Document Detail

Pharmacokinetics of detomidine administered to horses at rest and after maximal exercise.
MedLine Citation:
PMID:  19642399     Owner:  NLM     Status:  MEDLINE    
REASON FOR PERFORMING STUDY: Increased doses of detomidine are required to produce sedation in horses after maximal exercise compared to calm or resting horses. OBJECTIVES: To determine if the pharmacokinetics of detomidine in Thoroughbred horses are different when the drug is given during recuperation from a brief period of maximal exercise compared to administration at rest. METHODS: Six Thoroughbred horses were preconditioned by exercising them on a treadmill. Each horse ran a simulated race at a treadmill speed that caused it to exercise at 120% of its maximal oxygen consumption. One minute after the end of exercise, horses were treated with detomidine. Each horse was treated with the same dose of detomidine on a second occasion a minimum of 14 days later while standing in a stocks. Samples of heparinised blood were obtained at various time points on both occasions. Plasma detomidine concentrations were determined by liquid chromatography-mass spectrometry. The plasma concentration vs. time data were analysed by nonlinear regression analysis. RESULTS: Median back-extrapolated time zero plasma concentration was significantly lower and median plasma half-life and median mean residence time were significantly longer when detomidine was administered after exercise compared to administration at rest. Median volume of distribution was significantly higher after exercise but median plasma clearance was not different between the 2 administrations. CONCLUSIONS AND POTENTIAL RELEVANCE: Detomidine i.v. is more widely distributed when administered to horses immediately after exercise compared to administration at rest resulting in lower peak plasma concentrations and a slower rate of elimination. The dose requirement to produce an equivalent effect may be higher in horses after exercise than in resting horses and less frequent subsequent doses may be required to produce a sustained effect.
J A E Hubbell; R A Sams; L M Schmall; J T Robertson; K W Hinchcliff; W W Muir
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Equine veterinary journal     Volume:  41     ISSN:  0425-1644     ISO Abbreviation:  Equine Vet. J.     Publication Date:  2009 May 
Date Detail:
Created Date:  2009-07-31     Completed Date:  2009-09-22     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0173320     Medline TA:  Equine Vet J     Country:  England    
Other Details:
Languages:  eng     Pagination:  419-22     Citation Subset:  IM    
Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Columbus, Ohio 43210, USA.
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MeSH Terms
Analgesics / blood,  pharmacokinetics*
Horses / metabolism*
Imidazoles / blood,  pharmacokinetics*
Physical Conditioning, Animal / physiology*
Reg. No./Substance:
0/Analgesics; 0/Imidazoles; 76631-46-4/detomidine

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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