Pharmacodynamics in horses refers to the study of how drugs affect the equine body, encompassing the mechanisms of action, the relationship between drug concentration and effect, and the duration of these effects. This field examines how drugs interact with biological systems in horses to produce therapeutic or adverse effects. Key aspects include receptor binding, post-receptor effects, and chemical interactions. Understanding pharmacodynamics is essential for determining appropriate dosages, predicting drug interactions, and assessing therapeutic outcomes in equine medicine. This page compiles peer-reviewed research studies and scholarly articles that explore the pharmacodynamic properties of various drugs in horses, focusing on their effects, efficacy, and safety profiles.
CLARKE EG.This research article explores the topic of doping racehorses, looking at the history of the practice, the reasons for it, various methods used, and the substances utilized. It also presents [...]
Sullivan J, Blea J, Morales CJ, McKemie DS, Kass PH, Knych HK.Corticosteroids, such as isoflupredone, are effective anti-inflammatory medications and as such are commonly used to treat inflammation associated with training and injuries in performance horses. While the pharmacokinetics and pharmacodynamics of isoflupredone acetate (IPA) following intra-articular administration to horses has been well described, studies characterizing intramuscular (IM) administration are lacking. The objective of the current study was to describe the pharmacokinetics and anti-inflammatory effects of IPA following IM administration to horses. Twelve horses received a singl...
Chiavaccini L, Moura RA, Azevedo TMBPR, De Gennaro C, Vettorato E, Romano M, Portela DA.Dexmedetomidine improves pulmonary function in dogs and humans, but evidence in horses is scarce. This study evaluated dexmedetomidine infusion on oxygenation and respiratory mechanics in anesthetized horses. Twenty horses undergoing elective surgery were included in a prospective, non-randomized, observational study. Horses received either lidocaine alone (1.3 mg/kg over 15 min, then 3 mg/kg/hour; LIDO) or combined with dexmedetomidine (1.75 μg/kg over 15 min, then 1.75 μg/kg/hour; DL). Respiratory mechanics, gas exchange, and cardiovascular variables were recorded at baseline, post-loading...
Rudeekiatthamrong A, Nguyen GT, Kamyingkird K. infection (Surra) remains a major constraint to equine health and productivity in Thailand. The only available trypanocidal drug, diminazene aceturate (DA), has limited efficacy, poor blood-brain barrier penetration, and toxicity in horses. This study aimed to investigate the inhibitory effects of commonly used equine antibiotics, gentamicin (GMC), ceftiofur (CTF), and trimethoprim-sulfamethoxazole (TS), against (Thai strain isolated from dairy cattle number 953; TEDC 953) to identify potential therapeutic alternatives or adjuncts for equine trypanosomosis. Unassigned: An growth inhibition...
Ajeebsanu MM, Koshy SA, Karakka Kal AK, Subhahar MB, Karatt TK, Philip M.Suzetrigine, a recently approved Na1.8 sodium channel blocker, shows strong potential in the treatment of neurological, psychiatric, and pain-related conditions. Its peripheral selectivity enables effective pain management while avoiding central nervous system complications and addiction risks linked to opioid use. Following FDA approval in January 2025, concerns have emerged regarding its possible misuse for performance enhancement in sports, highlighting the need for reliable detection tools in doping control. Methods: An analytical procedure was designed and validated to detect suzetrigine ...
Kim A, Lee I, Lee K, Lee EB, Seo JP.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 ...
White GW.Polysulfated glycosaminoglycan (PSGAG) is an antiarthritic drug that has been used in veterinary medicine for many years. PSGAG is rapidly distributed to diseased joint tissue after intraarticular or intramuscular administration, as shown in pharmacological studies conducted on a variety of animal species. In diseased joint tissue, PSGAG stimulates: 1) its own incorporation into the cartilage matrix, 2) inhibition of catabolic enzymes, 3) anabolic effects in the synovial and cartilage tissue, and 4) anti-inflammatory effects. Laboratory and clinical studies in humans, rabbits, horses, and dogs...
Whitfield-Cargile C, Coleman M, Hart K, Gomes D, Berghaus L, Duberstein KJ, Ellis K, Tinkle A, Shirzad R.Insulin dysregulation (ID) is common and diminishes welfare of horses. Current management relies on diet and exercise, with variable responses and limited medical options. Alpha-glucosidase inhibitors (AGIs) might provide adjunctive therapy. Objective: To evaluate the tolerance and effects of Reducose®, a Morus alba leaf extract standardized to 5% 1-deoxynojirimycin (DNJ), in healthy horses and horses at risk of ID. We hypothesized DNJ would be well-tolerated and reduce insulin responses to oral sugar tests (OSTs). Methods: Twenty-seven horses: 6 healthy (Phase I), 5 at risk for ID (Phase II)...
Cardinaux EM, Oltmanns H, Rohn K, Meißner J, Geburek F.Oxytetracycline has been successfully used to treat flexural limb deformities in foals. However, its antimicrobial properties and potential adverse side effects warrant the investigation of alternatives. Inhibition of matrix metalloproteinases (MMPs) or collagen cross-linking have been suggested as possible mechanisms of action. This study assessed the influence of potential alternative substances lacking antimicrobial properties on collagen gel contraction by juvenile equine myofibroblasts in vitro. Myofibroblasts were isolated from forelimb SDFTs and inferior check ligaments from foals eutha...
Ohnuma K, Fukazawa M, Uchida T, Kato T, Sugai-Bannai M, Shibuya M, Yamada M, Hirano-Kodaira M.The use of drugs for enhancing bone strength is prohibited under international regulations governing horse racing and equestrian sports. Elcatonin, a synthetic peptide with analgesic and bone-strengthening properties, is routinely monitored for compliance. However, its cyclic structure and high molecular weight hinder reliable detection. In this study, we developed and validated a sensitive liquid chromatography-high-field asymmetric waveform ion mobility spectrometry-tandem mass spectrometry method for quantifying elcatonin in equine plasma and urine. Sample preparation was optimised via weak...
Yu R, Toutain PL, Ekstrand C, Jusko WJ.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...
Lynch AD, Mama KR, McKemie DS, Kass PH, Knych HK.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 ...
Riley HL, Mama KR, Jacobs ME, McKemie DS, Kass PH, Knych HK.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...
Di Paolo V, Ferrari FM, Poggesi I, Dacasto M, Quintieri L, Capolongo F. 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...
Kuroda T, Minamijima Y, Takahashi Y, Ebisuda Y, Yoshida K, Ishikawa H, Ishihara KI, Mita H, Nomura M, Nukada T, Ishikawa Y.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...
Seeger MG, Gressler LT, Huber L, Alvarez-Narvaez S, Cargnelutti JF, Bordin AI, Lawhon SD, Cohen ND.Rhodococcus equi is a facultative intracellular pathogen and a major cause of pneumonia in foals worldwide. The standard treatment for affected foals is a combination of a macrolide with rifampicin. The widespread use of this combination has led to the emergence of multidrug-resistant (MDR) strains of R. equi. Consequently, antimicrobial susceptibility testing is essential for guiding treatment of rhodococcal pneumonia. Unfortunately, clinical breakpoints for macrolides and other antimicrobials against R. equi for foals are lacking, thereby complicating clinical interpretation of in vitro resu...
Kuroda T, Machnik M, Thevis M, Minamijima Y, Leung GN, Nomura M, Mizobe F, Ishikawa Y, Kamiya K, Toutain PL.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...
Stemmet GP, Parsons P, Johns J, Reddell P, Labens R.Intra-tumoural administration of tigilanol tiglate has been shown effective in local treatment of cutaneous equine neoplasias. The drug causes rapid oncolysis and tumour slough, but may also be associated with comorbidities in sensitive and/or intricate anatomical sites due to its initial pro-inflammatory mode of action. Here we describe two approaches to optimise and further de-risk treatment of equine sarcoids with tigilanol tiglate, especially in difficult locations. Firstly, we provide preliminary clinical and observational data on the efficacy of low dose administration of tigilanol tigla...
