摘要:

Digoxin was administered orally and intravenously to seven healthy adult mares and geldings in two separate trials. At a dose of 44 μg digoxin/kg body weight, the oral study was characterized by an absorption phase with a mean (± 1 standard deviation) peak serum digoxin concentration of 2.21 ng/ml (± 0.45) at a mean of 2.29 h (± 1.52) after administration. A second rise in serum digoxin concentration started about 6–8 h after administration and extended to about 20 h after administration. The mean bioavailability (F) was 23.38% (± 5.96).At a dose of 22 μg digoxin/kg body weight, the intravenous study was characterized by a two‐compartment model with the following mean pharmacokinetic measurements: distribution rate constant (α), 1.391 h‐1(± 0.1909); zero‐time serum digoxin concentration determined from the distribution phase (A), 21.247 ng/ml (± 5.6614); elimination rate constant (β), 0.0409 h‐1(± 0.0069); zero‐time serum digoxin concentration determined from the elimination phase (B), 3.82 ng/ml (± 0.433); apparent specific volume of distribution uncorrected for protein binding (Vdβ), 5.003 1/kg (± 0.5177). The mean β corresponded to a biological half‐life (t1/2 ±) of 16.9 h.Based upon results of this study, theoretically achievable steady‐state serum digoxin concentrations were calculated for maintenance doses given by oral and intravenous routes of administration with appropriate two‐compartment, multiple‐dose formulae. Loading doses were also calculated for each route. It is the opinion of the authors that the oral route of administration of digoxin is effective in the horse and may preclude the potential risks posed by the high serum digoxin concentrations immediately f

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1983.tb00460.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

A radioimmunoassay for zeranol has been validated and used to measure the concentration of zeranol in the urine of sheep and cattle treated with zeranol (Ralgro). The assay uses an antibody raised against zeranol‐16‐carboxy‐propyl ether conjugated to human serum albumin. In sheep and cattle urine the limits of detection were approximately 2 ng/ml and 2.5 ng/ml, respectively.In two trials 13 sheep were implanted with 12 mg zeranol at the base of the ear. The mean maximum concentrations of zeranol observed in urine were 45 ng/ml (Trial I) on day 35 and 90 ng/ml (Trial II) on day 56, and had declined to 26 ng/ml 42 days after implantation (Trial I) and 11.7 ng/ml 70 days after implantation (Trial II). In four cattle implanted with 36 mg zeranol the concentrations of zeranol in urine reached a mean maximum concentration of 13.5 ng/ml 22 days after implantation and had declined to 2.9 ng/ml 69 days after implant

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1983.tb00461.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The pharmacokinetics of sodium and lysine cephalexins were investigated after intravenous and intramuscular administration of a single dose rate of 30 mg.kg‐1body weight in calves.The data for the two salts administered intravenously were pooled, the resulting pharmacokinetic disposition of cephalexin indicating a distribution half‐time (t1/2α) and an elimination half‐time (t1/2β) of 9.78 and 62.0 min, respectively.Following intramuscular administration some pharmacokinetic differences were recorded between the cephalexin preparations: lysine cephalexin was more rapidly eliminated (t1/2kel= 55.2 min) than sodium cephalexin (t1/2kel= 89.8 min), although the peak blood level was higher and attained after a longer time with lysine cep

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1983.tb00462.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

FiveE. colistrains carrying K99 antigen isolated from the intestines of calves which had succumbed to diarrhoea and six K88‐positive strains isolated from fatal cases of diarrhoea in piglets were examined for their mannose‐resistant haemagglutination (MRHA) capacity against pig erythrocytes. The bovine strains showed a geometric mean MRHA‐titre of 1/18 and the porcine strains one of 1/45. Similar experiments were carried out after addition of the following antibiotics in doubling dilutions: ampicillin, chloramphenicol, colistin, dihydro‐streptomycin, gentamicin, neomycin, polymyxin B and oxytetracycline. Colistin and polymyxin B had a marked concentration‐dependent inhibitory effect on MRHA. Neomycin and gentamicin also inhibited MRHA but to a lesser degree. Chloramphenicol, dihydrostreptomycin and oxytetracycline showed no effect. With ampicillin, a trend was found for the ratio values to be inversely proportional to the concentration. This suggests that this antibiotic has an enhancing effect on the haemaggl

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1983.tb00463.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The pharmacokinetics of imidocarb were studied in seven mongrel dogs and eight crossbred goats. An intravenous bolus dose (4 mg/kg) of 12% imidocarb dipropionate solution wasinjected into the cephalic vein in dogs and the jugular vein in goats. The plasma concentration of imidocarb was measured by spectro‐photometry. The experimental data were analysed using a two‐compartment open model. The apparent volume of the central compartment was significantly higher (P<0.01) in dogs than in goats. The significantly larger (P<0.05) apparent specific volume of distribution in goats than in dogs may be attributed to passive diffusion followed by ion trapping of the drug in rumen fluid. Neither the half‐life nor body clearance differed significantly between dogs (t1/2, 207 ± 45 min;ClB, 1.47 ± 0.38 ml/min kg) and goats (t1/2, 251 ± 94 min;ClB, 1.62 ± 0.50 ml/min kg). While almost 80% of the dose had been eliminated at 8 h in. both species, the high ratio of the imidocarb level in the peripheral‐to‐central compartment in goats suggests that a prolonged period may be required for complete eliminatio

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1983.tb00464.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Thiopentone pharmacokinetics and electrocorticogram patterns were studied in a group of six sheep given thiopentone intravenously (20 mg/kg). Plasma concentrations were determined using a high‐performance liquid chromatography method. A three‐compartment open model was selected to describe the disposition kinetics of thiopentone. The drug had an apparent volume of distribution of 1005 ± 196 ml/kg; body clearance was 3.5 ± 0.8 ml/minkg and the half‐life, based on the slope of the terminal portion of the curve, was 196 ± 64 min. From the electrocorticogram pattern, it seems likely that the highest concentrations in brain occurred between 47 and 217 sec after commencing administration and a brain penetration half‐time of 26.5 ± 2.87 sec was calculated. At the time of awakening (36.6 ± 6.36 min) 24.1 ± 6.3% of the dose was located in the central compartment, 12.6 ± 8.2 was in the shallow peripheral compartment, 38.8 ± 14.1 was in the deep peripheral compartment and 24.6 ± 10.3 had been eliminated. Using simulated curves, it appeared that suppression of the shallow peripheral compartment (muscle) did not change the time of awakening; in contrast when elimination‐rate constant was decreased, awakening was delayed. It was suggested that the relatively short duration of thiopentone anaesthesia in sheep should be attributed mainly to elimination of the drug by hepatic metabolism and uptake by body fat. This hypothesis, which differs from the widely accepted view that the duration of thiopentone anaesthesia is independent of the rate of hepatic metabolism, is discussed in terms of differences in regional blood flow between sheep and m

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1983.tb00465.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Both dopamine and apomorphine caused concentration‐dependent contractions of the bovine pulmonary artery from rest. Both of these compounds caused relaxation of histamine‐precontracted arterial and venous strips after α‐adrenoceptor blockade. Arterial contraction elicited by dopamine was inhibited either by phentolamine (α‐blocker) or by the dopamine‐selective antagonists, spiperone and butaclamol. Apomorphine in the highest concentration (<10‐5M) inhibited dopamine‐induced contractions. Dopamine‐ and apomorphine‐induced vascular relaxations were attenuated by propranolol but not by spiperone or butaclamol. These data suggest that dopamine‐ and apomorphine‐induced relaxation in these preparations is most likely mediated through β‐adrenergic mechanisms, whereas dopamine‐induced contractions seem to involve both α‐adrener

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1983.tb00466.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Chloramphenicol sodium succinate was administered as an intravenous bolus (50 mg/kg) to eight foals which weighed 49–57 kg (mean ± 1 standard deviation = 53.19 ± 2.66) each, and were 1–9 days (4.5 ± 2.56) of age. The drug was rapidly distributed and followed first‐order elimination. Mean pharmacokinetic values were: zero‐time serum concentration (C0) = 36.14 μg/ml (±14.80); apparent specific volume of distribution (Vd) = 1.614 1/kg (±0.669); and elimination rate constant (K) = 0.7295 h‐1(±0.3066) which corresponds to a biological half‐life (t1/2) = 0.95 h. These values do not differ greatly from those reported for adult horses and ponies.A suspension of chloramphenicol was administered by nasogastric tube (50 mg/kg) to a second group of seven foals which weighed 49 to 57 kg (51.34 ± 2.82) each and were 1 to 7 days (4.43 ± 1.90) of age. A mean peak serum chloramphenicol concentration of 23.97 μg/ml (±7.06) was achieved 1.14h (±0.63) after administration. The bioavailability of this prepar

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1983.tb00467.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1983.tb00468.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1983.tb00469.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY