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At least 19 recordsLinked to original sources
PubMed1997

Modeling drug residue uptake by eggs: yolks contain ampicillin residues even after drug withdrawal and nondetectability in the plasma.

The present study was conducted to determine whether: 1) preovulatory yolks may be an important storage depot for drug residues in eggs laid days to weeks after drug withdrawal; and 2) the prediction model based on the pattern of drug incorporation in developing yolks is predictive of the pattern of residues contained in the sequence of eggs laid during and after drug withdrawal. To test these possibilities, 24 hens were dosed for either 1, 2, or 3 d with ampicillin, and the content and pattern of residues in laid eggs were evaluated during and after dosing. Hens were bled 24 h after the final dosing, and plasma ampicillin concentrations were determined. Ampicillin was used in this study because it has an extremely short plasma halflife in laying hens that limits additional drug transfer after drug withdrawal. Ampicillin concentrations were not detectable in plasma from hens injected with ampicillin for either 1, 2 or 3 d (assay sensitivity of 0.6 ng/ml or 0.6 ppb). Hens from all three injection groups produced eggs containing detectable ampicillin residues for 6 d after the last injection. These data demonstrate that drug residues are contained in eggs laid a number of days after drug withdrawal. Because plasma ampicillin was not detectable even 24 h after final dosing, the majority, if not all, of the incurred ampicillin residues contained in eggs laid after drug withdrawal were due to incorporation and storage of drug in preovulatory yolks during the dosing period. Additionally, accounting for ampicillin's stability, our model is predictive of the pattern of residues contained in eggs. These data emphasize the importance of transfer and storage of drugs in preovulatory yolks as a significant contributing mechanism for the production of incurred drug residues in eggs.

Ampicillin↗
PubMed1978

Regulatory agency interaction in the control of drug residues in animal tissue.

The U.S. Department of Agriculture has the responsibility of determining if a method for residues of drugs and pesticides in animal tissues is acceptable for regulatory control, reviewing data on interfering compounds, validating methods, monitoring drug residues in animal and poultry tissues, assigning priority for monitoring drugs and pesticide residues. These responsibilities are carried out in cooperation with the U.S. Food and Drug Administration in the areas of method development, determination of priorities, and punitive action.

Animals↗
PubMed1996

Modeling residue uptake by eggs. 1. Similar drug residue patterns in developing yolks following injection with ampicillin or oxytetracycline.

This study was conducted to model the pattern of antibiotic drug uptake within yolks of developing follicles. In two separate experiments, 16 hens were divided into equal groups (n = 8) and injected only once with either 400 mg/kg ampicillin or 200 mg/kg oxytetracycline (OTC: total hens = 32) approximately 1 h after oviposition. Twenty-four hours following injections, hens were euthanatized and the ovaries were collected. Yolks were dissected free from the individual follicles with a blunt probe. Individual large yellow yolks (> or = 0.2 g) and a pool of 5 small yellow yolks (< 0.2 g) were collected for determination of ampicillin or OTC content. Samples were prepared and assayed using an agar diffusion microbiological method. Selected parameters were not different (P > 0.05) between Experiments 1 and 2 and the data were combined. Results indicate that short-term exposure in hens produced incorporation of drug residues in developing yolks in a specific pattern that does not appear to be drug dependent (P > 0.05). These incurred residues are contained in developing yolks that are days to weeks from being ovulated. Drug residues were greater (total microgram content) in some of the less mature yolks vs the largest preovulatory yolk. This may lead to a sequential release of eggs with increasing residue content, even after drug withdrawal. These data were used to construct a model to predict the pattern of incurred residues in formed eggs following a hen's exposure to drugs or other contaminants.

Ampicillin↗
PubMed1997

Public health impact on drug residues in animal tissues.

Consumers have expressed concern regarding the health impact of drug residues in their food. Animal residues in animal tissues above the legal tolerance clearly have an impact on human health. Tolerances represent the maximal level or concentration of antimicrobial residues permitted in animal tissues at the time of slaughter. The tolerances are intended to ensure that residual drugs will have no harmful effects if ingested. This paper describes the existing evidence for specific health hazards for certain pharmacological classes of drugs and explains the risks associated with drug residues in meat and poultry above the established tolerance. The primary focus is on possible public health consequences that may occur as a result of acute exposure to illegal residues. In addition, long-term effects are discussed with added comments about the effect of residues on the intestinal flora. Most residues of veterinary drugs occur in food at such low levels that they rarely pose a chronic or long-term health hazard to consumers. The importance of food safety through the reduction of residues in our food supply cannot be overemphasized. Food safety remains a major challenge confronting contemporary society.

Animals↗
PubMed1986

Codex committee on veterinary drug residues.

There has been widespread international concern over residues of veterinary drugs in food. However, until recently, there was little international cooperation in trying to find solutions to the problem. Many nations have taken steps to control the increased use of veterinary drugs, but the rules governing their use vary widely from country to country. Sharing of scientific expertise and other resources between countries would markedly improve this situation. With the need for international cooperation mounting, concerned drug regulators from 20 countries met in 1982 and again in 1984 to discuss international use of veterinary drugs. The group repeatedly called for a Codex committee on veterinary drug residues. At its 1983 meeting in Rome the Codex Alimentarius Commission convened an Expert Consultation to consider the need for a new committee. That international group of experts strongly agreed that a standing committee under the sponsorship of the commission should be established. In July of 1985, the commission unanimously voted to establish a new Committee on Residues of Veterinary Drugs in Food. The United States was chosen as host country. The committee will work closely with several existing Codex committees, but it has a clear mandate of its own. Its responsibilities will include establishing a list of priority drugs for review, recommending maximum residue levels, developing codes of practice, and reviewing analytical methods used to control veterinary drug residues. This fall, a new Codex committee has met for the first time--the Codex Committee on Residues of Veterinary Drugs in Food.(ABSTRACT TRUNCATED AT 250 WORDS)

Agriculture↗
PubMed1980

Safety assessment of drug residues.

The safety assessment of drug residues is part of the process for defining the conditions for the safe use of drugs in food-producing animals. The information needed to assess the safety of drug residues is provided by chemical and toxicity tests. Toxicity tests are conducted to identify the type of effect produced and to determine the exposure concentrations that would be expected not to produce the effect. These tests include acute, subacute, and chronic toxicity tests, as well as reproduction studies and other special tests. The results are used to find an acceptable daily intake for drug residues that can be used to set a tolerance.

Animals↗
PubMed1979

A study of drug residues in milk following intrauterine infusion of antibacterial drugs in lactating cows.

Intrauterine infusion of nine antibacterial compounds caused detectable drug residues in 17 out of 165 cows or in 25 out of 1110 posttreatment milkings. Four cows treated with pyrolidinomethyl tetracycline suspension had drug residues at the first milking. One cow had residues after oxytetracycline treatment, two after procaine penicillin G, three after acriflavin and after chloramphenicol-dapsone and four after hibitane. Nitrofurazone, nitrofurathiazide and Hibitane Compound(R) did not cause detectable inhibitory residues in any milk sample.

Animals↗
PubMed1999

The national milk safety program and drug residues in milk.

There are a number of factors that must be considered in any attempt to control animal drug residues in milk and milk products. Dairy herds vary greatly in number of cows. Milk from individual cows and farms is pooled, diluting drug residues that may be present in the milk from a single treated cow. Management techniques, including the handling, administration, and record keeping of animal drugs, vary greatly from one dairy to another. It is important that both veterinarians and nonveterinarians adhere to adequate milk discard times for animal drugs used to treat dairy animals. Observance of appropriate safeguards at the farm level, such as record keeping and clearly identifying treated animals, is critical for controlling and preventing the presence of illegal animal drug residues. Within the framework of the Federal Food, Drug, and Cosmetic Act and the Public Health Service Act, the FDA is working with state and other regulatory agencies and industry to better ensure the absence of illegal animal drug residues in milk and milk products. Preventive measures concentrate on minimizing the need to administer animal drugs to lactating cows, and diverting milk containing drug residues from the human food supply. Monitoring programs concentrate on screening milk and tracing violations to the individual producer. Minimizing illegal drug residues in milk and milk products requires close cooperation between farmers, veterinarians, the dairy industry, the pharmaceutical industry, and regulators.

Animals↗
PubMed1997

Problems associated with drug residues in beef from feeds and therapy.

Drug residues in beef have been reported internationally. These include antimicrobials, anti-inflammatories, growth promotants, parasiticides and insecticides. The main factors associated with residues are animal age and use, and failure to observe withdrawal time for regular or extra-label use. Public health concerns include toxic and anaphylactic reactions, and development of drug-resistant strains of bacteria. The maximum residue level (MRL) is the current standard for residues in food adopted by the Codex Committees of the Food and Agriculture Organisation and World Health Organisation, but is not universally accepted or standardised. Detection of residues at slaughter is a critical point in residue control. Several live animal tests are available, but these vary in reliability and usage. After slaughter, tissues sampled and tests used are more uniform. To prevent international trade barriers associated with drug residues in beef, the following conditions should be implemented: standardisation of testing methods used to detect drug residues; standardisation of methods for determining MRLs; establishment of active surveillance programmes to monitor residues.

Age Factors↗
PubMed2005

False-positive outcome and drug residue in milk samples over withdrawal times.

This study was conducted to identify false-positive outcomes and drug residues in milk samples over withdrawal times and to determine whether the positive results were caused by drug residues or natural inhibitors. A total of 73 milk samples over withdrawal times after the last intramammary infusion were collected from each treated quarter of cows and tested using the Delvotest SP assay. Reading time was 150, 165, and 180 min, and results of samples were recorded according to the color of the well containing the control milk sample. There were 24, 20, and 12 positive samples at the reading times of 150, 165, and 180 min, respectively. All 24 positive milk samples were heated at 82 degrees C for 5 min and retested to verify that the positive results were caused by drug residues or natural inhibitors. Twenty-one samples that exhibited positive results were negative after heat treatment, and drug residues were not identified by LacTek and Charm tests. However, 3 samples that exhibited positive results from heat treatment of 82 degrees C were positive for drugs. In our study, most positive results (89%) in the milk samples over withdrawal times were false-positive results by natural inhibitors. Moreover, the heat treatment is a fast, simple, and inexpensive method to remove false-positive results and has no effect on positive samples containing drugs. We suggest that heat treatment before screening tests is an effective way to reduce false-positive results in the milk samples.

Animals↗
PubMed1996

Drug residue considerations for anesthetics and adjunctive drugs in food-producing animals.

This article is a summary of residue concerns for anesthetics and anesthetic adjuncts used in food animals. The risks associated with residues of these drugs in food-producing animals, as well as the veterinarian's responsibility to reduce this risk, are discussed. The potential for residues and suggestions for prevention in each of the major anesthetic drug classes are described. Suggested withdrawal times are proposed for nonapproved drugs used off label. Each class of drug is summarized in the tables.

Adjuvants, Anesthesia↗
PubMed1992

Milk antimicrobial drug residue assay results in cattle with experimental, endotoxin-induced mastitis.

Antimicrobial drug residue testing was performed on milk samples obtained from 8 cows with experimental endotoxin-induced mastitis, using 4 commercially available assay kits. Although none of the cows in the study received antimicrobials, only 1 of the 4 assay procedures, assay C, had consistently negative results (specificity = 1.00). The proportion of positive assay results varied from 0 to 1.00 among combinations of sampling time, sample status (endotoxin-infused quarter vs composite noninfused sample). The proportion of positive results found when assay C was used (0) differed significantly from the proportion found when the 3 other assays were used. The proportion of positive results did not differ significantly between assay A (0.45) and assay B (0.48); however, both assays had a significantly lower proportion of positive assays than did assay D (0.86). Logistic regression models were developed predicting positive milk antimicrobial drug residue assay results as a function of assay kit, sample status, and time interval following experimental challenge exposure. Using assay A as a baseline risk, assay B and assay D were more likely to have positive assay results, and assay C had a decreased risk of positive assay results. Milk samples from endotoxin-infused quarters were at increased risk for positive assay results, compared with noninfused composite samples. Samples collected from endotoxin-infused quarters or control quarters were at increased risk for positive assay results following the intramammary infusion of endotoxin. Our findings suggest that specificity of milk antimicrobial drug residue assays varies greatly among assay kits and that intramammary inflammation may increase the proportion of false-positive assay results.

Animals↗
PubMed1984

[Veterinary drug residues in food].

When veterinary drug residues are constantly present in sufficient amounts, they may give rise to toxicological, clinical and allergenic effects, and resistance may occur. Dreaded effects are those which are carcinogenic and allergenic in character, and the appearance of resistance. Antibiotics and 'bacterial' chemotherapeutic agents constitute the most important group as regards these effects.

Animals↗
PubMed1980

[Pharmacokinetic model studies of sulfamerazine in domestic mammals. 6. Absence of drug residues].

The problem of no residues is elucidated and discussed under pharmacokinetic aspects. An equation with due consideration confidence by which to calculate the absence of residues in drugs is given under the assumption that elimination of such residues should follow the concepts of the monocompartment model. The time is calculated by which all residues of sulphamerazine have disappeared, following application of Mebacid 200 and Mebacid tablets to farm animals.

Animals↗
PubMedDate not supplied

A strategy for the assessment of the carcinogenic potency of veterinary drug residues: recommendations of the FDA.

The United States Food and Drug Administration's assessment strategy for the determination of the carcinogenic potential of drug residues in food-producing animals is embodied in its Human Food Safety Policy. This policy calls for the utilization of a threshold-assessment procedure to determine whether a veterinary drug possesses carcinogenic potential. Chronic lifetime studies in rodents must be performed if it is deemed that the agent may possess carcinogenic properties. A virtually safe level (VSL) of exposure for man is established by applying a modified statistical linear-extrapolation model to the carcinogenic dose-response relationship seen in the test-animal studies. Identification of the major metabolites in the total drug residue in the target animals is required, and the same process applied to the parent drug may be applied to the metabolites. If a carcinogenic metabolite is found in the edible tissue which is significantly more potent and/or more persistent than the parent drug, the VSL is established for the metabolite rather than for the parent compound. A rigorous identification of metabolites is required, which is followed by the development of analytical methodology to ensure that carcinogenic residues in tissue are below the VSL.

Animals↗
PubMed2000

Evaluation of certain veterinary drug residues in food.

This report presents the conclusions of a Joint FAO/WHO Expert Committee convened to evaluate the safety of residues of certain veterinary drugs and to recommend maximum levels for such residues. The first part of the report considers an approach to assessing the safety of antimicrobial drug residues and their effects on the human intestinal microflora and general issues relating to the recommendation of Maximum Residue Levels (MRLs) for veterinary drug residues in food. A summary follows of the Committee's evaluations of toxicological and residue data on a variety of veterinary drugs: one beta-adrenoceptor-blocking agent (carazolol), one anthelminthic agent (doramectin), four antimicrobial agents (dihydrostreptomycin, streptomycin, neomycin and thiamphenicol), two insecticides (deltamethrin and phoxim), four production aids (estradiol-17 beta, progesterone, testosterone and porcine somatotropins) and one tranquillizing agent (azaperone). Annexed to the report are a summary of the Committee's recommendations on these drugs, including Acceptable Daily Intakes and MRLs, and other information required.

Adrenergic beta-Antagonists↗
PubMed2004

Norepinephrine transporter function and desipramine: residual drug effects versus short-term regulation.

Previous research has shown that exposure of norepinephrine transporter (NET)-expressing cells to desipramine (DMI) downregulates the norepinephrine transporter, although changes in the several transporter parameters do not demonstrate the same time course. Exposures to desipramine for <1 day reduces only radioligand binding and uptake capacity while transporter-immunoreactivity is unaffected. Recent demonstration of persistent drug retention in cells following desipramine exposures raises the possibility that previous reported changes in the norepinephrine transporter may be partly accountable by residual drug. In this study, potential effects of residual desipramine on norepinephrine transporter binding and uptake were re-evaluated following exposures of PC12 cells to desipramine using different methods to remove residual drug. Using a method that minimizes residual drug, exposure of intact PC12 cells to desipramine for 4h had no effect on uptake capacity or [(3)H]nisoxetine binding to the norepinephrine transporter, while exposures for > or =16 h reduced uptake capacity. Desipramine-induced reductions in binding to the transporter required >24 h or greater periods of desipramine exposure. This study confirms that uptake capacity of the norepinephrine transporter is reduced earlier than changes in radioligand binding, but with a different time course than originally shown. Special pre-incubation procedures are required to abolish effects of residual transporter inhibitor when studying inhibitor-induced transporter regulation.

Adaptation, Physiological↗