1,720,976 research outputs found
Lack of in vitro lipolytic activity of clenbuterol metabolite produced by pig liver microsomes
No full textDetermination of tylosin residues in pig tissues using high-performance liquid chromatography
No full textIn accordance with the maximum residue limit of 100 micrograms kg-1 established by EU legislation, a simple and sensitive high-performance liquid chromatographic (HPLC) method was developed for the measurement of tylosin residues in pig tissues (fat, kidney, liver and muscle). Tylosin, a macrolide antibiotic, is extracted with water-methanol and cleaned-up by solid-phase extraction (SPE) on cation-exchange cartridges using methanol elution. Tylosin was determined by reversed-phase HPLC with UV detection at 280 nm and the mean recovery from pig tissues fortified in the range 50-200 micrograms kg-1 was 70-85%, with intra- and inter-day RSDs in the ranges 3.4-9.1 and 3.9-10.1% respectively
Contents and retentions of purine bases in turkey breast
No full textThe aim of this study was twofold: a) to quantify the content of purine bases in turkey breast roasts both raw and cooked by two methods; b) to determine and compare true and apparent retention values of these nutrients
LC-MS/MS identification of avilamycin and its in vitro metabolites by rabbit liver microsomes
No full textTissue didtribution and residue depletion of oxytetracycline in sea bream (Sparus aurata) and sea bass (Dicentrarchus labrax) after oral administration
No full textBenzydamine as a useful substrate of hepatic flavin-containing monooxygenase activity in veterinary species
No full textBenzydamine (BZ), a weak base and an indazole derivative with analgesic and antipyretic properties used in human and veterinary medicine, is metabolized in human, rat, cattle and rabbit to a wide range of metabolites. One of the main metabolites, BZ N-oxide (BZ-NO), is produced in the liver and brain by flavin-containing monooxygenases (FMOs), by liver and brain enzymes. To evaluate the suitability of BZ as an FMO probe in veterinary species, BZ metabolism was studied in vitro using liver microsomes from bovine, rabbit and swine. Kinetic parameters, K(m) and V(max), of BZ-NO production, were evaluated to corroborate the pivotal role of FMOs. Inhibition studies were carried out by heat inactivation and by specific FMO chemical inhibitors: trimethylamine and methimazole. The results confirmed the presence of FMO activity in the liver and the role of BZ as a suitable marker of FMO enzyme activities for the veterinary species considere
Relative bioavailability of microgranulated sulfamethazine in veal calves
No full textThe kinetics of free and microgranulated sulfadimidine were compared in milk-fed calves dosed orally (180 mg/kg) in a crossover study. Microgranulation results in delayed absorption of sulfadimidine and poor bioavailability, with the area under the plasma concentration-time curve (AUC(0-infinity)) reduced from 7400 to 3781 micrograms.h/mL, and maximum plasma concentration (Cmax) reduced from 188.1 +/- 39.0 to 84.41 +/- 22.6 micrograms/mL. It is concluded that sulfadimidine microgranulated with long chain fatty acids is not suitable for use in milk-fed calves; the gastrointestinal transit time is too rapid to allow full release of the drug, markedly limiting its bioavailability. In adult animals, or in the young of other animal species in which digesta transit time is slower than in calves, the bioavailability of microgranulated sulfadimidine may be much greater
In vitro metabolism of Clenbuterol and Bromobuterol using microsomes from swine liver
No full text1. Clenbuterol (CBL) and bromobuterol (BBL) were both extensively metabolized by hepatic microsomes of swine to only one polar metabolite which was separated by hplc and purified to perform mass analysis. 2. LC-MIS analysis by direct infusion into an ion trap system and after reverse-phase chromatograpy into a triple quadrupole system showed that the metabolites were the hydroxylamine-derivatives of CBL and BBL. GC-MS analysis by the CI and EI modes confirmed that the hydroxyl group was bound to the aniline nitrogen. The chemical instability of those metabolites probably as a consequence of spontaneous oxidation and reduction gave rise during the analysis to the corresponding nitroso and nitro derivatives, together with the original compound. 3. Thermal inactivation and CO complex formation were used selectively to inactivate flavin monooxygenase and cytochrome P450, respectively. Both inactivation procedures significantly reduced the formation of the hydroxyl metabolite
Relative oral bioavailability of microgranulated amoxicillin in pigs
No full textA new microgranulated formulation of amoxicillin trihydrate for in-feed medication was developed using a lipogelled matrix. Its relative bioavailability was compared with powdered drug in pigs and an assessment was made to determine whether therapeutic concentrations were achieved. Microgranules containing 10% (MICR10) and 30% (MICR30) amoxicillin and free amoxicillin trihydrate powder (reference, AMX) were administered at dosages of 50 mg of amoxicillin/kg b.w. using a three-way-crossover design. Amoxicillin analysis in serum was performed by a sensitive high performance liquid chromatography (HPLC) method with fluorometric detection, using an extraction procedure already described for edible tissues of fish and adapted and validated for pig serum. The oral bioavailability of both microgranulated formulations was higher than that of the reference formulation [relative bioavailability (F): 153.9 ± 58.2% for MICR10; 126.2 ± 70.5% for MICR30] and the area under the concentration-time curve (AUC) values of MICR10 and AMX formulations were significantly different (P < 0.05). Differences between the mean maximum concentration (Cmax), time of Cmax (tmax) and mean residence time (MRT) of the drug formulations were not significant. Microgranulated amoxicillin is suitable for in-feed administration to pigs and, because of its higher oral bioavailability compared with the powdered compound, it may be more effective for the treatment of susceptible infections
Comparative metabolism of Benzydamine in domestic animals
No full textBenzydamine is an antiinflammatiry drug used both in humans and animals. In man and in laboratory species it is largerly metabolized and two main unconiugated derivatives are described. BZY N-oxide and Nor-BZY, whose formation involves in rats flavin containing monooxigenases and cytochrome P-450 dependent mixed-function oxydases, respectively. The lack of data on BZY metabolism in domestic animals and the possibility that the drug might be used as a marker of different liver enzyme activity were the starting points of this investigation. Liver microsomes were prepared from cattle, swine, horse and laying hens (each = 4) and incubated with BZY at two different pHs (7.4 and 8.5). The analysis of BZY and its metabolites were performed by HPLC. Both the main metabolites of BZY were produced in all species
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