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Pharmacokinetics and pharmacodynamics of detomidine following sublingual administration to horses.
Abstract: To characterize pharmacokinetics and pharmacodynamics of detomidine gel administered sublingually in accordance with label instructions to establish appropriate withdrawal guidelines for horses before competition. Methods: 12 adult racehorses. Methods: Horses received a single sublingual administration of 0.04 mg of detomidine/kg. Blood samples were collected before and up to 72 hours after drug administration. Urine samples were collected for 5 days after detomidine administration. Plasma and urine samples were analyzed via liquid chromatography-mass spectrometry, and resulting data were analyzed by use of noncompartmental analysis. Chin-to-ground distance, heart rate and rhythm, glucose concentration, PCV, and plasma protein concentration were also assessed following detomidine administration. Results: Mean ± SD terminal elimination half-life of detomidine was 1.5 ± 1 hours. Metabolite concentrations were below the limit of detection (0.02, 0.1, and 0.5 ng/mL for detomidine, carboxydetomidine, and hydroxydetomidine, respectively) in plasma by 24 hours. Concentrations of detomidine and its metabolites were below the limit of detection (0.05 ng/mL for detomidine and 0.10 ng/mL for carboxydetomidine and hydroxydetomidine) in urine by 3 days. All horses had various degrees of sedation after detomidine administration. Time of onset was ≤ 40 minutes, and duration of sedation was approximately 2 hours. Significant decreases, relative to values at time 0, were detected for chin-to-ground distance and heart rate. There was an increased incidence and exacerbation of preexisting atrioventricular blocks after detomidine administration. Conclusions: A 48-hour and 3-day withdrawal period for detection in plasma and urine samples, respectively, should be adopted for sublingual administration of detomidine gel.
Publication Date: 2011-10-04 PubMed ID: 21962281DOI: 10.2460/ajvr.72.10.1378Google Scholar: Lookup The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.
The study documents the analysis of the effects, detection, and elimination of the drug detomidine in the system after it’s been administered to horses. The aim is to help establish the necessary withdrawal time before competition and ensure the welfare of the animal.
Methods Used in the Research
- The research was carried out on 12 adult racehorses, where each received a single sublingual administration of 0.04 mg of detomidine/kg.
- Blood and urine samples were collected from the horses at specific intervals to determine the concentration of the drug and its metabolites in their system.
- The blood samples were collected before the detomidine administration and for up to 72 hours afterward.
- Urine samples were instead taken for 5 days after the drug administration.
- These samples were then analyzed using liquid chromatography-mass spectrometry, a technology that enables the separation and quantification of substances within a sample.
- Apart from sample collection, several physiological parameters were also monitored after detomidine administration. These included chin-to-ground distance, heart rate and rhythm, glucose concentration, packed cell volume (PCV), and plasma protein concentration.
Findings of the Research
- The study found that the mean terminal elimination half-life of detomidine was approximately 1.5 hours. In simpler terms, detomidine’s concentration in the body decreases by half every 1.5 hours.
- By 24 hours post-administration, concentrations of detomidine and its metabolites in the plasma were minimal and below the detection limit.
- In urine, detomidine and its metabolites were undetectable by the third day after administration.
- Immediately after administration, the horses showed varying degrees of sedation. The onset was within 40 minutes, and the sedation lasted around 2 hours.
- Physiological parameters also changed with detomidine administration. There were significant decreases in the horses’ chin-to-ground distance and heart rate, and an increased incidence of preexisting atrioventricular blocks, which indicate disruptions in heart rhythms.
Conclusion of the Study
- Based on the research findings, it is recommended that a 48-hour and 3-day withdrawal period should be followed for detection in plasma and urine samples, respectively, after the sublingual administration of detomidine gel to horses.
- This withdrawal period ensures that the drug and its metabolites are no longer detectable in the system before the horse participates in a competition. It safeguards both the fairness of the competition and the welfare of the horse.
Cite This Article
APA
Dimaio Knych HK, Stanley SD.
(2011).
Pharmacokinetics and pharmacodynamics of detomidine following sublingual administration to horses.
Am J Vet Res, 72(10), 1378-1385.
https://doi.org/10.2460/ajvr.72.10.1378 Publication
Researcher Affiliations
- K. L. Maddy Equine Analytical Chemistry Laboratory, Department of Veterinary Molecular Biosciences, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616, USA. hkknych@ucdavis.edu
MeSH Terms
- Administration, Sublingual
- Analysis of Variance
- Animals
- Blood Glucose / analysis
- Blood Proteins / analysis
- Chromatography, Liquid / veterinary
- Half-Life
- Heart Rate / drug effects
- Horses / metabolism
- Hypnotics and Sedatives / administration & dosage
- Hypnotics and Sedatives / blood
- Hypnotics and Sedatives / pharmacokinetics
- Hypnotics and Sedatives / urine
- Imidazoles / administration & dosage
- Imidazoles / blood
- Imidazoles / pharmacokinetics
- Imidazoles / urine
- Male
- Mass Spectrometry / veterinary
- Time Factors
Citations
This article has been cited 5 times.- Williams MD, Long CT, Durrant JR, McKeon GP, Shive HR, Griffith EH, Messenger KM, Fish RE. Oral Transmucosal Detomidine Gel in New Zealand White Rabbits (Oryctolagus cuniculus). J Am Assoc Lab Anim Sci 2017 Jul 1;56(4):436-442.
- Cohen AE, Bennett SL. Oral transmucosal administration of dexmedetomidine for sedation in 4 dogs. Can Vet J 2015 Nov;56(11):1144-8.
- Hokkanen AH, Raekallio MR, Salla K, Hänninen L, Viitasaari E, Norring M, Raussi S, Rinne VM, Scheinin M, Vainio OM. Sublingual administration of detomidine to calves prior to disbudding: a comparison with the intravenous route. Vet Anaesth Analg 2014 Jul;41(4):372-7.
- Di Salvo A, Bazzano M, Rocca GD, Galarini R, Marchegiani A, Paoletti F, Giusepponi D, Mantovani M, Laus F. Pharmacokinetics of a single oral administration of two cannabidiol formulations in fed and fasted horses. Front Vet Sci 2025;12:1515833.
- Smith P, Tolbert MK, Gould E, Taylor A, Knych H, Messenger K. Pharmacokinetics, sedation and hemodynamic changes following the administration of oral transmucosal detomidine gel in cats. J Feline Med Surg 2020 Dec;22(12):1184-1190.
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