Pharmaceuticals in equine medicine encompass a wide range of drugs and therapeutic agents used to treat various conditions in horses. These substances include analgesics, anti-inflammatories, antibiotics, sedatives, and anthelmintics, among others. Each class of pharmaceuticals is designed to address specific health issues, such as pain management, infection control, or parasitic infestations. The pharmacokinetics and pharmacodynamics of these drugs can vary significantly between horses and other species, necessitating careful consideration of dosage and administration methods. This page compiles peer-reviewed research studies and scholarly articles that explore the development, efficacy, safety, and regulatory aspects of pharmaceuticals used in equine healthcare.
Malone ED.Many compounds are being investigated for the control of symptoms of osteoarthritis in people and animals. Ideally, treatment should include analgesia, inflammation control, and chondroprotection. With further progress in this area, combination therapies tailored to the needs of the individual animal should enable us to maximize efficacy and minimize side effects. Only a few of the newer therapies and pharmaceutic agents have been investigated in the horse, however. With more rigorous investigation, they may be determined to be ineffective or unsafe. Meanwhile, as much information should be ga...
Eenoo PV, Delbeke FT.Salbutamol is a beta-adrenergic agonist that is used in the treatment of asthma in humans and chronic obstructive pulmonary disease in horses. Because of its stimulating and growth promoting properties, it is prohibited by horse racing authorities. Recently a number of adapters (eg Equinehaler) have been designed, allowing the use of metered dose inhalers (MDI) approved for human use. However, information on detection times of salbutamol after administration of salbutamol in therapeutic doses by inhalation is lacking. In this study, 2 mg salbutamol (Ventolin) was administered to four standardb...
McKellar QA, Gokbulut C, Muzandu K, Benchaoui H.The present study was designed to describe the pharmacokinetics and fecal excretion of fenbendazole (FBZ) and fenbendazole sulphoxide (FBZSO) and their metabolites in horses, to investigate the effects which concurrent feeding has on the absorption and pharmacokinetics of FBZ, and to determine the effect of coadministration of the metabolic inhibitor piperonyl-butoxide on the in vivo pharmacokinetics and in vitro liver microsomal metabolism of sulfide and sulfoxide benzimidazoles. The effect of piperonyl-butoxide on the enantiomeric genesis of the sulfoxide moiety was also investigated. Follow...
Van Eenoo P, Delbeke FT, Deprez P.Clenbuterol, a beta-adrenergic agonist, is used in the treatment of recurrent airway obstruction in horses. It is prohibited by horse racing authorities, because of its stimulating and growth-promoting properties. However, information on detection times of clenbuterol after administration by nebulization is lacking. In this study, a fast, sensitive quantitative GC-MS(2) method for the detection of clenbuterol in urine was developed. Alkaline liquid-liquid extraction was followed by derivatization to a cyclic methyl boronate derivative and analysis on a Finnigan MAT GCQ instrument. Method valid...
Van Eenoo P, Deventer K, Delbeke FT.A sensitive, accurate and precise liquid chromatography/tandem mass spectrometry (LC/MS(2)) method was developed for the quantification of salmeterol in the urine of horses. The method consists of a liquid-liquid extraction with tert-butylmethyl ether and isopropanol at pH 12 after enzymatic hydrolysis. The extracts are analysed using an LC/MS system equipped with an electrospray ionisation (ESI) probe. Method validation showed excellent linearity, specificity, accuracy, precision and intra-laboratory repeatability and reproducibility. The limit of quantitative detection was 0.25 ng/mL and the...
Dart AJ, Cries L, Jeffcott LB, Hodgson DR, Rose RJ.To evaluate the effect of a commercially available 25% propylene glycol hydrogel preparation (Solugel; Johnson and Johnson Medical, North Ryde, Australia) on healing of full-thickness skin wounds on the distal aspect of the limb in horses. Methods: Experimental. Methods: Eight Standardbred horses. Methods: Standardized (2.5 x 2.5 cm) full-thickness skin wounds were created over the mid-dorsomedial aspect of both metacarpi in 8 horses. One wound in each horse was dressed with saline solution (0.9% NaCl) soaked gauze, and one was treated with Solugel under dry regular gauze; wounds were then ban...
Baller LS, Hendrickson DA.Pain management is an extremely vital part of equine orthopedic surgery. Providing optimum analgesia for the patient will decrease recovery time, decrease physiologic stress on the animal, and provide maximum comfort during the post-operative period. The major analgesic drug categories and routes covered are nonsteroidal anti-inflammatory drugs, local anesthetics, intra-articular drugs, and epidurals.
Hagedorn HW, Meiser H, Zankl H, Schulz R.Due to its tranquilizing properties, the tricyclic antidepressant doxepin may be misused as a doping agent in competition horses. Therefore, efficient analytical procedures are required to detect this drug in samples submitted for doping control. To screen for parent doxepin in equine blood and urine, a less specific method has been accepted employing gas chromatography (GC) combined with electron impact (EI) mass spectrometry (MS). The aim of this study was identification of doxepin metabolites providing more specific MS data to verify positives resulting from screening. Thus, after a horse w...
Colahan PT, Bailey JE, Johnson M, Rice BL, Chou CC, Cheeks JP, Jones GL, Yang M.Following the regimen used to treat equine protozoal myeloencephalitis, sulfadiazine (20 mg/kg) and pyrimethamine (1mg/kg) were administered orally once daily to 12 physically conditioned Thoroughbred horses for 4 consecutive days. The horses were randomly assigned to two test groups in a crossover design, with each horse serving as its own control. A stepwise exercise stress test was conducted to exhaustion. No effect on athletic performance was observed, and only marginal effects were noted in some hematologic and serochemical measurements, including decreased total white blood cell counts, ...
Cohen ND, Peck KE, Smith SA, Ray AC.The distribution of specific gravity values for 2,599 urine samples collected from racing Thoroughbred horses that were known to have received furosemide prior to racing was compared with that for 1,669 urine samples from racing Thoroughbred horses that reportedly had not received furosemide. Values of specific gravity for furosemide-treated horses were significantly lower (P < 0.001) than those for horses that had not received furosemide, and the proportion of horses with urine specific gravity either <1.010 or <1.012 was significantly greater (P < 0.001) among the furosemide-trea...
Dyson SJ.It was hypothesised that in solar bone images of the front feet of clinically normal horses, or horses with lameness unrelated to the front feet, there would be less than a 10% difference in the ratio of uptake of radiopharmaceutical in either the region of the navicular bone, or the region of insertion of the deep digital flexor tendon (DDFT), compared to the peripheral regions of the distal phalanx. Nuclear scintigraphic examination of the front feet of 15 Grand Prix show jumping horses, all of which were free from detectable lameness, was performed using dorsal, lateral and solar images. Th...
Dumasia MC, Houghton E, Hyde W, Greulich D, Nelson T, Peterson J.Studies related to the in vivo biotransforrmation and urinary excretion of fenspiride hydrochloride in the horse are described. After oral administration, the drug is metabolised by both phase I functionalisation and phase II conjugation pathways. Following enzymatic deconjugation, fenspiride and its phase I metabolites were isolated from post-administration biofluids using bonded co-polymeric mixed mode solid-phase extraction cartridges to isolate the basic compounds. Following trimethylsilylation (TMS), the parent drug and metabolites were identified by capillary gas chromatography-mass spec...
Dehennin L, Bonnaire Y, Plou P.The dietary supplements 19-norandrostenedione and 19-norandrostenediol are potential metabolic precursors of nandrolone. They are considered by law in the United States as prohormones without proven therapeutic, curative or diagnostic properties, and therefore available as over-the-counter drugs. Oral dosages of 0.1-1 mg/kg body weight were readily absorbed in the equine intestinal tract and thereby led to urinary excretion of drastically increased 5alpha-estrane-3beta,17alpha-diol conjugates, which are known to be final metabolites of nandrolone. The actual rules for detection of illicit nand...
McKinney AR, Ridley DD, Suann CJ.The phase I and phase II metabolism of the anabolic steroid methandrostenolone was investigated following oral administration to a standardbred gelding. In the phase I study, metabolites were isolated from the urine by solid-phase extraction, deconjugated by acid catalysed methanolysis and converted to their O-methyloxime trimethylsilyl derivatives. GC-MS analysis indicated the major metabolic processes to be sequential reduction of the A-ring and hydroxylation at C6 and C16. In the phase II study, unconjugated, beta-glucuronidated and sulfated metabolites were fractionated and deconjugated us...
Gehring R.The Veterinary Pharmacovigilance Centre received 59 reports of suspected adverse drug reactions during the period January 1998 - February 2001. The number of reports received increased after the establishment of a formal procedure for recording and responding to reports. The number of reports received per species was: dogs 19, cats 15, cattle 7, sheep/ goats 6, chickens 4, pigs 3, horses 2 and giraffe 1. Many different types of adverse reactions were reported, including lack of efficacy, hypersensitivity, inappropriate use of products by non-veterinarians, known adverse effects and adverse eff...
Brumbaugh GW.Drugs undergo extensive evaluation before they are marketed. The occurrence of adverse reactions, however, may be so rare that thousands of patients must receive the drug before reliable data are available. It is necessary that veterinarians be informed about the drugs they use, be able to recognize drug-associated complications, know how to evaluate the patient for evidence of drug-associated toxicity, report adverse effects of drugs to the respective manufacturers, and be prepared to provide medical support and antidotal treatment (if it exists) for a patient if toxicosis occurs.
Kollias-Baker C.Analytic chemistry laboratories responding to the concerns of the industry over drug use and abuse in performance horses should continue to develop more sensitive methods of drug detection. The unwanted result of this increase in sensitivity is the detection of therapeutic medications days to weeks after administration. The adoption of decision or threshold concentrations for residues of nonpermitted medications should allow laboratories to focus their efforts on drugs of abuse in the performance horse industries and permit veterinarians to provide appropriate medical care to these equine athl...
Vercruysse J, Holdsworth P, Letonja T, Conder G, Hamamoto K, Okano K, Rehbein S.The "International Co-operation on Harmonisation of Technical Requirements for Registration of Veterinary Medicinal Products (VICH)" is an international programme of co-operation between regulatory authorities and the animal health industries of the European Union, Japan and the United States of America which aims to harmonise the technical requirements for the registration of veterinary medicinal products. Australia and New Zealand participate as active observers. The objective of this second paper is to present additional guidelines established by the Working Group on anthelmintic guidelines...
Kim JY, Kim SJ, Paeng KJ, Chung BC.A gas chromatographic-mass spectrometric (GC-MS) method for the determination of ketoprofen, a non-steroidal anti-inflammatory drug (NSAID), in horse urine by selected ion monitoring (SIM) mode is described. Urine samples (2 mL) were extracted by liquid-liquid extraction with diethyl ether. The residues were then evaporated, derivatized and injected into the GC-MS system. Validation of the GC-MS method in the SIM mode using flurbiprofen as the internal standard (IS) included linearity studies (10-10 000 ng/mL), recovery (95%) and limit of quantitation (LOQ) (10 ng/mL). The response was linear,...
Martin-Downum K, Yazwinski T, Tucker C, Fincher M, Ralph J, Hamilton J.Commercial preparations of fenbendazole (Safe-Guard, Intervet), ivermectin (Eqvalan, Merial) or moxidectin (Quest, Fort Dodge) were administered once to horses scheduled for routine parasiticide treatment. In total, 93 horses from six cooperating farms were used in the study. Computer generated, random allocation of horses to treatment group was conducted at each farm. Fecal egg counts were determined for all horses on trial days 0, 56, 84 and 112, with corresponding calendar dates that were unique to each farm. Only strongyle egg counts from animals which were positive at day 0 were used for ...
Tang FP, Leung GN, Wan TS.A capillary electrophoresis-mass spectrometry (CE-MS) method for the analysis of quaternary ammonium drugs in equine urine was developed. Quaternary ammonium drugs were first extracted from equine urine by ion-pair extraction and then analysed by CE-MS in the positive electrospray ionization (ESI) mode. Within 12 min, eight quaternary ammonium drugs, each at 1 ng/mL in horse urine, could be detected. The confirmation of these drugs in urine samples was achieved by capillary electrophoresis tandem mass spectrometry (CE-MS/MS). A direct comparison of this method was made with existing liquid chr...
Takeda A, Tanaka H, Shinohara T, Ohtake I.A sample preparation method for mass chromatographic detection of doping drugs from horse plasma is described. Bond Elut Certify (1 g/6 ml) is used for the extraction of 4 ml of horse plasma. Fractionation is performed with 6 ml of CHCl3-Me2CO (8:2) and 5 ml of 1% TEA-MeOH according to its property. Simple and effective clean-up based on non-aqueous partitioning is adopted to remove co-eluted contaminants in both acid and basic fractions. Two kinds of 1-(N,N-diisopropylamino)-n-alkanes are co-injected with the sample into the GC-MS system for the calculation of the retention index. Total recov...
Chapman CB, Courage P, Huntington PJ.A high-performance liquid chromatography (HPLC) assay was developed for the detection of reserpine. The assay was used to monitor the plasma concentrations of the drug given intramuscularly on one or two occasions to five horses. The blood concentrations of reserpine varied quite considerably between horses given the same dose of the drug. However, on average, reserpine could be detected consistently, and quantified, for 48 h after a single dose of 2.5 mg, and for a similar period after the second of two 2.5 mg doses given 13 d apart. Because of the apparently large variability in the pharmaco...
de Jong EG, Kiffers J, Maes RA.Results are given for a more sensitive screening procedure for non-steroidal anti-inflammatory drugs using GC-MS-MS. By monitoring a selected characteristic reaction for each drug very low detection limits are reached even in a difficult biological matrix such as equine urine. Detection down to 5 ng ml-1 for ibuprofen, ibufenac, alclofenac, fenoprofen, ketoprofen, naproxen and diclofenac is possible in contrast to the 0.5 microgram ml-1 limit for normal GC-MS detection. Examples are given of real positive cases for diclofenac and ibuprofen.
Brewer K, Dirikolu L, Hughes CG, Tobin T.Scopolamine (L-hyoscine) identifications, often in small-number clusters, have been reported worldwide in performance horses over the last 30 years. Scopolamine is an Association of Racing Commissioners International (ARCI) class 3, penalty class B, substance with potential to affect performance. As such, scopolamine identification(s) in race or performance horses can result in significant penalties for the connections of the horse(s). Reviewed here is the worldwide distribution of scopolamine containing plants (primarily Datura spp.), with estimates of their potential toxicity to horses throu...
Waitt Wolker LH, Veltri CA, Pearman K, Lozoya M, Norris JW.This study aimed to investigate pharmacokinetics of fluoxetine in horses and validate a method for liquid chromatography mass spectrometry analysis of serum levels. Fluoxetine pharmacokinetics were determined using 10Â healthy, adult horses. Fluoxetine pharmacokinetics following a single oral dose (0.25Â mg/kg) were determined using blood samples collected prior to and at several time points over 7Â days following administration. Serum concentrations of fluoxetine and its bioactive metabolite norfluoxetine were measured using liquid chromatography coupled to an accurate mass/high-resolution ma...
Stevenson AJ, Weber MP, Todi F, Mendonca M, Fenwick JD, Kwong E, Young L, Leavitt R, Nespolo R, Beaumier P.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...
Moeller BC, Flores L, Clifford A, Alarcio G, Mosburg M, Arthur RM.Methylphenidate is a powerful central nervous system stimulant with a high potential for abuse in horse racing. The detection of methylphenidate use is of interest to horse racing authorities for both prior to and during competition. The use of hair as an alternative sampling matrix for equine anti-doping has increased as the number of detectable compounds has expanded. Our laboratory developed a liquid chromatography-high-resolution mass spectrometry method to detect the presence of methylphenidate in submitted samples. Briefly, hair was decontaminated, cut, and pulverized prior to liquid-liq...
Neto LM, Andraus MH, Salvadori MC.A method is described for the qualitative and quantitative determination of phenylbutazone and oxyphenbutazone in horse urine and plasma samples viewing antidoping control. A horse was administered intravenously with 3 g of phenylbutazone. For the qualitative determination, a screening by HPLC was performed after acidic extraction of the urine samples and the confirmation process was realized by GC-MS. Using the proposed method it was possible to detect phenylbutazone and oxyphenbutazone in urine for up to 48 and 120 h, respectively. For the quantitation of these drugs the plasma was deprotein...
Shibany KA, Tötemeyer S, Pratt SL, Paine SW.Despite reports of the successful isolation of primary equine hepatocytes, there are no published data regarding the successful cryopreservation of these isolated cells. In this study, a detailed description of the procedures for isolation, cryopreservation, and recovery of equine hepatocytes are presented. Furthermore, the intrinsic clearance (Cl) and production of metabolites for three drugs were compared between freshly isolated and recovered cryopreserved hepatocytes. Primary equine hepatocytes were isolated using a two-step collagenase perfusion method, with an average cell yield of 2.47Â...
Tang FP, Leung GN, Wan TS.A capillary electrophoresis-mass spectrometry (CE-MS) method for the analysis of quaternary ammonium drugs in equine urine was developed. Quaternary ammonium drugs were first extracted from equine urine by ion-pair extraction and then analysed by CE-MS in the positive electrospray ionization (ESI) mode. Within 12 min, eight quaternary ammonium drugs, each at 1 ng/mL in horse urine, could be detected. The confirmation of these drugs in urine samples was achieved by capillary electrophoresis tandem mass spectrometry (CE-MS/MS). A direct comparison of this method was made with existing liquid chr...
Mizobe F, Mori M, Nagata SI, Yamashita S, Okada J, Kusano K.Ever since 'One Health' concept was introduced in early 2000s, judicious use of antimicrobials by veterinarians has become an issue of great concern. Recently, findings of anti-inflammatory effects in certain types of antimicrobials have raised a subject for discussion among racing authorities. Regulatory framework of antimicrobials in racing should be based on best interest of horse welfare and doping control perspective, but basic data on prevalence of antimicrobials are lacking. Analysis of 100 postrace urinary samples collected from 10 Japanese racecourses by targeting 21 antimicrobials us...
Sellon DC, Sanz M, Kopper JJ.Little is known about the acquisition and use of equine analgesic drugs by horse owners in the United States (US). Objective: To determine factors associated with possession of analgesic drugs by horse owners in the US or with analgesic drug acquisition from sources noncompliant with a valid veterinarian-client-patient (VCPR) relationship. Methods: Cross-sectional survey. Methods: An internet-based questionnaire included items related to experiences with horses and equine analgesic drugs. Factors associated with possession of ≥5 types of analgesic drugs and with the acquisition of drugs from...
Houston T, Chay S, Woods WE, Combs G, Kamerling S, Blake JW, Edmundson AG, Vessiney R, Tobin T.A survey of plasma and urinary concentrations of phenylbutazone and its metabolites in thoroughbred horses racing in Kentucky was carried out. Post-race blood samples from more than 200 horses running at Latonia Racetrack and Keeneland in the Spring of 1983 were analysed. The modal plasma concentration of phenylbutazone was between 1 and 2 micrograms/ml, the mean concentration was 3.5 micrograms/ml and the range was up to 15 micrograms/ml. Oxyphenbutazone had a modal plasma concentration between 1 and 2 micrograms/ml, a mean concentration of 2.07 micrograms/ml and a range of up to 13 microgram...
Tsitsimpikou C, Spyridaki MH, Georgoulakis I, Kouretas D, Konstantinidou M, Georgakopoulos CG.Flurbiprofen and its main acidic metabolites were detected in equine urine after a single-dose administration of 500 mg flurbiprofen to two 2.5-3.5-years-old mares, in order to be used in equine doping control routine analysis. The urine levels of the parent drug were determined using GC/MS. Five acidic metabolites were found in the urine. The structure of the proposed metabolites was confirmed by HRMS accurate mass measurements. The highest flurbiprofen concentration was 204 mug ml(-1) at 1-3 h post administration. Flurbiprofen could be detected for 24-37 h in urine using the standard screeni...
Soma LR, Gallis DE, Davis WL, Cochran TA, Woodward CB.Phenylbutazone (PBZ) was administered (8.8 mg/kg of body weight) every 24 hours for 5 consecutive days, orally for the first 4 days and IV on day 5. The half-life (t 1/2) after this daily administration was 6.2 hours and the volume of distribution was 0.152 +/- 0.014 L/kg; the bioavailability after oral administration was 91.8 +/- 2.5%. The plasma concentration of PBZ at experimental hour (EH) 24 (24 hours after the 1st oral dose) was 1.7 +/- 0.39 micrograms/ml and increased to 4.2 +/- 0.29 micrograms/ml at EH 48 (24 hours after the 2nd oral dose). Values at EH 72, 96, and 120 (24 hours after ...
Gray B, Viljanto M, Menzies E, Vanhaecke L.The detection of drugs in human hair samples has been performed by laboratories around the world for many years and the matrix is popular in disciplines, such as workplace drug testing. To date, however, hair has not become a routinely utilised matrix in sports drug detection. The analysis of hair samples offers several potential advantages to doping control laboratories, not least of which are the greatly extended detection window and the ease of sample collection and storage. This article describes the development, validation, and utilisation of a sensitive ultra-high performance liquid chro...
Zientek KD, Anderson DF, Wegner K, Cole C.A method for the extraction and quantitation of procaine in equine plasma was developed for use with liquid chromatography-mass spectrometry (LC-MS). Procaine was isolated from equine plasma by liquid-liquid extraction at pH 11 with dichloromethane using procaine-d10 as an internal standard. Quantitation was achieved by LC-MS using a 3-microm C-18 column coupled to an electrospray ionization source on a linear ion-trap mass spectrometer. The limit of detection and limit of quantitation was determined to be 50 and 200 pg/mL, respectively. The lowest limit of detection determined by previous met...
Yi R, Sandhu J, Zhao S, Lam G, Loganathan D, Morrissey B.Efaproxiral (RSR 13) is an experimental synthetic allosteric modifier of haemoglobin (Hb) that acts by increasing the release of oxygen from Hb to the surrounding tissues. It has been shown to increase maximum oxygen uptake (VO(2max)) in a canine skeletal muscle model. The ability to increase maximal muscle oxygen uptake makes efaproxiral a potential performance-enhancing agent and is therefore prohibited by the World Anti-Doping Agency. In this study, a method for the detection and elimination of efaproxiral in equine plasma and urine after a 2.5 g intravenous administration of efaproxiral ...
Gadaj A, Ventura E, Healy J, Botrè F, Sterk SS, Buckley T, Mooney MH.Selective androgen receptor modulators (SARMs) represent non-steroidal agents commonly abused in human and animal (i.e. equine, canine) sports, with potential for further misuse as growth promoting agents in livestock-based farming. As a direct response to the real and possible implications of illicit application in both sport as well as food production systems, this study incorporated enzymatic hydrolysis (β-glucuronidase/arylsulfatase) into a previously established protocol while maintaining the minimal volume (200 µL) of urine sample required to detect SARMs encompassing various pharmacop...
Kwok WH, Leung DK, Leung GN, Wan TS, Wong CH, Wong JK.A rapid liquid chromatography-tandem mass spectrometry (LC-MS-MS) method was developed for the simultaneous screening of 19 drugs of different classes in equine plasma using automated on-line solid-phase extraction (SPE) coupled with a triple quadrupole mass spectrometer. Plasma samples were first protein precipitated using acetonitrile. After centrifugation, the supernatant was directly injected into the on-line SPE system and analysed by a triple quadrupole LC-MS-MS in positive electrospray ionisation (+ESI) mode with selected reaction monitoring (SRM) scan function. On-line extraction and c...
Ingvast-Larsson C, Paalzow G, Paalzow L, Ottosson T, Lindholm A, Appelgren LE.The pharmacokinetics of theophylline were determined in Standardbred trotters after single intravenous and oral administration. A bi-exponential equation was fitted to the intravenous data and a tri-exponential equation to the oral data. The biological half-life of theophylline was found to be 14.8 h, the volume of distribution 1.02 l/kg and the total plasma clearance 0.86 ml/kg/min. The oral absorption of the drug was complete (bioavailability 108%) and rapid (absorption half-life 0.4 h).
Houghton E, Dumasia MC, Wellby JK.Negative ion chemical ionization mass spectra of some corticosteroids have been obtained by direct syringe introduction on to the Finnigan moving belt high-performance liquid chromatography-mass spectrometer interface. Proprietary preparations based upon dexamethasone, betamethasone and prednisolone were administered to horses at therapeutic dose level. Urine samples were extracted, the extracts purified by Sephadex LH-20 chromatography and the presence of the parent steroids in the eluates was confirmed by combined high-performance liquid chromatography negative ion chemical ionization mass s...
Johnson E, van Heemst J, Benavides J, Gray B.Etizolam is a benzodiazepine analogue that is approved for use in Japan, Italy and India but has recently appeared as a nonapproved product on the illicit drug market in Europe and North America. Etizolam was identified in a crystalline material seized at a Kentucky racetrack, raising concerns that this drug may have been used in racing. The aim of this study was to characterize the metabolism and excretion of etizolam in horses to generate information on its disposition and to incorporate the correct urinary and serum target analytes into anti-doping screening procedures. Etizolam was adminis...
Nielsen BD.Much research has been conducted in an attempt to decrease skeletal injuries in athletic horses. The objective of this literature review is to compile the findings of over three decades of research in this area, make practical recommendations, and describe how research can develop over the years. An initial study investigating the role of bioavailable silicon in the diets of horses in race training produced the unexpected finding of decreased bone mineral content of the third metacarpus subsequent to the onset of training. Further studies revealed this decrease to be associated with stall hous...
Koupai-Abyazani MR, Esaw B, Laviolette B.Urine and serum samples collected from four standard-bred mares after and oral regimen administration of methocarbamol were extracted and analyzed. The method consisted of enzyme hydrolysis followed by a one-step liquid-liquid extraction, separation on a reversed-phase (RP-18) column, and detection using an ultraviolet (UV) detector. The confirmation was carried out using a liquid chromatography-atmospheric pressure ionization-mass spectrometry (LC-API-MS) system. Maximum methocarbamol concentrations of 1498, 1734, 1547, 2322 micrograms/mL in urine and 4.9, 1.7, and 3.6 micrograms/mL in serum ...
Stanley SM, Wee WK, Lim BH, Foo HC.Direct-injection LC-LC hybrid tandem MS methods have been developed for undertaking broad-based screening for acidic drugs in protein-precipitated plasma and neutral doping agents in equine urine. In both analyses, analytes present in the matrix were trapped using a HLB extraction column before being refocused and separated on a Chromolith RP-18e monolithic analytical column using a controlled differential gradient generated by proportional dilution of the first column's eluent with water. Each method has been optimised by the adoption of a mobile phase and gradient that was tailored to enhanc...
Longhofer SL, Reinemeyer CR, Radecki SV.The efficacy of top-dress antiinflammatory drugs ultimately depends on a patient's willingness to consume treated feed. The current study compares the palatability of two phenylbutazone top-dress formulations (Equipalazone Powder, Dechra Pharmaceuticals, and Pro-Dynam, VetXX, Ltd.) and a suxibuzone top-dress formulation (Danilon Equidos, Janssen Animal Health). Results of a three-period, crossover study on 18 healthy horses showed that Pro-Dynam was significantly less palatable, with significantly less consumption of treated feed compared with either Equipalazone Powder or Danilon Equidos. The...
Barker SA.Advances in analytical technology now make it feasible to detect and confirm exceptionally low concentrations (pg to fg/mL) of drugs and their metabolites in equine biological fluids. These new capabilities complicate the regulatory interpretation of drug positives and bring into question the fair application of medication rules. Such approaches and policies are further complicated by the possibility that drug positives may arise from contamination of the equine environment on the backstretch of the race track. This manuscript provides data demonstrating that the general environment of the bac...
Delbeke FT, Debackere M.The prototype of a commercial ELISA test kit designed for fentanyl determination in human urine has been evaluated for screening fentanyl in horse urine and plasma. The measurement of fentanyl after intravenous (2 mg) and intramuscular (0.25 mg) administration in undiluted plasma was not reproducible while accurate quantification of fentanyl in urine greatly depends on the composition of the horse urine. The ELISA assay, however, is simple and could be successfully used for quantitative measurements in diluted urine and for rapid qualitative screening for fentanyl in large numbers of urine sam...
Dumasia MC, Houghton E, Moss MS, Chakraborty J, Marks V.The pro-drugs of dexamethasone, a potent glucocorticoid, are frequently used as anti-inflammatory steroids in equine veterinary practice. In the present study the biotransformation and urinary excretion of tritium labelled dexamethasone were investigated in cross-bred castrated male horses after therapeutic doses. Between 40-50% of the administered radioactivity was excreted in the urine within 24 h; a further 10% being excreted over the next 3 days. The urinary radioactivity was largely excreted in the unconjugated steroid fraction. In the first 24 h urine sample, 26-36% of the total dose was...
Higgins AJ, Lees P, Sharma SC, Taylor JB.An accurate and reliable method for the separation of flunixin from, and measurement in, equine inflammatory exudate and plasma by high performance liquid chromatography has been developed. Flunixin can be detected in concentrations as low as 0.05 micrograms/ml using an ultraviolet spectrophotometric detector at 285 nm. Samples were acidified with 2M hydrochloric acid and extracted with dichloromethane. The extract was evaporated and reconstituted in acetonitrile. Iminodibenzyl was used as internal standard. The mean recovery of flunixin from plasma was 97.6 +/- 3.9 per cent. Particular advant...
