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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.
Toltrazuril sulfone sodium salt: synthesis, analytical detection, and pharmacokinetics in the horse. Toltrazuril sulfone (ponazuril) is a triazine-based antiprotozoal agent with clinical application in the treatment of equine protozoal myeloencephalomyelitis (EPM). In this study, we synthesized and determined the bioavailability of a sodium salt formulation of toltrazuril sulfone that can be used for the treatment and prophylaxis of EPM in horses. Toltrazuril sulfone sodium salt was rapidly absorbed, with a mean peak plasma concentration of 2400 ± 169 (SEM) ng/mL occurring at 8 h after oral-mucosal dosing and was about 56% bioavailable compared with the i.v. administration of toltrazuril sul...
Effects of constant rate infusion of lidocaine and ketamine, with or without morphine, on isoflurane MAC in horses. Lidocaine and ketamine are administered to horses as a constant rate infusion (CRI) during inhalation anaesthesia to reduce anaesthetic requirements. Morphine decreases the minimum alveolar concentration (MAC) in some domestic animals; when administered as a CRI in horses, morphine does not promote haemodynamic and ventilatory changes and exerts a positive effect on recovery. Isoflurane-sparing effect of lidocaine, ketamine and morphine coadministration has been evaluated in small animals but not in horses. Objective: To determine the reduction in isoflurane MAC produced by a CRI of lidocaine ...
Effect of feed restriction on plasma dantrolene concentrations in horses. Dantrolene sodium is used to prevent exertional rhabdomyolysis in predisposed horses. Food intake might negatively impact dantrolene bioavailability in horses; however, prolonged feed restriction might be detrimental to performance. Objective: To determine a minimum duration of feed restriction that would optimise plasma dantrolene concentrations in horses after nasogastric administration. It was hypothesised that feed restriction for 4, 8 or 12 h before dantrolene administration would result in higher plasma dantrolene concentrations than achieved with no feed restriction before treatment. Me...
Antibiotic resistance in faecal bacteria isolated from horses receiving virginiamycin for the prevention of pasture-associated laminitis. Enterococcus faecium, a major cause of potentially life-threatening hospital-acquired human infections, can be resistant to several antimicrobials, such that streptogramin quinupristin-dalfopristin (Q/D) is one of the few antibiotics still effective. Consequently use of the streptogramin virginiamycin as an animal growth promoter was banned in the EU in 1999 as some believed this contributed to the emergence of Q/D resistant E. faecium. Virginiamycin is advocated for preventing equine pasture-associated laminitis, but its effect on equine faecal bacterial Q/D resistance has not been determined...
Owner assessment in judging the efficacy of airway disease treatment. Efficacy of medications for recurrent airway obstruction is typically tested using clinical, cytological and lung function examinations of severely affected animals. These trials are technically challenging and may not adequately reflect the spectrum of disease and owner complaints encountered in clinical practice. Objective: To determine if owners of horses with chronic airway disease are better able to detect drug efficacy than a veterinarian who clinically examines horses infrequently. Methods: In a double-blinded randomised controlled trial, owners and a veterinarian compared the efficacy ...
In vitro and in vivo characteristics of celecoxib in situ formed suspensions for intra-articular administration. The objective of the present study was to explore the potential of using an in situ suspension forming drug delivery system of celecoxib to provide sustained drug exposure in the joint cavity following intra-articular administration. In vitro, precipitates were formed upon addition of a 400 mg/mL solution of celecoxib in polyethylene glycol 400 (PEG 400) to phosphate buffer, pH 7.4, or synovial fluid. The in vitro release profiles of the in situ formed suspensions were characterized by an initial fast release followed by a slower constant flux. In buffer solutions, these fluxes were comparable...
Comparison of two tourniquets and determination of amikacin sulfate concentrations after metacarpophalangeal joint lavage performed simultaneously with intravenous regional limb perfusion in horses. To determine whether joint lavage performed simultaneously with IV regional limb perfusion (IVRLP) reduces the effectiveness of IVRLP and to compare 2 types of tourniquets used for this procedure in horses. Methods: 11 adult horses. Methods: 2 groups of 6 horses were tested by use of a pneumatic or an Esmarch tourniquet (1 horse was tested twice [once in each group]). Standing IVRLP with amikacin (500 mg) was performed for 30 minutes. Simultaneously, the metacarpophalangeal joint was lavaged with 2 L of lactated Ringer's solution and the egress fluids were collected. Samples of the distal inte...
A broad-spectrum equine urine screening method for free and enzyme-hydrolysed conjugated drugs with ultra performance liquid chromatography/tandem mass spectrometry. The authors' laboratory at one time employed four liquid chromatography/mass spectrometric (LC/MS) methods for the detection of a large variety of drugs in equine urine. Drug classes covered by these methods included anti-diabetics, anti-ulcers, cyclooxygenase-2 (COX-2) inhibitors, sedatives, corticosteroids, anabolic steroids, sulfur diuretics, xanthines, etc. With the objective to reduce labour and instrumental workload, a new ultra performance liquid chromatography/tandem mass spectrometric (UPLC/MS/MS) method has been developed, which encompasses all target analytes detected by the origina...
Pharmacokinetics of pioglitazone after multiple oral dose administration in horses. Pioglitazone is a thiazolidinedione class of antidiabetic agent with proven efficacy in increasing insulin sensitivity in humans with noninsulin-dependent diabetes mellitus, a syndrome of insulin resistance sharing similarities with equine metabolic syndrome. The purpose of this study was to determine the pharmacokinetics of pioglitazone in adult horses following multiple oral dose administration. Pioglitazone hydrochloride (1 mg/kg) was administered orally for 11 doses at 24-h intervals, and plasma samples were collected. Initially, a pilot study was performed using one horse; and thereafter ...
Pharmacokinetics and metabolism of dantrolene in horses. Dantrolene is a skeletal muscle relaxant used commonly in performance horses to prevent exertional rhabdomyolysis. The goal of the study reported here was to begin to characterize cytochrome P450-mediated metabolism of dantrolene in the horse and describe the pharmacokinetics of the compound, formulated as a capsule or a compounded paste formulation, following oral administration. Dantrolene is rapidly metabolized to 5-hydroxydantrolene both in vivo and in vitro. Preliminary work with equine liver microsomes suggest that two enzymes are responsible for the metabolism of dantrolene, as evidence...
Further evaluation in field tests of the activity of three anthelmintics (fenbendazole, oxibendazole, and pyrantel pamoate) against the ascarid Parascaris equorum in horse foals on eight farms in Central Kentucky (2009-2010). The activity of three anthelmintics (fenbendazole-FBZ; oxibendazole-OBZ; and pyrantel pamoate-PRT) was ascertained against the ascarid Parascaris equorum in horse foals on eight farms in Central Kentucky (2009-2010) in field tests. A total of 316 foals were treated, and 168 (53.2%) were passing ascarid eggs on the day of treatment. Evaluation of drug efficacy was determined qualitatively by comparing the number of foals passing ascarid eggs in their feces before and after treatment. The main purpose was to obtain data on current activity of these compounds against ascarids. Additionally, the o...
Assessment of the sedative effects of buprenorphine administered with 20 microg/kg detomidine in horses. The aim of this randomised, observer-blinded, crossover study was to compare the effects of four treatments, administered intravenously to six horses: saline and saline; 10 µg/kg detomidine and 7.5 µg/kg buprenorphine; 20 µg/kg detomidine and 7.5 µg/kg buprenorphine; and 20 µg/kg detomidine and 10 µg/kg buprenorphine. Sedation was subjectively assessed and recorded on a visual analogue scale. Peak sedation and duration of sedation were investigated using a univariate general linear model with post-hoc Tukey tests (P<0.05). Increasing the dose of detomidine from 10 to 20 µg/kg increas...
Effect of Buscopan compositum on the motility of the duodenum, cecum and left ventral colon in healthy conscious horses. Seven adult, healthy, conscious warmblood horses were used in a crossover study. They were fed twice a day on 1 kg hay/100 kg BW and 0.5 kg concentrates with unlimited access to water. One hour after feeding, the contractive motility of the descending duodenum, cecal body and left ventral colon were measured using a 5 MHz transcutaneus ultrasonographic transducer. Each horse was treated with 0.9% NaCl (5 ml/100 kg BW; i.v.), and with Buscopan compositum (BC) at its therapeutic dosage (25 mg/kg BW; metamizol-sodium, 0.2 mg/kg BW; N-butylscopolammonium bromide, i.v.) in a control and an experime...
Sedative and cardiopulmonary effects of buprenorphine and xylazine in horses. This study investigated the sedative, cardiopulmonary, and gastrointestinal effects produced by buprenorphine and xylazine given in combination to horses. Six healthy adult horses underwent 4 randomized treatments, with an interval of 1 wk between treatments. A control group was given a saline solution intravenously (IV) and the experimental groups received buprenorphine [10 μg/kg bodyweight (BW)] in combination with 1 of 3 different doses of xylazine: 0.25 mg/kg BW (BX25), 0.50 mg/kg BW (BX50), or 0.75 mg/kg BW (BX75), all of them by IV. Cardiopulmonary parameters were evaluated for 120 min ...
Assessment of the sedative effects of buprenorphine administered with 10 μg/kg detomidine in horses. The aim of this randomised, observer-blinded, crossover study was to compare the effects of six treatments, administered intravenously to six horses: saline and saline (S/S); detomidine and saline (D/S); detomidine and 5 µg/kg buprenorphine (D/B5); detomidine and 7.5 µg/kg buprenorphine (D/B7.5); detomidine and 10 µg/kg buprenorphine (D/B10); and detomidine and 25 µg/kg butorphanol (D/BUT). The detomidine dose was 10 µg/kg for all treatments in which it was included. Sedation was subjectively assessed and recorded on a visual analogue scale. Peak sedation, duration of sedation and the are...
Characterization of in vivo plasma metabolites of tepoxalin in horses using LC-MS-MS. Tepoxalin is a veterinary drug registered for use in the dog as a dual inhibitor (cyclooxygenase-5 lipoxygenase). In the horse, it predominantly triggers a strong cyclooxygenase inhibition; this bias seems to be due to the action of its metabolite(s). Among these, only the RWJ-20142 is well known, while to the best of our knowledge no information is available on the other metabolites produced in vivo. Hence, the identification of its main metabolic pathway is pivotal to better understand its clinical activity. A suitable high performance liquid chromatography method has been applied to liquid ...
Plasma pharmacokinetics, pulmonary distribution, and in vitro activity of gamithromycin in foals. The objectives of this study were to determine the plasma and pulmonary disposition of gamithromycin in foals and to investigate the in vitro activity of the drug against Streptococcus equi subsp. zooepidemicus (S. zooepidemicus) and Rhodococcus equi. A single dose of gamithromycin (6 mg/kg of body weight) was administered intramuscularly. Concentrations of gamithromycin in plasma, pulmonary epithelial lining fluid (PELF), bronchoalveolar lavage (BAL) cells, and blood neutrophils were determined using HPLC with tandem mass spectrometry detection. The minimum inhibitory concentration of gamithr...
Intra-articular injection of morphine to the horse: establishment of an in vitro-in vivo relationship. In the area of parenteral depots, a strong need exists for the development of suitable in vitro drug release models that might enable establishment of in vitro-in vivo relations (IVIVRs). Objective: The objective of this study was to investigate the possibility of establishing an IVIVR between morphine disappearance from the joint cavity and in vitro release data obtained employing the rotating dialysis cell model. Methods: In vitro release experiments were conducted using the rotating dialysis cell model. For establishment of an IVIVR, data from a previous study on pharmacokinetics of intra-a...
Physical, behavioral, endocrinologic, and cytogenetic evaluation of two Standardbred racehorses competing as mares with an intersex condition and high postrace serum testosterone concentrations. 2 Standardbred racehorses that had been winning races while competing as mares underwent postrace drug testing and had serum testosterone concentrations above the acceptable limit for female racehorses. Results: Initial physical examinations by the referring veterinarian revealed ambiguous external genitalia and suspected intra-abdominally located testes leading to a preliminary diagnosis of male pseudohermaphroditism. Horses were referred for further evaluation of sex. Physical examination of the external genitalia confirmed the findings of the referring veterinarian. Transrectal palpation an...
Easy stereoselective synthesis of 5α-estrane-3β,17α-diol, the major metabolite of nandrolone in the horse. 5α-Estrane-3β,17α-diol is the major metabolite of nandrolone in horse urine. The presence of 5α-estrane-3β,17α-diol in female and gelding urines is prohibited by Racing Rules and its natural presence in male urine led regulation authorities to establish a concentration threshold of 45 ng/mL. This paper describes a rapid, simple and stereoselective synthesis of 5α-estrane-3β,17α-diol, providing horseracing laboratories with an essential reference material for their antidoping performance.
Analysis of gabapentin in equine plasma with measurement uncertainty estimation by liquid chromatography-tandem mass spectrometry. Gabapentin (GPT) is an antiepileptic drug that was approved in 1993 for use in the management of neurotrophic pain and as an adjunctive therapy for refractory partial seizure in humans. It is also being tested in veterinary medicine as an adjunctive medication in the treatment of pain due to laminitis, neuropathic, or chronic pain. Gabapentin is readily available by prescription and even on the internet; therefore, it has the potential of being used in racehorses to mask pain. It is for this reason that a sensitive liquid chromatography-tandem mass spectrometry method has now been developed fo...
Pharmacokinetics of intravenous and intramuscular buprenorphine in the horse. The purpose of this study was to determine the pharmacokinetics of buprenorphine following intravenous (i.v.) and intramuscular (i.m.) administration in horses. Six horses received i.v. or i.m. buprenorphine (0.005 mg/kg) in a randomized, crossover design. Plasma samples were collected at predetermined times and horses were monitored for adverse reactions. Buprenorphine concentrations were measured using ultra-performance liquid chromatography with electrospray ionization mass spectrometry. Following i.v. administration, clearance was 7.97±5.16 mL/kg/min, and half-life (T(1/2)) was 3.58 h (ha...
Tear, cornea, and aqueous humor concentrations of ciprofloxacin and moxifloxacin after topical ocular application in ophthalmologically normal horses. To determine ocular tissue drug concentrations after topical ocular administration of 0.3% ciprofloxacin and 0.5% moxifloxacin in ophthalmologically normal horses. Methods: 24 ophthalmologically normal adult horses. Methods: 0.3% ciprofloxacin and 0.5% moxifloxacin solutions (0.1 mL) were applied to the ventral conjunctival fornix of 1 eye in each horse as follows: group 1 (n = 8) at 0, 2, 4, and 6 hours; group 2 (8) at 0, 2, 4, 6, and 10 hours; and group 3 (8) at 0, 2, 4, 6, 10, and 14 hours. Tears, cornea, and aqueous humor (AH) were collected at 8, 14, and 18 hours for groups 1, 2, and 3, r...
An interlaboratory study of the pharmacokinetics of testosterone following intramuscular administration to Thoroughbred horses. Testosterone is an anabolic androgenic steroid (AAS) that is endogenously produced by both male and female horses that also has the potential for abuse when administered exogenously to race horses. To recommend appropriate withdrawal guidelines so that veterinarians can discontinue therapeutic use prior to competition, the pharmacokinetics and elimination of testosterone were investigated. An aqueous testosterone suspension was administered intramuscularly in the neck of Thoroughbred horses (n = 20). The disposition of testosterone from this formulation was characterized by an initial, rapid a...
The effect of oral metformin on insulin sensitivity in insulin-resistant ponies. Metformin may be an effective therapeutic option for insulin-resistant (I-R) horses/ponies because, in humans, it reportedly enhances insulin sensitivity (SI) of peripheral tissues without stimulating insulin secretion. To determine the effect of metformin on insulin and glucose dynamics in I-R ponies, six ponies were studied in a cross-over design by Minimal Model analysis of a frequently-sampled intravenous glucose tolerance test (FSIGT). Metformin was administered at 15 mg/kg bodyweight (BW), orally, twice-daily, for 21 days to the metformin-treated group. The control group received a place...
The use of in vitro technologies and high-resolution/accurate-mass LC-MS to screen for metabolites of ‘designer’ steroids in the equine. Detection of androgenic-anabolic steroid abuse in equine sports requires knowledge of the drug's metabolism in order to target appropriate metabolites, especially where urine is the matrix of choice. Studying 'designer' steroid metabolism is problematic since it is difficult to obtain ethical approval for in vivo metabolism studies due to a lack of toxicological data. In this study, the equine in vitro metabolism of eight steroids available for purchase on the Internet is reported; including androsta-1,4,6-triene-3,17-dione, 4-chloro,17α-methyl-androsta-1,4-diene-3,17β-diol, estra-4,9-diene-...
Pharmacokinetics of ceftiofur crystalline-free acid sterile suspension in the equine. Absolute bioavailability and dose proportionality studies were performed with ceftiofur in horses. In the absolute bioavailability study, thirty animals received either an intravenous dose of ceftiofur sodium at 1.0 mg/kg or an intramuscular (i.m.) dose of ceftiofur crystalline-free acid (CCFA) at 6.6 mg/kg. In the dose proportionality study, 48 animals received daily i.m. ceftiofur sodium injections at 1.0 mg/kg for ten doses or two doses of CCFA separated by 96 h, with CCFA doses of 3.3, 6.6, or 13.2 mg/kg. Noncompartmental and mixed-effect modeling procedures were used to assess pharmacokin...
