bluuebunny/crossref_metadata_2025_split huggingface dataset:
Antagonism of endotoxin‐induced disruption of equine gastrointestinal motility with the platelet‐activating factor antagonist WEB 2086
Authors: KING J. N. , GERRING E. L. 
Published: April 2008

King, J.N. & Gerring, E.L. Antagonism of endotoxin‐induced disruption of equine gastrointestinal motility with the platelet‐activating factor antagonist WEB 2086. J. vet. Pharmacol. Therap. 13, 333–339.The effect of pre‐treatment with a selective platelet‐activating factor (PAF) antagonist, WEB 2086, on the actions of low‐dose endotoxin was evaluated in ponies prepared with gastrointestinal strain gauges. Endotoxin (0.1 μg/kg i.v.) produced a marked reduction in gastric contraction amplitude and rate, and an increased frequency and reduced duration of jejunal phase III activity fronts (AFs). WEB 2086 (6.6 mg/kg) administered i.v. 10 min before the endotoxin, produced significant antagonism (P < 0.001) of the effect of endotoxin on gastric contraction amplitude and rate. The combination of WEB 2086 and endotoxin produced gastric contractions of significantly (P < 0.01) higher frequency than in the control studies. WEB 2086 also reduced endotoxin‐induced abnormal phase III AFs in the jejunum and increases in heart rate and packed cell volume. These results provide evidence that endogenous PAF plays a role in mediating the acute effects of endotoxin on equine gastrointestinal motility. J. N. King, Centre de Recherches Agricoles, CH‐1566 St‐Aubin FR, Switzerland.
Pharmacokinetics of intravenously, intramuscularly and intra‐adiposely administered carazolol in pigs
Authors: KADIR F. , ZUIDEMA J. , PIJPERS A. , MELENDEZ R. , VULTO A. , VERHEIJDEN J. H. M. 
Published: April 2008

Kadir, F., Zuidema, J., Pijpers, A., Melendez, R., Vulto, A. & Verheijden, J.H.M. Pharmacokinetics of intravenously, intramuscularly and intra‐adiposely administered carazolol in pigs. J. vet. Pharmacol. Therap. 13, 350–355.The ß‐blocking agent carazolol is used for the prevention of stress syndromes in pigs. Little is known of the pharmacokinetics of this drug, and therefore of its residue status in meat. In this study carazolol pharmacokinetics were investigated in a randomized three‐way cross‐over design in five pigs. A dose of 0.025 mg/kg was given intravenously, intramuscularly and intra‐adiposely (in the subcutaneous fat layer). Carazolol was rapidly distributed and had a short half‐life of 1.2–4.2 h. The distribution volume was calculated to be 0.22‐0.65 1/kg. After intramuscular or intra‐adipose administration the absorption pattern was biphasic. A rapid initial phase was followed by a slow second phase. Absorption was found to be incomplete at 24 h after intramuscular and intra‐adipose administration ranging from 24 to 59% and 25 to 66%, respectively. The biphasic behaviour could be explained by retention of the drug in the tissues after absorption of the solvent was complete. A few hours after intravenous administration only negligible amounts of the drug were circulating in the body; however, considerable amounts of drug might have remained at the intramuscular or intra‐adipose injection site. F. Kadir, Department of Pharmaceutics, University of Utrecht, Croesestraat 79, 3522 AD, Utrecht, The Netherlands.
Pharmacokinetics and bioavailability of erythromycin in pigeons (Columba livia)
Authors: VANHAECKE E. , De BACKER P. , REMON J. P. , DEVRIESE L. A. 
Published: April 2008

Vanhaecke, E., De Backer, P., Remon, J.P. & Devriese, L.A. Pharmacokinetics and bioavailability of erythromycin in pigeons (Columba livia). J. vet. Pharmacol. Therap. 13, 356–360.Tissue and plasma concentrations were determined after intravenous and oral administration of erythromycin to pigeons to establish the pharmacokinetics and bioavailability of the drug. A short mean half‐life of elimination of 0.9 h was found. The relative bioavailability after direct crop administration of erythromycin thiocyanate or erythromycin ethylsuccinate at a dosage rate of 100 mg/kg was less than 10%. At a drug concentration in drinking water of I g/I, erythromycin plasma levels were barely detectable, whilst lung and trachea concentrations reached a maximum of 1.6 μg/ml. Even after crop administration of 100‐mg/kg erythromycin thiocyanate, low plasma levels were obtained, whilst lung and trachea concentrations were substantially higher. Prescribed drinking‐water regimens seemed unable to yield therapeutic tissue concentrations. Only individual crop administration seemed an appropriate medication method. The use of erythromycin ethylsuccinate did not present any advantage in comparison with erythromycin thiocyanate. J. P. Remon, Laboratory of Pharmaceutical Technology, Slate University of Ghent, Harelbekestraat 72, B‐9000 Ghent, Belgium.
Oral chloramphenicol in dwarf goats‐influence of vasopressin on its absorption and effect of diet on its biodegradation in ruminal fluid samples
Authors: NIJMEIJER S. M. , SAMURIWO E. , van DUIN C. T. M. , van MIERT A.S.J.P.A.M. 
Published: April 2008

Nijmeijer, S.M., Samuriwo, E., van Duin, C.T.M. & van Miert, A.S.J.P.A.M. Oral chloramphenicol in dwarf goats‐influence of vasopressin on its absorption and effect of diet on its biodegradation in ruminal fluid samples. J. vet. Pharmacol. Therap. 13, 408–414.The biodegradation of chloramphenicol was studied by incubating the drug (at concentrations of 72, 48 and 24 g/ml) with ruminal fluid samples from dwarf goats fed two different diets. Biodegradation of the drug was much faster in samples from animals which were fed with hay and concentrate than in those obtained from goats which were fed grass pellets only. Recently, it has been suggested that lysine‐vasopressin injected intravenously induces closure of the oesophageal groove in catde and goats. Therefore, the influence of lysine‐vasopressin on the oral absorption of chloramphenicol (50 mg/kg body wt) was studied in dwarf goats, using two formulations of chloramphenicol. The results suggest that vasopressin failed to induce this reflex mechanism. Furthermore, the shapes of the plasma concentration‐time curves after oral administration of chloramphenicol palmitate and chloramphenicol dissolved in propylene glycol were markedly different. Possible mechanisms for the observed differences are discussed. S. M. Nijmeijer, Department of Veterinary Basic Sciences, Division PPPT, Faculty of Veterinary Medicine, PO Box 80.176, 3508 TD Utrecht, the Netherlands.
Plasma protein binding of nitroxynil in several species
Authors: ALVINERIE M. , FLOC'H R. , GALTIER P. 
Published: April 2008

The binding of nitroxynil to total plasma proteins of cows, sheep and rabbits was characterized using equilibrium dialysis. The data indicate clearly that nitroxynil was highly (97‐98%) bound to plasma protein of each animal. This linear binding would be due to the particular power exerted by serum albumin.The results are in good agreement with known pharmacokinetic properties of nitroxynil in domestic species.
Pharmacokinetics and intramuscular bioavailability of amikacin in chickens following single and multiple dosing
Authors: EL‐GAMMAL A. A. , RAVISt W. R. , KRISTA L. M. , TOLBERT D. S. , SAAD A. 
Published: April 2008

The pharmacokinetics of amikacin were studied in healthy mature female chickens (n =6). Single doses of amikacin were injected as an i.v. bolus (10 mg/ kg) and im. (20 mg/kg) into the same birds with a 30‐day rest period between treatments. Amikacin was determined by the fluorescence polarization im‐munoassay method. The i.v. pharmacokinetics could be described by a two‐compartment model with a t1/2αof 0.150 ± 0.064 h and a t1/2βof 1.44 ± 0.34 h. The total body clearance was 0.109 ± 0.017 l/h/kg and the volume of distribution at steady‐state was 0.193 ± 0.060 Vkg. Following a single i.m. injection. the peak plasma concentration (Cmax) was 50.79 ± 4.05 μg/ml and occurred at 0.50 ± 0.26 h. The i.m. extent of absorption was 91.2 ± 17.65%. Simultaneous modeling of i.v. antl i.m. results provided estiinates of an absorption half‐life of 0.480 ± 0.158 h.The i.m. pharmacokinetics after repeated administration were stittlied following the tenth close (20 mg/kg, every 8 h). The Cssmaxwas 38.58 ± 6.96 pgi nil and occurred at 0.79 ± 0.37 11, and the biological half‐life of aniikncin was 1.86 5 0.47 11. The multiple closing yielded peak concentrations of 39 μg/ml and trough concentrations of 3.26 μg/ml. Based on these data, the recomnienclecl amikacin dosage in chickens is 20 mg/kg body weight every 8 h.
Prescribing of drugs for food‐producing animals in Norway. Information about withdrawal times
Authors: BANGEN M. , SKJERVE E. , GRAVE K. , SØLI N. E. 
Published: April 2008

The prescribing of drugs for food‐producing animals in Norway was investigated with special emphasis on written information given about withdrawal times. The study was designed as a cross‐sectional prescription survey.Of 1518 prescriptions for food‐producing animals, it was concluded that 1224 of the prescriptions were for drugs requiring withdrawal times for meat, milk or eggs. Of these 1224 prescriptions, 82.8% were for veterinary preparations, 6.6% were for human preparations and 10.6% were for other drugs.For 20.8% of the prescriptions, information about withdrawal time(s) was missing. For prescriptions for veterinary preparations this figure was 5.9%, and for prescriptions for human preparations and other drugs 95.1% and 90.8%, respectively. For veterinary preparations approved for the intended species, as many as 99.2% gave information about withdrawal times on the drug container label.Lack of information about withdrawal times might give rise to drug residues in food for human consumption and thus pose a potential hazard to human health.
Pharmacokinetics of single intravenous and single and multiple dose oral administration of rifampin in mares
Authors: KOHN C. W. , SAMS R. , KOWALSKI J. J. , POWERS J. , WALLACE S. 
Published: April 2008

The disposition of rifampin in six healthy mares after single intravenous (i.v.) and oral (p.o.) doses and after seven oral doses of 10 mg/kg administered twice a day was investigated using a high performance liquid chromatographic (HPLC) method. Pharmacokinetic variables for rifampin determined using the HPLC method were comparable to variables reported from earlier studies utilizing a microbiological assay. Desascetylrifampin, a major metabolite of the parent compound, could not be detected in the serum but was detected at low concentrations in urine. Mean trough concentrations of rifampin increased from the first to the second dose of the multiple dose oral study and then remained unchanged through 72 h. At 84 h after the first dose (i.e. 12 h after the final dose) the rifampin concentration was significantly decreased (P= 0.001). The harmonic mean of the half‐life of rifampin decreased significantly from 13.3 h after a single oral dose of 7.99 h after the seventh oral dose. The mean serum protein binding of rifampin over the concentration range of 2–20 μg/ml was 78%. Mean trough serum concentrations of unbound rifampin after multiple oral doses ranged from 0.67 μg/ml at 24 h to 0.40 μg/ml at 72 h. The mean unbound serum rifampin concentration at 84 h (i.e., 12 h after the final dose) was 0.30 μg/ml. Trough concentrations and the 84‐h sample concentration of unbound rifampin exceeded the minimum inhibitory concentration for most gram positive bacterial isolates from horses reported in this study. All organisms with minimum inhibitory concentrations less than 0.125 μg/ml were considered susceptible.Based on the pharmacokinetics of rifampin after p.o. administration, we concur with the current dosage recommendation of 10 mg/kg twice a day by mouth. At this dose, most streptococci,Rhodococcus equi, and coagulase‐positive staphylococci would be considered susceptible to rifampin.
The disposition of suxibuzone in the horse
Authors: DELBEKE F. T. , VYNCKIER L. , DEBACKERE M. 
Published: April 2008

A high performance liquid chromatographic method is described to determine the anti‐inflammatory drug suxibuzone (SXB) and its major metabolites phenylbutazone (PBZ) and oxyphenbutazone (OPBZ) in equine plasma and urine. When suxibuzone (6 mg/kg) was administered intravenously (i.v.) or orally (p.o.) no parent drug was detected in plasma or in urine. The disposition of the metabolite PBZ (i.v.) could be described by a 2 compartment model with a P half‐life varying from 7.40 to 8.35 h. Due to severe side effects the use of i.v. suxibuzone should not be encouraged in the horse. PBZ and OPBZ were detected in plasma and urine after p.o. SXB administration. Peak plasma PBZ concentrations (8.8 ± 3.0 μg/ml) occurred 6 h after oral dosing and the terminal exponential constant was 0.11 ± 0.01 h‐1. Phenylbutazone and oxyphenbutazone were detectable in urine (> 1 μg/ml) for at least 36 h, after p.o. administration.SXB was not hydrolyzed in vitro by horse plasma. Equine liver homogenates however appeared to have a very high capacity for hydrolysing SXB, indicating that first‐pass effect could be responsible for the rapid disappearance of this NSAID in the horse.
Effect of endotoxin on tirilazad mesylate (U74006F) pharmacokinetic parameters in neonatal calves
Authors: ROSE M. L. , SEMRAD S. D. , PUTNAM M. L. , BROWN S. A. 
Published: April 2008

Rose, M.L., Semrad, S.D., Putnam, M.L., Brown, S.A. Effect of endotoxin on tirilazad mesylate (U74006F) pharmacokinetic parameters in neonatal calves.J. vet. Pharmacol. Therap. 16, 438–445.The pharmacokinetics of the 21‐aminosteroid tirilazad mesylate (U74006F) were studied in both healthy and endotoxin‐challenged neonatal calves. Group I calves received a 3‐h intravenous (i.v.) infusion of sterile saline (250 ml) and tirilazad mesylate (1.5 mg/kg i.v.) 1 h after the start of the saline infusion. Group II calves received tirilazad mesylate 1 h after the start of a 3‐h endotoxin (3.25 &#x006d;̈g/kg) infusion. The data obtained indicate that tirilazad mesylate follows a biexponential equation in neonatal calves. The area‐derived volume of distribution (Vdarea) was 9.68 ± 0.759 1/kg in healthy calves and 6.53 ± 1.20 1/kg in endotoxin‐challenged calves (P< 0.05). Similarly, significant(P<0.05) decreases in steady‐state volume of distribution (Vjss) and central volume (VJ were observed in endotoxin‐challenged calves (5.32 ± 0.979 1/kg and 1.68 ± 0.189 1/kg, respectively) compared to healthy calves (7.58 ± 0.834 1/kg and 2.43 ± 0.452 1/kg, respectively). A and B were significantly larger in endotoxin‐challenged calves than in healthy calves (P< 0.05). Rate constants and their associated half‐lives, area under the curve and clearance were not significantly altered by endotoxin challenge. Serum thromboxane generation(ex vivo)was evaluated as a marker of the drug's physiologic activity. There was no significant difference in thromboxane generation during clotting of blood from healthy and endotoxemic calves treated with tirilazad mesylate.
Disturbances in ex vivo vascular smooth muscle responses following exposure to Pasteurella haemolytica vaccines
Authors: WEEKLEY L. B. , EYRE P. 
Published: April 2008

Weekley, L.B., Eyre, P. Disturbances in ex vivo vascular smooth muscle responses following exposure to Pasturella haemolytica vaccines. J. vet. Pharmacol. Therap.16, 446–453.Rats were vaccinated with saline (control) or one of the two commercially availablePasteurella haemolyticavaccines Presponse or Precon‐PH. Animals were killed 3 days later and thoracic aorta removed for evaluation of theex vivobiophysical responses to carbachol (CCh). In some experiments, vascular endothelium was mechanically removed. Vaccination of rats impairs the endothelial‐dependent relaxation to CCh. In vessels with endothelium removed, the contractile response to CCh is converted into a relaxation following vaccination. Treatment of endothelial‐denuded vascular ringsex vivowith methylene blue, a guanylate cyclase inhibitor, reduced the vaccination effect. Treatment of vascular rings with the superoxide dismutase inhibitor diethyl‐dithiocarbamate, impairs the relaxant reponse of de‐endothelialized vessels to CCh in Presponse vaccinated rats while enhancing the relaxation response of vessels from Precon‐PH vaccinated rats. De‐endothelialized vessels from vaccinated rats, but not control rats, relaxed in the presence of 7V‐monomethyl‐L‐arginine (L‐NMMA), a competitive inhibitor of nitric oxide synthetase. Furthermore, in the presence of L‐NMMA, the relaxant response to CCh is significantly enhanced by Precon‐PH but not Presponse. The normal relaxant response to hydrogen peroxide is converted into a contraction following vaccination. Results suggest that exposure to commercially availableP. haemolyticavaccines alters vascular smooth muscle reactivity to CCh and that several independent pathways may be altered.
Propofol as an induction agent in the goat: a pharmacokinetic study
Authors: REID J. , NOLAN A. M. , WELSH E. 
Published: April 2008

Reid, J., Nolan, A.M., Welsh, E. Propofol as an induction agent in the goat: a pharmacokinetic study. J. vet. Pharmacol. Therap. 16, 488–493.The pharmacokinetics of propofol, 4 mg/kg, administered as a bolus dose intravenously (i.v.) prior to the maintenance of anaesthesia with halothane in oxygen, were determined in five goats, and a clinical impression of its use as an induction agent was made. Induction of anaesthesia was rapid and smooth, providing satisfactory conditions for intubation in all animals. Post‐induction apnoea occurred in one goat and minimal regurgitation of ruminal contents was recorded in two animals. Recovery times were rapid with a mean time to standing after halothane inhalation ceased of 13.7 min. The blood propofol concentration time profile was best described by a bi‐exponential decline in all five goats. The mean elimination half‐life was short (15.5 min), the volume of distribution at steady state large (2,56 1/kg) and the clearance rapid (275 ml/min.kg). Propofol was shown to be a very satisfactory induction agent in the goat.
Pharmacokinetic disposition of intravenous and oral pentoxifylline in horses
Authors: CRISMAN M. V. , WILCKE J. R. , CORRELL L. S. , IRBY M. H. 
Published: April 2008

The pharmacokinetics of pentoxifylline (P) and its alcohol metabolite I (MI) were determined after administration of intravenous pentoxifylline, sustained release pentoxifylline tablets (Trental®), and crushed pentoxifylline tablets in corn syrup, to five healthy adult horses. Pharmacokinetics were evaluated in a model‐independent manner. After intravenous administration, pentoxifylline was rapidly eliminated (mean residence time 1.09 f 0.67 h), had a large steady‐state volume of distribution (2.81 f 1.16 Vkg), and high clearance (3.06 51.05 I/kg/h). Oral absorption of pentoxifylline from both dose forms variedconsiderably between individuals. Times to peak concentration ranged from 1–10 h for either dose form. There was no difference in relative bioavailability (Fâ'™)between whole (0.98 k 0.30) and crushed Trental® tablets. Ratios between areas under the curve (AUC) for pentoxifylline and MI were different following administration of oral versus intravenous doses. This finding suggests that route of administration may affect the metabolic profile of pentoxifylline. Given the extreme differences in absorption characteristics between indi‐viduals in this study, recommendations are not made as to appropriate dose, dose interval, or dose form for administration of pentoxifylline to horses.
Plasma ronidazole concentrations in sheep after intravenous, oral, intraruminal and intraabomasal administration
Authors: VYNCKIER L. J. , DEBACKERE M. 
Published: April 2008

Plasnia ronidazole concentrations were examined after intravenous (i.v.) antloral administration of ronidazole in sheep (t i = 6) at;I dosage of 5 mg/kg Iiody weight. In three sheep a ruminal and an abomasal fistula were inserted. l'heronidazole determinations were performed by an HPLC method. Oral bioav;iil‐ability in the fistulated sheep was only 5.5 k 1.8% (mean k SE). Somewhat lower values (4.6 k 1.45%) were obtained when the drug was administered through the ruminal fistula in the rumen. After administration of the sanie dose directly in the abomasum through the intraaboiiiasal fistula, 1)ioavailability was increased t o 86.0 k 8.9%. In the non‐fistulated sheep, oral biodisponibility was 2.6 k 0.5%.After water was restricted for 48 h before the oral ronidazole administration t othese sheep, bioavailability was slightly increased (6.0 k 9.1 %). When desmo‐pressin acetate was injected i.v. before the oral ronidazole;idministration,bioavailability was 10.6 k 6.5%. When glypressiii,;t1101her vasopressin analogue,was used, oral bioavailability was not influenced: 2.4 f 1.3%. Konitlazole wasalso incubated with ruminal contents antl the ronitlamle concer1tr;ition tle‐creased with a first order rate constant of ‘0.122 rfr 0.050 miri‐’ (mean f SF,).These results suggest that oral atfrniiiistration of ronidazole to sheep is o f littletherapeutic use, because most is metabolised by the ruminal triicro‐organisiiisbefore it can reach the circulation. A second conclusion we can make is that i t isvery difficult, if not impossible, at least with the methods used, to influencegastro‐intestinal motility in sheep to get a reprotlucahle closure of I heoesophageal groove.
Endothelin and vasoactive peptides: new cardiovascular mediators
Authors: GWATHMEY J. K. , PAIGE J. A. 
Published: April 2008

Gwathmey, J.K., Paige, J.A. Endothelin and vasoactive peptides: new cardiovascular mediators. J, vet. Pharmacol. Therap. 17,420–425.A newly discovered family of vasoactive peptides, endothelins, have strong inotropic and chronotropic effects on the myocardium. Recent studies suggest a possible role for endothelin in pathophysiological states. The ability of these peptides to stimulate mitogenesis in smooth muscle and fibroblasts, coupled with their contribution to the regulation of gene expression and secretion of other neurohumoral mediators, raises the possibility that endothelins may contribute to the development of heart disease. Elevated levels of circulating endothelin have been found in the setting of elevated peak systolic pressure, pulmonary hypertension myocardial infartion, and congestive heart failure. This paper discusses the potential role of endothelin as a regional mediator of pathophysiological states.
Thiamphenicol pharmacokinetics in sheep
Authors: ABDENNEBI E. H. , KHALES N. , SAWCHUK R. J. , STOWE C M 
Published: April 2008

Abdennebi, E.H., Khales, N., Sawchuk, R.J., Stowe, CM. Thiamphenicol pharmacokinetics in sheep. J. vet. Pharmacol. Therap. 17, 12–16.The pharmacokinetics of thiamphenicol were investigated after intravenous (i‐v.). intramuscular (i.m.) and oral (p.o.) administration to sheep. It was found that the drug is almost completely absorbed following intramuscular injection, with a bioavailability of about 8 7.5%. Thiamphenicol appears to be widely distributed into extravascular compartments, yielding a volume of distribution [V(b)] of approximately 1 1/Kg. Elimination from the blood is relatively rapid, with a biological half‐life of about 1.5 h. Oral treatment showed that thiamphenicol is absorbed from the gastrointestinal tract yielding very low plasma concentrations which were maintained for at least 24 h. Although only 30% of the oral dose was systemically available, in contrast to chloramphenicol, thiamphenicol is truly absorbed when given orally to adult sheep. One possible reason for this observation is that rumen flora do not biotransform this drug as they do for chloramphenicol. Metabolism investigations are, however, needed to confirm this finding.