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1.
Differences in bioavailability of many drugs from their various dosage forms have been shown to be relatively common in human medicine. Although comparable bioavailability ('bioequivalence') is though to ensure comparable clinical effectiveness and safety ('therapeutic equivalence'), the relationship between bioinequivalence and therapeutic inequivalence is less clear. Thus the prevalence of clinically important differences in bioavailability is unknown. While similar concerns have arisen about drug products used in small animal practice, there have been few investigations and some earlier reports are incomplete. However, there are indications of bioinequivalence with enteral formulations of ampicillin, aspirin, chloramphenicol, digoxin, mitotane, oxytetracycline, penicillin V and theophylline. Other studies have suggested bioequivalence with enteral formulations of chloramphenicol, digoxin, phenytoin, oxytetracycline and thyroxine. Limited data for injectable preparations showed bioinequivalence with chloramphenicol and possibly oxytetracycline. There is no reason to expect formulation-related bioinequivalence to be less prevalent in veterinary than in human medicine. Indeed, it may be more common in veterinary practice because other potential influences on bioavailability (food, diseases, other drugs, etc.) are frequently ignored, and cheaper generic products are often favoured for economic reasons.  相似文献   

2.
Milk from dairy farms in England and Wales has been tested regularly for antibiotic residues since 1965. The sensitivity of the test organism was 0.02 iu/ml penicillin or equivalent until the change to 0.01 iu/ml in January 1986. In 1984-85, 99.6 per cent of the 2,000,000 milk samples tested passed the test and there was an average of 695 failures per month. From 7500 on-farm investigations over the two years 1983-85 the most frequent reasons suggested by farmers for their test failures were not withholding milk for the full withdrawal period (19.3 to 16.5 per cent) and accidental transfer of milk (16.3 to 16.7 per cent). Lactating and dry cow intramammary antibiotic preparations were held responsible for rather over 50 per cent and 25 per cent respectively of the failures in both years.  相似文献   

3.
This study examined characteristics of the use of drugs, especially antimicrobials, on Ontario sheep farms. Forty-nine sheep farms participated in a 12-month prospective study. Producers documented treatment events during the study period and drug use data from the records were summarized. The most frequently used drugs of the 15 drug categories used by producers belonged to the following categories: antimicrobial (40.7%, n=2710), vitamin/mineral (12.0%), and biological (11.1%). Short-acting penicillin (27.2%, n=1103), long-acting oxytetracycline (22.9%), and long-acting penicillin (21.9%) were the most frequently used antimicrobials. The drugs that were used most frequently on sheep farms were antimicrobials, of which 93% of treatments were extra-label. Extensive extra-label drug use may be the result of the limited number of drugs that are approved in Canada for use in sheep.  相似文献   

4.
Penicillin G is widely used in food‐producing animals at extralabel doses and is one of the most frequently identified violative drug residues in animal‐derived food products. In this study, the plasma pharmacokinetics and tissue residue depletion of penicillin G in heavy sows after repeated intramuscular administrations at label (6.5 mg/kg) and 5 × label (32.5 mg/kg) doses were determined. Plasma, urine, and environmental samples were tested as potential antemortem markers for penicillin G residues. The collected new data and other available data from the literature were used to develop a population physiologically based pharmacokinetic (PBPK) model for penicillin G in heavy sows. The results showed that antemortem testing of urine provided potential correlation with tissue residue levels. Based on the United States Department of Agriculture Food Safety and Inspection Service action limit of 25 ng/g, the model estimated a withdrawal interval of 38 days for penicillin G in heavy sows after 3 repeated intramuscular injections at 5 × label dose. This study improves our understanding of penicillin G pharmacokinetics and tissue residue depletion in heavy sows and provides a tool to predict proper withdrawal intervals after extralabel use of penicillin G in heavy sows, thereby helping safety assessment of sow‐derived meat products.  相似文献   

5.
The occurrence of pesticide residues was studied in samples of feed-stuffs produced in Sweden or imported to Sweden during the years 1972--1976. In all, 278 samples representing 37 types of feed-stuffs (components, as well as finished feeds) and 18 countries were analyzed. Residues of chlorinated hydrocarbon pesticides and PCBs were looked for in 224 samples, mostly feed components. The analytical method used involved solvent extraction, florisil-column clean-up, thinlayer chromatographic separation and gas-chromatographic determination. Chlorinated hydrocarbons were found in several samples. DDT and its transformation products were detected in 66 samples (29.5%), lindane in 44 (19.5%), PCBs in 25 (11.2%), alpha-BHC in 22 (9.8%), beta-BHC in 11 (4.9%) and dieldrin in 9 (4.0%). The levels were usually low (Table I). The chloropesticides occurred most frequently and at the highest levels in feed-stuffs of animal origin and in imported oil-feeds. In 25 of the samples the contents of sigmaDDT exceeded the maximum limit accepted by the National (Swedish) Food Administration for grain and bran intended for human consumption (0.05 mg/kg, Talbe IV). The highest residue level of sigmaDDT (0.66 mg/kg) was encountered in a sample of fish meal. The PCB levels found did not exceed the temporary tolerance established by FDA (1973) for finished animal feeds (0.2 mg/kg). One hundred and seven samples were analyzed for phenoxy acid residues using a thin-layer chromatographic and gas-chromatographic technique. Phenoxy acids were detected in only 2 of 62 randomly selected feed samples (0.05 and 0.2 mg/kg, respectively). The residue limit established by the National Food Administration for 2,4-D and MCPA in grain and bran intended for human consumption is 0.1 mg/kg. Fortyfour samples of feeds were submitted because of suspected phenoxy acid contamination. In 12 of the samples phenoxy acid residues were found. The highest level (3.5 mg/kg, MCPA) was observed in a sample of accidentally contaminated molasses. Considering the apparently low level of contamination of Swedish grain with chloropesticides, PCBs and phenoxy acids and the dilution on compounding feed-stuffs of animal origin and oil-feeds, only very low pesticide residue levels can be expected in Swedish finished animal feeds.  相似文献   

6.
Residue persistence in sheep milk following antibiotic therapy   总被引：2，自引：0，他引：2  
Drug residues in milk supplies may have public health implications and can interfere in the manufacture of dairy products, such as cheese. In Spain, most ewe milk production is destined for cheese making, often using raw milk. This study analyses the main factors influencing antibiotic depletion time in lactating dairy sheep. 42, Manchega ewes were distributed into three groups, each receiving a different treatment (cephalexin intramammary infusion, penicillin G intramuscular, and oxytetracycline intravenous injections). During and after the recommended withdrawal period, milk samples were taken at each milking. A microbiological inhibition test (Brilliant Black Reduction, BRT) was used to screen all samples and antibiotic withholding times were established using a logistic regression model. The response to the BRT method in milk from individual ewes treated showed that the effect of the milking order was significant (P<0.001) with the three antibiotics. However the only influence on milk yield was with the intramammary treatment (P<0.005). The BRT method was found to be very sensitive, particularly to the two beta-lactamic antibiotics.  相似文献   

7.
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® did not cause detectable inhibitory residues in any milk sample.  相似文献   

8.
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.  相似文献   

9.
Penetration of penicillin G, dihydrostreptomycin, oxytetracycline, and chloramphenicol into interstitial fluid of calves was estimated using subcutaneously implanted, multiple perforated spherical polypropylene capsules as a model. Antibiotic concentrations were determined in simultaneously withdrawn serum and capsular fluid (CF) samples at intervals after single and multiple intramuscular injections of antibiotics at recommended dose schedules. Peak concentrations of penicillin G in CF were 57% of those in serum, and the drug was eliminated from CF at a slower rate than from serum. Dihydrostreptomycin diffused into CF to a limited degree and was eliminated from CF much more slowly than from serum leading to gradual drug accumulation in CF upon repeated dosing. Multiple injections of oxytetracycline resulted in CF drug levels comparable with those in serum. Concentrations of chloramphenicol in CF were generally similar to free (non-protein bound) serum drug levels. CF concentrations of penicillin G were within the range of the minimal inhibitory concentrations of the drug for pathogenic gram positive micro-organisms and CF levels of dihydrostreptomycin, oxytetracycline, and chloramphenicol were apparently sufficient to inhibit the majority of gram negative pathogens involved in bovine injections. Advantages and limitations of the tissue cage model are briefly discussed.  相似文献   

10.
The concentrations of five antibiotics (erythromycin, lincomycin, penicillin G, streptomycin and oxytetracycline) were determined in chicken serum before and after induced fatty liver. The pharmacokinetic variables were calculated according to the obtained data. The crossover trial design involved 10 chickens for each antibiotic. The fatty liver was produced by oestradiol-dipropionate injections and monitored by serum malic enzyme activity determinations. Protein binding of the respective antibiotics was determined in vitro in the serum obtained from normal and oestrogen-treated birds. Induction of fatty liver caused several changes in the determined variables. The measured peak concentrations were higher for lincomycin and erythromycin and lower for penicillin and oxytetracycline while streptomycin remained unchanged. The peak concentration of streptomycin appeared earlier and the peak of oxytetracycline later than in the normal chickens. The elimination half-lives were shorter for erythromycin, lincomycin and streptomycin and increased for penicillin and oxytetracycline. The area under the concentration curve (AUC) decreased for erythromycin, penicillin and streptomycin, increased for oxytetracycline and remained unchanged for lincomycin. The body clearance (ClB/f) and the apparent specific volume of distribution (Vd(area'/f) were considerably changed in association with fatty liver induction. Since the fraction of the drug absorbed (f) is not known, it can only be speculated that changes in distribution rather than reduced liver function altered the kinetics. The protein binding was decreased for all the antibiotics, but this did not seem to be the reason for changes in kinetics, except perhaps in the case of penicillin.  相似文献   

11.
Objective To investigate tissue residues of two longacting oxytetracycline (OTC) preparations in cattle.
Design A randomised drug residue trial.  

Animals


Two hundred and forty beef cattle in 24 groups of ten.
Procedure Two blind-coded 200 mg/mL OTC preparations were used in five treatment regimens of various combinations of injection sites (from one to five) and administrations (one or two). Five cattle from each group were slaughtered at 21, 30 and 60 days after injection and the injection site, urine, kidney and diaphragm muscle analysed for residues.
Results The OTC concentration exceeded the maximum residue limit in kidney in animals slaughtered 21 days after treatment, which is the prescribed withholding period. Concentration at the injection site was much greater than the maximum residue limit 30 days post-treatment, but not 45 days post-treatment. The residue was smaller when OTC had been injected in multiple sites. There was no difference between the two OTC preparations.
Conclusion A review of the maximum injection volume, site of injection and the withholding period is needed for long-acting OTC formulations.  相似文献   

12.
Sulfamethazine (SMZ) is an antibacterial drug used in approximately 75% of all hogs marketed in the U.S. The tolerance for residues of SMZ in uncooked tissues is .1 ppm, and the withdrawal time is 15 d. The rate of illegal residues in swine from the use of SMZ has continued to fluctuate between 4% and 5% from 1980 through 1987. This was not acceptable. The Center for Veterinary Medicine (CVM) also has received from the National Center for Toxicological Research a report showing that SMZ produces a dose-related increase in follicular cell adenomas of the thyroid gland in rats and mice. The FDA has discovered three major causes of SMZ residues by investigating violators. The number one cause was a lack of sequencing, flushing, and cleaning of mixer equipment. Failure to follow withdrawal times was another major cause, and the third major reason was the use of a soluble powder solution. At least 16% of SMZ residue violations have resulted in no follow-up due to lack of animal identification. The FDA district offices are conducting on-farm investigations of swine producers who have caused SMZ violations. Repeat violators and those that produce higher residue levels will receive a higher priority. The FDA currently is attempting to obtain more state support, particularly for investigation of first-time violators. The CVM is serious about resolving the SMZ residue problem.  相似文献   

13.
Although cryptosporidiosis is frequently diagnosed in the U.S., there has been very little assessment of obstetrician–gynaecologist knowledge about this disease. In 2010, we surveyed U.S. obstetricians about the diagnosis, treatment and epidemiology of cryptosporidiosis. Data were examined through univariable analysis and multivariable regression models. Of 1000 obstetrician–gynaecologists surveyed, 431 (43.1%) responded. Only 44.4% of respondents correctly identified that prolonged, intermittent diarrhoea would lead them to consider cryptosporidiosis in a differential diagnosis. Routine ova and parasites (O&P) testing was incorrectly chosen to identify Cryptosporidium in stool by 30.4% of respondents. Questions about nitazoxanide, the only drug approved by the U.S. Food & Drug Administration (FDA) for treatment of cryptosporidiosis, were the most frequently missed questions. Only 9.0% of respondents correctly classified nitazoxanide as an FDA pregnancy Category B drug, and only 5.6% of respondents correctly indicated that FDA approved nitazoxanide for immunocompetent patients aged ≥1 years. Regarding prevention‐ and control‐related knowledge, only 14.1% of respondents correctly indicated that alcohol‐based hand sanitizers were not effective at inactivating Cryptosporidium spp., and <10% correctly indicated that cryptosporidiosis is a reportable disease in their state of practice. Multivariable analysis found that ≥19 years in practice was positively associated with O&P diagnostic testing knowledge, while rural and urban non‐inner city practice location, compared with suburban practice location, was positively associated with nitazoxanide knowledge. The low level of knowledge among obstetrician–gynaecologists about cryptosporidiosis indicates a need to develop resources for physicians about all aspects of cryptosporidiosis, particularly on diagnosis, treatment and prevention strategies.  相似文献   

14.
Drug and chemical residues in livestock   总被引：1，自引：0，他引：1  
The problem of drug and chemical residues in foods of animal origin has become increasingly important to the entire livestock industry as growing consumer health concerns continue to erode the demand for these products. Although nearly 90 per cent of all drugs approved for use in livestock are available for over-the-counter sales, in the public's view, it is only the veterinarian who administers drugs to animals and who, therefore, is responsible for all drug residues in food. Congress has responded to these consumer concerns by applying increased pressure on the FDA to restrict the extra-label use of drugs by veterinarians. The veterinary profession now finds itself in a position in which it must reexamine its current drug-use policies and strive to develop policies that are more responsible to the consumer, both in appearance and substance.  相似文献   

15.
动物性食品中兽药残留的原因、危害及控制对策   总被引：7，自引：0，他引：7  
兽药残留主要是使用伪劣兽药和违规用药引起的,动物性食品兽药残留对人体安全有很大威胁,并影响我国畜牧业的发展和走向国际市场。因此,必须采取有效措施减少和控制兽药残留的发生,如合理使用兽药、开发研究高效低残留兽药等。本文主要概述兽药残留的原因、危害及控制措施最新进展。  相似文献   

16.
The study was carried out on a single herd of 500 Holstein breed dairy cattle. Only 50 dairy cows (10%) were found to be suffering from focal ulcerative and papillomatous digital dermatitis of the pastern region. The cows were subjected to clinical and histopathological examinations. Early ulcerative stage was seen in 30 cows and late papillomatous stage was observed in 20 cows. The topical application of oxytetracycline solution or benzathine penicillin powder appeared to be effective for the treatment of the ulcerative lesions. The histopathological findings showed signs of epidermopoiesis and papilloma formation. The dermal reaction revealed signs of fibroplasia and perivascular aggregation of inflammatory cells. Silver stained sections indicated the presence of longer filamentous spiral spirochetes, cocci and large-sized anaerobic bacilli invading the stratum spinosum. In conclusion it can be said that bovine digital dermatitis was observed in ulcerative and papillomatous form at the pastern region bordering the dewclaws. Spirochetes are frequently associated with and may be responsible for pathological changes in the lesion.  相似文献   

17.
Two commercially available long-acting oxytetracycline (OTC) formulations were administered by the intramuscular (i.m.) route to six healthy pigs at the recommended dose of 30 mg/kg. After 2 h the mean maximum concentration (C(max)) reached values of 8.1 +/- 2.2 and 15.4 +/- 11.1 microg/mL, respectively. These concentrations remained higher than 0.5 microg/mL for more than 5 days after drug administration. The area under the concentration time curve (AUC09 days) of each formulation was 255 +/- 76.5 and 399.2 +/- 123 microg. h/mL, respectively, and the mean residence time (MRT) was around 3 days for both formulations. No significant differences were observed between the pharmacokinetic parameters of the two formulations, showing the bioequivalence of the two formulations studied according to the criteria established by the Food and Drug Administration (FDA) and the Committee for Veterinary Medicinal Products (CVMP).  相似文献   

18.
Six groups of swine (85 animals) were fed a combination of antimicrobial drugs (sulfamethazine 100 g/ton, chlortetracycline 100 g/ton and penicillin 50 g/ton). After two weeks the antimicronial drugs were removed from the diet of two groups (28 animals). These swine were compared to four groups fed the medicated diet to determine the effect of duration of treatment and degree of animal isolation on the persistence of resistance in lactose-fermenting enteric organisms. The degree of resistance to penicillin, oxytetracycline, dihydrostreptomycin and neomycin as determined by minimum inhibitory concentrations and the incidence of resistant organisms were examined during and after antibiotic feedings. Ninety-two percent or greater of all isolates tested during and after treatment had minimum inhibitory concentrations for oxytetracycline of greater than 100 mug/ml. Thirty-two weeks after cessation of dietary antibiotic, resistance to oxytetracycline and dihydrostreptomycin remained at 100% and 89% respectively. Variation in degree of contact between swine receiving medicated feed and those receiving nonmedicated feed was not sufficient to reduce the incidence of resistance to oxytetracycline or dihydrostreptomycin in all animals. Factors influencing persistence of resistant enteric organisms are discussed. Addition of the antimicrobials to the ration resulted in significantly greater weight gains for treated animals than for the controls but did not alter feed conversion.  相似文献   

19.
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20.
从部分兽药残留检测状况浅谈畜产品质量安全   总被引：3，自引：0，他引：3  
阐述了青霉素、喹乙醇、盐酸克仑特罗、阿苯达唑、磺胺类等部分兽药残留对人体的危害及残留检测现状,表明畜产品质量安全存在隐患;分析了造成兽药残留的各种原因,并就如何控制兽药残留提高畜产品质量提出对策.  相似文献   

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