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1.
Plasma pharmacokinetics and urine concentrations of meropenem in ewes   总被引：1，自引：0，他引：1  
The pharmacokinetics of meropenem was studied in five ewes after single i.v. and i.m. dose of 20 mg/kg bw. Meropenem concentrations in plasma and urine were determined using microbiological assay method. A two-compartment open model was best described the decrease of meropenem concentration in plasma after an i.v. injection. The drug was rapidly eliminated with a half-life of elimination ( t 1/2 β ) of 0.39 ± 0.30 h. Meropenem showed a small steady-state volume of distribution [ V d(ss)] 0.055 ± 0.09 L/kg. Following i.m. injection, meropenem was rapidly absorbed with a t 1/2ab of 0.25 ± 0.04 h. The peak plasma concentration ( C max) was 48.79 ± 8.83  μ g/mL was attained after 0.57 ± 0.13 h ( t max). The elimination half-life ( t 1/2el) of meropenem was 0.71 ± 0.12 h and the mean residence time ( MRT ) was 1.38 ± 0.26 h. The systemic bioavailability (F) after i.m. injection was 112.67 ± 10.13%. In vitro protein-binding percentage of meropenem in ewe's plasma was 42.80%. The mean urinary recoveries of meropenem over 24 h were 83% and 91% of the administered dose after i.v. and i.m. injections respectively. Thus, meropenem is likely to be efficacious in the eradication of many urinary tract pathogens in sheep.  相似文献   

2.
Phenylbutazone was administered intravenously (i.v.) to a group of four lactating cows at a dosage of 6 mg/kg body weight. Whole plasma, protein-free plasma and milk were analysed for phenylbutazone residues. Pharmacokinetic parameters of total and free phenylbutazone in plasma were calculated using a non compartmental method. In regards to whole plasma data, the mean volume of distribution at steady state ( V ss), was 147 mL/kg body weight, with a mean (± SEM) terminal elimination half-life ( t 1/2) of 40 ± 6 h. The mean clearance ( Cl ) was 3 mL/h/kg body weight. The V ss as determined from the protein-free plasma fraction was 50 021 mL/kg body weight. This larger V ss of free phenylbutazone compared to total plasma phenylbutazone was attributed to a high degree of plasma protein binding, as well as the greater penetration of free phenylbutazone into tissues. The mean t 1/2 of free phenylbutazone was 39 ± 5 h. This similarity to the t 1/2 estimated from total plasma phenylbutazone data is attributed to an equilibrium between free and plasma phenylbutazone during the terminal elimination phase. Mean t 1/2 as determined from milk, applying a urinary excretion rate model, was 47 ± 4 h. Milk clearance of phenylbutazone was 0.009 mL/h/kg body weight, or about 0.34% of total body clearance. Furthermore, evidence suggests that phenylbutazone either binds to milk proteins, or is actively transported into milk, as its concentration in milk was greater than that predicted due to a simple partitioning from plasma into milk.  相似文献   

3.
The pharmacokinetics of sulphadiazine (SDZ) (100 mg/kg, body weight) were investigated in six camels ( Camelus dromedarius ) after intravenous (i.v.) and oral (p.o.) administration. Following i.v. administration, the overall elimination rate constant (β) was 0.029±0.001/h and the half-life ( t ½β) was 23.14±1.06 h. The apparent volume of distribution ( V d(area)) was 0.790±0.075 L/kg and the total body clearance ( Cl B) was 23.29±2.50 mL/h/kg. After p.o. administration, SDZ reached a peak plasma concentration ( C max(cal.)) of 62.93±2.79 μg/mL at a post injection time of ( T max(cal.)) 22.98±0.83 h. The elimination half-life was 19.79±1.22 h, not significantly different from that obtained by the i.v. route. The mean absorption rate constant (Ka) was 0.056±0.002 h−1 and the mean absorption half-life ( t ½Ka) was 12.33±0.37 h. The mean availability ( F ) of sulphadiazine was 88.2±6.2%.
  To achieve and maintain therapeutically satisfactory plasma SDZ levels of 50 μg/mL, the priming and maintenance doses would be 80 mg/kg and 40 mg/kg intravenously and 90 mg/kg and 45 mg/kg orally, respectively, to be repeated at 24 h intervals.  相似文献   

4.
Hens were given single intravenous or oral doses (30 mg/kg body weight) of metronidazole and the plasma concentrations of the drug were determined by high-performance liquid chromatography (HPLC) at intervals from 10 min to 24 h after drug administration. Pharmacokinetic variables were calculated by the Lagrange algorithm technique. The elimination half-life ( t 1/2β) after the intravenous injection was 4.2 ± 0.5 h, the volume of distribution ( V d(ss)) 1.1±0.2 L/kg and the total body clearance ( Cl B) 131.2 ± 20 mL/h.kg. Oral bioavailability of the metronidazole was 78 ± 16%. The plasma maximum concentration ( C max) 31.9 ± 2.3 μg/mL was reached 2 h after the oral administration and the oral elimination half-life ( t 1/2β) was 4.7 ± 0.2 h. The binding of metronidazole to proteins in hen plasma was very low (less than 3%). Whole body autoradiography of [3H] metronidazole in hens and quails showed an even distribution of labelled material in various tissues at short survival intervals (1-4 h) after oral or intravenous administration. A high labelling was seen in the contents of the small and large intestines. In the laying quails a labelling was also seen in the albumen and in a ring in the periphery of the yolk at long survival intervals. Our results show that a concentration twofold above the MIC is maintained in the plasma of hens for at least 12 h at an oral dose of 30 mg/kg metronidazole.  相似文献   

5.
Bioavailability and pharmacokinetics of metoclopramide in cattle   总被引：1，自引：0，他引：1  
The bioavailability of metoclopramide was investigated in three steers following administration of 8 mg/kg by the oral, abomasal (cannula), and intravenous routes, using a Latin square design. The mean (± SD) oral and abomasal bioavailabilitles were 51.3 ± 30.7% and 76.2 ± 15.5%, respectively. The mean value for clearance ( C1 ) was 20.1 ± 5.9 ml/min and the volume of distribution ( V d) was 0.51 ± 0.19 1/kg. Additionalpharmacokmetic parameters for metoclopramide were determined following intravenous administration to seven cows. A predominate two-compartment model of distribution was found in six cows with a t 1/2α harmonic mean of 24.2 min and a range of 11.2–72.4 min, a t 1/2β harmonic mean of 53.1 min and a range of 31.1–134.1 min, a Cl of 42.2 ± 8.7 ml/min, and a V d of 2.1 ± 0.8 1/kg. To better define the relationship between metoclopramide concentration and release of prolactin, a treatment-by-subjects infusion study was conducted in which four different loading doses followed by constant infusion were used. A steady-state metoclopramide concentration ( MCP ss) of 8.8 ± 2.6 ng/ml was associated with a three-fold elevation of prolactin to a mean value of 12.1 ± 3.1 ng/ml in six yearling steers. Steady state serum prolactin concentrations ( PRL ss) did not rise significantly above 23.3 ± 6.9 ng/ml, even when MCP ss reached a concentration of 518.5 ±151.2 ng/ml. The short half-life, moderate V d, low minimum pharmacologically effective concentration, and rapid C1 found for metoclopramide in cattle in this study, suggest that a continuous release device could potentially be useful in the application of this drug in the prevention and treatment of fescue toxicosis.  相似文献   

6.
Abo-El-Sooud, K., Goudah, A. Influence of Pasteurella multocida infection on the pharmacokinetic behavior of marbofloxacin after intravenous and intramuscular administrations in rabbits. J. vet. Pharmacol. Therap. 33 , 63–68.
The pharmacokinetic behavior of marbofloxacin was studied in healthy ( n  = 12) and Pasteurella multocida infected rabbits ( n  = 12) after single intravenous (i.v.) and intramuscular (i.m.) administrations. Six rabbits in each group (control and diseased) were given a single dose of 2 mg/kg body weight (bw) of marbofloxacin intravenously. The other six rabbits in each group were given the same dose of the drug intramuscularly. The concentration of marbofloxacin in plasma was determined using high-performance liquid chromatography. The plasma concentrations were higher in diseased rabbits than in healthy rabbits following both routes of injections. Following i.v. administration, the values of the elimination half-life ( t 1/2β), and area under the curve were significantly higher, whereas total body clearance was significantly lower in diseased rabbits. After i.m. administration, the elimination half-life ( t 1/2el), mean residence time, and maximum plasma concentration ( C max) were higher in diseased rabbits (5.33 h, 7.35 h and 2.24 μg/mL) than in healthy rabbits (4.33 h, 6.81 h and 1.81 μg/mL, respectively). Marbofloxacin was bound to the extent of 26 ± 1.3% and 23 ± 1.6% to plasma protein of healthy and diseased rabbits, respectively. The C max /MIC (minimum inhibitory concentration) and AUC/MIC ratios were significantly higher in diseased rabbits (28 and 189 h) than in healthy rabbits (23 and 157 h), indicating the favorable pharmacodynamic characteristics of the drug in diseased rabbits.  相似文献   

7.
The anti-inflammatory agent, tepoxalin, was administered to eight healthy 6-month-old female New Zealand white rabbits once daily at an oral dose of 10 mg/kg. Blood samples were obtained immediately before and at 0.25, 0.5, 1, 2, 3, 4, 6, 8, 12, and 24 h postadministration on days 1 and 10. Tepoxalin and its active metabolite, RWJ 20142, concentrations were determined in plasma by use of high-performance liquid chromatography with mass spectrometry. C max of the parent compound was reached between 3 and 8 h of drug administration, with a harmonic mean t 1/2 of 3.6 h. Peak tepoxalin plasma concentrations were 207 ± 49 ng/mL. After oral administration, the metabolite RWJ 20142 achieved C max in plasma 2–8 h after administration, with a t 1/2 of 1.9–4.8 h (harmonic mean 2.8 h). Peak plasma concentrations of RWJ 20142 on day 1 were 2551 ± 1034 ng/mL.  相似文献   

8.
Oxytetracycline (OTC) pharmacokinetics were studied in the red pacu ( Colossoma brachypomum ) following intravenous (i.v.) and intramuscular (i.m.) administration at a dose of 5 mg/kg body weight. OTC plasma concentrations were determined by high-performance-liquid-chromatography (HPLC). A non-compartmental model was used to describe plasma drug disposition after OTC administration. Following i.m. administration, the elimination half-life ( t ½) was 62.65 ± 1.25 h and the bioavailability was 49.80 ± 0.01%. After i.v. administration the t ½ was 50.97 ± 2.99 h, the V d was 534.11 ± 38.58 mL/kg, and CI b was 0.121 ± 0.003 mL/min.kg. The 5 mg/kg i.v. dose used in this experiment resulted in up to 48 h plasma concentrations of OTC above the reported MIC values for some strains of fish pathogens such as Aeromonas hydrophila , A. liquefaciens , A. salmonicida , Cytophaga columnaris , Edwardsiella ictaluri , Vibrio anguillarium , V. ordalii , V. salmonicida and Yeersinia ruckeri . These MIC values are below the susceptible range (4 μg/mL) listed by the National Committee for Clinical Laboratory Standards (NCCLS) as determined by the NCCLS susceptibility interpretive criteria.  相似文献   

9.
The pharmacokinetic properties of norfloxacin were determined in healthy pigs after single intramuscular (i.m.) and intravenous (i.v.) dosage of 8 mg/kg body weight After i.m. and i.v. administration, the plasma concentration-time graph was characteristic of a two-compartment open model. After single i.m. administration, norfloxacin was absorbed rapidly, with a t max of 1.46 ± 0.06 h. The elimination half-life ( t 1/2β) and the mean residence time of norfloxacin in plasma were 4.99 ± 0.28 and 6.05 ± 0.22 h, respectively, after i.m. administration and 3.65 ± 0.16 and 3.34 ± 0.16 h, respectively, after i.v. administration. Intramuscular bioavailability was found to be 53.7 ± 4.4%. Plasma concentrations greater than 0.2 μg/mL were achieved at 20 min and persisted up to 8 h post-administration. Maximal plasma concentration was 1.11 ± 0.03 μg/mL. Statistically significant differences between the two routes of administration were found for the half-lives of both distribution and elimination phases ( t 1/2α, t 1/2β) and apparent volume of distribution (Vd(area)). In pigs, norfloxacin was mainly converted to desethylenenorfloxacln and oxonorfloxacin. Considerable tissue concentrations of norfloxacin, desethylenenorfloxacin, and oxonorfloxacin were found when norfloxacin was administered intramuscularly (8 mg/kg on 4 consecutive days). The concentration of the parent fluoroquinolone in liver and kidney ranged between 0.015 and 0.017 μg/g on day 12 after the end of dosing.  相似文献   

10.
The purpose of this study was to determine the pharmacokinetics and physicochemical characteristics of orbifloxacin in the horse. Six healthy adult horses were administered oral and intravenous orbifloxacin at a dose of 2.5 mg/kg. Plasma samples were collected and analyzed by high-pressure liquid chromatography with ultraviolet detection. Plasma protein binding and lipophilicity were determined in vitro . Following i.v. administration, orbifloxacin had a terminal half-life ( t 1/2) of 5.08 h and a volume of distribution (Vd(ss)) of 1.58 L/kg. Following oral administration, the average maximum plasma concentration ( C max) was 1.25  μ g/mL with a t 1/2 of 3.42 h. Systemic bioavailability was 68.35%. Plasma protein binding was 20.64%. The octanol:water partition coefficient (pH 7.4) was 0.2 ± 0.11. No adverse reactions were noted during this study. Dosage regimens were determined from the pharmacokinetic–pharmacodynamic parameters established for fluoroquinolone antibiotics. For susceptible bacteria, an oral dose of approximately 5 mg/kg once daily will produce plasma concentrations within the suggested range. This dose is suggested for further studies on the clinical efficacy of orbifloxacin for treatment of susceptible bacterial infections in the horse.  相似文献   

11.
Pharmacokinetics of cefoperazone in horses   总被引：1，自引：0，他引：1  
The pharmacokinetics and bioavailabilty of cefoperazone (CPZ) were studied following intravenous (IV) and intramuscular (IM) administration of single doses (30 mg/kg) to horses. Concentrations in serum, urine and synovial fluid samples were measured following IV administration. CPZ concentrations in serum, synovial fluid and spongy bone samples were measured following IM administration. After IV administration a rapid distribution phase ( t 1/2(α):4.22 ± 2.73 min) was followed by a slower elimination phase ( t 1/2(β) 0.77 ± 0.19 h). The apparent volume of distribution was 0.68 ± 0.10 L/kg. Mean synovial fluid peak concentration was 5.76 ± 0.74 μg/mL. After IM administration a bioavailability of 42.00±5.33% was obtained. Half-life of absorption was 2.51 ± 0.72 min and t 1/2(β) was 1.52±0.15 h. The mean synovial fluid and spongy bone peak concentrations at 2 h after IM administration were 2.91±0.85 μg/mL and 5.56±0.70 μg/mL, respectively.  相似文献   

12.
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 high k 12/ k 21 ratios. The excellent tissue penetration of this drug further contributed to the high volume of distribution and high k 12/ k 21 ratios 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 oxytetracycline tissue residues.  相似文献   

13.
This paper describes the pharmacokinetic profile of procaine penicillin G after intraperitoneal (IP) administration in eight lactating dairy cows. Procaine pencillin G (PPG, 21 000 IU/kg) was deposited into the abdominal cavity of each cow following an incision in the right paralumbar fossa. Blood and milk samples were taken over the following 10 days, at which point the cows were euthanized. Plasma, milk, muscle, liver, and kidney penicillin concentrations were determined by HPLC, with a limit of quantification of 5 ng/mL for plasma and milk and 40 ng/g for tissue samples. A noncompartmental method was used to analyze plasma kinetics. The mean pharmacokinetic parameters (±SD) were: C max, 5.5 ± 2.6 μg/mL; T max, 0.75 ± 0.27 h; AUC 0-∞, 10.8 ± 4.9 μg·h/mL; MRT , 2.2 ± 0.9 h. All milk from treated cows contained detectable penicillin residues for a minimum of three milkings (31 h) and maximum of five milkings (52 h) after administration. Concentrations of penicillin in all muscle, liver, and kidney samples taken 10 days postadministration were below the limit of quantification. Necropsy examinations revealed foci of hemorrhage on the rumenal omentum of most cows but peritonitis was not observed. Systemic inflammation as determined by change in leukogram or plasma fibrinogen was noted in one cow. The results of this study demonstrate that IP PPG is absorbed and eliminated rapidly in lactating dairy cows.  相似文献   

14.
Pharmacokinetics of diminazene in female Boran (Bos indicus) cattle   总被引：1，自引：0，他引：1  
The disposition kinetics and bioavailability of diminazene in five healthy heifers were determined after single intravenous (i.v.) and intramuscular (i.m.) administration of the drug in sequence with a wash-out period between administrations of 6 weeks. Intact diminazene in plasma, whole blood and urine samples was analysed using high-performance liquid chromatography. Nonlinear regression analysis of the i.v. and i.m. data indicated that, for either route, the plasma disappearance curves of diminazene were best described by triexponential equations. The i.v. bolus was followed by rapid and biphasic distribution with half-life values of 0.04 h and 0.58 h, Vd(ss) was 1.91 ± 0.42 1/kg, elimination half-life was 31.71 h while CI averaged 1.74 ± 0.40 ml/min/kg. Within 30 min of the i.v. dose, the erythrocyte/plasma partition ratio of diminazene was 0.30 ± 0.15. Diminazene was rapidly absorbed following i.m. administration; t ½ka was 0.60 h. Cmax, 4.68 ± 1.12 μg/ml, was attained in 10–15 min and systemic availability was 102.42 ± 7.25%. The half-life of the terminal disappearance phase was 145.48 h. About 8.26% of the i.m. dose was excreted intact in the urine within the first 24 h of treatment. In vitro , diminazene was bound to bovine plasma albumin to the extent of 38.01–91.10%.  相似文献   

15.
A regime for administration of ampicillin sodium by continuous intravenous infusions to horses was designed. The aim was to achieve plasma ampicillin concentrations between 5 and 10 pgiml over a 4-h period. A 2 mgikg bodyweight loading dose of ampicillin sodium was administered intravenously at the beginning of the infusion in order to achieve steady-state plasma concentra-tions rapidly. The infusion system subsequently administered ampicillin at a rate of approximately 19.2 pglminikg bodyweight. The plasma concentrations obtained over the infusion period correlated very well with predicted calculations based on pharmacokinetic parameters. A mean ± SEM steady-state plasma concentration (Cpss) of 5.94 ± 0.33 was obtained and ampicillin was shown to have an apparent steady-state volume of distribution (Vdss) of 175.43 ± 13.63 ml/kg. When the pump was disconnected the concentrations declined over the following 4 h in an exponential way with an elimination half-life (t1/2β) of 0.62 h. In addition, three different infusion dose rates (13.78, 19.34 and 2 l 4 8 pg/min/kg) were administered to a single animal showing that a good correlation(correlation coefficient > 0.99) existed between the dose administered the steady-state plasma concentrations and the corresponding areas under the plasma concentration versus time curve.  相似文献   

16.
Concentrations of the non-steroidal anti-inflammatory drug (NSAID) alclofenac were determined by a sensitive high performance liquid chromatographic procedure in plasma and urine of horses following oral administration of a dose of 3 g. In plasma, alclofenac was present in detectable concentrations for 72 h. The plasma disposition in individual horses was best described by a bi-compartmental model with two successive rate constants ka1= 0.05 ± 0.06 h-1 and ka2= 0.06 ± 0.01 h-l. Alclofenac half-lives t ½ and t 1/2β were 1.0 ± 0.8 h and 6.9 ± 1.5 h, respectively. Maximal concentrations (38.9 ± 16.2 μg/ml) were obtained after 8.5 ± 2.4 h. Alclofenac was detected in urine for at least 48 h after dosing. The percentage of the dose excreted as unchanged alclofenac in 12 h was very low (0.68 ± 0.19%), total (free + conjugated) alclofenac accounted for 2.16 ± 0.55% of the dose.  相似文献   

17.
Pentoxifylline (7.5 mg/kg) was bolused intravenously to eight healthy horses and was immediately followed by infusion (1.5 mg/kg/h) for 3 h. Clinical parameters were recorded and blood samples were collected for 24 h. Plasma was separated and concentrations of pentoxifylline, its reduced metabolite I, and 6-keto-prostaglandin F1α were determined. Heparinized whole blood was also incubated ex vivo with 1 ng Escherichi coli endotoxin/mL blood for 6 h before determination of plasma tumour necrosis factor activity. The peak plasma concentrations of pentoxifylline and metabolite I occurred at 15 min after bolus injection and were 9.2± 1.4 and 7.8± 4.3 μg/mL, respectively. The half-life of elimination ( t ½β) of pentoxifylline was 1.44 h and volume of distribution ( V darea) was 0.94 L/kg. The mean plasma concentration of 6-keto-prostaglandin F1α increased over time, with a significant increase occurring 30 min after the bolus administration. Ex vivo plasma endotoxin-induced tumour necrosis factor activity was significantly decreased at 1.5 and 3 h of infusion. These results indicate that infusion of pentoxifylline will increase 6-keto-prostaglandin F1α and significantly suppress endotoxin-induced tumour necrosis factor activity in horses during the period of infusion.  相似文献   

18.
The pharmacokinetics of theophylline were investigated in dogs following intravenous, single oral, and multiple oral doses of aminophylline. Mean half-life ( t 1/2) of theophylline following single intravenous administration was 5.7 h and the apparent specific volume of distribution ( V'd area) was 0.82 litre/kg. The bioavailability of theophylline was high (91%) following oral administration of aminophylline tablets and the absorption half-life ( t 1/2 ab) was 0.4 h.
Theophylline plasma concentrations observed following repeated oral administration of aminophylline tablets were somewhat greater than predicted. This suggests that theophylline plasma concentrations should be monitored and the dosage regimen individually adjusted in critically ill animals.  相似文献   

19.
The purpose of this study was to evaluate the pharmacokinetics of lidocaine in mature Holstein cows following an inverted L and caudal epidural nerve block. Plasma and milk concentrations were determined using high-performance liquid chromatography assay. Pharmacokinetic parameters were estimated using a noncompartmental method. Following administration via inverted L nerve block, serum Tmax was 0.521 ± 0.226 h and serum Cmax was 572 ± 207 ng/mL. Serum AUC was 1348 ± 335 ng·h/mL. Apparent serum t½β was 4.19 ± 1.69 h and MRT was 5.13 ± 2.33 h with clearance uncorrected for the extent of absorption of 2.75 ± 0.68 L/kg/h. The last measurable time of lidocaine detection in serum was 8.5 ± 1.4 h with a mean concentration of 51 ± 30 ng/mL. Milk Tmax was detected at 1.75 ± 0.46 h with Cmax of 300 ± 139 ng/mL. Milk AUC till the last time was 1869 ± 450 ng·h/mL with the mean AUC milk to AUC serum ratio of 1.439 ± 0.374. The last measurable time of lidocaine detection in milk was 32.5 ± 16.2 h with a mean concentration of 46 ± 30 ng/mL. There was no detectable lidocaine concentration in any samples following caudal epidural administration.  相似文献   

20.
A high-performance liquid chromatographic method for the determination of the non-steroidal anti-inflammatory drug, oxindanac, in calf plasma is described. Recoveries over the concentration range 0.3 75 to 62.5 μg/ml were 90.2–107.8% with interassay coefficients of variation of 2.1–22.3%. The limit of detection was estimated as 0.10 μg/ml and the limit of quantification calculated to be 0.24 pg/ml in a 1 ml plasma sample. This method was used to establish the pharmacokinetics following intravenous (i.v.), intramuscular (i.m.) and oral (p.o.) administration to calves of oxindanac at a dose rate of 2 mg/kg. The elimination t 1/2, was long ( t 1/2 21.2 h after i.v. injection) and absorption was rapid (t1/2B 0.072 h) and complete ( F > 100%) following i.m. administration. Bioavailability was incomplete ( F = 66.6%) following p.o. administration to calves that had been fed on milk, and Wagner-Nelson analysis revealed twoabsorption phases ( t 1/2's 0.20 and 1.9 h). Oxindanac produced long-lasting inhibition of serum TxB2 production, with mean kmax values (% inhibition) of 96.8, 94.1 and 81.3 following i.v., i.m. and p.0. administration, respectively. A single i.v. or i.m. injection of 2 mg/kg oxindanac will probably be active in calves for at least 36–48 h.  相似文献   

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