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1.
The bioavailability of ascorbic acid administered to thoroughbreds by intramuscular injection was investigated. For intramuscular injection two preparations were studied, and the percentage bioavailability up to 24 h of 10 g of ascorbic acid was 95% +/- 22 in four horses and 60% in two horses with preparations A and B, respectively. Bioavailability at 24 h in three horses injected subcutaneously with 10 g of preparation B was 82%. Intramuscular injection of both preparations was apparently well tolerated while subcutaneous injection of preparation B (pH 6.0) was associated with marked irritancy. In a cross-over trial in seven thoroughbreds the effect of 13 or 15 days of oral administration of crystalline ascorbic acid (20 g) or ascorbyl palmitate (47 g) on plasma ascorbic-acid concentrations was investigated. Marked differences occurred between individuals. There was a greater increase in plasma ascorbic-acid concentration with ascorbyl palmitate compared to ascorbic acid at 6 and 24 h following administration. In two horses there was no increase in plasma ascorbic acid at 6 h following either oral preparation. The finding of lowered plasma ascorbic-acid concentrations following a period of supplementation warrants further investigation to assess its significance.  相似文献   

2.
1. Florfenicol (30 mg/kg body weight) was administered to broiler chickens via intravenous (iv), intramuscular (im) and oral routes to study its plasma concentrations, kinetic behaviour, systemic bioavailability and tissue content.

2. Following a single iv injection, the kinetic disposition of florfenicol followed a 2‐compartmental open model with an elimination half‐life of 173 min, total body clearance of 26.9 ml/kg/min and a steady state volume of distribution of 5.11 1/kg.

3. The highest plasma concentrations of florfenicol were 3.82 and 3.20 μg/ml following single im and oral administration, respectively. The systemic bioavailability was 96.6% and 55.3% after im and oral administration. The plasma protein binding of florfenicol was 18.5%.

4. Following its administration, the highest tissue concentrations of the drug were found in the kidney bile, lung, muscle, intestine, heart, liver, spleen and plasma. Low concentrations of the drug were found in brain, bone marrow and fat. No florfenicol residues were detected in tissues and plasma after 72 h except in the bile from where it disappeared after 96 h.  相似文献   


3.
The use of suitable therapeutic protocols is particularly important when extra-label drugs are used or when physiological parameters are modified, as in the case of the administration of alkaline substances to racehorses. The pharmacokinetics of naproxen (NAP), after both intravenous (iv) and oral administration of 10 mg/kg body weight (BW), was investigated in horses under normal metabolic conditions and in horses whose conditions were modified by the iv administration of 250 mg/kg BW of sodium bicarbonate (NaHCO3). The hypothesis that blood and consequent urinary alkalization could modify NAP pharmacokinetics was evaluated. Drug quantification was performed on serum and urine using High Performance Liquid Chromatography (HPLC) with ultraviolet-visible detection. Results were also integrated with cycloxygenase (COX)-inhibition published data to suggest an appropriate schedule for NAP dosage in horses. After iv administration, NAP was rapidly distributed (t1/2α: 0.71 ± 0.43 iv NaHCO3 and 0.55 ± 0.62 hours No NaHCO3), whereas its elimination was quite slow (t1/2β: 6.74 ± 0.41 hours), particularly in iv NaHCO3 animals (t1/2β: 8.95 ± 1.37 hours). After oral treatments, NAP was more rapidly absorbed and elimination was slower in iv NaHCO3 animals (t1/2λz: 17.50 ± 6.66 vs. 7.17 ± 0.91 hours). The oral bioavailability of NAP was approximately 87% and 77% in No NaHCO3 and iv NaHCO3, respectively. Urinary excretion of the drug as a parent compound was low. The alkalization procedure did not anticipate the elimination of the acidic drug as expected, but it also influenced the absorption of the drug that was administered orally. The dosage scheme of 10 mg/kg BW iv or orally seems to be appropriate to produce an anti-inflammatory effect for 12 to 24 hours.  相似文献   

4.
Carprofen, a non-steroidal anti-inflammatory drug (NSAID) was administered to three Thoroughbred geldings and three Shetland ponies to determine its plasma disposition and tolerance. The main pharmacokinetic characteristics of carprofen in horses and ponies were a volume of distribution of 0.08 to 0.32 litres/kg (mean +/- se = 0.23 +/- 0.04) a systemic clearance of 26.4 to 78.5 ml/min (mean +/- se = 44.9 +/- 8.0) and a plasma elimination half-life of 14.5 to 31.4 h (mean +/- se = 21.9 +/- 2.3). There was no evidence of any accumulation of carprofen in plasma when the drug was given orally at a dose rate of 0.7 mg/kg for 14 consecutive days. Carprofen was well tolerated following intravenous (iv) and oral administration. Intramuscular (im) administration resulted in elevated levels of plasma creatine kinase suggesting muscle cell damage. According to the results of this study carprofen can be regarded as a long-acting NSAID in horses from a pharmacokinetic point of view. Either iv, im or the oral route of administration could be used to achieve high carprofen plasma concentrations.  相似文献   

5.
The pharmacokinetic aspects of sulphadimidine were studied in clinically healthy (control) and Flunixin-medicated horses after a single intravenous and oral administration of 100 mg/kg body weight. Plasma sulphadimidine concentration were determined by high-performance liquid chromatography (HPLC). Following the intravenous injection, all plasma sulphadimidine data were best approximated by a two-compartment open model using sequential, weight non-linear regression. Flunixin induced a 67% increase in the rate of sulphadimidine return to the central compartment from peripheral tissues (K21) and there were a trend to a 30% increase in K12. The sulphadimidine elimination half-life was decreased 21%, the Vdss was reduced by 18% and MRT was decreased by 20%. Following the oral administration, sulphadimidine was rapidly absorbed in control and Flunixin-medicated horses with absorption half-lives (t1/2 ab) of 0.5 and 0.43 hours respectively. The peak plasma concentration (Cmax) were 93.7 and 109 micrograms/ml attained at (tmax) 2.36 and 1.9 hours respectively. The elimination half-life after oral administration (t1/2 ab) was shorter in flunixin pre-medicated horses than in control ones. The systemic bioavalability percentages (F%) of sulphadimidine after oral administration of 100 mg/kg body weight was 79.3 and 71.2% in control and flunixin medicated horses, respectively. Therefore care should be exercised in the use of sulphadimidine in equine patients concurrently treated with flunixin.  相似文献   

6.
Pharmacokinetic studies of cimetidine hydrochloride in adult horses   总被引：1，自引：0，他引：1  
Histamine type II (H2) antagonists inhibit gastric acid secretion and are useful in treating gastric and duodenal ulcer disease. To provide some information on the pharmacokinetics of the H2 antagonist cimetidine, adult horses were given 3.3 mg/kg cimetidine intravenously (iv) or 3.3 and 10 mg/kg orally. Plasma cimetidine concentrations after 3.3 mg/kg orally were too low to measure. Following 3.3 mg/kg iv, cimetidine displayed two-compartment characteristics with a t1/2 of 0.083 +/- 0.039 h and t1/2 of 2.23 +/- 0.64 h. The total body clearance was 0.443 +/- 0.160 litre/h/kg and the mean residence time was 2.74 +/- 1.11 h. This clearance and t1/2 are similar to that in man. The volume of distribution (Vss) and volume of the central compartment (Vc) were 1.138 +/- 0.230 and 0.276 +/- 0.102 litre/kg, respectively. After a single oral dose of 10 mg/kg as crushed tablets, peak plasma concentration of 1.81 +/- 0.82 micrograms/ml occurred at approximately 1.4 h. Oral absorption of cimetidine appeared variable and slow with an extent of absorption of 0.296 +/- 0.183 and a mean residence time for absorption of 1.99 +/- 0.79 h. This was less than in man. Based on a desired average steady state plasma concentration of 1.0 microgram/ml, 11.0 mg/kg/day iv and 48 mg/kg/day orally can be recommended in adult horses.  相似文献   

7.
OBJECTIVE: To determine pharmacokinetics of terbutaline in healthy horses and to relate serum terbutaline concentrations with the drug's pharmacodynamic effects. ANIMALS: 6 healthy horses. PROCEDURE: Horses were given terbutaline i.v. (10 microg/kg of body weight) and, 1 week later, p.o. (100 microg/kg). Responses to drug administration (eg, heart rate and serum lactate concentration) were measured. Serum terbutaline concentration was measured by means of gas chromatography with mass spectrometry. Protein binding was determined in vitro. RESULTS: Following i.v. administration, median maximum serum terbutaline concentration and mean residence time were 9.3 ng/ml and 30 minutes, respectively. Bioavailability following oral administration was < 1%. All horses developed sweating, trembling, excitement, and tachycardia during i.v. infusion. The 2 horses with the highest serum terbutaline concentrations developed severe tachycardia and CNS stimulation; 30 minutes after the i.v. infusion was completed, they were hyperventilating and lethargic. Heart rate and serum lactate concentration increased as serum terbutaline concentration increased. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that terbutaline is rapidly cleared from the bloodstream following i.v. administration to horses, suggesting that continuous i.v. infusion would be needed to maintain therapeutic serum concentrations. Oral administration of terbutaline to horses is not practical because of the low bioavailability.  相似文献   

8.
Two horses with red maple (Acer rubrum) toxicity responded to treatment with high doses of vitamin C (ascorbic acid), in addition to blood transfusions, and intravenous fluid therapy. The clinical course included Heinz body anemia, marked methemoglobinemia, depression, and evidence of severe tissue anoxia. Clinical recovery was dramatic with stabilization achieved 36 hours following the initiation of ascorbic acid therapy.  相似文献   

9.
The absorption of crystalline ascorbic acid, ascorbyl palmitate, ascorbyl stearate and a formulation of ascorbic acid was investigated in six mature Thoroughbred horses following oral administration. It was found that ascorbyl palmitate gave both highest plasma concentrations and greatest area under the curve (AUC) for ascorbic acid. Least variation between animals also occured for this preparation. No apparent absorption was seen in some animals given ascorbic acid or ascorbyl stearate.  相似文献   

10.
OBJECTIVE: To determine concentrations of alpha-tocopherol in serum and CSF of healthy horses following administration of supplemental vitamin E in feed. ANIMALS: 10 healthy adult horses. PROCEDURES: Horses were allocated to receive supplemental d-alpha-tocopherol (1,000 U/d [group A; n=5] or 10,000 U/d [group B; 5]) in feed for 10 days. Blood samples were collected before (baseline), during, and at intervals for 10 days after discontinuation of vitamin E administration for assessment of serum alpha-tocopherol concentration. Cerebrospinal fluid samples were collected prior to and 24 hours after cessation of vitamin E administration. Alpha-tocopherol concentrations in serum and CSF samples were analyzed via high-performance liquid chromatography; changes in those values during the treatment period were compared between groups, and the relationship of serum and CSF alpha-tocopherol concentrations was evaluated. RESULTS: In both groups, serum alpha-tocopherol concentration increased significantly from baseline during vitamin E administration; values in group B were significantly greater than those in group A during and after treatment. At the end of vitamin E administration, CSF alpha-tocopherol concentration was not significantly greater than the baseline value in either group; however, the increase in CSF concentration was significant when the group data were combined and analyzed. Serum and CSF alpha-tocopherol concentrations were significantly correlated at baseline for all horses, but were not strongly correlated after 10 days of vitamin E administration. CONCLUSIONS AND CLINICAL RELEVANCE: In healthy horses, daily oral administration of supplemental vitamin E in feed resulted in increases in serum and CSF alpha-tocopherol concentrations.  相似文献   

11.
Age-related changes in the absorption and distribution patterns of trimethoprim/sulfadiazine were studied following oral or subcutaneous administration of 15 mg/kg of the drug combination in calves. Following oral administration, the time course of trimethoprim/sulfadiazine appearance and dissipation in serum, synovial fluid and urine was followed for periods up to 48 hours in calves one day, one week and six weeks of age. The profiles of drug appearance-disappearance in these body fluids were also determined after subcutaneous administration in seven week old calves. The peak serum and synovial fluid levels of trimethoprim/sulfadiazine achieved following oral administration were substantially lower with increasing maturation. In ruminating (six and seven week old) calves, subcutaneous or oral administration of the combination led to high serum levels of sulfadiazine but little or no serum trimethoprim was detected in animals at this age. The data indicate that, while therapeutic concentrations and optimum ratios of the drugs may be achieved for extended time periods in neonatal life, this dosage is unable to produce optimum serum and synovial fluid concentrations as the calves mature.  相似文献   

12.
Oral administration of ascorbic acid to horses   总被引：1，自引：0，他引：1  
The effects of oral administration of high doses of ascorbic acid on plasma concentrations were investigated in both experimental Thoroughbred horses and those within racing stables. A single oral dose (20 g) did not result in any increase in plasma concentrations. However, daily administration of either 4.5 g or 20 g doses resulted in significant increases in plasma concentrations. Monthly variations in plasma ascorbate concentrations were found in both supplemented (20 g daily) and unsupplemented stables. It is concluded that oral supplementation with ascorbic acid is a satisfactory route to increase plasma and tissue concentrations.  相似文献   

13.
The objective of this study was to investigate the pharmacokinetics of marbofloxacin (MAR) following intravenous (iv) and intramuscular (im) administration of a 2.0 mg/kg body weight dosage to five healthy Egyptian buffalo steers. A cross-over design was used with a washout period of 2 weeks. Blood samples were obtained at 0, 5,10,15, and 20 min and at 0.5,0.75,1,2,4,6,8,10,12,24,30 and 48 hours after marbofloxacin administration.The serum marbofloxacin concentrations were quantitated using a modified agar diffusion bioassay method. Marbofloxacin exhibited a relatively high volume of distribution at steady-state (Vdss = 1.77 Lkg), which suggests good tissue penetration, and a total body clearance (Cltot) of 0.18 L/kgxh,which is associated with a long elimination half-life (tl/2beta = 7.52 h). Marbofloxacin was rapidly absorbed at a dosage of 2.0 mg/kg after im administration with an observed maximum serum concentration (Cmax) value of 2.004 microg/mL obtained at a time to peak concentration (tmax) of 0.5 h, and an absolute bioavailability (F %) of 86.79 +/- 5.53 %.The protein-binding ranged from 22 to 24.6 % with an average of 23.4 %. In conclusion, single iv and im administered doses of marbofloxacin were well tolerated by Egyptian buffalo steers. A dosage of 2 mg/kg body weight might not be enough to treat infections caused by bacteria with minimum inhibitory concentration (MIC) at or above 0.2 microg/mL, based on the calculated area under the inhibitory concentration (AUIC).  相似文献   

14.
The reversal of the cardiovascular effects of the α2-adrenoceptor agonist detomidine by the α2-antagonist atipamezole was studied. Nine horses were given detomidine 20 μg/kg iv. On a separate occasion they were given atipamezole 100 μg/kg iv 15 mins after the detomidine injection. Blood gas tensions were measured and clinical signs of sedation were also observed. Bradycardia and the frequency of heart blocks induced by detomidine were reduced after atipamezole and blood pressure decreased. These reversal effects of atipamezole were of short duration (a few minutes) at the dose level tested. Two of the nine horses exhibited premature depolarisations after administration of detomidine, but not after atipamezole injection. PaO2 decreased and PaCO2 increased slightly after detomidine injection, but the arterial pH was within reference values or slightly elevated. Administration of atipamezole did not alter these values. Base excess rose after detomidine, and it decreased more quickly towards the baseline level, when the horses were given detomidine alone. No clinical adverse effects were seen from the administration of atipamezole. Atipamezole may be beneficial, if detomidine-induced bradycardia needs to be reversed in horses.  相似文献   

15.
1. This study was conducted using male broiler chickens to determine the effects of ascorbic acid, aspirin, ascorbic acid+aspirin, vitamin E+selenium and ascorbic acid+aspirin+vitamin E+selenium supplementations on haematological parameters and serum superoxide dismutase concentration. 2. One hundred and twenty day-old male Hubbunt broiler chicks were randomly divided into 6 experimental groups of 20 chicks each and placed in different pens. Groups 2, 3, 4, 5 and 6 were given a diet supplemented with ascorbic acid, aspirin (in water), ascorbic acid+aspirin, vitamin E+selenium and ascorbic acid+aspirin+vitamin E+selenium, respectively for 45 d while group 1 was given a commercial broiler diet. 3. There was no significant effect of ascorbic acid, aspirin, ascorbic acid+aspirin, vitamin E+selenium supplementations on any of the haematological parameters (red blood cell, haemoglobin, haematocrit, mean corpuscular volume, mean corpuscular haemoglobin concentration, mean corpuscular haemoglobin) in broilers but ascorbic acid+aspirin+vitamin E+selenium supplementation significantly decreased the white blood cell counts. 4. In addition to this, ascorbic acid, aspirin, ascorbic acid+aspirin and ascorbic acid+aspirin+vitamin E+selenium supplementations had no significant effect on the serum superoxide dismutase level, but vitamin E+selenium supplementation increased the serum superoxide dismutase level.  相似文献   

16.
An oral vitamin E absorption test used in human beings was modified for use in horses. The most appropriate techniques with which to measure gastrointestinal tract absorption of vitamin E (alpha-tocopherol) in horses were developed. Vitamin E was administered orally, and serum values of alpha-tocopherol were measured by use of high-performance liquid chromatography at 0, 3, 6, 9, 12, and 24 hours after vitamin E administration. Variables included comparison of 2 dosages (45 and 90 IU/kg of body weight), routes of administration, and absorption dynamics of 3 preparations of dl-alpha-tocopherol. Absorption of the 2 doses of dl-alpha-tocopherol acetate indicated a dose response; the area under the curve at 24 hours (AUC24) was 4.3 micrograms.h/ml for the 45-IU/kg dose and 32.2 micrograms.h/ml (P less than 0.01) for the 90-IU/kg dose. Maximal absorption was apparent when vitamin E was naturally consumed in grain, compared with administration of identical preparations by stomach tube or paste. In the same horses, dl-alpha-tocopherol and dl-alpha-tocopherol acetate plus polyethylene glycol had statistically similar absorption curves and both had significantly greater AUC24, compared with dl-alpha-tocopherol acetate; values for the 3 compounds were 23.6, 25.8, and 12.6 micrograms.h/ml, respectively. The AUC24 varied between individual horses, but time of peak value was consistently observed between 6 and 9 hours.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

17.
Medetomidine/ketamine sedation in calves and its reversal with atipamezole   总被引：1，自引：0，他引：1  
Atipamezole was used to reverse the sedation induced in calves by medetomidine/ketamine. Thirteen claves subjected to umbilical surgery received medetomidine 20 μg/kg bodyweight (bwt) and ketamine 0.5 mg/kg bwt intravenously (iv) from a mixture of the drugs in one syringe. Atipamezole was given at doses of 20 to 60 μg/kg iv and intramuscularly (im) to the calves at the end of the operation. Following the administration of medetomidine and ketamine, PaCO2 increased whereas pH, PaO2 and heart rate decreased. Reversing the effects of medetomidine with atipamezole did not cause undesirable effects; recovery was rapid and smooth, most of the animals reached a standing position within 1 to 3 mins after the atipamezole injection.  相似文献   

18.
1. Disposition kinetics were compared in healthy chickens and in chickens naturally infected with E. coli following the intravenous, intramuscular and oral administration of chloramphenicol in a single dose of 20 mg/kg body weight. 2. Lower serum chloramphenicol concentration in diseased chickens were reported after intravenous injection, but they were higher than normal 30 min after intramuscular and oral administration. Following intravenous injection the volume of distribution was increased in diseased chickens. 3. The biological half-life in normal chickens was 8.32 +/- 0.5 h and was prolonged in diseased birds (26.21 +/- 0.2 h). The body clearance of chloramphenicol was reduced in diseased chickens. 4. The rate of absorption of chloramphenicol was delayed after administration via the oral route but the extent of absorption was increased. The maximum concentration was higher and it was reached after a longer time in diseased than in normal chickens after administration by both intramuscular and oral routes.  相似文献   

19.
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 phenytoin.  相似文献   

20.
The purpose of this study was to determine the pharmacokinetics of etodolac following oral and intravenous administration to six horses. Additionally, in vitro cyclooxygenase (COX) selectivity assays were performed using equine whole blood. Using a randomized two-way crossover design, horses were administered etodolac (20 mg/kg) orally or intravenously, with a minimum 3-week washout period. Plasma samples were collected after administration for analysis using high pressure liquid chromatography with ultraviolet detection. Following intravenous administration, etodolac had a mean plasma half-life (t(1/2)) of 2.67 h, volume of distribution (Vd) of 0.29 L/kg and clearance (Cl) of 234.87 mL/h kg. Following oral administration, the average maximum plasma concentration (Cmax)) was 32.57 mug/mL with a t(1/2) of 3.02 h. Bioavailability was approximately 77.02%. Results of in vitro COX selectivity assays showed that etodolac was only slightly selective for COX-2 with a COX-1/COX-2 selectivity ratio effective concentration (EC)50 of 4.32 and for EC80 of 4.77. This study showed that etodolac is well absorbed in the horse after oral administration, and may offer a useful alternative for anti-inflammatory treatment of various conditions in the horse.  相似文献   

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