ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1982.tb00494.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

After intravenous (i.v.) injection, acepromazine was distributed widely in the horse (Vd= 6.6 litres/kg) and bound extensively (>99%) to plasma proteins. Plasma levels of the drug declined with an α phase half‐life of 4.2 min, while the β phase or elimination half‐life was 184.8 min. At a dosage level of 0.3 mg/kg acepromazine was detectable in the plasma for 8 h post dosing. The whole blood partitioning of acepromazine was 46% in the plasma phase and 54% in the erythrocyte phase.Penile prolapse was clearly evident at doses from 0.01 mg/kg to 0.4 mg/kg i.v., and the duration and extent of protrusion were dose related. Hematocrit levels were significantly lowered by administration of 0.002 mg/kg i.v. (about 1 mg to a 500 kg horse) and increasing dosages resulted in greater than 20% lowering of the hematocrit from control levels. Pretreatment of horses with acepromazine also reduced the variable interval (VI 60) responding rate in all horses tested.These data show that hematocrit changes are the most sensitive pharmacological responses to acepromazine, followed by changes in penile extension, respiratory rate, VI responding and locomotor responses. Acepromazine is difficult to detect in plasma at normal clinical doses. However, because of its large volume of distribution, its urinary elimination is likely prolonged, and further work on its elimination in equine urine is req

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1982.tb00495.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

The pharmacokinetics of Dexamethasone (DXM) was studied in four cows all of which received DXM alcohol and DXM 21 isonicotinate (as a solution) by the intravenous and intramuscular routes. Concentrations of DXM and cortisol were determined using high performance liquid chromatography. An additional study was made in a second group of four cows which received intramuscular DXM 21 isonicotinate suspension for the assessment of DXM suppression of adrenal gland function. This was determined by measurements of base‐line and ACTH‐stimulated cortisol concentrations, before and following DXM administration.Following intravenous administration, the disposition kinetics of both formulations were described by a two‐compartment open model. The half‐times of elimination were similar; 335 and 291 min, respectively, for DXM alcohol and DXM 21 isonicotinate. All other pharmacokinetic parameters were not statistically different indicating that DXM was almost totally available (from DXM 21 isonicotinate). Following intramuscular administration, no significant difference in parameters was observed between the two formulations. Peak plasma concentrations were reached at 3 to 4 h post injection and bioavailability was approximately 70%. DXM was not detected in the plasma after the intramuscular administration of the suspension.The mean control plasma cortisol concentration was 8.8 ± 3.03 ng/ml. Following intravenous and intramuscular administrations of DXM alcohol and DXM 21 isonicotinate (solution), cortisol concentrations initially increased. However, at 120 min (intravenous) and 2–4 h (intramuscular), concentrations were negligible; 24–72 h and 48–96 h, respectively elapsed before concentrations returned control values. Following DXM 21 isonicotinate (suspension) there was no initial increase and concentrations had not returned to normal in all four cows until 52 days post administration. Similarly, ACTH‐stimulated plasma cortisol concentrations decreased progressively and significantly post administration. At 52 days, response to ACTH was norma

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1982.tb00496.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Following a single intravenous injection of polymyxin B, colistin (5 mg/kg, each) and gentamicin (3 mg/kg) to calves, the decline in serum antibiotic concentration generally suggested a three‐compartment (open system) pharmacokinetic model. Tissue binding is a dominant factor in the distribution and elimination kinetics of the drugs. Less than 65% of the dose of polymyxin B and colistin was recovered in the urine during 48 h after treatment. Concentrations of nonbound polymyxin B and colistin in the kidney, liver, lung, heart, and skeletal muscles were similar to total (free and bound) serum drug levels, but considerably higher concentrations were found, in bound form, in chloroform‐ethanol extracts of these organs.At 24 h after treatment, more than 50% of the doses of polymyxin B and colistin were present bound to the tissues; the largest amount was in the skeletal muscles. Gentamicin was concentrated in the kidney, predominantly in the free form. At 48 h after treatment the amount of gentamicin in the kidney was 6.3% of the administered dose, being more than five times greater than the corresponding amounts of polymyxin B and colistin.The extent of tissue uptake of polymyxin B and colistin limits the usefulness of kinetic values, which are derived from the analysis of serum drug levels, for the purpose of designing dosage schedules. The strong affinity of the polymyxins to the muscle tissue, and gentamicin to the kidney, can result in drug residues persisting in the body for several we

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1982.tb00497.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

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 discus

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1982.tb00498.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

An investigation was undertaken to evaluate the comparative efficacy of single dose treatment with santonin and piperazine against naturally acquiredNeoascaris vitulorumin sixty‐two buffalo calves of 20–60 days of age. Santonin was administered orally in doses of 5 mg, 10 mg and 15 mg/kg body weight to thirteen, eighteen, and sixteen buffalo calves, respectively. As a control, piperazine (88 mg/kg) was given by drench to a group of fifteen infected buffalo calves. Pretreatment and post treatment faecal eggs per gram (EPG) counts were determined by the Stoll's technique. The percentage reductions in EPG counts on the third and seventh days after administration of the two drugs were calculated. The percentage reduction in EPG counts in the piperazine treated group on the third day was 82 ± 15, 90.2 ± 3 and 91.3 ± 2.3% while on the seventh day these values were 88 ± 16, 97 ± 3, and 98 ± 2% in high, moderate and heavy infection calves, respectively. Treatment with santonin at 5, 10 and 15 mg/kg body weight also reduced the EPG counts. The percentage reduction in EPG counts in the calves treated with 15 mg/kg of santonin on the third day was 92.3 ± 18, 95.8 ± 7 and 93.5 ± 4% while on the seventh day these values were 100 ± 0, 100 ± 0 and 99.7 ± 2% in high, moderate and heavily infected calves, respectively. Both piperazine and santonin were associated with some side effects like diarrhoea, restlessness, etc. but their percentage incidence was not significantly different from each other. These findings suggest that santonin in a 15 mg/kg dose has an efficacy similar to piperazine given at the 88 mg/kg dose level for the treatment of ascariasis in

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1982.tb00499.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

摘要:

Metaldehyde, when administered orally to mice at a dose of 1 g kg‐1, produced convulsions and death within 2 h. Brain concentrations of noradrenaline (NA) 5‐hydroxytryptamine (5‐HT) and 5‐hydroxyindoleacetic acid (5‐HIAA) were significantly reduced in these animals relative to controls. Treatment with either intraperitoneal clonidine or diazepam 20 min after administration of metaldehyde reduced the mortality rate and in mice surviving for 5 h, the decrease in brain NA and 5‐HT concentrations were significan

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1982.tb00500.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1982.tb00501.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1982.tb00502.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY

ISSN:0140-7783    

DOI:10.1111/j.1365-2885.1982.tb00503.x

出版商:Blackwell Publishing Ltd    

年代:1982

数据来源: WILEY