Topic:Drug
The topic of drugs and horses encompasses the study of various pharmacological agents used in equine medicine for therapeutic purposes. This includes the administration of medications for pain management, disease treatment, and performance enhancement. The pharmacokinetics and pharmacodynamics of drugs in horses are key areas of research, as they determine the absorption, distribution, metabolism, and excretion of these substances. Additionally, the topic covers the detection and regulation of substances in competitive equestrian sports to ensure fair play and animal welfare. This page compiles peer-reviewed research studies and scholarly articles that explore the effects, safety, and regulatory aspects of drug use in equine health and performance.
Clinical use of epidural xylazine in the horse. Xylazine was administered into the epidural space of nine horses to facilitate various perineal manipulations (ie rectovaginal laceration repair, replacement of prolapsed rectum and urethral extension). The resulting caudal analgesia was sufficient for all procedures. The duration of analgesia from a single injection of epidural xylazine (0.17 to 0.22 mg/kg bodyweight) was at least 3.5 h. No horses were ataxic during or after the treatment. This trial demonstrates that xylazine given into the epidural space of horses provides prolonged regional analgesia which is sufficient for clinical use.
Influence of furosemide on the detection of flunixin meglumine in horse urine samples. The possibility of false negative results from TLC when a diuretic is administered concomitantly with flunixin was studied. Samples were subjected to solvent extraction from acidic aqueous solutions; duplicate samples were also subjected to alkaline hydrolysis at pH 12.5. The internal standard was flufenamic acid. The quantification of flunixin was performed by HPLC and the results confirmed by GC/MS. The data show that furosemide influences the urinary concentration of flunixin.
Effects of furosemide on the racing times of Thoroughbreds. The effects of furosemide on the racing times of 79 horses without exercise-induced pulmonary hemorrhage (EIPH) and 52 horses with EIPH were investigated. Racing times were adjusted to 1-mile equivalent racing times by 2 speed handicapping methods, and analysis of covariance was used to adjust actual racing times by winning time and distance for each race. All 3 methods of determining racing time indicated that geldings without EIPH had significantly faster racing times (P less than 0.05) when given furosemide before racing than when furosemide was not given before racing. Females and colts wi...
Plasma disposition and tolerance of aditoprim in horses after single intravenous injection. Aditoprim, a broad spectrum antimicrobial agent acting as a reversible dihydrofolate reductase inhibitor, was intravenously injected into four 12 to 24-year old horses at a dosage of 5 mg/kg b. w. Blood samples were collected over a 48-hour period after drug injection, and the separated plasma samples were assayed for aditoprim by high performance liquid chromatography. The body temperature, heart rate, respiration rate, and behaviour were recorded during the experiment. The bilirubin and urea concentrations were also determined in several plasma samples, and liver function tests were carried ...
Effect of clenbuterol on arterial oxygen tension in the anaesthetised horse. In horses in dorsal recumbency, spontaneously breathing oxygen, with halothane at a constant end-tidal concentration, the arterial oxygen tension (PO2) increased from 9.9 +/- 0.3 SEM kPa to 21.7 +/- 4.0 kPa with 0.8 micrograms kg-1 clenbuterol and to 29.1 +/- 3.8 kPa with 2.4 micrograms kg-1 clenbuterol. In horses initially in dorsal recumbency then turned to sternal recumbency the PaO2 rose to 54.0 +/- 3.0 kPa, but this rise was unaffected by clenbuterol administration. The response in dorsal recumbency was consistent with clenbuterol counteracting the factor postulated to direct the pulmonar...
Propafenone kinetics in the horse. Comparative analysis of compartmental and noncompartmental models. The propafenone kinetics after intravenous (i.v.) administration have been studied in the horse by a comparative analysis of compartmental and noncompartmental models. The pharmacokinetic parameters showed a large distribution (Vdss = 1021 +/- 211 L) and a high clearance (CI = 7019 +/- 1746 mL/min) of the drug. The plasma concentrations were very low, under 1 microgram/mL, in most cases; after 30 min these concentrations can be considered as nonefficient for the treatment of arrhythmia. There were no significant differences between pharmacokinetic parameters found with the use of compartmental...
Effect of age and training status on pharmacokinetics of flunixin meglumine in thoroughbreds. The effect of age and training status on the pharmacokinetics of flunixin meglumine was evaluated in 16 Thoroughbreds. Horses were assigned to 1 of 3 groups on the basis of age and training status: group A (n = 6), horses in active training and less than or equal to 5 years old; group B (n = 5), horses out of training for a minimum of 6 weeks and less than or equal to 5 years old; and group C (n = 5), horses out of training for at least 2 years and greater than or equal to 9 years old. After administration of 500 mg of flunixin meglumine IV, multiple serum and urine samples were obtained over ...
The influence of furosemide on plasma elimination and urinary excretion of drugs in standardbred horses. A study of the effects of intravenous administration of either 150 mg or 250 mg of furosemide to standardbred mares pre-treated with other drugs was undertaken to determine whether a unique pattern of drug elimination into urine and from plasma for each compound occurred. Furosemide significantly reduced the plasma concentrations of codeine compared to control 2-6 h after furosemide administration. In contrast, the plasma concentrations of theophylline, phenylbutazone, pentazocine, guaifenesin and flunixin were not markedly altered by furosemide. In the case of acepromazine, clenbuterol and fe...
Copper salicylate and copper phenylbutazone as topically applied anti-inflammatory agents in the rat and horse. Topically applied copper phenylbutazone, phenylbutazone, copper salicylate, salicylate and dimethylsulfoxide glycerol (80:20) were investigated as anti-inflammatory agents in rats and horses. Dimethylsulfoxide and glycerol (80:20) or dimethylsulfoxide, ethanol and glycerol (60:20:20) were used as the drug solvents. Subcutaneously administered carrageenin was used to induce inflammatory oedema, either in the paws of rats or the alar fold of the horse. The severity of the oedema and the anti-inflammatory effect of the drugs were assessed by measuring changes in the paw or alar-fold diameters. Co...
Pharmacokinetics of tinidazole in the horse. Serum tinidazole concentrations were monitored in five clinically healthy adult horses after intravenous (i.v.) and oral administration of the drug (15 mg/kg and 25 mg/kg, respectively). After i.v. administration, the mean residence time was 7.0 h, the elimination half-life 5.2 h and the body clearance rate 1.6 ml/min/kg. The distribution volume was found to be 660 ml/kg. After oral administration, the mean residence time was 8.5 h, the absorption half-life 1.1 h and the bioavailability essentially 100%. In view of the in-vitro sensitivities of various anaerobic bacteria, a dosage of 10-15 mg/...
Endometrial concentrations of ampicillin in mares after intrauterine infusion of the drug. Serum concentration of ampicillin, a semisynthetic penicillin, was measured in mares at various time intervals up to 24 hours after intrauterine infusion of 3 g of ampicillin. Blood samples were drawn immediately before infusion and at 1-, 4-, 10- and 24-hour intervals after infusion. At postinfusion hour 24, two endometrial biopsy specimens were obtained to measure endometrial concentrations of ampicillin. Blood was drawn twice as part of the 24-hour postinfusion sample collection, once before removal of the biopsy specimens and again 5 minutes after removal of the biopsy specimens. After dru...
Gas chromatographic mass-specific investigation of dextromoramide (Palfium) metabolism in the horse. Dextromoramide (Palfium) was given by intravenous injection to a Thoroughbred horse at a dosage of 20 mg and urine was collected 2, 4, 6 and 8 h after drug administration. Enzymatic hydrolysis of the urine followed by solvent extraction gave a residue which was back-extracted into 0.1 M sulphuric acid. After basification to pH 9 and solvent extraction, the resulting residue was submitted to gas chromatographic-mass spectrometric analysis. Both electron-impact and ammonia chemical-ionization mass spectra were recorded and, based on the observed fragmentation patterns, the principal metabolites ...
Pharmacodynamic evaluation of the peripheral pain inhibition by carprofen and flunixin in the horse. Carprofen, flunixin meglumine and placebo in the form of a physiological solution of sodium chloride were tested in an open randomised cross-over trial for analgesic efficacy in horses with two external skin-stimulation systems. Both systems, the withers model and the "heating element" model, were compared in order to find an optimal way to measure pain perception after stimulating the skin with high temperature. No analgesic effect of flunixin or carprofen could be demonstrated when using the withers model. In the "heating element" model, a 1.1 mg/kg i.v. dose of flunixin meglumine failed to ...
Pharmacokinetic studies of cimetidine hydrochloride in adult horses. 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 resid...
A preliminary study on the effects of atropine sulphate on bradycardia and heart blocks during romifidine sedation in the horse. Romifidine (STH 2130-Cl or Sedivet) is an alpha 2-agonistic imino-imidazol sedative for intravenous use in horses recently developed by Boehringer Ingelheim, Vetmedica GmbH. An exploratory study was done in nine warm-blood horses, randomly divided into three groups, which received different dosages of romifidine (0.04, 0.08 and 0.12 mg/kg of body weight (BWT) intravenously (i.v.)) with at least one week's interval between tests. Romifidine induced a marked bradycardia accompanied by second degree atrioventricular (AV) block and some sinus blocks at all tested dosages. A placebo (NaCl 0.9% i.v....
[Anesthesia by injection of xylazine, ketamine and the benzodiazepine derivative climazolam and the use of the benzodiazepine antagonist Ro 15-3505]. 25 horses which entered the clinic for minor surgery, received ketamine (2.2 mg/kg i.v.) for induction of anesthesia after previous sedation with xylazine (1.1 mg/kg i.v.). As soon as the horses were in the lateral recumbency, the benzodiazepine derivate climazolam was administered at a dose of 0.1 mg/kg i.v. (10 horses) or 0.2 mg/kg i.v. (15 horses). The anesthesia was maintained with repeated injections of ketamine (1.1 mg/kg i.v. every 9-12 minutes). At the end of the surgery, 20 minutes after the last ketamine injection, Ro 15-3505, a benzodiazepine antagonist, was injected at a dose of 0....
High-performance liquid chromatography/tandem mass spectrometry: its use for the identification of stanozolol and its major metabolites in human and equine urine. A screening procedure for the anabolic steroid stanozolol in human and equine urine was developed based on enzymatic hydrolysis, liquid-liquid extraction and reversed-phase liquid chromatography combined on-line with tandem mass spectrometry. The column effluent was introduced into the atmospheric pressure ionization source of a triple-quadrupole mass spectrometer via a heated pneumatic nebulizer liquid chromatograph/mass spectrometer interface. Abundant protonated molecular ions were generated by corona discharge ionization. Confirmation of stanozolol and several of its hydroxylated and dihyd...
Rapid determination of methandrostenolone in equine urine by isotope dilution liquid chromatography-tandem mass spectrometry. Urine samples were spiked with [17-methyl-2H3]methandrostenolone as internal standard and extracted with a mixture of dichloromethane and cyclohexane. The organic phase was concentrated and injected onto a short octyl-silica column (30 mm x 4.6 mm I.D.) for separation of methandrostenolone and 17-epimethandrostenolone. The effluent from the column was connected to a Sciex TAGA 6000E triple quadrupole mass spectrometer equipped with an atmospheric pressure ion source for sampling of ions generated by a heated pneumatic nebulizer with corona discharge ionization. This ion source produced abundan...
Principles of wound healing. Wound healing can be divided into immediate (zero to 1 hour), early (1 to 24 hours), intermediate (1 to 7 days), and late (greater than 7 days) stages. Many physical and physiologic events occur simultaneously and sequentially during these stages to produce the final wound scar. The processes of skin retraction, scab formation, would debridement, wound contraction, epithelial migration and proliferation, fibroplasia, and collagen maturation all must occur for healing to be successful. Many factors affect the size and shape of the resulting scar, including anatomic location and skin tension for...
Cardiovascular effects of detomidine, a new alpha 2-adrenoceptor agonist, in the conscious pony. The cardiovascular effects of detomidine and xylazine were compared in six chronically instrumented, conscious ponies. Ponies were instrumented with a micromanometer in the left ventricular chamber, a Doppler flow probe on a coronary artery and sonomicrometer crystals in the left ventricular free wall. Heart rate, ventricular systolic pressure, stroke work, dP/dtmax, minute work and coronary blood flow were measured for 4 h following intravenous injection of detomidine at several doses or xylazine at 1.1 mg/kg. Both drugs caused a profound hypertensive response at 15 s post-injection. The magn...
Effects of atracurium administered by continuous intravenous infusion in halothane-anesthetized horses. Atracurium (0.4 mg/ml in isotonic NaCl solution) was administered by IV infusion to 7 healthy adult horses for 2 hours. Over the 2-hour period, a 95 to 99% reduction of train-of-four hoof-twitch response was maintained by 0.17 +/- 0.01 mg of atracurium/kg of body weight/h, for a total of 161 +/- 6 mg of atracurium (mean +/- SEM) for horses 1 to 4, 6, and 7. Horse 5, a mare in estrus, required 0.49 mg of atracurium/kg/h to maintain comparable relaxation. Hoof-twitch recovery time from 10 to 75% of baseline strength was 19.8 +/- 2.5 minutes for all horses. The 10 to 75% recovery time for horse 5...
Pharmacokinetic disposition of an immediate-release aminophylline and a sustained-release theophylline formulation in the horse. The pharmacokinetic disposition of theophylline was determined by high-performance liquid chromatographic analysis of plasma samples from six healthy, adult horses following the administration of intravenous aminophylline (dosed at 9.94 mg/kg as theophylline), immediate-release aminophylline tablets (dosed at 9.94 mg/kg as theophylline), and sustained-release theophylline tablets (dosed at 20 mg/kg). The elimination rate constant (lambda z), apparent volume of distribution (Vz), and clearance (Cl) determined by compartmental analysis of the intravenous data were 0.07 +/- 0.01 h-1, 0.80 +/- 0.0...
Absorption of two trimethoprim/sulphonamide combinations from the uterus of pony mares. Plasma drug concentrations were measured after two commercially available potentiated sulphonamides, trimethoprim and sulfadoxine and trimethoprim and sulphadiazine, were infused daily for 2 and 3 days, respectively, into the uteri of pony mares which had been mated before ovulation. Intravenous administration of trimethoprim and sulfadoxine allowed uterine absorption of trimethoprim (23-43%) and sulfadoxine (29-34%) to be calculated. After intra-uterine administration trimethoprim and sulphadiazine were detected in the milk of a lactating mare. In order to maintain plasma concentrations likel...
Thin-layer chromatographic screening procedure for some drugs in horse plasma. A thin-layer chromatographic screening procedure for some basic, neutral and acidic drugs was developed using 3 ml of horse plasma. Chloroform-2-propanol (95:5, v/v) was used as the extraction solvent. The drugs were identified by a high-performance thin-layer chromatographic plate and spraying successively with some detection reagents. In this study, the extraction recovery rates and the detection limits were determined at the same time.
Influence of clenbuterol on mucociliary transport in healthy horses and horses with chronic obstructive pulmonary disease. The mucociliary tracheal transport rate and clearance index were measured in 16 healthy horses and 16 horses suffering from chronic obstructive pulmonary disease. A marker, Indian ink in syrup, was placed in the mucus layer of the interior wall of the trachea, just in front of the carina, and its displacement was measured after 30 and 60 minutes. The same procedure was repeated 30 minutes after the intravenous administration of 0.8 microgram clenbuterol/kg bodyweight. In the diseased horses the mucociliary transport rate was significantly lower than in the healthy horses. After clenbuterol adm...
Simultaneous analysis of furosemide and bumetanide in horse plasma using high performance liquid chromatography. A high performance liquid chromatographic method is described for the simultaneous determination of furosemide and bumetanide in horse plasma. The C8 (3 microns) reversed phase column (4.8 x 150 mm) provided clear separation of furosemide and bumetanide with other components present in the horse plasma. The detection limit for both the drugs was 10 ng/mL. Both drugs were stable in plasma (at natural or acidic pH) for up to 24 h. The method is sufficiently sensitive to detect furosemide levels in plasma obtained from horses receiving a therapeutic dose of furosemide.
Controlled test and clinical evaluation of dienbendazole against naturally acquired gastrointestinal parasites in ponies. A controlled test was performed to titrate the anthelmintic dosage of dienbendazole in 24 mixed-breed ponies naturally infected with Strongylus vulgaris, S edentatus, and small strongyle species, as determined by parasitic egg and larval counts in feces. Comparison of results of treatment was made among 3 dienbendazole dosages--2.5, 5, and 10 mg/kg of body weight--and a gum (excipient) mixture given by nasogastric intubation. All ponies were euthanatized and necropsied at 7 or 8 days after treatment. Trichostrongylus axei, Habronema muscae, S vulgaris, S edentatus, small strongyles, and Oxyuri...