Agricultural contaminants in amphibian breeding ponds: Occurrence, risk and correlation with agricultural land use.

Anthropogenic pressure such as agricultural pollution globally affects amphibian populations. In this study, a total of 178 different compounds from five agrochemical groups (i.e. antimicrobial drugs residues (ADRs), coccidiostats and anthelmintics, heavy metals, mycotoxins and pesticides) were determined monthly, from March until June 2019 in 26 amphibian breeding ponds in Flanders, Belgium. Furthermore, a possible correlation between the number and concentration of selected contaminants that were found and the percentage of arable land within a 200 m radius was studied. Within each group, the highest detected concentrations were obtained for 4-epioxytetracycline (0.422 µg L-1), levamisole (0.550 µg L-1), zinc (333.1 µg L-1), 3-acetyldeoxynivalenol (0.013 µg L-1), and terbuthylazine (38.7 µg L-1), respectively, with detection frequencies ranging from 1 (i.e. 3-acetyldeoxynivalenol) to 26 (i.e. zinc) out of 26 ponds. Based on reported acute and chronic ecotoxicological endpoints, detected concentrations of bifenthrin, cadmium, copper, cypermethrin, hexachlorobenzene, mercury, terbuthylazine, and zinc pose a substantial ecological risk to aquatic invertebrates such as Daphnia magna and Ceriodaphnia dubia, which both play a role in the food web and potentially in amphibian disease dynamics. Additionally, the detected concentrations of copper were high enough to exert chronic toxicity in the gray treefrog (Hyla versicolor). The number of detected compounds per pond ranged between 0 and 5 (ADRs), 0 - 2 (coccidiostats and anthelmintics), 1 - 7 (heavy metals), 0 - 4 (mycotoxins), and 0 - 12 (pesticides) across the four months. Furthermore, no significant correlation was demonstrated between the number of detected compounds per pond, as well as the detected concentrations of 4-epioxytetracycline, levamisole, copper, zinc, enniatin B and terbuthylazine, and the percentage of arable land within a 200 m radius. For heavy metals and pesticides, the number of compounds per pond varied significantly between months. Conclusively, amphibian breeding ponds in Flanders were frequently contaminated with agrochemicals, yielding concentrations up to the high µg per liter level, regardless of the percentage surrounding arable land, however showing temporal variation for heavy metals and pesticides. This research also identifies potential hazardous substances which may be added to the European watch list (CD 2018/408/EC) in the future.

Pharmacokinetics of florfenicol in turkey plasma, lung tissue, and pulmonary epithelial lining fluid after single oral bolus or continuous administration in the drinking water.

Florfenicol (FF) is registered for treatment of bovine and swine respiratory diseases. Although, turkeys often suffer from bacterial respiratory tract infections, there is no registered formulation based on FF for poultry available in Europe. The aim of this study was to evaluate the pharmacokinetic behavior of FF in turkeys in plasma, lung tissue, and pulmonary epithelial lining fluid (PELF).The concentration and pharmacokinetic characteristics of FF in plasma, lung tissue, and PELF in turkeys were determined, either after a single oral bolus (30 mg/kg body weight, BW) or during and after continuous drinking water medication (30 mg/kg BW/d for 5 d). Plasma, lung tissue, and PELF samples were collected at different intervals after administration, and FF was quantified by liquid chromatography-tandem mass spectrometry. After single bolus administration, FF was rapidly absorbed in plasma (the time to maximum concentration, tmax, was 1.02 h) and distributed to the respiratory tract (mean tmax = 1.00 h). The mean t1/2el in plasma and lung tissue was similar, around 6 h, whereas it was slightly higher in PELF, namely, 8.7 hours. After oral bolus dosing, the mean maximum concentration in plasma was twice as high as in the lung tissue, 4.26 µg/mL and 2.64 µg/g, respectively, while in PELF it was much lower, 0.39 µg/mL. During continuous drinking water medication, lung FF concentrations were slightly higher than plasma concentrations, with lung/plasma ratios of 2.01 and 1.27 after 24 h and 72 h, respectively. FF was not detected in PELF during continuous drinking water medication.

Factors influencing the process of medication (non-)adherence and (non-)persistence in breast cancer patients with adjuvant antihormonal therapy: a qualitative study.

Non-adherence and non-persistence in breast cancer patients taking antihormonal therapy (AHT) is common. However, the complex patterns and dynamics of adherence and persistence are still not fully understood. This study aims to give insight into the process of (non-)adherence and (non-)persistence by researching influencing factors and their interrelatedness in breast cancer patients taking AHT by means of a qualitative study with semi-structured interviews. The sample consisted of 31 breast cancer patients treated with AHT. Purposive and theoretical sampling and the constant comparison method based on a grounded theory approach were used. Expectations regarding the impact of AHT, social support from family and friends, and recognition from healthcare professionals were found to influence the process of non-adherence and non-persistence. The results of this study can help healthcare professionals understand why breast cancer patients taking AHT do not always adhere to or persist in taking the therapy and may facilitate patient-tailored interventions.

Feed contamination with Fusarium mycotoxins induces a corticosterone stress response in broiler chickens.

The aim of the present study was to evaluate the effect of the Fusarium mycotoxins deoxynivalenol (DON) and fumonisins (FBs) on the stress response in broiler chickens, using corticosterone (CORT) in plasma as a biomarker. Chickens were fed either a control diet, a DON contaminated diet, a FBs contaminated diet, or a DON and FBs contaminated diet for 15 d at concentrations close to the European Union maximum guidance levels for DON and FBs in poultry. Mean plasma CORT levels were significantly higher in broiler chickens fed a DON contaminated and a DON and FBs contaminated diet compared to birds fed a control diet. A similar trend was observed for animals fed a FBs contaminated diet. Consequently, feeding broilers a diet contaminated with DON and/or FBs induced a CORT stress response, which may indicate a negative effect on animal welfare.

Pharmacokinetics of intravenously and orally administered sotalol hydrochloride in horses and effects on surface electrocardiogram and left ventricular systolic function.

Arrhythmias are common in horses. Some, such as frequent atrial or ventricular premature beats, may require long-term anti-arrhythmic therapy. In humans and small animals, sotalol hydrochloride (STL) is often used for chronic oral anti-arrhythmic therapy. STL prolongs repolarization and the effective refractory period in all cardiac tissues. No information on STL pharmacokinetics or pharmacodynamics in horses is available and the aim of this study was to evaluate the pharmacokinetics of intravenously (IV) and orally (PO) administered STL and the effects on surface electrocardiogram and left ventricular systolic function. Six healthy horses were given 1 mg STL/kg bodyweight either IV or PO. Blood samples to determine plasma STL concentrations were taken before and at several time points after STL administration. Electrocardiography and echocardiography were performed at different time points before and after IV STL administration. Mean peak plasma concentrations after IV and PO administration of STL were 1624 ng/mL and 317 ng/mL, respectively. The oral bioavailability was intermediate (48%) with maximal absorption after 0.94 h, a moderate distribution and a mean elimination half-life of 15.24 h. After IV administration, there was a significant increase in QT interval, but no significant changes in other electrocardiographic and echocardiographic parameters. Transient transpiration was observed after IV administration, but no adverse effects were noted after a single oral dose of 1 mg/kg STL in any of the horses. It was concluded that STL has an intermediate oral bioavailability in the horse and might be useful in the treatment of equine arrhythmias.

Effects of Xylo-Oligosaccharides on Broiler Chicken Performance and Microbiota.

In broiler chickens, feed additives, including prebiotics, are widely used to improve gut health and to stimulate performance. Xylo-oligosaccharides (XOS) are hydrolytic degradation products of arabinoxylans that can be fermented by the gut microbiota. In the current study, we aimed to analyze the prebiotic properties of XOS when added to the broiler diet. Administration of XOS to chickens, in addition to a wheat-rye-based diet, significantly improved the feed conversion ratio. XOS significantly increased villus length in the ileum. It also significantly increased numbers of lactobacilli in the colon and Clostridium cluster XIVa in the ceca. Moreover, the number of gene copies encoding the key bacterial enzyme for butyrate production, butyryl-coenzyme A (butyryl-CoA):acetate CoA transferase, was significantly increased in the ceca of chickens administered XOS. In this group of chickens, at the species level, Lactobacillus crispatus and Anaerostipes butyraticus were significantly increased in abundance in the colon and cecum, respectively. In vitro fermentation of XOS revealed cross-feeding between L. crispatus and A. butyraticus. Lactate, produced by L. crispatus during XOS fermentation, was utilized by the butyrate-producing Anaerostipes species. These data show the beneficial effects of XOS on broiler performance when added to the feed, which potentially can be explained by stimulation of butyrate-producing bacteria through cross-feeding of lactate and subsequent effects of butyrate on gastrointestinal function.

Enantioselective pharmacokinetics of ketoprofen in calves after intramuscular administration of a racemic mixture.

The pharmacokinetic properties of ketoprofen were determined in 4-week-old calves after intramuscular (i.m.) injection of a racemic mixture at a dose of 3 mg/kg body weight. Due to possible enantioselective disposition kinetics and chiral inversion, the plasma concentrations of the R(-) and S(+) enantiomer were quantified separately, using a stereospecific HPLC-UV assay. A distinct predominance of the S(+) enantiomer was observed, as well as significantly different pharmacokinetic parameters between R(-) and S(+) ketoprofen. More in specific, a greater value for the mean area under the plasma concentration-time curve (AUC(0→∞)) (46.92 ± 7.75 and 11.13 ± 2.18 µg·h/mL for the S(+) and R(-) enantiomer, respectively), a lower apparent clearance (Cl/F) (32.8 ± 5.7 and 139.0 ± 25.1 mL/h·kg for the S(+) and R(-) enantiomer, respectively) and a lower apparent volume of distribution (V(d)/F) (139 ± 14.7 and 496 ± 139.4 mL/kg for the S(+) and R(-) enantiomer, respectively) were calculated for the S(+) enantiomer, indicating enantioselective pharmacokinetics for ketoprofen in calves following i.m. administration.

Development and validation of an LC-MS/MS method for the toxicokinetic study of deoxynivalenol and its acetylated derivatives in chicken and pig plasma.

This study aims to develop an LC-MS/MS method allowing the determination of 3-acetyl-deoxynivalenol, 15-acetyl-deoxynivalenol, deoxynivalenol and its main in vivo metabolite, deepoxy-deoxynivalenol, in broiler chickens and pigs. These species have a high exposure to these toxins, given their mainly cereal based diet. Several sample cleanup strategies were tested and further optimized by means of fractional factorial designs. A simple and straightforward sample preparation method was developed consisting out of a deproteinisation step with acetonitrile, followed by evaporation of the supernatant and reconstitution in water. The method was single laboratory validated according to European guidelines and found to be applicable for the intended purpose, with a linear response up to 200ngml(-1) and limits of quantification of 0.1-2ngml(-1). As a proof of concept, biological samples from a broiler chicken that received either deoxynivalenol, 3- or 15-acetyl-deoxynivalenol were analyzed. Preliminary results indicate nearly complete hydrolysis of 3-acetyl-deoxynivalenol to deoxynivalenol; and to a lesser extent of 15-acetyl-deoxynivalenol to deoxynivalenol. No deepoxy-deoxynivalenol was detected in any of the plasma samples. The method will be applied to study full toxicokinetic properties of deoxynivalenol, 3-acetyl-deoxynivalenol and 15-acetyl-deoxynivalenol in broiler chickens and pigs.

Pharmacokinetics of gamithromycin after intravenous and subcutaneous administration in pigs.

The aim of this study was to investigate the pharmacokinetic properties of gamithromycin in pigs after an intravenous (i.v.) or subcutaneous (s.c.) bolus injection of 6 mg/kg body weight. The plasma concentrations of gamithromycin were determined using a validated high-performance liquid chromatography-tandem mass spectrometry method, and the pharmacokinetics were noncompartmentally analysed. Following i.v. administration, the mean area under the plasma concentration-time curve extrapolated to infinity (AUCinf) and the mean elimination half-life (t1/2λz) were 3.67 ± 0.75 µg.h/mL and 16.03 h, respectively. The volume of distribution at steady state (Vss) and the plasma clearance were 31.03 ± 6.68 L/kg and 1.69 ± 0.33 L/h.kg, respectively. The mean residence time (MRTinf) was 18.84 ± 4.94 h. Gamithromycin administered subcutaneously to pigs demonstrated a rapid and complete absorption, with a mean maximal plasma concentration (Cmax) of 0.41 ± 0.090 µg/ml at 0.63 ± 0.21 h and a high absolute bioavailability of 118%. None of the reported pharmacokinetic variables significantly differed between both administration routes.

Chronic exposure to the mycotoxin T-2 promotes oral absorption of chlortetracycline in pigs.

The aim of this study was to investigate whether T-2 toxin, a potent Fusarium mycotoxin, affects the oral absorption of the antibiotic chlortetracycline in pigs. Animals were allocated to blank feed without T-2 toxin (controls), feed containing 111 µg T-2/kg feed, T-2-contaminated feed supplemented with a yeast-derived feed additive, or blank feed supplemented solely with the feed additive, respectively. After 21 days, an intragastric bolus of chlortetracycline was given to assess potential alterations in the pharmacokinetics of this commonly used antibiotic. A significantly higher area under the plasma concentration-time curve and maximal plasma concentration of chlortetracycline was observed after intake of T-2-contaminated feed compared with control. Thus, exposure to T-2-contaminated feed can influence the oral bioavailability of chlortetracycline. This effect could have consequences for the withdrawal time of the drug and the occurrence of undesirable residues in edible tissues.

Pharmacokinetics of gamithromycin after intravenous and subcutaneous administration in broiler chickens.

Gamithromycin is a new macrolide antibiotic that is only registered for use in cattle to treat respiratory disorders such as bovine respiratory disease. The aim of this study was to determine the pharmacokinetics of gamithromycin in broiler chickens. Gamithromycin (6 mg/kg of BW) was injected intravenously (IV) or subcutaneously (SC) to six 4-wk-old chickens in a parallel study design, and blood was collected at different time points postadministration. Quantification of gamithromycin in plasma was performed using an in-house validated liquid chromatography-tandem mass spectrometry method and the pharmacokinetics analyzed according to a 2-compartmental model. Following IV administration, the mean area under the plasma concentration-time curve (AUC0→∞), and α and ß half-life of elimination (t1/2el α and t1/2el ß) were 3,998 h•ng/mL, 0.90 h, and 14.12 h, respectively. Similar values were obtained after a SC bolus injection, i.e., 4,095 h•ng/mL, 0.34 h, and 11.63 h, for AUC0→∞, t1/2el α, and t1/2el ß, respectively. The mean maximum plasma concentration (889.46 ng/mL) appeared at 0.13 h. Gamithromycin showed a large volume of distribution after IV as well as SC administration, 27.08 and 20.89 L/kg, respectively, and a total body clearance of 1.61 and 1.77 L/h•kg, respectively. The absolute bioavailability was 102.4%, showing that there is a complete absorption of gamithromycin after a SC bolus injection of 6 mg/kg of BW.

Development of a HPLC-UV method for the quantitative determination of four short-chain fatty acids and lactic acid produced by intestinal bacteria during in vitro fermentation.

A rapid and sensitive HPLC-UV method for the quantitative determination of four short-chain fatty acids (SCFAs) and lactic acid (LA) produced during in vitro fermentation is presented. Extraction of SCFAs from supernatants of bacterial cultures is aggravated due to their polarity and volatility. Detection can only be performed at a short, non-selective UV wavelength (210nm), due to the lack of any significant chromophore. Therefore special attention was paid to the optimization of the sample preparation procedure and the HPLC-UV conditions. The final extraction procedure consisted of a liquid-liquid back extraction using diethylether. Prior to HPLC-UV analysis the samples were acidified (pH<2) in order to improve retention of the SCFA's and LA on the Hypersil Gold aQ column. Matrix-matched calibration graphs were prepared for all analytes of interest (range 0.5-50mM) and correlation and goodness-of-fit coefficients were between 0.9951-0.9993 and 3.88-8.27%, respectively. Limits of detection and quantification ranged from 0.13 to 0.33mM and 0.5 to 1.0mM, respectively. The results for the within-day and between-day precision and accuracy fell within the ranges specified. The reported validated method has been successfully used for the in vitro screening of supernatants of bacterial cultures for the presence of butyric acid, aiming to select for butyric acid-producing bacteria. In addition, the method has been used to determine the production pattern of selected fatty acids by bacterial species isolated from human feces and chicken caeca.

Development of a liquid-chromatography tandem mass spectrometry and ultra-high-performance liquid chromatography high-resolution mass spectrometry method for the quantitative determination of zearalenone and its major metabolites in chicken and pig plasma.

A sensitive and specific method for the quantitative determination of zearalenone (ZEN) and its major metabolites (α-zearalenol (α-ZEL), ß-zearalenol (ß-ZEL), α-zearalanol (α-ZAL), ß-zearalanol (ß-ZAL) and zearalanone (ZAN)) in animal plasma using liquid chromatography combined with heated electrospray ionization (h-ESI) tandem mass spectrometry (LC-MS/MS) and high-resolution Orbitrap(®) mass spectrometry ((U)HPLC-HR-MS) is presented. The sample preparation was straightforward, and consisted of a deproteinization step using acetonitrile. Chromatography was performed on a Hypersil Gold column (50 mm × 2.1 mm i.d., dp: 1.9 µm, run-time: 10 min) using 0.01% acetic acid in water (A) and acetonitrile (B) as mobile phases. Both mass spectrometers were operated in the negative h-ESI mode. The method was in-house validated for all analytes: matrix-matched calibration graphs were prepared and good linearity (r≥0.99) was achieved over the concentration range tested (0.2-200 ng mL(-1)). Limits of quantification (LOQ) in plasma were between 0.2 and 5 ng mL(-1) for all compounds. Limits of detection in plasma ranged from 0.004 to 0.070 ng mL(-1). The results for the within-day and between-day precision, expressed as relative standard deviation (RSD), fell within the maximal RSD values (within-day precision: RSD(max)=2((1-0.5logConc)) x 2/3; between-day precision: RSD(max)=2((1-0.5logConc))). The accuracy fell within -50% to +20% (concentrations <1 ng mL(-1)), -30% to +10% (concentrations between 1 and 10 ng mL(-1)) or -20% to +10% (concentrations >10 ng mL(-1)) of the theoretical concentration. The method has been successfully used for the quantitative determination of ZEN in plasma samples from broiler chickens and pigs. α-ZEL and ß-ZEL were the only metabolites that could be detected, but the concentrations were around the LOQ levels. The intact ZEN-glucuronide conjugate could be detected using the (U)HPLC-HR-MS instrument. A good correlation (r(2)=0.9979) was observed between the results for ZEN obtained with the LC-MS/MS and (U)HPLC-HR-MS instruments. The results prove the usefulness of the developed method for application in the field of toxicokinetic analysis and for exposure assessment of mycotoxins.

Efficacy and safety testing of mycotoxin-detoxifying agents in broilers following the European Food Safety Authority guidelines.

Contamination of feeds with mycotoxins is a worldwide problem and mycotoxin-detoxifying agents are used to decrease their negative effect. The European Food Safety Authority recently stated guidelines and end-points for the efficacy testing of detoxifiers. Our study revealed that plasma concentrations of deoxynivalenol and deepoxy-deoxynivalenol were too low to assess efficacy of 2 commercially available mycotoxin-detoxifying agents against deoxynivalenol after 3 wk of continuous feeding of this mycotoxin at concentrations of 2.44±0.70 mg/kg of feed and 7.54±2.20 mg/kg of feed in broilers. This correlates with the poor absorption of deoxynivalenol in poultry. A safety study with 2 commercially available detoxifying agents and veterinary drugs showed innovative results with regard to the pharmacokinetics of 2 antibiotics after oral dosing in the drinking water. The plasma and kidney tissue concentrations of oxytetracycline were significantly higher in broilers receiving a biotransforming agent in the feed compared with control birds. For amoxicillin, the plasma concentrations were significantly higher for broilers receiving an adsorbing agent in comparison to birds receiving the biotransforming agent, but not to the control group. Mycotoxin-detoxifying agents can thus interact with the oral bioavailability of antibiotics depending on the antibiotic and detoxifying agent, with possible adverse effects on the health of animals and humans.

New bolus models for in vivo efficacy testing of mycotoxin-detoxifying agents in relation to EFSA guidelines, assessed using deoxynivalenol in broiler chickens.

In this study, three new models were developed for efficacy testing of mycotoxin-detoxifying agents in relation to recent European guidelines. In the first model, deoxynivalenol was given to broiler chickens as an intra-crop bolus together with a mycotoxin-detoxifying agent in order to study the plasma concentration-time profile of deoxynivalenol. In the second model, the same oral bolus was given, preceded by an oral bolus of mycotoxin-detoxifying agent, to make sure the detoxifying agent was present in the whole intestinal tract when the mycotoxin was administered. In the third model, the mycotoxin-detoxifying agent was mixed in the feed of broiler chickens, and after 1 week's feeding, deoxynivalenol was given as an oral bolus. In order to evaluate the efficacy of these agents, plasma concentration-time profiles were set up and the main toxicokinetic parameters were compared. Two commercially available mycotoxin-detoxifying agents were tested, but they were not able to lower the oral availability of deoxynivalenol. As a positive control, activated carbon was used. We showed that activated carbon significantly reduces the absorption and oral availability of deoxynivalenol in all three models. Therefore, it can be concluded that these models are able to demonstrate the efficacy of mycotoxin-detoxifying agents in relation to European Food Safety Authority guidelines.

Quantitative determination of exo- and endo-iohexol in canine and feline samples using high performance liquid chromatography with ultraviolet detection.

A sensitive and specific high performance liquid chromatography-ultraviolet detection (HPLC-UV) method for quantitative determination of exo- and endo-iohexol in cat and dog serum/plasma is presented. Sample preparation consisted of a protein precipitation step performed by adding 15 µL of trifluoroacetic acid to 100 µL of serum/plasma. Following vortexing and centrifugation, an aliquot of the supernatant was injected onto a polymeric PLRP-S column (250 mm × 4.6 mm i.d., dp: 8 µm, 100 Å), maintained at 30 °C. The mobile phase consisted of water (A) and methanol (B) and a gradient elution (flow-rate: 1.0 mL min(-1), total run-time: 21 min). The UV detector was set at a wavelength of 254 nm. Matrix-matched calibration graphs were prepared for both exo- (0.44-657 µg mL(-1)) and endo-iohexol (0.62-93.0 µg mL(-1)). Correlation and goodness-of-fit coefficients were between 0.9985-0.9999 and 4.44-9.87%, respectively. Limits of quantification and detection were 0.44 and 0.15 µg mL(-1) for exo-iohexol and 0.62 and 0.20 µg mL(-1) for endo-iohexol, respectively. Results for within-day and between-day precision and accuracy fell within the ranges specified. The reported method is simple and cost-effective. It has been successfully used for the analysis of exo- and endo-iohexol in serum/plasma samples of cats and dogs as part of pharmacokinetic studies with iohexol in order to determine plasma clearance of exo- and endo-iohexol. This indicates the usefulness of the developed method for application in the field of veterinary clinical practice and research.

Quantitative determination of T-2 toxin, HT-2 toxin, deoxynivalenol and deepoxy-deoxynivalenol in animal body fluids using LC-MS/MS detection.

A sensitive and specific method for the quantitative determination of deoxynivalenol (DON), deepoxy-deoxynivalenol (DOM-1), T-2 toxin (T-2) and HT-2 toxin (HT-2) in animal body fluids (plasma and bile) using liquid chromatography combined with electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) is presented. The extraction of plasma consisted of a deproteinization step using methanol, followed by a clean-up using an Oasis HLB solid-phase extraction column. For bile analysis, an extraction using a methanol/water mixture (70/30, v/v), followed by a liquid-liquid extraction using ethyl acetate, was performed. Chromatographic separation was achieved on a reversed-phase Nucleosil (100-5 C18 G100 × 3.0 mm) column. For the analysis of DON and DOM-1, a mixture of 0.1% acetic acid in water and methanol was used as the mobile phase. T-2 and its metabolite HT-2 were separated using 5mM ammonium acetate in a mixture of water/methanol/acetic acid. The mass spectrometer was operated in the negative or positive ESI selected reaction monitoring mode for DON and T-2 analysis, respectively. Calibration graphs (1-250 ng mL(-1)) were prepared for all matrices and correlation and goodness-of-fit coefficients were between 0.9978-1.000 and 2.96-11.77%, respectively. Limits of quantification were between 1 and 2.5 ng mL(-1) for all compounds. Limits of detection ranged from 0.01 to 0.63 ng mL(-1). The results for the within-day precision and accuracy fell within the ranges specified. The method has been successfully used for the quantitative determination of DON, DOM-1, T-2 and HT-2 in plasma and the semi-quantitative determination of the same compounds in bile from broiler chickens and pigs, respectively.

Pharmacodynamics of tepoxalin, sodium-salicylate and ketoprofen in an intravenous lipopolysaccharide inflammation model in broiler chickens.

The pharmacodynamic properties of tepoxalin, Na-salicylate and ketoprofen were determined in an intravenous lipopolysaccharide (LPS) inflammation model in broiler chickens. The drugs were administered orally at a dose of 30, 50 and 3 mg/kg, respectively. LPS administration induces an increase in the intracellular expression of interleukin (IL)-1ß and IL-6 and the secreted IL-6 plasma concentration. Furthermore, an elevation in body temperature is noted. Despite pretreatment with a single dose of the drugs and LPS administration on the T(max) of the drug after a second dose, no decrease was seen in systemic IL-6 levels. The intracellular expression of IL-1ß in the heterophils was slightly decreased if LPS was administered in combination with each of the three drugs. Tepoxalin and Na-salicylate administration had no significant effect on the LPS-induced increase in prostaglandin E(2) plasma concentration, in contrast to ketoprofen. None of the three drugs were able to influence the elevation in body temperature after LPS administration. The pharmacokinetic properties of Na-salicylate and ketoprofen were not altered in combination with LPS administration. However, LPS significantly decreased the AUC(0→6 h) of the active metabolite of tepoxalin, RWJ-20142, indicating a perfusion-limited elimination for this molecule.

Quantitative determination of amoxicillin in animal feed using liquid chromatography with tandem mass spectrometric detection.

A liquid chromatographic tandem mass spectrometric (LC-MS/MS) method for the determination of amoxicillin (AMO) in animal feed was developed and validated. The method was used to examine the quality requirements for products intended for incorporation into animal feedingstuffs (medicated premixes), as documented in the EMEA/CVMP/080/95-Final guideline. After addition of the internal standard (ampicillin), the medicated feed samples were extracted using a 0.01 M potassium dihydrogenphosphate buffer solution (pH 4.5), followed by a centrifugation and filtration step. An appropriately diluted aliquot of the extract was analysed on a PLRP-S polymeric column (150 mm x 2.1 mm i.d., 100 A) using a mixture of 0.1% formic acid in water and acetonitrile as the mobile phase. Gradient elution was performed at a flow-rate of 0.2 mL min(-1). The mass spectrometer was used in the positive electrospray ionization MS/MS mode. The LC-MS/MS method was validated for linearity, trueness, precision, limit of quantification, limit of detection and specificity. The results fell within the ranges specified. The method was used for the homogeneity and stability testing of AMO in a commercial medicated feed. Some extracts were also injected onto a LC-UV and LC-fluorescence instrument (after pre-column derivatization with a formaldehyde reagent). These experiments showed that the LC-MS/MS method was superior with regard to speed of analysis, selectivity and sensitivity.

Pharmacokinetics and oral bioavailability of sulfadiazine and trimethoprim in broiler chickens.

Sulfonamides and trimethoprim are chemotherapeutics that are extensively used in various animal species. Little information about the pharmacokinetics of these compounds in chickens exists in the literature. In this study, a new commercial formulation of sulfadiazine in combination with trimethoprim was administered both intravenously and orally, according to a crossover design, to healthy, 7-week-old broilers. The plasma concentrations of the drugs were determined by validated high-performance liquid chromatographic methods, and pharmacokinetic parameters were calculated. After intravenous or oral administration of trimethoprim (6.67 mg/kg body weight) and sulfadiazine (33.34 mg/kg body weight), both active substances were rapidly eliminated from the plasma. There was a mean half-life of 1.61 h for trimethoprim and 3.2 h for sulfadiazine. The apparent volumes of distribution (2.2 and 0.43 L/kg, respectively, indicated that the tissue distribution of trimethoprim was more extensive than that of sulfadiazine. The oral bioavailability was approximately 80% for both components.