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.
Mirck MH.The use of trichlorfon as an anthelmintic in horses has increased since it was combined with mebendazole and febantel, and became commercially available as Telmin-trichlorfon and Rintal-plus respectively. Field studies showed that these combined preparations frequently gave rise to cases of poisoning. Mild to severe colic was observed up to six hours after treatment, diarrhoea and/or anorexia continuing to be present for one to six days after administration. The 'horse weight measurer' introduced by Janssen Pharmaceutica is not sufficiently accurate to prevent overdosage. It is advisable only ...
Yoxall AT.This paper is an introduction to a series of commissioned articles on therapeutic medicine to be published in Equine Veterinary Journal under differing authorship, during the next 2 years. It presents an account of fundamental concepts common to the use of all drugs and introduces some pharmacokinetic principles to which reference will be made in later articles.
Henion JD, Maylin GA.A sensitive, quantitative method has been developed for the determination of hydrochlorothiazide in equine plasma and urine. Thin-layer chromatography is used to screen for the presence of the drug in unknown samples. The TLC screening methods described provide minimum detection limits of 50 ng/mL in plasma and 25 ng/mL in urine. A silica micro chromatography column is used to clean up ethyl acetate extracts for HPLC analysis and mass spectral confirmation. An internal standard, trichloromethiazide, is used to derive quantitative data at concentrations as low as 25 ng/mL for plasma disappearan...
de Backer P, Vandecasteele-Thienpont LM, Jonckheere JA, Belpaire FM, Debackere M, de Leenheer AP.Bromhexine was administered orally (2 mg./kg.) and intravenously (i. v.) (1 mg./kg.) in 3 horses. Plasma levels were measured and the pharmacokinetic behaviour and bioavailability were estimated. The half-life of elimination after i. v. administration ranged from 3.1 to 4.4 hours. The mean values of the apparent volume of distribution and the volume of distribution of the central compartment amounted to 16.2 and 3.3 1./kg., respectively. A very high plasma clearance, ranging from 49.8 to 59 ml./kg./min., was found.
One hour after oral administration, a mean peak plasma level of about 14 ng....
Slocombe JO, McCraw BM.Trials were conducted in ponies to evaluate the efficacy of pyrantel pamoate (Strongid-T(R)) and two newer anthelmintics not yet commercially available, nitramisole and avermectin B(1)a, against migrating Strongylus vulgaris larvae. Ponies were removed from their mares within 24-48 hr after birth and reared in isolation, worm free. Between six and 14 weeks of age they were infected with 2000 or 2500 infective S. vulgaris larvae. Subsequently, they were monitored daily for clinical signs until the experiment terminated at 28 days postinfection. All ponies showed increased body temperature and r...
Hunt JP, Haywood PE, Moss MS.A gas chromatographic screening procedure for the non-steroidal anti-inflammatory group of drugs is described. The method invovles on-column methylation of the carboxylic acid group using trimethylanilinium hydroxide as the methylating reagent. Fifteen such drugs were studied. Eight of these were detected in urine collected from horses that had received these compounds orally and for these drugs, rates of urinary excretion are recorded. Seven other members of this group of drugs were shown to be detectable by this procedure but in these cases the drug was added to urine and not administered to...
Pippi NL, Lumb WV.An equine model, subjected to three kinds of pain (superficial, deep, and visceral) was used to test effects of analgesic drugs. Two groups of ponies were used. In the first group of six ponies, six drugs (fentanyl, meperidine, methadone, oxymorphone, pentazocine, and xylazine) were given according to a Latin square experimental design, and tests were made at 30-minute intervals for 4 hours. Mean values (control) for the three kinds of pain were obtained before and after the tests and were compared with the mean values (drugs) obtained over 2- and 4-hour intervals (four and eight measurements ...
Houghton E, Oxley GA, Moss MS, Evans S.A method is described to confirm the presence of 19-nortestosterone metabolites in urine after the administration of veterinary preparations of this anabolic steroid to horses. The method is based upon the detection, by gas chromatography mass spectrometry or selected ion monitoring, of an isomer of estrane-3,17-diol in the urine.
Dumasia MC.The in vivo biotransformation of metoprolol tartrate in the thoroughbred racehorse was studied after administration of a single oral dose. Metoprolol and its basic and bifunctional phase I metabolites were isolated from urine and plasma using mixed mode solid phase extraction (SPE) cartridges. The isolates were derivatised as trimethylsilyl ethers and analysed by capillary column gas chromatography--positive ion electron ionisation and ammonia chemical ionisation mass spectrometry. Metabolism was primarily confined to the oxidative transformations of the p-(2-methoxy)ethyl substituent. Metopro...
Marland A, Sarkar P, Leavitt R.A method for the extraction of diazepam and its metabolites (nordiazepam, temazepam, and oxazepam) from equine urine and serum and their quantitation and confirmation by liquid chromatography-tandem mass spectrometry is presented. Valium, a formulation of diazepam, was administered at a dose of 10 mg intramuscularly to four standard-bred mares. Diazepam is extensively metabolized in the horse to nordiazepam, temazepam, and oxazepam. Diazepam urinary concentrations were found to be less than 6 ng/mL. Nordiazepam was found to be mainly in its glucuronide-conjugated form and was measured out to a...
Janett F, Aebi L, Burger D, Imboden I, Hässig M, Kindahl H, Thun R.The objective of this study was to evaluate the effect of the non-steroidal anti-inflammatory drug (NSAID) vedaprofen (Quadrisol) on quality and freezability of stallion semen. Experiments were performed using 22 Franches Montagnes stallions from the National Stud in Avenches (Switzerland) randomly divided into a control and test group. Vedaprofen was given orally to all stallions of the test group at the recommended therapeutic dose (initial dose of 2mg/kg followed by 1mg/kg body weight every 12h) for 14 days. Control animals received the same amount of carrier substance. During treatment, bl...
Emmerich IU.In 2017, no new active pharmaceutical ingredients were released on the German market for horses or food-producing animals. Four established veterinary active pharmaceutical ingredients became available for additional species: the ectoparasitic Fluralaner (Exzolt®) of the isoxazoline group was additionally authorized for chickens, the macrolide antibiotics Gamithromycin (Zactran®) and Tulathromycin (Draxxin®) for sheep and the nonsteroidal anti-inflammatory drug Tolfenamic Acid (Tolfedol®) from the fenamate group for cattle and pigs. Additionally, one drug with a new combination of active i...
Kwok WH, Kwok KY, Leung DK, Leung GN, Wong CH, Wong JK, Wan TS.The positive findings of norbolethone in 2002 and tetrahydrogestrinone in 2003 in human athlete samples confirmed that designer steroids were indeed being abused in human sports. In 2005, an addition to the family of designer steroids called 'Madol' [also known as desoxy-methyltestosterone (DMT)] was seized by government officials at the US-Canadian border. Two years later, a positive finding of DMT was reported in a mixed martial arts athlete's sample. It is not uncommon that doping agents used in human sports would likewise be abused in equine sports. Designer steroids would, therefore, pose...
Koupai-Abyazani MR, Esaw B, Laviolette B.A high-performance liquid chromatographic method was used for the detection of etodolac in equine serum and urine. The method consisted of a one-step liquid-liquid extraction, separation on a reversed-phase (RP-18) column and detection using an ultraviolet detector. Additional confirmation methods included a HPLC coupled with an atmospheric pressure chemical ionization mass spectrometer (APCI-MS). Free (unbound) etodolac and its conjugates were present in the samples. Concentrations of the drug in the serum and urine samples collected from four standardbred mares after a single oral administra...
Nelis SA, Sievers C, Jarrett M, Nissen LM, Kirkpatrick CM, Shaw PN.In this paper, a method for the sensitive and reproducible analysis of lignocaine and its four principal metabolites, monoethylxylidide (MEGX), glycylxylidide (GX), 3-hydroxylignocaine (3-HO-LIG), 4-hydroxylignocaine (4-HO-LIG) in equine urine and plasma samples is presented. The method uses liquid chromatography coupled to tandem mass spectrometry operating in electrospray ionisation positive ion mode (+ESI) via multiple reaction monitoring (MRM). Sample preparation involved solid-phase extraction using a mixed-mode phase. The internal standard adopted was lignocaine-d(10). Lignocaine and its...
Benoit E, Jaussaud P, Besse S, Videmann B, Courtot D, Delatour P, Bonnaire Y.A benzhydrolic metabolite of ketoprofen, formed by reduction of the keto group of the drug, has been identified by gas chromatography-mass spectrometry in equine plasma and urine. After partial synthesis, its structure has been confirmed by UV, IR and 1H NMR spectroscopy. The kinetics of ketoprofen and this metabolite have been monitored in plasma by high-performance liquid chromatography. The two products were quantified in plasma up to 4 and 3 h, respectively, and were detected in urine up to 72 and 24 h, respectively, after a single intravenous administration to horses at the dose of 2.2 mg...
Pu F, McKinney AR, Stenhouse AM, Suann CJ, McLeod MD.A study of the equine phase II metabolism of the anabolic agent boldenone is reported. Boldenone sulfate, boldenone glucuronide and their C17-epimers were synthesised as reference standards in our lab and a method was developed for their detection in a horse urine matrix. Solid phase extraction was used to purify the analytes, which were then detected by ion trap LC/MS. Negative and positive ionisation mode MS(2) were used for the detection of sulfate and glucuronide conjugates, respectively. Boldenone sulfate and 17-epiboldenone glucuronide were detected as the major and minor phase II metabo...
Cook G, Papich MG, Roberts MC, Bowman KF.To determine the i.v. pharmacokinetics of cisapride and measure systemic absorption after rectal administration. Methods: 5 healthy adult mares (380 to 610 kg). Methods: Cisapride was administered, i.v., at a dosage of 0.1 mg/kg of body weight. In the same horses, after a 1-week washout period, cisapride was administered rectally at a dosage of 1 mg/kg by mixing crushed tablets with propylene glycol and administering the mixture into the rectum. After each drug administration, a series of blood samples were collected. Plasma was obtained and analyzed by high-performance liquid chromatography t...
