摘要:

The distribution of gentamicin (G) in plasma and uterine lumen was studied following intramuscular (i.m.) and intrauterine (i.u.) treatment. A Foley catheter was inserted into one uterine horn and retained in place by inflation of the cuff. This provided a closed system for collection of uterine lumen samples and analysis of the concentration of gentamicin for 6 h following treatment.Four normal cycling and healthy cows in dioestrus were given i.m. injections of 4 mg gentamicin/kg BW and another two were given i.m. injections of 2 mg gentamicin/kg BW gentamicin. The uteri were infused with 50 ml saline containing phenolsulphonphthalein (PSP) indicator.Blood and infused solution (IS) samples were periodically collected during the 6‐h period following i.m. administration. Six hours after injection, approximately 183.7 μg gentamicin and 39.4 μg gentamicin were accumulated in the uterine lumen of cows receiving 4 mg gentamicin/kg BW and 2 mg gentamicin/kg BW, respectively. The amount of gentamicin reaching the blood stream after i.m. administration of 4 mg gentamicin/kg BW was 2.89 times that reached after administration of 2 mg gentamicin/kg BW based on the area under the curve of plots of plasma concentration of gentamicin versus time.Four normal‐cycling and healthy cows in dioestrus were given i.u. infusions of gentamicin (225–275 mg) diluted in 50 ml saline containing PSP indicator using a Foley catheter in a closed system. Samples from the IS and blood were collected at various intervals for 6 h after infusion. Following i.u. infusion of gentamicin, an average of 29.4% of the dose was absorbed into the bloodstream. The majority of the dose of gentamicin (70.6%) remained in the uterine lumen throughout the 6

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1983.tb00383.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The effects of intracerebroventricular (i.c.v.) and intravenous (i.v.) administration of dopamine and its antagonists (domperidone and metoclopramide) on forestomach motility were investigated in four sheep fitted with Nichrome electrodes and strain gauges implanted on the reticulum and the caudo‐dorsal sac of the rumen.Infused by the i.c.v. route at a rate of 2 μg·kg‐1·min‐1, dopamine inhibited the phasic contractions of the reticulo‐rumen. A similar effect was obtained following i.v. administration of doses which were 10 times higher, but the effect was associated with an increased tone of the rumen wall. Prior i.v. administration of domperidone (0.5 μg·kg‐1) blocked these effects and a selective blockade of the dopamine‐induced inhibition of phasic contractions was obtained with higher dose of domperidone (2.5 μg·kg‐1) administered centrally.When dopamine was infused alone ventricularly or intravenously after metoclopramide (40 μg·kg‐1), it induced a transient (6–8 min) period of rumination, which could be blocked by a prior i.c.v. administration of tolazoline.It was concluded that dopamine acts on rumino‐reticular motility in sheep through specific dopamine receptors (i) centrally by inhibiting the frequency of reticular contraction and (ii) peripherally by increasing the muscular tone of the rumen, and its effects on rumination involved α2adrenergic receptors located

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1983.tb00384.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The pharmacokinetics of theophylline were determined in adult cats and the data were fitted to a two‐compartment model. Single intravenous and multiple oral doses of aminophylline were used. The mean plasma theophylline half‐life (t1/2) following the single intravenous dose was 7.8 h and the mean apparent specific volume of distribution (V'd(area)) was 0.46 l/kg. The absorption half‐life (t1/2ab) was 0.5 h and the bioavailability was 96% following oral administration. There was excellent agreement between the predicted and observed plasma theophylline concentrations following multiple oral

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1983.tb00385.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Lidocaine was infused at a fixed zero‐order rate to eight healthy mongrel dogs until tonic extension (n= 5) and cortical seizures (n= 7) were produced. Lidocaine concentrations determined at 5‐min intervals were used to calculate concentrations at which these effects occurred. The tonic extension phase occurred at a mean lidocaine concentration of 8.21 ± 1.69 μg/ml. After a 1‐month rest period, the same dogs were anaesthetized and ventricular tachycardia was produced by administering ouabain. Lidocaine was again infused at a fixed zero‐order rate until all beats of ventricular origin were abolished. This occurred at a mean lidocaine concentration of 6.25 ±

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1983.tb00386.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Pharmacokinetics of oxytetracycline (OTC) were studied in 10 pigs after administration of 20 mg/kg body weight of either a conventional (OTC‐C) or a long‐acting (OTC‐LA) preparation.After intravenous administration of OTC‐C the elimination half‐life for OTC was 3.75 h, with approximately 75% of the dose being excreted in the urine in 1 week. Intramuscular (i.m.) injection of OTC‐C resulted in plasma peak values after 4 h, while OTC‐LA after i.m. administration produced the highest plasma levels within 1 h, although these were lower than with OTC‐C.For both preparations the bioavailability after i.m. administration was 95–100% and about 70% of the dose was excreted in the urine during the first week.With OTC‐C given i.m., plasma concentrations above 0.5 μg/ml were maintained for 28 h and with OTC‐LA for 35 h indicating a weak retard effect of the latter.Pronounced tissue damage at the injection site was seen 1 and 2 weeks after the administration of OTC‐LA, while OTC‐C produced very little irritation. OTC could be found at the injection site for 2 weeks, the concentrations being higher

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1983.tb00387.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The effect of acepromazine maleate (ACP) on the equine venous haematocrit and total plasma protein concentration was studied in six clinically normal horses. Total plasma protein concentration was not appreciably influenced by ACP. However, the haematocrit decreased with the duration, but not the degree, of the decrease being dose‐related. Mean haematocrit values returned to control levels by 12 h after 0.05 mg ACP/kg body weight and 21 h after 0.15 mg ACP/kg body weigh

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1983.tb00388.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The effects of intravenous administration of 5‐HT on the patterns of reticulorumen contractions were studied in conscious sheep. Contractions were measured by strain gauges applied to the external wall of the reticulum and the ventral and/or dorsal sac of the rumen. The responses to 5‐HT comprised (i) a shortlived contraction followed by (ii) a sustained increase in muscle tone and (iii) a concomitant inhibition of the extrinsic reticulo‐rumen contractions. The corresponding blockades produced by (i) atropine, (ii) 5‐HT antagonists and (iii) chemical sympathectomy suggest involvement of a peripheral cholinergic mechanism in the initial contractile response and a central adrenergic mechanism in the reflex inhibition of extrinsic reticulo‐rumen con

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1983.tb00389.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The pharmacokinetics of the anti‐convulsant phenytoin were investigated in clinically healthy horses after oral (p.o.) and intravenous (i.v.) administration. A single dose of phenytoin (8.8 mg/kg body weight) was given i.v. as a bolus to nine horses and one horse received 13.2 mg/kg. A two‐compartment open model was used to describe the disposition of phenytoin. Four of the horses that received an i.v. dose (three at 8.8 mg/kg and one at 13.2 mg/kg) were then given the same dose 3 days later by the oral route. Phenytoin achieved a peak concentration in serum within 1–4 h after p.o. administration and was poorly absorbed with a bioavailability of 34.5 ± 8.6%. Oral dosage regimens were calculated on the basis of a dosing interval of 8 h to provide average serum steady‐state concentrations of 5 and 10 μg/ml for

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1983.tb00390.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Digoxin was administered as a single intravenous injection of 22 μg/kg to six cattle. The resulting serum concentrations were fitted by both a bi‐ and tri‐exponential equation with the latter providing the best fit to the data of a majority of the animals. The biological half‐life of digoxin in cattle was found to be 7.8 h. This relatively short half‐life in comparison to other animal species dictates that digoxin should be administered more frequently to cattle to provide therapeutic concentrations in serum without broad fluctuations in serum concentrations. Computer simulations of various intravenous dosage regimens suggested that a loading dose of 22 μg/kg followed by an infusion of 0.86 μg/kg/h would offer the greatest safety and efficacy in bovin

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1983.tb00391.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Chloralose may be used in a 10% solution as an anaesthetic in dogs. The solubility of chloralose was found to be much higher in polyethylene glycol‐200 (PEG‐200) than in either warm (body temperature) or cold saline (0.9% NaCl). The intravenous (i.v.) administration of chloralose in warm saline solution induced acidosis as a result of the increase in the level of metabolic acids. The acidity generated by chloralose in almost neutral saline was probably the result of increase in the base deficit in the animal. The infusion of PEG‐200 (almost neutral) significantly reduced the base deficit without disturbing the PaO2or PaCO2in the arterial blood. The base deficit value was significantly lower after administration of chloralose solution in PEG‐200 (almost neutral) than after administration in saline. The use of PEG‐200 as a solvent for chloralose was advantageous in two ways. Firstly, it prevented the production of acids in anaesthetic solution and neutralized the blood metabolic acids generated by chloralose administration in saline. Secondly, the solubility of chloralose (10% w/v solution) in PEG‐200 was very much higher than in warm or

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1983.tb00392.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY