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Antinociceptive effects of three escalating dexmedetomidine and lignocaine constant rate infusions in conscious horses.
- Source :
-
Veterinary journal (London, England : 1997) [Vet J] 2014 Dec; Vol. 202 (3), pp. 489-97. Date of Electronic Publication: 2014 Sep 16. - Publication Year :
- 2014
-
Abstract
- Dexmedetomidine and lignocaine IV are used clinically to provide analgesia in horses. The aims of this study were to investigate the antinociceptive effects, plasma concentrations and sedative effects of 2, 4 and 6 µg/kg/h dexmedetomidine IV, with a bolus of 0.96 µg/kg preceding each continuous rate infusion (CRI), and 20, 40 and 60 µg/kg/min lignocaine IV, with a bolus of 550 µg/kg preceding each CRI, in 10 Swiss Warmblood horses. Electrically elicited nociceptive withdrawal reflexes were evaluated by deltoid muscle electromyography. Nociceptive threshold and tolerance were determined by electromyography and behaviour following single and repeated stimulation. Plasma concentrations of drugs were determined by liquid chromatography and mass spectrometry. Sedation was scored on a visual analogue scale. Dexmedetomidine increased nociceptive threshold to single and repeated stimulation for all CRIs, except at 2 µg/kg/h, where no increase in single stimulation nociceptive threshold was observed. Dexmedetomidine increased nociceptive tolerance to single and repeated stimulation at all CRIs. There was large individual variability in dexmedetomidine plasma concentrations and levels of sedation; the median plasma concentration providing antinociceptive effects to all recorded parameters was 0.15 ng/mL, with a range from <0.02 ng/mL (below the lower limit of quantification) to 0.25 ng/mL. Lignocaine increased nociceptive threshold and tolerance to single and repeated stimulation at CRIs of 40 and 60 µg/kg/min, corresponding to plasma lignocaine concentrations >600 ng/mL. Only nociceptive tolerance to repeated stimulation increased at 20 µg/kg/min lignocaine. Lignocaine at 40 µg/kg/min and dexmedetomidine at 4 µg/kg/h were the lowest CRIs resulting in consistent antinociception. Lignocaine did not induce significant sedation.<br /> (Copyright © 2014 Elsevier Ltd. All rights reserved.)
- Subjects :
- Analgesics blood
Animals
Chromatography, Liquid veterinary
Cross-Over Studies
Dexmedetomidine blood
Dose-Response Relationship, Drug
Electric Stimulation
Hypnotics and Sedatives blood
Infusions, Intravenous veterinary
Lidocaine blood
Male
Mass Spectrometry veterinary
Random Allocation
Analgesics pharmacology
Dexmedetomidine pharmacology
Horses metabolism
Hypnotics and Sedatives pharmacology
Lidocaine pharmacology
Reflex drug effects
Subjects
Details
- Language :
- English
- ISSN :
- 1532-2971
- Volume :
- 202
- Issue :
- 3
- Database :
- MEDLINE
- Journal :
- Veterinary journal (London, England : 1997)
- Publication Type :
- Academic Journal
- Accession number :
- 25266648
- Full Text :
- https://doi.org/10.1016/j.tvjl.2014.09.007