ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1978.tb00312.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1978.tb00313.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1978.tb00314.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

Tissue distribution and elimination kinetics of oxytetracycline in sixteen organs and body fluids were determined in young pigs following intravenous and oral administration. Seventeen non‐fasted pigs, 8–10 weeks of age, weight range 16.4–34.5 kg were dosed intravenously at a dose rate of 11 mg/kg bodyweight. An additional seventeen weaning pigs, 12–14 weeks of age, weight range 27.2–36.3 kg were dosed orally at a dose rate of 48–65 mg/kg bodyweight. Oxytetracycline was rapidly distributed (half‐life, 6.71 ± 1.13 min) in swine. The mean volume of distribution was 1.26 ± 0.18 l/kg and overall body clearance was 3.82 ± 0.59 ml/kg/min. The elimination half‐life of oxytetracycline in pigs was 3.87 ± 0.62 h, which is shorter than has been observed in other domestic animal species. Oxytetracycline became rapidly and efficiently involved in enterohepatic cycling, with as much as 70% of a total intravenous dose being available for reabsorption from the gastrointestinal tract within 1 h after administration. This high degree of enterohepatic recycling prolonged the half‐life, and the large amount of drug that entered the enteric tract contributed to the high volumes of distribution and highk12/k21ratios. The excellent tissue penetration of this drug further contributed to the high volume of distribution and highk12/k21ratios obtained. Relationships between plasma and tissue depletion for several major edible organs were found to be statistically significant. Blood plasma is proposed as a body fluid for monitoring oxytetracy

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1978.tb00315.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

The biotransformation of chloramphenicol in the ruminant forestomachs was studied by incubating the antibiotic with ovine rumen contentsin vitro.Differential centrifugation of rumen contents showed that rapid reduction of the aromatic nitro group of chloramphenicol to an arylamine occurred in those fractions containing ciliates, and this activity was not inhibited by penicillin or streptomycin. It is concluded that in adult ruminants, chloramphenicol is metabolised by rumen microfauna more rapidly than it is absorbed, when administered orally.

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1978.tb00316.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

Three experiments were carried out to investigate the mechanisms whereby adequate plasma levels of chloramphenicol may be obtained following oral administration in young calves but not in older animals. In the first experiment, plasma levels of chloramphenicol following an oral dose of 50 mg/kg were followed in six calves, given weekly doses for the first 11 weeks of life. A plasma chloramphenicol level of 5 μg/ml, taken as the minimum therapeutic level, was attained only for a few hours in the 1 week old calves. Thereafter plasma levels decreased very rapidly until the fourth week, and rather more slowly between the fourth and eleventh weeks. At 11 weeks the plasma chloramphenicol level fell to around 0.3 μg/ml, which was the lower limit of sensitivity for the assay technique used. In the second experiment, the same single dose was administered to calves in the twelfth or eighteenth weeks of life which had not previously been exposed to the antibiotic. Plasma levels of 1 μg/ml were barely reached. This suggests that the non‐absorbtion of chloramphenicol is unlikely to be related to repeated administration of the antibiotic. In the third experiment, the same single dose was administered orally to two cows. Chloramphenicol could not be detected in the plasma following such administration, and some side‐effects were observed in the 48 h following dosing. It is suggested that rumen function may interfere with the absorbtion of chloramphenicol following oral administration to ruminants, even in relatively young a

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1978.tb00317.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

A comparison of the distribution and metabolism of intravenous and intra‐cerebroventricular ketamine hydrochloride in sheep showed that following intravenous administration there was a rapid biexponential decline in plasma ketamine, metabolism was rapid and both the demethylation and subsequent oxidation metabolites were detected. In the urine the second metabolite appeared to be the major one together with a third unidentified metabolite. In the CSF both ketamine and the first metabolite appeared to follow the plasma concentrations, but the entry of the second metabolite seemed to show a much slower pattern. Following injection of ketamine into the lateral cerebral ventricles the levels of ketamine in the CSF declined rapidly and the plasma concentration of ketamine showed a similar pattern to that seen following intravenous injection, indicating a rapid transfer to the blood. The levels of the metabolites found in the CSF suggest that their production does not take place in the CSF and that they penetrate back from the plasma. The findings of rapid metabolism following both routes of injection suggests that metabolism plays a major part in the termination of the effects of ketamine in the sheep, and that plasma levels of ketamine are of more importance than CSF levels in the maintenance of anaesthesi

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1978.tb00318.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

Chlorpromazine (CPZ) affects the hemolytic processin vitro.Hemolysis rates induced by CPZ at 10‐3M concentration were measured in blood from humans, monkeys, horses, cattle, goats, rats and dogs. Hemolysis data were plotted in the form of Lineweaver‐Burke plots and the kinetics considered. The canine red cell was markedly more resistant than the other species as represented by a smaller Vmax. Basal glutathione peroxidase levels of the red cell were assayed in an attempt to correlate the enzyme activity with the haemolysis rates in the species studied. A strong correlation would have explained the dog's high resistance and would have strongly indicated lipid peroxidation as the mechanism of CPZ‐inducedin vitrohemolysis. No such correlation was

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1978.tb00319.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

Plasma, urine and tissue concentrations of sulphathiazole were determined at various times following intravenous administration to fifteen cattle. The averaged plasma and urine data were consistent with a two‐compartment pharmacokinetic model with a half‐life of elimination of 1.3 h and a total volume of distribution of 0.41 l/kg body weight. Sulphathiazole was eliminated by excretion of unchanged drug into urine (48%) and by formation of acetylated and polar metabolites. The averaged data obtained from eight selected tissue sites were consistent with the two‐compartment pharmacokinetic model presented and confirmed that residues of sulphathiazole in edible tissue can be predicted from serum and urine concentrations of the

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1978.tb00320.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

The pharmacokinetics of kanamycin were studied in beagle dogs. A parenteral preparation of kanamycin sulphate (5% aqueous solution), which was given at a dosage level of 10 mg/kg of body weight, was the drug product used. The disposition curve which resulted from the intravenous administration of a single bolus dose of the drug was completely described by the biexponential equation:Cp= 50e‐0.1977t+ 36.3e‐0.0128twhereCprepresents concentration of the drug in the serum at timet(in minutes) and the experimental constants are mean values. Pseudo‐distribution equilibrium was rapidly attained and the apparent volumes of the central and peripheral compartments of the two‐compartment open model were the same (ca125 ml/kg). Body clearance (mean ± S.D.,n= 6) of kanamycin was 3.21 ±0.72 ml/kg/min. The half‐life of the drug was short (58.18 ± 18.43 min) and independent of the route of parenteral (intravenous and intramuscular) administration. Absorption of kanamycin from the intramuscular site was rapid, with a half‐time of 9.08 ± 1.10 min. A systemic availability of 89.1 ± 15.8% was obtained. Based on the bioavailability and disposition kinetics a dosage regimen consisting of the intramuscular injection of the dose (10 mg/kg) at 6 h intervals is proposed. An intravenous infusion rate of 48 μg/kgymin is predicted to establish a steady state serum concentration of 15 μg/ml, which is a therapeutic level of the antibiotic for susceptib

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1978.tb00321.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY