using SEM (scanning electron microscopy) and a Zetasizer. Release kinetics was performed in a phosphate buffer (pH 7.4) at 37°C simulating physiological conditions. Bacterial burden in various vital organs and survival data established enhanced efficacy of PLGA and HSA microspheres as compared with free drug. Among the two delivery systems, PLGA microspheres, when compared with HSA microspheres, imparted better efficacy in terms of reduction in bacterial load as well as increase in survival. The results of the present study clearly demonstrate that microparticles successfully target the infected macrophages and the approach could be well exploited for targeting the intracellular pathogens as well.

Aim: To synthesize two kinds of amoxicillin artificial antigen and to establish hybridoma cell lines secreting monoclonal antibody against amoxillin., Methods: Amoxicillin were respectively coupled with ovalbumin(OVA) and bovine serum albumin(BSA) by using N-hydroxysuc-cinimide active ester (NHS) method to prepared the immunogen and detection antigen. Molar ratio of conjugates were detected by ultraviolet spectrum analysis. BALB/c mice was immunized with AMX-OVA. The hybridomas were obtained by fusing mouse myeloma cells Sp2/0 with splenocytes from the mice immunized with AMX-OVA. The aseites with mAb were purified by octanoic acid-saturated ammonium sulphate method. Isotype was determined by Mouse Isotype kit (Bio-RadLabs.)., Results: UV spectra shows overlay features between a small molecular compound and carrier protein. Five hybridoma cell strains secreting specific mAb against amoxicillin were obtained and the five Amb belong to IgG1 kappa isotype. The limit of detection of AMX was 0.25 ng/mL and but there is mild degree of cross-reactions with ampicillin with same structure of β-lactam ring., Conclusion: The anti-AMX Amb could be used to develop immunoassay for detection of residues.

Well-defined dendronized cellulose substrates displaying multiple representations of dual-functionality were constructed by taking advantage of the efficiency of the click reaction combined with traditional anhydride chemistry. First, activated cellulose surfaces were decorated with several generations of dendrons, and their peripheral reactive groups were subsequently reacted with a trifunctional orthogonal monomer. The generated substrate tool box was successfully explored by accurately tuning the surface function using a versatile orthogonal dual postfunctionalization approach. In general, the reactions were monitored by using a click-dye reagent or a quartz crystal microbalance (QCM) technique, and the resulting surfaces were well-characterized using XPS, FT-IR, and contact angle measurements. Utilizing this approach two different surfaces have been obtained; that is, triethylenglycol oligomers and amoxicillin molecules were efficiently introduced to the dendritic surface. As a second example, mannose-decorated hydroxyl functional surfaces illustrated their potential as biosensors by multivalent detection of lectin protein at concentration as low as 5 nM.

Activated carbon-supported TiO(2) nanoparticles, termed integrated photocatalytic adsorbents (IPCAs), were prepared using an ultrasonic impregnation technique and investigated for the photocatalytic degradation of amoxicillin (AMO), a β-lactam antibiotic. The IPCAs had high adsorption affinity for AMO with the amount adsorbed proportional to the TiO(2) loading and the highest adsorption was at 10 wt% TiO(2) loading. A pseudo-second-order model was found to fit the experimental data and consistently predicted the amount of AMO adsorbed over the adsorption period. Equilibrium isotherm studies showed that the adsorption followed the Redlich-Peterson model with maximum adsorption capacity of 441.3 mg g(-1) for 10% IPCA, 23% higher than the pure activated carbon (AC). Kinetic studies on the photocatalytic degradation of AMO using non-linear regression analysis suggest that the degradation followed Langmuir-Hinshelwood (L-H) kinetics. The adsorption rate constant (K(ad)) was considerably higher than the photocatalytic rate constant (k(L-H)), indicating that the photocatalysis of AMO is the rate-determining step during the adsorption/photocatalysis process. The 10% IPCA exhibited excellent stability and reusability over four photodegradation cycles.

The decomposition of three β-lactam antibiotics (amoxicillin, oxacillin and ampicillin) in aqueous solution was investigated using a dielectric barrier discharge (DBD) in coaxial configuration. Solutions of concentration 100 mg/L were made to flow as a film over the surface of the inner electrode of the plasma reactor, so the discharge was generated at the gas-liquid interface. The electrical discharge was operated in pulsed regime, at room temperature and atmospheric pressure, in oxygen. Amoxicillin was degraded after 10 min plasma treatment, while the other two antibiotics required about 30 min for decomposition. The evolution of the degradation process was continuously followed using liquid chromatography-mass spectrometry (LC-MS), total organic carbon (TOC) and chemical oxygen demand (COD) analyses., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

A successful application of NIR spectroscopy (NIRS) in combination with multivariate data analysis (MVA) for the simultaneous identification and particle size determination of amoxicillin trihydrate particles was developed. Particle size analysis was ascertained by NIRS in diffuse reflection mode on different particle size fractions of amoxicillin trihydrate with D90 particle diameters ranging from 6.9 to 21.7 μm. The present problem of fractionating the powder into good enough size fractions to achieve a stable calibration model was solved. By probing dried suspensions measurement parameters were optimized and further combined with the best suitable chemometric operations. Thereby the quality of established regression models could be improved considerably. A linear coherence between particle size and absorbance signal was found at specific wavenumbers. Satisfactory clustering by particle size was achieved by principal component analysis (PCA) whereas partial least squares regression (PLSR) and principal component regression (PCR) was compared for quantitatively calibrating the NIRS data. PLSR turned out to predict unknown test samples slightly better than PCR., (Copyright © 2010 Elsevier B.V. All rights reserved.)

Purpose: To investigate the muco/bioadhesive properties of chitosan, polyvinylpyrrolidone (PVP), and chitosan/PVP blends and the release of amoxicillin (AMX) contained in AMX-alginate beads coated with these materials., Method: Chitosan, PVP, and chitosan/PVP blends at various volume ratios were coated onto calcium alginate beads containing AMX. The muco/bioadhesive properties of all materials and the AMX-alginate beads coated with these materials were characterized., Results: Measurements of their viscosity, texture, and adhesion to HT29 cells demonstrated that chitosan/PVP at a volume ratio of 5/5 had the best muco/bioadhesive properties when compared with chitosan, PVP, and blends of other ratios. Wash-off tests indicated that the mucoadhesive property of the coated AMX-alginate beads was significantly higher than that of the uncoated beads. Diffuse reflectance infrared Fourier transform spectroscopy showed that there were interactions between chitosan-PVP, chitosan-mucin, PVP-mucin, and chitosan/PVP blend-mucin. Scanning electron microscopy revealed that the surfaces of the coated beads were smoother than those of the uncoated beads. All coated AMX-alginate beads were able to provide a controlled release of AMX with Super Case II transport properties, at a pH of 4. This was probably a result of the rapid and extensive swelling of the alginate beads. The more rapid release of AMX at pH 1 was probably because of the rapid dissolution of the drug at this pH., Conclusions: From the controlled drug release and muco/bioadhesive properties of these coated AMX-alginate beads, we suggest that the alginate-coated beads might be a promising drug delivery system to assist with the eradication of Helicobacter pylori infections.

The identification of transformation products (TPs) of pharmaceuticals in the environment is essentially a challenging task due to the lack of standards and the instrumental capabilities required to detect compounds (sometimes unknowns) that are produced under environmental conditions. In this work, we report the use of liquid chromatography/electrospray quadrupole time-of-flight mass spectrometry (LC/QTOF-MS/MS) as a tool for the identification of amoxicillin (AMX) and its main TPs in wastewater and river water samples. Laboratory degradation experiments of AMX were performed in both alkaline and acidic media in order to confirm that the expected transformation pathway in the aquatic media is through the β-lactam ring cleavage. A thorough study was carried out with both standards and real samples (wastewater and river water samples). Four compounds were identified as main TPs: both amoxicillin diketopiperacine-2',5' and amoxilloic acid diastereomers. Amoxilloic acid stereoisomers are reported for the first time in environmental matrices. The transformation product (5R)-amoxicillin diketopiperacine-2',5' was frequently detected in river waters. Besides, another AMX transformation product formed during analysis was also structurally elucidated for the first time (amoxicilloic acid methyl ester) via accurate mass measurements. Collected data show that although AMX is not present as such in environmental samples, different TPs occur. This study represent a valuable indicator of the potential of LC/QTOF-MS/MS for the identification and structural elucidation of TPs in the environment using accurate MS/MS experiments, enabling thus the recognition of the environmental transformation pathway., (Copyright © 2011 John Wiley & Sons, Ltd.)

Single-nanopores have recently been used to electrically detect a wide range of analytes. Similarly, using electrophysiology, we demonstrate how a system comprised of an ion channel formed by α-hemolysin (α-HL) and single-cyclic γ-cyclodextrin (γ-CD) molecule permits the detection of, and differentiation between three different antibiotics from the β-lactam family. Specifically, histograms of the time between the successive binding events, and the residence time distributions of the antibiotic in the γ-CD molecular adapter vary with the antibiotic type. The results show that the association times of amoxicillin, azlocillin, and ampicillin are τ(on) = 2.1 ± 0.2, 2.2 ± 0.3, and 3.1 ± 0.4 ms, respectively. Interestingly, we found that the residence time of the bulkier and negatively charged azlocillin (τ(off) = 0.008 ± 0.0005 ms) is much less than that of ampicillin (τ(off) = 0.07 ± 0.005 ms) and amoxicillin (τ(off) = 0.1 ± 0.02 ms), even though the γ-CD-α-HL complex is anionic selective. The data were also used to estimate the standard free energy of binding between ampicillin to γ-CDs binding (-12 kJ mol(-1) [corrected]). The difference in association times might be due to γ-CDs-imposed steric hindrance or an energetically more expensive desolvation step for the antibiotics to gain access to the binding site in the CD. We suggest that this technique may be used to detect other analytes used in pharmaceutical applications., (Copyright © 2010 John Wiley & Sons, Ltd.)

Sustained release mucoadhesive amoxicillin tablets with tolerance to acid degradation in the stomach were studied. The sustained-release tablets of amoxicillin were prepared from amoxicillin coated with ethyl cellulose (EC) and then formulated into tablets using chitosan (CS) or a mixture of CS and beta-cyclodextrin (CD) as the retard polymer. The effects of various (w/w) ratios of EC/amoxicillin, the particle sized of EC coated amoxicillin and the different (w/w) ratios of CS/CD for the retard polymer, on the amoxicillin release profile were investigated. The physicochemical properties of the EC coated amoxicillin particles and tablets were determined by scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, and differential scanning calorimetry. The result showed that the release profiles of amoxicillin were greatly improved upon coating with EC, while the inclusion of CD to the CS retardant additionally prolonged the release of the drug slightly. Overall, a sustained release of amoxicillin was achieved using amoxicillin coated with EC at a (w/w) ratio of 1:1 and a particle size of 75-100 μm. Therefore, the tablet formulation of amoxicillin may be an advantageous alternative as an orally administered sustained-release formulation for the treatment of peptic ulcers., (© 2010 American Association of Pharmaceutical Scientists)

In this paper, we report the synthesis and characterization of a novel cross-linked N-isopropylacrylamide-acrylic acid-hydroxyethyl methacrylate [P (NIPASM-AA-HEM)] hydrogel nanoparticles (NPs) containing amoxicillin. The aim of present study was to investigate whether these hydrogel NPs have the potential to be used in antibiotic delivery to stomach for treatment of Helicobacter pylori. Amoxicillin-loaded hydrogel NPs were prepared using cross-linked P (NIPASM-AA-HEM) as mucoadhesive polymer for the potential use of treating gastric and duodenal ulcers. Aiming at predicting the in vivo behavior of the amoxicillin-loaded NPs, the physicochemical properties in terms of entrapment efficiency (EE%), mean diameter, and morphology of NPs was evaluated. The dependence of the EE% of the drug on the organic to aqueous phase ratio was also studied. The profile of amoxicillin release from P (NIPASM-AA-HEM) NPs system was studied under various conditions. In all these experiments, amoxicillin release in the free form was studied by ultraviolet (UV) spectrophotometric analysis. Experimental results showed that at pH 7.4, drug release rises when polymer concentration in the formulation increases; in human plasma on the contrary, drug release is reduced as concentration of the polymer in the formulation rises. In vitro amoxicillin release rate was also higher in pH 1 than that in pH 7.4. About 88.5% of amoxicillin entrapped in the NPs was released in 4 h in the pH 1.0 medium, whereas in phosphate buffer at pH 7.4 no more than 45% was released after 4 h incubation at 37 °C. Amoxicillin concentration in rat's gastric tissue was determined. The results of in vivo studies showed that the hydrogel NPs enhance drug concentration at topical site than powder amoxicillin. Thus, amoxicillin-loaded hydrogel NPs may provide therapeutic concentration at a much lower dose that may reduce the adverse effects of amoxicillin in high doses., (Copyright © 2010 Wiley-Liss, Inc.)

Amoxicillin is a widely used antibiotic and has been detected in natural waters. Its environmental fate is in part determined by hydrolysis, and, direct and indirect photolysis. The hydrolysis rate in distilled water and water to which five different isolated of dissolved organic matter (DOM) was added, were evaluated. In the five different DOM solutions hydrolysis accounted for 5-18% loss of amoxicillin. Direct and indirect photolysis rates were determined using a solar simulator and it appeared that indirect photolysis was the dominant loss mechanism. Direct photolysis, in a solar simulator, accounted for 6-21% loss of amoxicillin in the simulated natural waters. The steady-state concentrations of singlet oxygen, (1)ΔO(2) (∼10(-13) M) and hydroxyl radical, •OH (∼10(-17) M) were obtained in aqueous solutions of five different dissolved organic matter samples using a solar simulator. The bimolecular reaction rate constant of (1)ΔO(2) with amoxicillin was measured in the different solutions, k(ΔO(2)) = 1.44 × 10(4) M(-1) s(-1). The sunlight mediated amoxicillin loss rate with (1)ΔO(2) (∼10(-9) s(-1)), and with •OH (∼10(-7) s(-1)), were also determined for the different samples of DOM. While (1)ΔO(2) only accounted for 0.03-0.08% of the total loss rate, the hydroxyl radical contributed 10-22%. It appears that the direct reaction of singlet and triplet excited state DOM ((3)DOM(∗)) with amoxicillin accounts for 48-74% of the loss of amoxicillin. Furthermore, the pseudo first-order photodegradation rate showed a positive correlation with the sorption of amoxicillin to DOM, which further supported the assumption that excited state DOM∗ plays a key role in the photochemical transformation of amoxicillin in natural waters. This is the first study to report the relative contribution of all five processes to the fate of amoxicillin in aqueous solution., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

The influence of iron species on amoxicillin (AMX) degradation, intermediate products generated and toxicity during the photo-Fenton process using a solar simulator were evaluated in this work. The AMX degradation was favored in the presence of the potassium ferrioxalate complex (FeOx) when compared to FeSO(4). Total oxidation of AMX in the presence of FeOx was obtained after 5 min, while 15 min were necessary using FeSO(4). The results obtained with Daphnia magna biossays showed that the toxicity decreased from 65 to 5% after 90 min of irradiation in the presence of FeSO(4). However, it increased again to a maximum of 100% after 150 min, what indicates the generation of more toxic intermediates than AMX, reaching 45% after 240 min. However, using FeOx, the inhibition of mobility varied between 100 and 70% during treatment, probably due to the presence of oxalate, which is toxic to the neonates. After 240 min, between 73 and 81% TOC removal was observed. Different pathways of AMX degradation were suggested including the opening of the four-membered β-lactamic ring and further oxidations of the methyl group to aldehyde and/or hydroxylation of the benzoic ring, generating other intermediates after bound cleavage between different atoms and further oxidation to carboxylates such acetate, oxalate and propionate, besides the generation of nitrate and ammonium., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

The purpose of the present study was to design muco-adhesive chitosan microspheres containing amoxicillin. Chitosan microspheres with a small particle size and good sphericity were prepared by a spray-drying method followed by chemical treatment with a chemical crosslinking agent (glutaraldehyde). Parameters affecting the crosslinking extent of the crosslinking time and the concentration of the crosslinker agent. Crosslinked spray-dried chitosan microspheres were analyzed for their morphological aspects, particle size, drug entrapment efficiency, swelling percent and in vitro drug release. Batch M4 with a drug polymer ratio of 1:2, dissolved in minimum concentration of acetic acid solution treated with glutaraldehyde, was found to be optimal giving controlled drug release for 10 h. It was found that both the increase of glutaraldehyde concentration and crosslinking duration decreased the swelling capacity of chitosan microspheres. This could be directly correlated to drug release from the microspheres.

A central composite factorial design methodology was employed to optimise the amoxicillin degradation using the Fenton's oxidation treatment. In this study, the variables considered for the process optimisation were the hydrogen peroxide and ferrous ion initial concentrations and the temperature, for an antibiotic concentration of 450μg L(-1) at pH=3.5. This methodology also allowed assessing and identifying the effects of the different factors studied and their interactions in the process response. An appropriate quadratic model was developed in order to plot the response surface and contour curves, which was used to perform the process optimisation. From this study, it was concluded that ferrous ion concentration and temperature were the variables that most influenced the response. Under the optimal conditions (hydrogen peroxide concentration=3.50-4.28mg L(-1), ferrous ion concentration=254-350μg L(-1) and temperature=20-30°C), it was possible to achieve total amoxicillin degradation after 30min of reaction., (Copyright © 2010 Elsevier B.V. All rights reserved.)

Objectives: During the survey of substandard medicines in Cambodia in 2007, it was found that more than 90% of 500-mg amoxicillin (AMPC) capsules failed the United States Pharmacopeia (USP) 30 TEST 1 dissolution test. In the USP, several monographs provide multiple methods for performing the dissolution test. By using the 500-mg AMPC capsule as an example, we aimed to identify the problems and implications of the USP methods adopted for the dissolution test as a global standard., Methods: All AMPC samples were collected from the Cambodian market in 2007. For the quantitative test, we referred to USP 30. We performed the USP 28 and USP 30 TEST 2 dissolution tests and compared these results with those of the USP 30 TEST 1., Results: All 500-mg AMPC capsules used for the comparison passed the quantitative test. Samples that passed the USP 28 and USP 30 TEST 2 dissolution tests were identical, and the pass rate was 97.1% (34/35), whereas the pass rate with the USP 30 TEST 1 was 8.6% (3/35). The difference in the dissolution results between the three methods was significant (P<0.0001)., Conclusion: This study revealed that many users would select the most stringent method when multiple methods exist in the USP. This may lead to a high failure rate of the tests. Because USP is a global standard, we recommend that it take into consideration the developing countries and create a more detailed user-friendly manual for selection for appropriate methods., (© 2010 Blackwell Publishing Ltd.)

A new ion source has been developed for rapid, noncontact analysis of materials at ambient conditions. The method provides desorption of analytes under ambient conditions directly from different surfaces with little or no sample preparation. The new method, termed electrode-assisted desorption electrospray ionization (EADESI), is on the basis of the ionization of molecules on different surfaces by highly charged droplets produced on a sharp-edged high voltage tip, and ions produced are introduced into the mass spectrometer through a capillary. The EADESI technique can be applied to various samples including amino acids, peptides, proteins, drugs and human fluids such as urine and blood. EADESI is promising for routine analyses in different fields such as forensic, environmental and material sciences. EADESI interface can be fit to a conventional ion-trap mass spectrometer. It can be used for various types of samples with a broad mass range. EADESI can also provide real-time analysis which is very valuable for biomedical applications., (Copyright © 2010 John Wiley & Sons, Ltd.)

A novel strategy to trace the origins of commercial pharmaceutical products has been developed based on the direct chemical profiling of the pharmaceutical products by surface desorption atmospheric pressure chemical ionization mass spectrometry (DAPCI-MS). Besides the unambiguous identification of active drug components, various compounds present in the matrixes are simultaneously detected without sample pretreatment, providing valuable information for drug quality control and origin differentiation. Four sources of commercial amoxicillin products made by different manufacturers have been successfully differentiated. This strategy has been extended to secerning six sources of Liuwei Dihuang Teapills, which are herbal medicine preparations with extremely complex matrixes. The photolysis status of chemical drug products and the inferior natural herd medicine products prepared with different processes (e.g., extra heating) were also screened using the method reported here. The limit of detection achieved in the MS/MS experiments was estimated to be 1 ng/g for amoxicillin inside the capsule product. Our experimental data demonstrate that DAPCI-MS is a useful tool for rapid pharmaceutical analysis, showing promising perspectives for tracking the entire pharmaceutical supply chain to prevent counterfeit intrusions.

The aim of this study was to develop polymeric biodegradable microspheres (MSs) of poly(D-L lactide-co-glycolide) (PLGA) and zein capable of delivering amoxicillin (AMX) at significant levels for root canal disinfection. PLGA/zein MSs were prepared using a spray-drying technique. The systems were characterized in terms of particle size, morphology, drug loading and in vitro release. Drug levels were reached to be effective during the intracanal dressing in between visits during the endodontic treatment. In vitro release studies were carried out to understand the release profile of the MSs. Antimicrobial activity of AMX was performed by antibiograms. Enterococcus faecalis was the bacteria selected due to its prevalence in endodontic failure. Drug microencapsulation yielded MSs with spherical morphology and an average particle size of between 5 and 38 µm. Different drug-release patterns were obtained among the formulations. Release features related to the MSs were strongly dependent on drug nature as it was demonstrated by using a hydrophobic drug (indomethacin). Finally, AMX-loaded MSs were efficient against E faecalis as demonstrated by the antibiogram results. In conclusion, PLGA/zein MSs prepared by spray drying may be a useful drug delivery system for root canal disinfection.

Advanced oxidation of amoxicillin was realized in aqueous solution by using Fenton's reagent treatment. Box-Behnken statistical experiment design was used to determine the effects of reagent concentrations on amoxicillin degradation and mineralization. Amoxicillin (10-200 mg L(-1)), hydrogen peroxide (10-500 mg L(-1)) and Fe(II) (0-50 mg L(-1)) concentrations were considered as independent variables in batch oxidation experiments. Percent amoxicillin and total organic carbon (TOC) removals (mineralization) were considered as the objective functions to be maximized. Required reaction times were 2.5 min and 15 min, respectively for degradation and mineralization of amoxicillin. Both peroxide and amoxicillin concentrations affected the extent of amoxicillin degradation and mineralization. Complete amoxicillin degradation was obtained within 2.5 min while 37% mineralization took place within 15 min. The optimum peroxide/Fe/amoxicillin ratio resulting in complete amoxicillin degradation and 37% mineralization was 255/25/105 mg L(-1)., (2010 Elsevier B.V. All rights reserved.)

Inhibitive and adsorption properties of Penicillin G, Amoxicillin and Penicillin V potassium were studied using gravimetric, gasometric and quantum chemical methods. The results obtained indicate that these compounds are good adsorption inhibitors for the corrosion of mild steel in HCl solution. The adsorption of the inhibitors on mild steel surface is spontaneous, exothermic and supports the mechanism of physical adsorption. From DFT results, the sites for nucleophilic attacks in the inhibitors are the carboxylic acid functional group while the sites for electrophilic attacks are in the phenyl ring. There was a strong correlation between theoretical and experimental inhibition efficiencies.

Apparent rate constants for the reactions of four selected pharmaceutical compounds (metoprolol, naproxen, amoxicillin, and phenacetin) with chlorine in ultra-pure (UP) water were determined as a function of the pH. It was found that amoxicillin (in the whole pH range 3-12), and naproxen (in the low pH range 2-4) presented high reaction rates, while naproxen (in the pH range 5-9), and phenacetin and metoprolol (in the pH range 2.5-12 for phenacetin, and 3-10 for metoprolol) followed intermediate and slow reaction rates. A mechanism is proposed for the chlorination reaction, which allowed the evaluation of the intrinsic rate constants for the elementary reactions of the ionized and un-ionized species of each selected pharmaceutical with chlorine. An excellent agreement is obtained between experimental and calculated rate constants by this mechanism.The elimination of these substances in several waters (a groundwater, a surface water from a public reservoir, and two effluents from municipal wastewater treatment plants) was also investigated at neutral pH. The efficiency of the chlorination process with respect to the pharmaceuticals elimination and the formation THMs was also established. It is generally observed that the increasing presence of organic and inorganic matter in the water matrices demand more oxidant agent (chlorine), and therefore, less chlorine is available for the oxidation of these compounds. Finally, half-life times and oxidant exposures (CT) required for the removal of 99% of the four pharmaceuticals are also evaluated. These parameters are useful for the establishment of safety chlorine doses in oxidation or disinfection stages of pharmaceuticals in treatment plants.

In this paper, we propose an effective protocol for bacterial detection using antibody microarray-based strategies with gold nanoparticle probes. In this approach, bacteria are captured by immobilized IgGs on the microarray spots. The capturing events are marked by attachment of lectin (e.g. Ricinus Communis Agglutini (RCA) and Concanavalin A (ConA)) conjugated gold nanoparticles followed by silver deposition for signal enhancement. The detection principle is resonance light scattering (RLS). Using this technique, highly selective discrimination of bacterial strain types (i.e., gram-negative, gram-positive and fungus) down to 10(3) cells per assay with a dynamic range of nearly three orders of magnitude are demonstrated. In addition, the capturing process can be inhibited by lipopolysaccharides (LPS), which gives further evidence of the binding mechanism. Furthermore, antibacterial assay with antibacterial drugs (amoxicillin and vancomycin) demonstrates that the approach enables to detect antibacterial efficiency as well as derive MIC (minimum inhibitory concentration) plots.

A cascade reaction combining the enzymatic hydrolysis of Penicillin G potassium salt (PGK) with the kinetically controlled enzymatic coupling of in situ formed 6-aminopenicillanic acid (6-APA) with p-hydroxyphenylglycine methyl ester (D-HPGM) to give amoxicillin as the final product by using a single enzyme has been demonstrated successfully. Ethylene glycol (EG) was employed as a component of reaction buffer to improve the synthesis yield. Reaction parameters, including different cosolvents, EG content, the loading of immobilized penicillin G acylase (IPA), and reaction temperature and time were studied to evaluate their effects on the reaction. The best result of 55.2% yield was obtained from the reaction which was carried out in the mixed media containing 40% sodium dihydrogen phosphate buffer (apparent pH 6.0) and 60% EG (v/v), with the initial concentration 150 mM and 450 mM of PGK and D-HPGM, respectively, catalyzed by 50 IU/mL IPA at 25 degrees C for 10 h. The IPA could be recycled for nine batches without obviously losing of catalytic activity. The important strategy will have potential application in the beta-lactam antibiotics industry due to the advantages of saving the effort of isolating 6-APA, reducing usual enzymatic steps and the industrial cost of amoxicillin synthesis.

The study examined the effect of operating conditions (zinc oxide concentration, pH and irradiation time) of the UV/ZnO photocatalytic process on degradation of amoxicillin, ampicillin and cloxacillin in aqueous solution. pH has a great effect on amoxicillin, ampicillin and cloxacillin degradation. The optimum operating conditions for complete degradation of antibiotics in an aqueous solution containing 104, 105 and 103 mg/L amoxicillin, ampicillin and cloxacillin, respectively were: zinc oxide 0.5 g/L, irradiation time 180 min and pH 11. Under optimum operating conditions, complete degradation of amoxicillin, ampicillin and cloxacillin occurred and COD and DOC removal were 23.9 and 9.7%, respectively. The photocatalytic reactions under optimum conditions approximately followed a pseudo-first order kinetics with rate constant (k) 0.018, 0.015 and 0.029 min(-1) for amoxicillin, ampicillin and cloxacillin, respectively. UV/ZnO photocatalysis can be used for amoxicillin, ampicillin and cloxacillin degradation in aqueous solution.

The study examined degradation of the antibiotics amoxicillin, ampicillin and cloxacillin in aqueous solution by the photo-Fenton process. The optimum operating conditions for treatment of an aqueous solution containing 104, 105 and 103 mg/L amoxicillin, ampicillin, and cloxacillin, respectively was observed to be H(2)O(2)/COD molar ratio 1.5, H(2)O(2)/Fe(2+) molar ratio 20 and pH 3. Under optimum operating conditions, complete degradation of amoxicillin, ampicillin and cloxacillin occurred in 2 min. Biodegradability (BOD(5)/COD ratio) improved from approximately 0 to 0.4, and COD and DOC degradation were 80.8 and 58.4%, respectively in 50 min. Photo-Fenton treatment resulted in the release and mineralization of organic carbon and nitrogen in the antibiotic molecule. Increase in ammonia and nitrate concentration, and DOC degradation were observed as a result of organic carbon and nitrogen mineralization. DOC degradation increased to 58.4% and ammonia increased from 8 to 13.5mg/L, and nitrate increased from 0.3 to 14.2mg/L in 50 min.

The short half-life of aminopenicillin antibiotics in the aquatic environment put to the challenge the detection of their degradation products among environmental hydro-chemists. In a quest to study the occurrence of a new emerging micro-pollutant in the aquatic environment we attempted this by analyzing samples from a wastewater treatment plant for a major degradation product of amoxicillin (i.e., amoxicillin-diketopiperazine-2', 5') using a high-performance liquid chromatography technique coupled with tandem mass spectrometry method. ADP was repeatedly detected in all wastewater and effluent samples (18) from which it was extracted. To the best of our knowledge, this is the first study that evidently proves the occurrence of the chemically stable form of AMX, its Diketopiperazine-2', 5', in wastewater and effluent samples. Furthermore, penicillins are known to cause most allergic drug reactions. There is a risk that residues of hypersensitivity-inducing drugs, such as penicillins and their degradation products, may elicit allergic reactions in human consumers of water and food of animal origin.

The study examined the effect of operating conditions of the Fenton process on biodegradability improvement and mineralization of amoxicillin, ampicillin and cloxacillin antibiotics in aqueous solution. In addition, degradation of amoxicillin, ampicillin and cloxacillin under optimum operating conditions were evaluated. The optimum operating conditions for an aqueous solution containing 104, 105 and 103 mg/L amoxicillin, ampicillin, and cloxacillin, respectively were observed to be COD/H2O2/Fe2+ molar ratio 1:3:0.30 and pH 3. Under optimum operating conditions, complete degradation of amoxicillin, ampicillin and cloxacillin occurred in 2 min. In addition, biodegradability improved from approximately 0 to 0.37 in 10 min, and COD and DOC degradation were 81.4% and 54.3%, respectively in 60 min. Maximum biodegradability (BOD5/COD ratio) improvement was achieved in 10, 20 and 40 min at antibiotics concentration 100, 250 and 500 mg/L, respectively for each antibiotic in aqueous solution. Increase in nitrate and ammonia concentration were observed due to mineralization of organic nitrogen, concentration of nitrate increased from 0.3 to 10 mg/L and concentration of ammonia increased from 8 to 13 mg/L in 60 min. The study indicated that Fenton process can be used for pretreatment of amoxicillin, ampicillin and cloxacillin wastewater for biological treatment.

In order to investigate the combined effects of antibiotics on anaerobic digestion of piggery wastewater, batch tests based on orthogonal test were adopted. Amoxicillin, aureomycin, sulfadimethoxine, florfenicol which are the most common antibiotics used in the prevention and treatment of pig diseases were chosen in the experiment. The results showed that the methane production rate was affected most by the combination of 130 mg/L of florfenicol, 210 mg/L of amoxicillin, 10 mg/L doxycycline and 210 mg/L sulfadimethoxine and the inhibitory effect on maximum methane production rate amounted to 87.8%. No inhibitory effect but stimulus was observed on anaerobic digestion in the presence of florfenicol, amoxicillin, aureomycin, sulfadimethoxine with 10 mg/L. The significance of the inhibitory effect of the selected antibiotics was in an order of aureomycin, amoxicillin, florfenicol and sulfadimethoxine (p > 0.005). Different kinds of first-order interactions between either two antibiotics were concluded from the experiment. Except that florfenicol was in a additivity relationship with amoxicillin and sulfadimethoxine the interaction in other antibitotics was antagonistic.

Background: This study compared bacterial penetration through guided tissue regeneration (GTR) membranes impregnated with antibiotics., Methods: Three barrier membranes, expanded polytetrafluoroethylene (ePTFE) membrane, collagen membrane, and glycolide fiber composite membrane, were loaded with amoxicillin or tetracycline. The penetration of Streptococcus mutans and Aggregatibacter actinomycetemcomitans (previously Actinobacillus actinomycetemcomitans) through the GTR membranes was achieved using a device consisting of an inner tube and an outer bottle filled with culture media., Results: The penetration of S. mutans or A. actinomycetemcomitans into the inner tubes significantly decreased with all of the antibiotic-loaded membranes compared to membranes without antibiotics. However, differences were found in the behavior of the three membranes. The antibiotic-loaded ePTFE membranes showed the best barrier effect. Moreover, the inhibitory effect of tetracycline on S. mutans was greater than that of amoxicillin for all GTR membranes. Furthermore, the inhibitory effect of tetracycline on A. actinomycetemcomitans was lower than that of amoxicillin with the glycolide fiber membrane., Conclusions: The results showed that penetration of S. mutans and A. actinomycetemcomitans through amoxicillin- or tetracycline-loaded ePTFE membrane, glycolide fiber membrane, and collagen membrane was delayed and/or reduced. Thus, incorporation of an antibiotic into the membrane may be of value when controlling membrane-associated infection during GTR therapy.