Elimination of oxolinic acid in eggs after oral treatment of laying hens

Pharmacokinetics of veterinary drugs in laying hens and residues in eggs: a review of the literature

Poultry treated with pharmaceutical products can produce eggs contaminated with drug residues. Such residues could pose a risk to consumer health. The following is a review of the information available in the literature regarding drug pharmacokinetics in laying hens, and the deposition of drugs into eggs of poultry species, primarily chickens. The available data suggest that, when administered to laying hens, a wide variety of drugs leave detectable residues in eggs laid days to weeks after the cessation of treatment.

Study of enrofloxacin and flumequine residues depletion in eggs of laying hens after oral administration

Two groups of laying hens (each n=12) were administered 10 mg/kg enrofloxacin (ENRO) (group A) or 26.6 mg/kg flumequine (FLU) (group B) by gastric catheter daily for five consecutive days. A third group (n=6) was untreated controls. Eggs were collected from day one of treatment and up to 30 days after withdrawal of the drug. Egg white and yolk from each egg were separated, and ENRO, its metabolite ciprofloxacin (CIP) and FLU residues were analysed by a high-performance liquid chromatography method with fluorescence detection. The sum of ENRO and CIP was detectable in egg white on the first day of treatment in high-level concentrations (2007.7 μg/kg) and remained steady during administration. In egg yolk, residues were detectable at day one in lower concentrations (324.4 μg/kg), increasing to the end of treatment. After treatment, these residues decreased and were detectable up to day 8 in egg white, and day 10 in yolk. FLU residues during drug administration in white were detectable in high concentrations from day one to five (6788.4-6525.9 μg/kg), and in yolk, concentrations were lower during administration (629.6-853.9 μg/kg). After drug withdrawal, FLU residues remained longer in egg white (30 days) than in yolk (26 days). For both drugs, differences of concentrations between matrices were significant.

Study of enrofloxacin depletion in the eggs of laying hens using diphasic dialysis extraction/purification and determinative HPLC-MS analysis

A study of the depletion of enrofloxacin residues in eggs was carried out using a diphasic dialysis procedure for the extraction of fluoroquinolone residues from the matrix. Enrofloxacin was administered to laying hens through the intramuscular route (15 mg/day) and orally (12 mg/day). After daily collection, the egg albumen and the egg yolk were separated, and the residue levels were determined using an HPLC-MS (API-ESI) method. The enrofloxacin and ciprofloxacin peaks gradually increased until the fifth day, because the drug was employed for 5 days. However, differences were observed in the depletion curves of enrofloxacin and its metabolite when both parts of the egg and the mode of administration were considered.

Sulphonamide residues in eggs following drug administration via the drinking water

The aim was to determine concentrations of sulphadimidine (SDM) and sulphadimethoxine (SDT) in eggs following oral administration through drinking water for 5 days (0.5 g l(-1) for SDT, 1 and 2 g l(-1) for SDM). Residues of sulphonamides in albumen and yolk were monitored by high-performance liquid chromatography with UV detection. The limit of quantification was 0.005 microg g(-1) for the two egg components. The results indicate that 0.9-1.4% of the dose administered was deposited in eggs. Maximum concentrations in albumen were much higher than those in yolk. More than 75% of the overall sulphonamides detected in eggs was concentrated in the albumen. The residue levels declined below the limit of quantification within 12-20 days for albumen and 14-15 days for yolk after treatment was discontinued.

Analysis of quinolone residues in edible animal products

A comprehensive review on the analysis of quinolone antibacterials is presented. The review covers most of the methods described for the determination of quinolone residues in edible animal products. Sample handling, chromatographic conditions and detection methods have been discussed. A summary of the most relevant information about the analytical procedures has been included.

Residues of veterinary drugs in eggs and their distribution between yolk and white

Veterinary drugs and feed additives (especially some coccidiostats) can be absorbed by the digestive tract of laying hens and transferred to the egg. Physicochemical characteristics of these compounds determine their pharmacokinetic behavior and distribution to and within the egg. Traditionally the quite lipid soluble drugs and additives are expected to yield residues only in the fat-rich yolk. However, the quite lipid soluble drug doxycycline--as well as many other drugs--showed during long-term administration higher residues in white than in yolk. In a model study with 11 sulfonamides differing in pK(a) value and lipid solubility, their distribution in vivo between yolk and white was determined. Neither differences in pK(a) values nor those in lipid solubility could explain the distributions found. Binding to egg white macromolecules in vivo as an explanatory factor was tested with five sulfonamides, and no correlation between binding and the distribution of sulfonamides between white and yolk was found. Literature data on the distribution of drugs between egg white and yolk showed a reasonable consistency within drugs and a large variability among drugs (as could be expected). This larger database also did not provide a clue as to what factor determines the distribution of a drug between egg white and yolk when given to laying hens.

Food safety implication: certain antibiotics may rapidly contaminate egg albumen during the process of its formation

1. Egg white formation occurs in 3 phases: synthesis and storage of albumen proteins prior to ovulation, secretion of proteins during passage of the ovum down the reproductive tract (preplumping) and addition of water (plumping phase). 2. This study was to determine if oxytetracycline would transfer into egg albumen during the latter 2 phases of albumen formation. 3. In 2 experiments 48 hens were injected with either 400 mg/kg oxytetracycline or physiological saline. Hens were dosed at 0.5 h (preplumping phase) or 5.5 h (plumping phase) after oviposition. 4. Five hours following injections, hens were euthanised and albumen was collected from the reproductive tract. 5. Oxytetracycline transferred into albumen during both phases of albumen formation. Concentrations (ppm) were greater in the preplump vs plump phase (3.2 vs 1.8 in experiment 1; or 2.8 vs 1.6 in experiment 2. However, when differences in albumen weights were accounted for, total microg transfer did not differ between the 2 phases. 6. Drugs may transfer into egg whites during the latter phases of formation prior to oviposition. Therefore, poultry producers or veterinary practitioners dosing laying hens must consider that egg whites contained in the 1st egg laid after dosing may contain drug residues.