摘要:

Ruckebusch, Y.&Allal, C. Depression of reticulo‐ruminal motor functions through the stimulation of α2‐adrenoceptors.J. vet. Pharmacol. Therap.10, 1‐10.Inhibition of the cyclical contractions of the reticulum and the rumen by detomidine (10–40 (μg/kg, i.v.), xylazine (20–80 μg/kg, i.v.) and clonidine (2.5–10 μg/kg, i.v.) were compared in sheep and cattle housed individually in box stalls. Two (X2‐adrenergic receptor blocking agents, tolazoline and yohimbine, were administered intravenously for prevention (0.1‐0.4 mg/kg) or reversal (0.4‐1.2 mg/kg) of these effects. Continuous recording of the reticulo‐ruminal contractions and measurement of the volume of ruminal gas eliminated through the upper respiratory tract indicated that the three a2‐agonists inhibited the primary ruminal contractions associated with the reticular contractions. The occurrence of secondary ruminal contractions was also blocked in sheep, but only suppressed in cattle. The inhibition of reticulo‐ruminal contractions was prevented or reversed competitively by the two ct2‐blocking agents, suggesting an ci2‐adrenoceptor mediation of the inhibition of cyclical motor activity of the reticulo‐rumen. In contrast with tolazoline, yohimbine was unable to alleviate the accumulation of gas resulting from inhibition of t

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1987.tb00069.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Kokkonen, U.‐M.&Eriksson, L. Cardiovascular and allied actions of xylazine and atropine in the unanaesthetized goat. J. vet. Pharmacol. Therap.10, 11–16.The cardiovascular effects of xylazine and atropine, separately and in combination, were studied in goats. Methylatropine was used to distinguish between the central and peripheral effects of atropine. Mean arterial blood pressure and heart rate were recorded, and the sedative effect and changes in respiration and salivation noted. Intravenous infusion of xylazine (2.4–80.0 μg/kg) decreased mean arterial blood pressure and heart rate in a dose‐dependent manner. Single intravenous injections of both atropine sulphate (0.1 mg/kg) and methylatropine bromide (0.05 mg/kg) increased blood pressure and heart rate. After methylatropine, tachycardia lasted twice as long as after atropine. Following atropin‐ization, a potentiated rise in mean arterial blood pressure was present during the infusion of xylazine (80 μg/kg). Xylazine‐induced bradycardia was reversed by both atropine and methylatropine. The action of atropine is presumed to be primarily peripheral because of the similar effects with methylatropine. Xylazine‐induced sedation was dose dependent. At the highest dose the goats were unable to stand for 30–60 min, respiration became irregular with periods of apnoea, and saliva started to drip a few minutes after infusion without increased salivation. Atropine had no visible effect on the sedation, pattern of respiration or saliva dripping e

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1987.tb00070.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Soback, S., Kurtz, B.&Ziv, G. Pharmacokinetics of phenoxymethyl penicillin (penicillin V) in calves. J. vet. Pharmacol. Therap.10, 17–22.Phenoxymethyl penicillin (penicillin V) was administered intravenously (i.v.) and orally to pre–ruminant calves and the distribution and elimination kinetics, as well as the oral bioavailability, were determined. After i.v. injection, the drug was distributed rapidly in the body, the elimination half–life (t1/2β) was 34 min and the apparent volume of distribution at steady–state (Vd ss) was 0.30 I/kg. Mean peak serum drug concentrations were directly related to the oral dose administered, i.e. 0.22 μ/ml, 1.06 μ/ml and 2.14 μ/ml after dosing at 10, 20 and 40 mg/kg, respectively. The elimination t1/2of the drug after oral dosing varied between 90 and 110 min, and the oral bioavailability was approximately 30% of the dose. The co–administration of phenoxymethyl penicillin and probenecid resulted in elevation and prolongation of serum drug concentration. The percentage of drug bound to serum proteins was 78.8%± 8.2%. Phenoxymethyl penicillin was probably inactivated and degraded in the gastrointestinal tract of 6–week–old calves fed exclusively hay, silage and concentrates as very low and erratic serum drug concentrations were measured after these calves were dosed orally with the drug at 40 mg/kg.In view of the narrow antibacterial spectrum of the drug and the relatively high dose required, it appears that phenoxymethyl penicillin can only be of limited practical value for the treatment of bacterial infections in

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1987.tb00071.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Jacobs, D.E. Control of Toxocara cards in puppies: a comparison of screening techniques and evaluation of a dosing programme. J. vet. Pharmacol. Therap. 10, 23–29.Conventional chemoprophylaxis of canine toxocariasis is based upon the treatment of young puppies. It is proposed that physiological considerations and the complexity of the host–parasite relationship in the case ofToxocara canisdemand that anthelmintic evaluation should properly be conducted in such animals rather than in adolescent or adult dogs. A screening model using the critical trial technique in early weaned pups gave variable results even with compounds known to be of high efficacy in older dogs. Circumstantial evidence suggested that this inconsistency may be related to the rate of passage of ingesta through such young animals. More satisfactory results were obtained by pairing unweaned naturally infected puppies by weight and sex and treating one of each pair with the test compound. Naturalin uteroand transmammary infection was found to give fairly consistent worm‐burdens within each litter and a good indication of efficacy could therefore be estimated by comparingpost mortemworm‐counts. On this basis, the apparent efficacies of pyrantel pamoate (5 mg kg‐1) and piperazine (100 mg kg‐1) were found to be 83.5 and 82.5%, respectively. This method was extended to evaluate a prophylactic programme in which anthelmintic therapy was given to pups when aged 10, 20 and 30 days. IntestinalT. canispopulations were reduced, at 35 days of age, by between 94.2% and 98.0%. This programme increased overall weight gains between 10 and 30 days of age by 18% (P<0.05) although there was great variation between litters. The biggest response was observed in male pups between 20 and

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1987.tb00072.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Jacobs, D.E., Fox, M.T., Cowling, C, Foster, J. Pitt, S.R.&Gerrelli, D. Field evaluation of the oxfendazole pulse bolus for the chemoprophylaxis of bovine parasitic gastroenteritis: a comparison with three other control strategies.J. vet. Pharmacol. Therap.10, 30–36.Three trials were conducted in southern England involving 120 autumn‐born calves to evaluate the ability of an oxfendazole pulse‐release intraluminal device (OPRB) to control parasitic gastroenteritis (PGE). Matched groups were set‐stocked on adjacent paddocks. One group received an OPRB at turn‐out; one was treated with an alternative chemoprophylactic programme; while the third acted as an untreated control. In each trial clinical PGE occurred in the latter group but not in OPRB or alternative strategy groups. The OPRB, the morantel sustained release bolus (MSRB) and fenbendazole administered at 3 and 6 weeks after turn‐out gave similar weight‐gain benefits when compared with untreated controls(P<0.01), but the growth rate of animals given regular levamisole treatments from July to housing was significantly poorer than the matching OPRB group(P<0.05) although better than controls. Faecal egg‐output of OPRB calves was reduced by 97.0–99.9% compared with 95.5 and 58.9% for MSRB and fenbendazole treatments. Consequently, the late summer/ autumn peaks in pasture larval counts were considerably reduced in all treatment groups other than the late‐season levamisole strategy which reduced overall egg‐output by only 37.6%. Serum pepsinogen and gastrin values confirmed a greater degree of abomasal disturbance in calves grazing on the more highly contaminated pastures. Incidental lungworm infections became clinically apparent in the control groups of two trials but not in any OPRB or altern

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1987.tb00073.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Punch, P.I., Costa, N.D., Edwards, M.E.&Wilcox, G.E. The release of insoluble antibiotics from collagen ocular insertsin vitroand their insertion into the conjunctival sac of cattle.J. vet. Pharmacol. Therap.10, 37–42.The release rate of procaine penicillin, erythromycin and erythromycin estolate from soluble and insoluble collagen films was investigatedin vitroto develop an ocular insert for the treatment of infectious bovine keratoconjunctivitis. The release rate and duration of release varied according to the selection of antibiotic and vehicle. The combination of erythromycin estolate and soluble collagen produced the most sustained drug‐delivery system. However, due to the inappropriate physical properties of collagen and poor retention of ocular inserts, it was considered that the development of an antibiotic‐impregnated collagen ocular insert requires further investig

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1987.tb00074.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Belpaire, F.M., De Rick, A., Dello, C., Fraeyman, N.&Bogaert, M.G. apacid glycoprotein and serum binding of drugs in healthy and diseased dogs.J. vet. Pharmacol. Therap.10, 43–48.Inter‐individual variation in drug serum protein binding was studied in healthy dogs and in dogs with inflammatory diseases for lidocaine, oxprenolol and propranolol, which bind mainly to α1‐acid glycoprotein (α1‐AGP), and for diazepam, digitoxin and phenytoin, which bind mainly to albumin. For the drugs mostly bound to α1‐AGP, in both groups of dogs binding varied considerably, and it was markedly higher in dogs with inflammatory disease. For the other drugs, the variation in binding was smaller and did not differ between the two groups of dogs. In both groups of dogs, the α1‐AGP concentration varied widely; it was higher in the serum of the dogs with inflammation, while the concentration of albumin was lower in these animals. There was a significant negative correlation between percentage free lidocaine, oxprenolol or propranolol and α1‐AGP concentration, suggesting that the inter‐individual variation in binding of these drugs is due to the variation in α1‐AGP concentration. There was a marked intra‐individual variation in lidocaine binding and in serum α1‐AGP concentration, studied over a period of 3 weeks in healthy dogs; a significant negative correlation between percentage free lidocaine and α1

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1987.tb00075.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Depelchin, B.O., Bloden, S.&Ansay, M. Antipyrine disposition in calves. I. Effects of some drugs. J. vet. Pharmacol. Therap.10, 49–53.The influence of four drugs on antipyrine pharmacokinetic parameters was studied after 3 h, 2 and 6 days in 32 Friesian calves. Dexamethasone phosphate and griseofulvin led to increased antipyrine elimination. The effect of dexamethasone remained significant 2 and 6 days later. The rate of antipyrine elimination was markedly but transiently depressed by chloramphenicol and oxytetracycline. The apparent volume of antipyrine distribution remained unaltered during treatmen

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1987.tb00076.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Burrows, G.E., Barto, P.B.&Martin, B. Comparative pharmacokinetics of gentamicin, neomycin and oxytetracycline in newborn calves.J. vet. Pharmacol. Therap.10, 54–63.The pharmacokinetics of three antibiotics – gentamicin, neomycin and oxytetracycline were determined in newborn calves. The kinetic determinations, using two‐compartment open models, were made at increasing ages from 1 day to 42 days and compared with those made from older calves (250+ days). Although all three antibiotics are eliminated unchanged primarily by glomerular filtration, there were marked differences in the development of elimination processes for individual drugs. The pharmacokinetics of neomycin were not influenced by age. Although the elimination half‐life of gentamicin appeared to decrease with age, the changes were not significant and were due to an increased elimination rate in only one calf. There was no change with age in the remaining three calves. Oxytetracycline elimination was significantly reduced in newborn calves. This was exemplified by a decrease in the half‐life of eliminationt1/2(β) from 672.5 ± 99.4 in the newborn to 385.6 ± 76.8 at 6 weeks of age, and 377.3 ± 40.8 min in the 250‐day‐old calf. These changes were consistent in all four calves. The rate of elimination remained low for the first 4 weeks of life. The volume of distributionVd, areawas not changed after the first week of life. Based on pharmacokinetic changes, an adjustment of dosage is indicated for oxytetracycline in the newborn calf as compared to the ol

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1987.tb00077.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Hennessy, D.R., Lacey, E., Steel, J.W.&Prichard, R.K. The kinetics of triclabendazole disposition in sheep. J. vet. Pharmacol. Therap. 10, 64–72.To investigate whether the disposition of triclabendazole (TCBZ) and its metabolites in blood or bile influenced its flukicidal potency, TCBZ was administered intraruminally at 10 mg kg‐1to sheep surgically fitted with a permanent re‐entrant bile duct cannula. The profiles of TCBZ metabolites in peripheral plasma and bile were determined using high performance liquid chromatography.In plasma, only TCBZ sulphoxide (TCBZ‐SO) and TCBZ sulphone were present and reached their maximum concentrations (>13 μg ml‐1) at 18 and 36 h, respectively, after administration. TCBZ metabolites were specifically bound to plasma albumin, which is believed to exert a major influence on the duration of plasma TCBZ metabolite concentrations and consequent exposure of liver fluke.In bile, the major TCBZ metabolites were hydroxylated in the 4'position and secreted predominantly as sulphate esters with lesser proportions as glucuronide conjugates. The major biliary metabolite was conjugated hydroxy TCBZ‐SO which reached a maximum concentration in excess of 40 μg ml‐′ and contributed almost half the total conjugated metabolites. The major free biliary metabolite was TCBZ‐SO. Of the administered TCBZ dose, 9.7% was secreted as free metabolites in bile whereas 35.8% was secreted as conjugated metabolites. Approximately 6.5% of the dose wa

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1987.tb00078.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY