Correlation between tissue and plasma concentrations of oxytetracycline in veal calves

Tissue depletion and concentration correlations between edible tissues and biological fluids of 3-amino-2-oxazolidinone in pigs fed with a furazolidone-medicated feed

Furazolidone has been prohibited for use in food animal production worldwide for its carcinogenicity and mutagenicity, but it is still illegally used in some farms because of its effectiveness and cheap price. Because of the food safety and economical concerns, it is necessary to find an efficient and low-cost way to monitor the misuse of furazolidone in food-producing animals. For this regard, the tissue depletion and tissue-biological fluid concentration correlations of 3-amino-2-oxazolidinone (AOZ), which is the marker residue of furazolidone, were studied in pigs. Pigs were dosed with 400 mg/kg of furazolidone in feed for 7 days and were sacrificed at the withdrawal time of 0.5, 7, 21, 35, 56, and 63 days. Muscle, liver, kidney, urine, and plasma were collected to detect the AOZ by a simplified indirect competitive enzyme-linked immunosorbent assay (ic-ELISA). Results showed that AOZ was widely distributed in pigs and eliminated slowly after the digestion of furazolidone. The half-lives of AOZ in the plasma, urine, liver, kidney, and muscle were 13.7, 14.7, 13.6, 13.6, and 15.0 days, respectively. Good correlations of the AOZ concentration were found between plasma and muscle, plasma and liver, urine and liver, and urine and kidney in the depletion period of 7-63 or 21-63 days, with correlation coefficients of more than 0.97 and p values less than 0.05. These correlations can provide a basis for a simple and economical way using plasma/urine to monitor the illegal use of furazolidone in pigs without slaughter.

Bovine kidney tissue/biological fluid correlation for penicillin

Penicillin is one of the most commonly misused drugs in steers and dairy cows. In the US, at slaughter the tolerance is 50 ng/g in kidney and other edible tissues. If the tolerance is exceeded, the carcass may not be used for human food. A preslaughter test for penicillin in an easily accessible biological fluid is needed to predict if the concentration of penicillin is below tolerance in the kidney before the bovine is slaughtered. In this study, 12 steers were injected three times with the approved dose (7000 IU) of penicillin at 12-h intervals. Blood and urine samples were collected at intervals after the final dose of penicillin. At each sampling point, one kidney biopsy sample was collected by laparoscopic surgery in the live animal. Another kidney sample was collected at slaughter. Correlations between plasma and kidney concentrations and between urine and kidney concentrations were determined. These correlations predict with 95% confidence that 99% of the animals will have kidney tissue below penicillin tolerance when the plasma concentration of penicillin is below 0.4 ng/mL and/or the urine penicillin concentration is below 140 ng/mL.

Serum pharmacokinetics of oxytetracycline in sheep and calves and tissue residues in sheep following a single intramuscular injection of a long-acting preparation

The pharmacokinetics of a long-acting oxytetracycline (OTC) formulation (Liquamycin LA-200) injected intramuscularly (i.m.) at a dose of 20 mg/kg were determined in four calves and 24 sheep to determine if the approved label dose for cattle provided a similar serum time/concentration profile in sheep. The AUC for the calves was 168+/-14.6 (microg ? h/mL) and was significantly less than the AUC for sheep (209+/-43 microg ? h/mL). Using the standard two-stage approach and a one-compartment model, the mean Cmax for the calves was 5.2+/-0.8 microg /mL, and for the sheep was 6.1+/-1.3 microg /mL. The mean terminal phase rate constants were 0.031 and 0.033 h, and the Vdss were 3.3 and 3.08 L/kg for the calves and sheep respectively. Analysis of the data using the standard two-stage approach, the naive pooled-data approach and a population model gave very similar results for both the cattle and sheep data. Sheep tissue residues of OTC in serum, liver, kidney, fat, muscle and injection site were measured at 1, 2, 3, 5, 7 and 14 days after a single i.m. injection of 20 mg/kg OTC. Half-lives of OTC residues in the tissues were 38.6, 33.4, 28.6, 25.4, 21.3, and 19.9 h for injection site, kidney, muscle, liver, mesenteric fat and renal fat, respectively. The ratio of tissue to serum concentration was fairly consistent at all slaughter times, except for the fat and injection sites. The mean ratios were 1.72, 4.19, 0.11, 0.061, 0.84 and 827 for the liver, kidney, renal fat, mesenteric fat, muscle and injection sites, respectively. The tissue concentrations of OTC residues were below the established cattle tolerances for OTC in liver (6 p.p.m.), muscle (2 p.p.m.) and kidney (12 p.p.m.) by 48 h, and in injection site muscle by 14 days after the single i.m. injection of 20 mg/kg.

Plasma concentrations and tissue residues of bicozamycin given orally to pigs

Bicozamycin was dissolved in water and administered to pigs by stomach tube at 40 mg/kg once daily for 7 consecutive days. The plasma concentration was determined on days 1 and 7 of the dosing period. The mean (+/- SD) peak plasma concentrations were 2.06 +/- 0.36 micrograms/ml at 3.08 +/- 0.80 h on day 1 and 2.36 +/- 1.32 micrograms/ml at 2.80 +/- 0.74 h on day 7, the elimination half-lives being 3.80 +/- 0.92 h and 2.43 +/- 1.41 h, respectively. The mean areas under the plasma concentration-time curves were 15.88 +/- 2.18 (micrograms h)/ml on day 1 and 12.31 +/- 6.98 (micrograms h)/ml on day 7. These pharmacokinetic parameters did not differ between days 1 and 7, suggesting that there was no accumulation in the plasma after consecutive oral dosing. The residues in kidney, liver and muscle were examined in pigs slaughtered on days 1, 3 and 5 after the last dosing. One day after withdrawal, residues were found in the kidneys of all three pigs examined, at a mean concentration of 0.26 microgram/g, and in muscle from one pig, but not in liver from any of the pigs. Bicozamycin was not detected in any of the samples taken 3 or 5 days after withdrawal.