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Biomedical subjects

P De Backer

Publications and source records attributed to P De Backer.

At least 19 recordsLinked to original sources
PubMed2006

Determination of amiodarone and desethylamiodarone in horse plasma and urine by high-performance liquid chromatography combined with UV detection and electrospray ionization mass spectrometry.

A rapid method for the quantification of amiodarone and desethylamiodarone in animal plasma using high-performance liquid chromatography combined with UV detection (HPLC-UV) is presented. The sample preparation includes a simple deproteinisation step with acetonitrile. In addition, a sensitive method for the quantification of amiodarone and desethylamiodarone in horse plasma and urine using high-performance liquid chromatography combined with electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) is described. The sample preparation includes a solid-phase extraction (SPE) with a SCX column. Tamoxifen is used as an internal standard for both chromatographic methods. Chromatographic separation is achieved on an ODS Hypersil column using isocratic elution with 0.01% diethylamine and acetonitrile as mobile phase for the HPLC-UV method and with 0.1% formic acid and acetonitrile as mobile phase for the LC-MS/MS method. For the HPLC-UV method, good linearity was observed in the range 0-5 microg ml(-1), and in the range 0-1 microg ml(-1) for the LC-MS/MS method. The limit of quantification (LOQ) was set at 50 and 5 ng ml(-1) for the HPLC-UV method and the LC-MS/MS method, respectively. For the UV method, the limit of detection (LOD) was 15 and 10 ng ml(-1) for amiodarone and desethylamiodarone, respectively. The LODs of the LC-MS/MS method in plasma were much lower, i.e. 0.10 and 0.04 ng ml(-1) for amiodarone and desethylamiodarone, respectively. The LODs obtained for the urine samples were 0.16 and 0.09 ng ml(-1) for amiodarone and desethylamiodarone, respectively. The methods were shown to be of use in horses. The rapid HPLC-UV method was used for therapeutic drug monitoring after amiodarone treatment, while the LC-MS/MS method showed its applicability for single dose pharmacokinetic studies.

Amiodarone↗
PubMed2006

Intravenous amiodarone treatment in horses with chronic atrial fibrillation.

Six horses without underlying cardiac disease were presented because of atrial fibrillation of between 5 and 12 months duration. These horses received an intravenous amiodarone treatment of 5mg/kg/h for 1 h followed by 0.83mg/kg/h for 23h and subsequently 1.9mg/kg/h for 30h. During treatment, clinical signs were monitored and a surface ECG and an intra-atrial electrogram were recorded. Infusion was discontinued when sinus rhythm or side effects occurred. Four horses successfully cardioverted, of which one showed symptoms of hind limb weakness and weight shifting. Two horses did not cardiovert and showed similar side effects. In all horses, side effects disappeared within 6h after termination of treatment. Cardiac side effects, such as pro-arrhythmia, were not seen in any of the horses. Total bilirubin slightly increased in three horses and normalised within four days. It was concluded that amiodarone has the potential to treat naturally occurring chronic atrial fibrillation in horses, although further research is needed to refine the infusion protocol.

Amiodarone↗
PubMed2006

Pharmacokinetics of a lidocaine patch 5% in dogs.

Lidocaine is increasingly used in transdermal drug delivery systems for different pain conditions in human medicine whereby several pharmacokinetic studies have demonstrated minimal systemic absorption in men. In the present study, the pharmacokinetics of a lidocaine patch 5% was studied in six dogs. In the first experiment, one single lidocaine patch was applied for 12 h to the lateral side of the thorax after removing the hair either by clipping or by the application of a depilatory agent, according to a two-way crossover design. No potential adverse effects induced by the patches were observed in either group. In dogs with clipped hair, a mean peak plasma lidocaine concentration of 62.94 ng/ml was obtained after 10.67 h. In the depilatory group, a mean peak plasma concentration of 103.55 ng/ml was reached after 9.27 h. Significant differences in the AUC(0 --> infinity), C(max), k(a) and T(1/2a) were noticed between the two groups. No significant differences were found for the elimination parameters and for T(max). In the second experiment, the patches were applied for 60 h to the clipped skin in order to study the absorption kinetics after a prolonged application period. There, the mean peak lidocaine plasma concentration was 45.18 ng/ml achieved after 24 h and a final concentration of 29.37 ng/ml was obtained at 60 h. In conclusion, all dogs tolerated the transdermal lidocaine patch well. The results of this study suggest that there is an overall minimal absorption from the lidocaine patch. However, the application of a depilatory agent leads to a more rapid and increased absorption of lidocaine.

Administration, Cutaneous↗
PubMed2005

Sodium salicylate attenuates lipopolysaccharide (LPS)-induced adipsia, but not hypophagia, in broiler chickens.

A study was conducted to determine the influence of sodium salicylate on the behaviour and the food and water consumption of broiler chickens after lipopolysaccharide (LPS) injection. An oral dose of 100 mg/kg sodium salicylate was given and an acute phase reaction in broiler chickens was provoked through the intravenous injection of Escherichia coli LPS. Water intake was higher in the LPS and salicylate-treated group than in the positive control group. The salicylate treatment, however, did not restore the food intake, or influence the behaviour of the chickens. These data show that sodium salicylate has a positive effect on the water intake after intravenous injection of LPS in chickens and suggests that there is a difference in mechanism of action of food and water consumption after LPS injection in chickens.

Animals↗
PubMed2005

Antipyretic effect of oral sodium salicylate after an intravenous E. coli LPS injection in broiler chickens.

A study was set up to investigate the influence of sodium salicylate on fever and acute phase reaction after lipopolysaccharide (LPS) injection in broiler chickens. An acute phase reaction was provoked through the intravenous injection of Escherichia coli LPS. Four oral doses of sodium salicylate were tested. Apart from body temperature, other inflammation indices, such as plasma corticosterone and ceruloplasmin, serum thromboxane B2 and zinc concentrations were monitored. Intravenous LPS induced a fever of about 1 degree C. A dose-dependent attenuation of the fever response of the chickens in the salicylate treated groups was observed. LPS-injected chickens also showed elevated plasma corticosterone and ceruloplasmin, while serum thromboxane and zinc concentrations decreased. Except for thromboxane B2, no linear relationship with increasing salicylate dose could be shown for the other blood variables. These data confirm that sodium salicylate is an effective antipyretic agent after injection of LPS in chickens, if used at an appropriate dosage. No dose-related change could be found for the other inflammation indices.

Acute-Phase Reaction↗
PubMed2005

Pharmacokinetics and oral bioavailability of pentoxyfylline in broiler chickens.

The pharmacokinetic properties of pentoxyfylline and its metabolites were determined in healthy chickens after single intravenous and oral dosage of 100 mg/kg pentoxyfylline. Plasma concentrations of pentoxyfylline and its metabolites were determined by a validated high-performance liquid chromatographic method. After intravenous (i.v.) and oral (p.o.) administration, the plasma concentration-time curves were best described by a one-compartment open model. The mean elimination half-life (t(1/2el)) of pentoxyfylline was 1.05 h, total body clearance 1.90 L/h x kg, volume of distribution 2.40 L/kg and the mean residence time was 2.73 h, after i.v. administration. After oral dosing, mean maximal plasma concentration of pentoxyfylline was 4.01 microg/mL and the interval from p.o. administration until maximum concentration was 1.15 h. The mean oral bioavailability was found to be 28.2%. Metabolites I, IV and V were present in chicken plasma after both i.v. and p.o. administration, with metabolite V being the most dominant.

Administration, Oral↗
PubMed2004

Evaluation and establishing the performance of different screening tests for tetracycline residues in animal tissues.

Four methods intended for screening muscle tissue for residues belonging to the tetracycline group were compared using artificially contaminated as well as incurred samples. Two agar diffusion methods were studied: one with Bacillus subtilis as a test strain, the second with Bacillus cereus. Two variants of each method were compared: thin plates for analysis of intact or minced meat, and thick plates for analysis of meat fluid. The thin plate variants could not be evaluated with artificially contaminated samples because it was impossible to prepare homogeneously spiked, undiluted meat. The thick plates were suited for doxycycline and chlortetracycline, but they did not detect oxytetracycline or tetracycline in spiked meat fluid. The results of these tests done on incurred meat were very good for doxycycline and satisfying or just failing for oxytetracycline, while the best detection capability was obtained when intact frozen meat was examined on thin plates seeded with B. cereus. Two commercially available screening tests were also evaluated. The Premi(R) test, an inhibitor test with Bacillus stearothermophilus as a test strain and an indicator for growth, was not suited for detection of tetracyclines up to the maximum residue limit. Tetrasensor(R), a receptor test specific for tetracyclines, proved a quick and simple test able to detect meat samples artificially contaminated with tetracycline, oxytetracycline, doxycycline or chlortetracycline, as well as meat incurred with oxytetracycline or doxycycline.

Animals↗
PubMed2003

Comparison of a liquid chromatographic method with ultraviolet and ion-trap tandem mass spectrometric detection for the simultaneous determination of sulfadiazine and trimethoprim in plasma from dogs.

A method for the simultaneous determination of sulfadiazine and trimethoprim in plasma from Beagle dogs was developed and validated. Samples were deproteinized with acetonitrile and extracted with ethyl acetate. Sulfachloropyridazine and ormethoprim were used as internal standards for the sulfadiazine and trimethoprim analysis, respectively. The chromatography was carried out both on an LC-UV (liquid chromatography-ultraviolet detection) and ion-trap LC-MS(n) (liquid chromatography-mass spectrometric detection) instrument, operating in the positive APCI mode (atmospheric pressure chemical ionization). The purpose of this work was to compare the quantification results of both methods. Both the LC-UV and LC-MS-MS methods were validated for their linearity, accuracy, precision, limit of detection and limit of quantification, according to the requirements defined by the European Community. Calibration curves using plasma fortified between 0.1 and 1 microg/ml of sulfadiazine, 0.1 and 2 microg/ml of trimethoprim, 1 and 20 microg/ml of sulfadiazine showed a good linear correlation (r> or =0.9990, goodness-of-fit< or =8.4%). The results for the accuracy and precision at 1 microg/ml of sulfadiazine and trimethoprim and at 20 microg/ml of sulfadiazine fell within the ranges specified. The limits of quantification of both methods were 0.1 microg/ml. The limits of detection were 0.019 microg/ml of sulfadiazine and 0.024 microg/ml of trimethoprim for the LC-UV method, and 0.020 microg/ml of sulfadiazine and 0.062 microg/ml of trimethoprim for the LC-MS-MS method. The methods have been successfully applied in a pharmacokinetic study to determine the drug concentrations in plasma samples from dogs. A good correlation between the results of both methods was observed (R=0.9724, slope=1.0239, intercept=-0.2080 microg/ml for sulfadiazine and R=0.9357, slope=1.0433, intercept=0.0325 microg/ml for trimethoprim). The precision of both methods was also tested on the results of the same samples using an F-test (alpha=0.05), indicating that both methods did not differ in precision.

Animals↗
PubMed2003

Comparative pharmacokinetics of three non-steroidal anti-inflammatory drugs in five bird species.

Information on the pharmacokinetics and pharmacodynamics of anti-inflammatory drugs in birds is scarce. Choice of drug and of dosage is usually empirical, since studies of anti-inflammatory drugs are lacking. In this study, three common veterinary non-steroidal anti-inflammatory drugs (NSAIDs) were administered intravenously to five different bird species. Sodium salicylate, flunixin and meloxicam were selected as anti-inflammatory drugs. These NSAIDs were administered intravenously to chickens (Gallus gallus), ostriches (Struthio camelus), ducks (Anas platyrhynchos), turkeys (Meleagris gallopavo) and pigeons (Columba livia). Plasma concentrations of the drugs were determined by validated high-performance liquid chromatography methods and pharmacokinetic parameters were calculated. Most bird species exhibited rapid elimination of these drugs. Ostriches had the fastest elimination rate for all three NSAIDs, but there were some interesting species differences. Chickens had a half-life that was approximately 10-fold as long as the other bird species for flunixin. The half-life of chickens and pigeons was three-fold as long as the other bird species for meloxicam, and, for salicylic acid, the half-life in pigeons was at least three-five-fold longer than in the other bird species.

Animals↗
PubMed2003

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.

Administration, Oral↗
PubMed2002

Drug administration to poultry.

Drugs can be administered to birds either individually or as a flock treatment. For poultry, drinking water and feed medication are preferred, but in the case of serious disease, parenteral administration can be an alternative. For an efficient and safe therapy, data on drug pharmacodynamics and pharmacokinetics are required. Therefore, the gastrointestinal anatomy and physiology of birds, and the elimination of drugs in birds are discussed in this review. In addition, important aspects of drinking water medication, such as water quality, individual water uptake, drinking water system, lighting periods and drug formulations are discussed. Also, some requirements concerning feed medication are mentioned. Finally, parenteral and vaccine administration in the poultry industry are described.

Administration, Oral↗
PubMed2002

Determination of ivermectin B(1a) in animal plasma by liquid chromatography combined with electrospray ionization mass spectrometry.

A novel, sensitive and specific method for the quantitative determination of ivermectin B(1a) in animal plasma using liquid chromatography combined with positive electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) is presented. Abamectin was used as the internal standard. Extraction of the samples was performed with a deproteinization step using acetonitrile. Chromatographic separation was achieved on a Nucleosil ODS 5 microm column, using gradient elution with 0.2% (v/v) acetic acid in water and 0.2% (v/v) acetic acid in acetonitrile. The method was validated according to the requirements defined by the European Community. Calibration curves using plasma fortified between 1 and 100 ng ml(-1) showed a good linear correlation (r > or = 0.9989, goodness-of-fit coefficient < or =8.1%). The trueness at 2 and 25 ng ml(-1) (n = 6) was +4.2 and -17.1%, respectively. The trueness and between-run precision for the analysis of quality control samples at 25 ng ml(-1) was -4.0 and 11.0%, respectively (n = 16). The limit of quantification of the method was 1.0 ng ml(-1), for which the trueness and precision also fell within acceptable limits. Using a signal-to-noise ratio of 3 : 1, the limit of detection was calculated to be 0.2 ng ml(-1). The specificity was demonstrated with respect to ivermectin B(1b). The method was successfully used for the quantitative determination of ivermectin B(1a) in plasma samples from treated bovines, demonstrating the usefulness of the developed method for application in the field of pharmacokinetics.

Animals↗
PubMed2002

Disposition of sodium salicylate, flunixin and meloxicam after intravenous administration in broiler chickens.

Three nonsteroidal anti-inflammatory drugs (NSAIDs) [sodium salicylate, flunixin (FLU) and meloxicam (MEL)] were administered intravenously to broiler chickens. Plasma concentrations were determined by high-performance liquid chromatography methods and pharmacokinetic parameters were calculated. After intravenous administration of sodium salicylate (50 mg/kg), FLU (1.1 mg/kg) and MEL (0.5 mg/kg), these drugs were eliminated from plasma with a mean half-life of 04.04, 05.45 and 03.20 h, respectively. Apparent volumes of distribution (0.39, 0.08 and 0.12 L/kg, respectively) indicated that tissue distribution was limited for the three drugs. Total body clearance was 70 mL/h.kg for sodium salicylate and 10 and 25 mL/kg.h for FLU and MEL, respectively. Based on the pharmacokinetic parameters these NSAIDs may offer possibilities for treatment of various conditions in chickens.

Animals↗
PubMed2001

Simultaneous quantitation of ephedrines in urine by gas chromatography-nitrogen-phosphorus detection for doping control purposes.

A gas chromatographic method for the simultaneous quantitation of ephedrine, pseudoephedrine, norephedrine (phenylpropanolamine), norpseudoephedrine (cathine) and methylephedrine in urine is described. The method consists of a liquid-liquid extraction with tert.-butyl methyl ether at pH 14. The extracts are analysed on a GC system equipped with an Rtx-5 Amine column and a nitrogen-phosphorus detector. Method validation shows excellent separation, linearity, specificity, accuracy, precision, intra-laboratory repeatability and reproducibility, making the method especially suitable for quantitation of ephedrines in urine samples for doping control purposes. A statistical analysis on the abuse of the different ephedrines in urine from athletes controlled in the Flemish doping control laboratory during the period 1993-2000 is included.

Calibration↗
PubMed2001

Detection and determination of anabolic steroids in nutritional supplements.

A method is described for the determination of anabolic steroids including testosterone, 19-nor-4-androstene-3,17-dione, 4-androstene-3,17-dione and nandrolone in food supplements. Initial clean-up is done by HPLC followed by determination with GC/MS. A 'contaminated' food supplement was analysed and appeared to contain 19-nor-4-androstene-3,17-dione and 4-androstene-3,17-dione. One capsule of this nutritional supplement was ingested by five male volunteers. Urine samples were collected and analysed by GC/MS and GC/MS-MS. Neither the ratio testosterone/epitestosterone, nor the ratio androstenedione/epitestosterone increased significantly. Concentrations above 2 ng/ml for norandrosterone, the major metabolite of nandrolone, were detected until 48-144 h after ingestion of the food supplement.

Anabolic Agents↗
PubMed2001

Endogenous origin of norandrosterone in female urine: indirect evidence for the production of 19-norsteroids as by-products in the conversion from androgen to estrogen.

Recently the use of high resolution mass spectrometry or tandem mass spectrometry has enabled the detection of low amounts of anabolic steroids. As a consequence, the post-administration detection time of these drugs has been extended. Recent investigations have shown that norandrosterone, previously unequivocally regarded as evidence of nandrolone administration, might be an endogenous steroid present in small amounts in urine of humans. In this study, very low concentrations (<1 ng/ml) of norandrosterone in urine of a female athlete were detected using tandem mass spectrometry. The presence of norandrosterone was strongly correlated with high plasma 17beta-estradiol levels during the menstrual cycle. Analysis of urine samples from pregnant women supports the hypothesis of formation of precursors for urinary 19-norandrosterone during aromatization of androgens to estrogens. The detection of low urinary concentrations of norandrosterone (0.2-0.5 ng/ml) in samples after strenuous exercise could be regarded as an additional evidence for the existence of such a pathway.

Androgens↗