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.
Brown MP, Kelly RH, Gronwall RR, Stover SM.Six healthy adult mares were given a single IV dose (25 mg/kg of body weight) of chloramphenicol sodium succinate. Chloramphenicol concentrations in serum, synovial fluid, peritoneal fluid, and urine were measured serially over a 48-hour period. The highest measured serum chloramphenicol concentration was 6.21 micrograms/ml at 0.5 hour. Chloramphenicol was detected in synovial and peritoneal fluids, with mean peak concentrations of 3.89 micrograms/ml and 3.50 micrograms/ml, respectively, at 0.5 hour. Serum and synovial concentrations declined rapidly and were not measurable at 3 hours. Chloram...
Johansson IM, Schubert B.Flunixin is determined in equine plasma by liquid chromatography on LiChrosorb RP-18 with 70% methanol in phosphate buffer pH 3.1 as the eluent, with detection at 284 nm. Plasma is deproteinized with methanol and the supernatant is then injected directly into the system. With a short pre-column (5 x 3 mm i.d.), which is replaced after 25-40 injections of sample, 420 plasma samples could be analysed on one analytical column. The detection limit in plasma is 0.30 micromol/l (89 ng/ml) and the method can be used in pharmacokinetic studies.
Dewey EA, Maylin GA.The metabolism of propionylpromazine in the horse was studied. Although propionylpromazine is not currently approved or recommended for use in horses, it has been used illegally to alter their performance. Propionylpromazine hydrochloride was administered intramuscularly at clinical and subclinical doses. Three metabolites were detected in urine. The major metabolite was identified as 2-(1-hydroxypropyl) promazine sulfoxide. The detection of this metabolite in routine drug testing has been described.
Moss M S..A review of positive Jockey Club "dope tests" during the 12 years from 1970 to 1981 inclusive is presented and a comparison made with certain overseas racing authorities for varying periods between 1975 and 1981. Urinary pH of post race urine samples is predominantly acidic (although varying in a significant manner throughout the year) and thus favours excretion of the generally more potent basic drugs. The proportion of positive results was about the same in winners and non-winners, ie, one in 400 horses sampled. Drugs found fell mainly into four categories: methylxanthines; non-steroidal ant...
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 ...
Marsh MV, Caldwell J, Sloan TP, Smith RL, Horner M, Moss MS.14C-Fenclofenac (2-(2'-4'-dichlorophenoxy)-phenylacetic acid) was administered orally to horses, and urinary metabolites investigated by chromatography. Fenclofenac was rapidly absorbed and eliminated, with a plasma half-life (t1/2) of 2.3 h, with 83.2 and 85.8% of the dose being recovered in the urine in 0-24 h. The major urinary metabolite was the ester glucuronide (58.8, 70.0% dose), and evidence is presented that this metabolite undergoes a structural rearrangement to give beta-glucuronidase-resistant isomers. The other 14C-labelled components in horse urine were unchanged fenclofenac (13....
Houghton E, Teale P, Dumasia MC, Wellby JK.The negative ion chemical ionization mass spectra of the MO-TMS derivatives of the corticosteroids prednisolone, betamethasone and dexamethasone have been obtained using capillary column gas chromatography mass spectrometry. The spectra showed abundant diagnostic ions at m/z greater than 300 allowing for clear discrimination between the three steroid derivatives. A capillary column gas chromatographic mass spectrometric method using negative ion chemical ionization mass spectrometry has been developed to confirm the presence of the parent steroids in horse urine following the administration of...
Marsh MV, Caldwell J, Hutt AJ, Smith RL, Horner MW, Houghton E, Moss MS.The metabolism of benzoic acid has been examined in the horse, using 14C- and deuterium-labelled compounds. Chromatographic analysis of the urine showed the presence of hippuric acid, benzoyl glucuronide and benzoic acid and a discrete band which accounted for 2% of the dose administered. This material was isolated by solvent extraction and HPLC and, following treatment with diazomethane, examined by GC/MS. The major component of this fraction was 3-hydroxy-3-phenylpropionic acid methyl ester, which was accompanied by very much smaller amounts of cinnamic acid methyl ester and acetophenone. Th...
Eckers C, Skrabalak DS, Henion J.We describe an integrated micro-liquid chromatograph/mass spectrometer (micro-LC/MS) system capable of performing routine determinations for 1--10 ng of drugs and their metabolites extracted from biological fluids. The micro-LC is constructed from conventional "high-performance" liquid-chromatographic instrumentation by using commercially available components. The mass spectrometer is operated in the chemical ionization mode. The direct liquid introduction micro-LC/MS interface can be constructed from commercially available materials. Chromatographic and mass spectral results demonstrate the a...
Hood DM, Stephens KA, Bowen MJ.Phenoxybenzamine, an alpha adrenergic antagonist, was administered IV to 6 clinically normal horses, 5 horses with experimentally induced diarrhea, and 7 horses with naturally-occurring diarrhea. It was established that a total of 2 mg of phenoxybenzamine/kg of body weight given in divided doses resulted in alpha adrenergic blockage of approximately 72 hours' duration, tranquilization, and mild constipation in the normal horse. The 5 experimental cases of diarrhea were involved in a laminitis research protocol in which laminitis was induced by oral carbohydrate overload. In all 5 of those case...
Cordes B.The research article titled, “Effects of compounding and storage conditions on stability of pergolide mesylate” investigates the importance of adhering to the official US Pharmacopeia (USP) when formulating pergolide mesylate […]
Allen RG.The presently used procedures for the colorimetric determination of conjugated estrogens (equine) have been modified for the assay of tablets, capsules, liquids, and creams of low declaration per dosage unit. Modifications in sample chromatographic column preparation and elution have provided a more efficient extraction of the steroids.
Bampidis V, Azimonti G, Bastos ML, Christensen H, Durjava M, Kouba M, López-Alonso M, López Puente S, Marcon F, Mayo B, Pechová A, Petkova M....Following a request from the European Commission, EFSA was asked to deliver a scientific opinion on the safety and efficacy of an essential oil from the seeds of Houtt. (nutmeg oil), when used as a sensory additive in feed and water for drinking for all animal species. The additive contains myristicin (up to 12%), safrole (2.30%), elemicin (0.40%) and methyleugenol (0.33%). For long-living and reproductive animals, the Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) considered of low concern the use of the additive in complete feed at 0.2 mg/kg for laying hens and...
Marchenko VA, Khalikov SS, Biryukov IV, Efremova EA, Ilyin MM, Sazmand A.This study aimed to develop new complex preparations of ivermectin, niclosamide and albendazole based on solid-phase mechanochemical technology, and to evaluate their efficacy against equine nematodosis and cestodosis. Unassigned: Novel formulation of antiparasitic paste were prepared using joint mechano-chemical treatment of ivermectin (0.2 mg/kg bodyweight; BW), niclosamide (10 mg/kg BW) and albendazole (3, 5, 10 mg/kg BW) substances with polyvinylpyrrolidone and arabinogalactan. For the evaluation of activity of different doses of formulations against gastrointestinal tract helminths a tota...
Bondesson U, Johansson IM.This study demonstrates the development of a method using gas chromatography-mass spectrometry for determining nefopam, a non-narcotic pain reliever that is sometimes abused in horse doping, in equine plasma. Background […]
Serrano-Rodríguez JM, Miraz R, Saitua A, Díez de Castro E, Ledesma-Escobar C, Ferreiro-Vera C, Priego-Capote F, Sánchez de Medina V....Cannabigerol (CBG) is a non-psychoactive cannabinoid with growing interest in veterinary medicine; however, its pharmacokinetic profile in horses remains unknown. Understanding its absorption, distribution, metabolism, and elimination is essential to optimizing dosing strategies and evaluating its potential for clinical use in equine patients. Unassigned: A prospective crossover study was conducted in eight healthy adult horses to assess the metabolism and the pharmacokinetics after intravenous (IV) administration at 1 mg/kg and oral administrations at 10 mg/kg with two formulations (mice...
Emmerich IU.In 2011, three newly developed active pharmaceutical ingredients for horses and food producing animals were released on the German market for veterinary drug products. Two of these new products represent different drug classes of antibiotics, the polypeptide antibiotic Bacitracin (Bacivet™) and the macrolide antibiotic Clorsulon (Levatum®). The third product represents an anticestodal antiparasitic (Tildipirosin, Zuprevo®). Furthermore, three established veterinary active pharmaceutical ingredients were modified to allow their application for additional species. Thus the nonsteroidal anti-...
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...
Cox D.Many clinicians are experiencing consumer resistance to the prescription of equine HRT (that is hormone replacement therapy which has been manufactured from mare's urine). In this paper I consider the ethical implications of prescribing these preparations. I decide that patients should have a right to refuse such treatment but also ask whether a prescribing doctor should choose one preparation over another on moral grounds. I determine that there is prima facie evidence to suggest that mares may suffer and that prescription of equine HRT (instead of synthetic oestrogen-oestriol) would therefor...
Cazalet E.The paper examines the responsibilities of the veterinary surgeon in relation to the advances more recently made in the field of equine cardiology. Notwithstanding such advances it is stated that the normal established legal principles apply, in particular in relation to the preparation of certificates, namely that the veterinary surgeon must be sufficiently expert to give the opinion sought, that he must make himself fully aware of the purpose for which the certificate is required and that he must make clear the nature and limitations of any examination carried out.
Thomas DP, Foley JP.Detection of prohibited substances in equestrian sports typically involves time-consuming and tedious sample-preparation methods. Micellar LC (MLC) allows for direct injection of equine serum to detect prohibited NSAIDs. Results: The method was linear over the range of standards examined, with recoveries of 94.2-95.1% for phenylbutazone (12-18 µg/ml), and 83.9-88.7% and 87.9-105.0% for diclofenac and flunixin, respectively (0.1-1.2 µg/ml). The limit of detection was 0.1 µg/ml for all compounds and the limit of quantitation was 0.2 µg/ml for phenylbutazone and 0.3 µg/ml for diclofenac and ...
