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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.
Anesthetic Recovery Following a Midazolam-Containing Co-Induction Protocol in Horses Undergoing Total Intravenous Anesthesia. Anesthetic recovery is a critical phase in horses under field conditions, and induction protocols may influence recovery quality during total intravenous anesthesia. Objective: To compare two anesthetic induction protocols, one including midazolam and the other based solely on xylazine and ketamine, regarding anesthetic induction and recovery quality, total recovery time, and attempts to achieve standing in horses undergoing total intravenous anesthesia. Methods: Twelve healthy male horses older than 2 years were randomly assigned to XC (xylazine 1 mg/kg and ketamine 2 mg/kg) or XCM (xylazine ...
Use of Sildenafil Citrate for the Treatment of Erectile Dysfunction in Stallions: First Case Reports. Pharmacological aids can be useful alternatives to enhance penile erection and/or improve ejaculatory function, thereby prolonging the reproductive life of stallions with ejaculatory disorders. This study aimed to evaluate the effects of sildenafil citrate in the treatment of erectile dysfunction and on semen quality in two aged stallions, a Quarter Horse (18 years) and a Mangalarga Marchador (25 years), presented to the Veterinary Hospital of FMVZ-UNESP, Botucatu, SP, Brazil. The treatment consisted of oral administration of sildenafil citrate at 0.2 mg/kg. Thirty minutes after administ...
Population Pharmacokinetics and Detection Times of Betamethasone After Intravenous, Intramuscular, and Intranasal Jet Administration of Betamethasone Sodium Phosphate in Horses. Betamethasone sodium phosphate (BETP) is a glucocorticosteroid used in humans. The primary objective was to estimate irrelevant plasma (IPC) and urine (IUC) concentrations using a pharmacokinetic/pharmacodynamic approach based on systemic clearance estimated from intravenous (IV) pharmacokinetic data. As a secondary objective, detection times (DTs) following IV, intramuscular (IM), and intranasal jet (INJ) administration were estimated for medication control. Plasma and urine concentrations were obtained from a total of 20 horses in Japan and Germany, with some horses contributing to more than...
Synthesis and Characterization of 2-(1-Hydroxyethyl)Promazine Sulfoxide-d4 HCl as an Internal Standard for the Accurate Quantitation of 2-(1-Hydroxyethyl)Promazine Sulfoxide in Equine Urine. Acetylpromazine, 1-{10-[3-(dimethylamino)propyl]-10H-phenothiazin-2-yl}ethenone, CHNOS, 326.46 g·mol is a phenothiazine derivative at one time used in human medicine as an antipsychotic medication but now predominantly used in veterinary medicine as a sedative/tranquilizer and referred to as acepromazine. In performance horses its use is regulated by using a 10 ng/mL threshold for the major urinary metabolite 2-(1-hydroxyethyl) promazine-sulfoxide (HEPS) in equine urine. To enable accurate quantitation of HEPS in equine urine we have synthesized and purified hydroxyethylpromazine sulfoxid...
Analgesic use, safety and pharmacokinetics of acetaminophen in equids: A structured scoping review. Despite its frequent use in equine clinical practice, scientific data on the use of acetaminophen in horses remain limited. Objective: To map and critically appraise the available evidence on the analgesic use, safety and pharmacokinetics of acetaminophen in horses. Methods: Structured scoping review. Methods: A comprehensive search was performed in accordance with the PRISMA Extension for Scoping Reviews using the terms '(paracetamol OR acetaminophen) AND (pain OR safety OR toxicosis OR pharmacokinetics) AND (horse OR pony OR donkey OR mule)' across Web of Science, Scopus, and PubMed from dat...
In Vivo Metabolite Formation and In Vitro Cytochrome P450-Mediated Metabolism of Vonoprazan in Horses. Vonoprazan is a potassium-competitive acid blocker with potential for the treatment of equine gastric ulcer syndrome. Vonoprazan metabolic pathways in horses have not been characterized. This study aimed to identify vonoprazan metabolites following oral administration and to determine the metabolic enzymes responsible for their metabolism using in vitro models. Six healthy adult Thoroughbred horses received vonoprazan (0.5 and 1 mg/kg PO) in a randomized crossover design. Plasma concentrations of vonoprazan-N-oxide (M-I) and vonoprazan-nitrone (M-III) were quantified using a validated liquid...
Effects of omeprazole therapy administered via different routes on urinary parameters and selected interleukins in horses with equine gastric ulcer syndrome. Equine gastric ulcer syndrome (EGUS) is commonly treated with proton pump inhibitors such as omeprazole, administered orally or by injection. In humans, omeprazole has been associated with acute interstitial nephritis (AIN) and acute kidney injury (AKI), potentially linked to oxidative stress, and urinary interleukins may serve as early non-invasive markers. However, this association has not been established in horses. Objective: To evaluate the effects of oral and injectable omeprazole on basic urinary parameters and selected interleukin levels, with particular emphasis on the potential risk ...
Pharmacokinetic/Pharmacodynamic Analysis of Quinidine-Induced Dominant Frequency Reduction in Thoroughbred Horses With Atrial Fibrillation. Quinidine has long been used for the pharmacological treatment of atrial fibrillation (AF) in horses; however, the plasma concentration required for conversion to sinus rhythm remains unclear. Dominant frequency (DF), derived from surface electrocardiograms, reflects atrial activation rate during AF. This study aimed to quantify the relationship between plasma quinidine concentration and DF using a pharmacokinetic/pharmacodynamic (PK/PD) approach. Ten Thoroughbred horses with naturally occurring AF received quinidine sulfate via a nasogastric tube. Plasma quinidine concentrations and DF values...
Detection of Cyclosporine in Horse Hair After Ocular Implant Administration. This study describes the detection and temporal distribution of cyclosporine in equine hair following ocular implant administration in a Thoroughbred gelding. Mane hair samples were collected at 172- and 217-day post-implantation and analysed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) after alkaline hydrolysis and liquid-liquid extraction. The method achieved an estimated limit of detection of 0.1 pg/mg. Cyclosporine was detected in hair at both sampling time points, with segmental analysis revealing distribution patterns consistent with systemic exposure and incorporation ...
Perineural dexamethasone does not prolong bupivacaine sensory blockade in equine palmar digital nerve blocks: a randomized crossover trial. To determine whether dexamethasone sodium phosphate (dexamethasone SP) prolongs the sensory blockade produced by perineural bupivacaine during medial and lateral palmar digital nerve blocks in horses. Unassigned: 8 healthy adult horses were enrolled in a blinded, randomized 4 X 4 crossover trial. Each horse received 1 of 4 perineural treatments over the palmar digital nerves of the left forelimb: bupivacaine, bupivacaine + dexamethasone SP, dexamethasone SP alone, or saline. A minimum 7-day washout was used between treatments. Mechanical nociceptive threshold (MNT) was measured at baseline and...
Nonsteroidal anti-inflammatory drug administration alters crypt distribution of the peroxisomal marker acyl-coenzyme A oxidase 1 in the equine right dorsal colon. To characterize and compare the distribution of peroxisomal markers in the right dorsal colon (RDC) and left ventral colon (LVC) of healthy horses and horses treated with NSAIDs. Unassigned: Archived colonic tissues were evaluated from 10 horses (n = 5/group) administered phenylbutazone (4.4 mg/kg, PO, twice daily for 10 days) or placebo prior to euthanasia. Samples from the RDC and LVC were analyzed using immunofluorescence to assess peroxisomal biogenesis factor 14 (PEX14) and acyl-coenzyme A oxidase 1 (ACOX1) distribution. Marker abundance was quantified within colonic crypts and compared b...
Plasma and Urinary Concentrations of Synephrine in Horses Following Controlled Oral Administration. Synephrine is a sympathomimetic alkaloid of regulatory interest in both horse racing and equestrian sports, where feed‑related exposure may lead to its detection in equine blood and urine. This study characterized plasma and urinary concentrations of synephrine in horses following controlled oral administration. Six Thoroughbred horses received single oral doses of 100 mg or 800 mg synephrine, and blood and urine samples were collected sequentially. Each sample was analyzed both before and after β‑glucuronidase hydrolysis, demonstrating that synephrine was present predominantly as conjuga...
Administration Study of Bedinvetmab, an Antinerve Growth Factor Monoclonal Antibody, in Horses for Doping Control Purposes. Monoclonal antibodies (mAbs) targeting nerve growth factor (NGF) represent a novel therapeutic approach for managing acute and chronic pain in humans and animals. However, their potential misuse as pain-masking agents in competitive equine sports raises significant welfare and integrity concerns. To enhance understanding of the elimination profile of anti-NGF mAb if misused in horses, this study describes the first administration of bedinvetmab (a canine anti-NGF mAb) in three geldings, establishing its plasma elimination profile following subcutaneous administration. Bedinvetmab plasma concen...
Correction: Phenylbutazone concentrations in synovial fluid following administration via intravenous regional limb perfusion in the forelimbs of six adult horses. [This corrects the article DOI: 10.3389/fmed.2026.1810077.].
Assessment of pharmacokinetic parameters, oral bioavailability, and physiological effects of amantadine in horses. Without adequate pain management, central nervous system plasticity can result in acute or adaptive pain developing into chronic or maladaptive pain. This is difficult to manage and often unresponsive to traditional analgesics. An important mechanism associated with maladaptive pain is central sensitization which results in part from increased NMDA (N-methyl-D-aspartate) receptor activation. Amantadine is an NMDA receptor antagonist that has been used in combination with opioids and NSAIDs in humans and dogs for the treatment of conditions associated with central sensitization. The goal of the...
Characterization of the Pharmacokinetics and Physiological Effects of Tapentadol in Horses. Tapentadol is a dual mechanism analgesic utilizing both μ-opioid receptor (MOR) agonism and norepinephrine reuptake inhibition (NRI). This study evaluated the pharmacokinetics and pharmacodynamics of tapentadol as a potential analgesic with the goal of treating pain in horses. Pharmacokinetics of both tapentadol and tapentadol-O-glucuronide were elucidated. Six horses received three separate escalating single oral doses (1, 3, and 5 mg/kg) and a single intravenous (0.32 mg/kg) dose of tapentadol in a four-period sequential design. Concentrations of tapentadol and tapentadol-O-glucuronide ...
Meta-Analysis and Physiologically-Based Modeling of the Pharmacokinetics and Pharmacodynamics of Dexamethasone in Horses. Dexamethasone (DEX) is widely used in equine practice for its potent anti-inflammatory effects and diverse studies have examined its pharmacology in horses. We integrated all available pharmacokinetic (PK) and pharmacodynamic (PD) data from 12 studies to quantify DEX disposition and endocrine effects in horses. Methods: DEX concentrations in blood, urine and synovial fluid, plus cortisol (CTS) and glucose (GLU) in plasma, following various administration routes (intravenous (IV), intramuscular (IM), intra-articular, oral) were available from original studies or digitized from literature. A mi...
Comparative Pharmacokinetics of Gentamicin in Healthy Young-Adult and Geriatric Horses. Aging may modify the pharmacokinetic disposition and excretion of gentamicin, although drug dose adjustments in aged horses are uncommon in clinical practice. Since high-dose, once daily dosing of gentamicin is considered therapeutically most effective, a comparative single-dose study was conducted to evaluate the differences in pharmacokinetics between healthy young-adult (5-10 years) and geriatric (≥ 25 years) horses receiving 6.6 mg/kg gentamicin intravenously. Blood samples were collected at designated time-points following drug administration and frozen at -80°C until assayed b...
Single-dose intravenous α2-agonists do not acutely alter anti-inflammatory bioactive protein profiles but reduce interleukin-8 in equine autologous protein solution and platelet-rich plasma. Determine the acute effects of xylazine and detomidine on concentrations of selected growth factors, cytokines, and α2-macroglobulin (A2M) in platelet-rich plasma (PRP) and autologous protein solution (APS) and the long-term effects of these sedatives on serum A2M. We hypothesized that sedative administration would decrease concentrations of all bioactive proteins in PRP and APS acutely and A2M in serum for 6 days following sedative administration. Unassigned: 6 horses were randomized to receive IV xylazine (200 mg) or detomidine (10 mg). Blood was collected before and 5 minutes after sedativ...
Plasma and urinary exposure of cannabidiol and cannabidiolic acid in horses following consumption of contaminated feed. Cannabidiol (CBD) and cannabidiolic acid (CBDA) are non-psychoactive cannabinoids naturally present in hemp-derived products. While these compounds are prohibited during equine competition, horses may be inadvertently exposed through contaminated feed. Data describing systemic and urinary exposure to CBD and CBDA following such low-dose, involuntary intake are limited. This study aimed to describe plasma and urine concentration-time profiles of CBD and CBDA in horses after consumption of experimentally contaminated feed. Results: Twelve Standardbred horses received feed containing low doses (1...
The Early Ophthalmic Effects of Vatinoxan in Healthy Detomidine-Sedated Horses. To evaluate the short-term ophthalmic effects of vatinoxan, a peripherally selective alpha2-adrenoceptor antagonist, in detomidine-sedated horses. Methods: Seven healthy horses without ophthalmic disease in a randomized, masked, two-period crossover study design, with a ≥ 7-day rest period. Methods: After a bilateral palpebral block (lidocaine 40 mg) and baseline data collection, horses received intravenous detomidine (20 μg/kg [DET]) or DET with vatinoxan (200 μg/kg [DET-VAT]). Intraocular pressure (IOP) was measured from the left eye while tear production (Schirmer tear test -1; ...
Oclacitinib for Controlling Pruritus and Associated Skin Lesions in 16 Horses With Allergic Dermatitis. Oclacitinib is a Janus kinase inhibitor approved for the treatment of pruritus associated with allergic dermatitis in dogs and may be effective in horses. Objective: To evaluate the efficacy of oclacitinib in reducing pruritus and skin lesions in horses with allergic dermatitis. Methods: Sixteen horses aged ≥ 18 months. Methods: Horses received oclacitinib at 0.25 mg/kg orally once daily for 21 days. Changes in haematological and biochemical parameters were measured on Day (D)0 and D21. The owners were instructed to evaluate the horses using the pruritus Visual Analog Scale (PVAS) on...
A Genetic Algorithm-Based Approach for Quantitative Prediction of Drug-Drug Interactions Caused by Cytochrome P450 3A Inhibition or Induction in Horses. A genetic algorithm (GA)-based approach was designed to predict drug-drug interactions (DDIs) triggered by cytochrome P450 3A (CYP3A) inhibition or induction in horses. Area under the concentration-time curve ratios (AUCRs), obtained from published in vivo DDI studies in horses, were used to compute the following parameters: (1) the contribution ratio (CR), i.e., the fraction of the substrate dose metabolized via the CYP3A pathway, and (2) the interacting drug's inhibitory potency or inducing efficacy (IR or IC, respectively). AUCRs for 9 substrates, 12 inhibitors, and 1 inducer of equine C...
Pharmacokinetics of Diclazuril in the Plasma and Cerebrospinal Fluid of Healthy Adult Horses After a Single Oral Dose Administered as a Pelleted Topdressing. Equine protozoal myeloencephalitis can cause acute infections with rapid onset of neurologic signs, necessitating immediate empiric therapy with antiprotozoal medication. The objective of the study was to identify when concentrations of diclazuril reached the MIC of Sarcocystis neurona in CSF (1 ng/mL) of healthy adult horses after a single oral dose. Six healthy adult horses were used. Blood and CSF were collected from indwelling intravenous jugular catheters and intrathecal catheters in the lumbosacral space prior to drug administration and then at 1-, 4-, 8-, 12-, 16-, 24-, 48-, 72-, 96-,...
Pharmacokinetics of Ertugliflozin, a Sodium-Glucose Co-Transporter-2 Inhibitor (SGLT2i) in Horses After Enteral Administration. Ertugliflozin is a sodium-glucose co-transporter-2 inhibitor that has demonstrated promise as a treatment for hyperinsulinaemia in horses. Despite the frequent use of ertugliflozin in equine clinical practice, the pharmacokinetics of this drug in horses has not been established. The aim of the present study was to determine the pharmacokinetics of one supratherapeutic dose (0.25 mg/kg) of ertugliflozin in eight horses. Horses were defined as being healthy by physical examination, haematological, blood biochemical and oral sugar test (OST) results. Plasma concentrations of ertugliflozin were qu...
Clodronate disodium reduced TRAP5b independent of affecting other systemic biomarkers of bone resorption or formation in yearling, exercising Quarter Horses. Clodronate disodium (CD), a bisphosphonate, modulates bone metabolism. Though extra-label use in juvenile horses is anecdotally reported, impacts on skeletal development are unknown. The objective was to determine the effects of CD on systemic markers of bone turnover in yearling horses undergoing exercise, hypothesizing that biomarkers of bone resorption would decrease while biomarkers of bone formation would not change, and that repeat CD treatments would have greater effect. To test this, 32 yearling Quarter Horses were used in a 168-d trial. Horses were stratified by age (500 ± 13 d),...
Effects of vatinoxan in horses sedated with detomidine and butorphanol for gastroscopy: a randomized clinical study. The peripheral alpha2-adrenoceptor antagonist vatinoxan attenuated the side effects of alpha2-adrenergic sedatives in experimental studies in horses. This clinical study investigated the effects of vatinoxan in horses sedated for gastroscopy with detomidine and butorphanol. Client-owned horses were randomly allocated to receive one of the following two intravenous treatments: detomidine hydrochloride (HCl) (12μg/kg) + butorphanol tartrate (12μg/kg) (DB; n=11) or DB + vatinoxan HCl (200μg/kg) (DBV; n=11). Borborygmi score and heart rate were recorded by auscultation. Sedation level was evalu...
Erythrocyte sequestration of metformin in horses: impact on matrix-specific pharmacokinetics and detection windows. BACKGROUND: Metformin is used for the treatment of type 2 diabetes and is one of the most prescribed medications in human medicine. It is less commonly prescribed in equine medicine, and its use is tightly regulated in several performance horse disciplines. In horseracing, it is considered a banned substance. A previous pharmacokinetic study of metformin in horses demonstrated a prolonged, unpredictable elimination phase. In the current study it was hypothesized that this was due to sequestration of metformin in a “deep” compartment, specifically red blood cells. This could result in pharm...
Atropine induces narrowing of the superior and inferior iridocorneal angle and ciliary cleft in normal horse eyes. To investigate the effects of atropine on the iridocorneal angle (ICA) and ciliary cleft (CC) of normal equine eyes using ultrasound biomicroscopy (UBM). Unassigned: 12 normal adult horses underwent measurement of intraocular pressure (IOP), vertical and horizontal pupil diameter, and UBM of the superior, temporal, inferior, and nasal ICA/CC in both eyes. Measurements were repeated 2 hours following ophthalmic atropine 1% solution application. Measurements of the ICA and CC, including pectinate ligament distance (PLD), CC length (CCL), height of opening distance (HOD), CC area (CCA), and pecti...
Behavioral and cardiorespiratory effects of a medetomidine and tramadol combination in horses. The use of combinations of sedative and analgesic drugs during standing procedures in horses is necessary to provide reliable sedation with minimal ataxia and reduced responses to surgical or other stimuli in horses. Objective: This study assessed the behavioral and cardiorespiratory effects of medetomidine (M) administered with and without tramadol (T) in horses. Methods: Eight horses were sedated intravenously with M (5 µg/kg) alone or with T (2 mg/kg) in a arandomized, blind, two-way crossover trial. Behavioral responses, including head height above the ground (HHAG), postural instability ...
