Subspecies Studies: Pharmacokinetics and Pharmacodynamics of a Single Intravenous Dose of Xylazine in Adult Mules and Adult Haflinger Horses

Latzel, Sylvia Tatjana

doi:10.1016/j.jevs.2012.04.002

Cited by 13 publications

(15 citation statements)

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“…In the presently reported study, serum xylazine concentrations were best fit by a 3‐compartment PK model. This differs from previous reports in horses where drug concentrations were best described by a two‐compartment model . Additionally, dramatic differences were noted in the elimination half‐life between the current and previous studies .…”

Section: Discussioncontrasting

confidence: 99%

“…This differs from previous reports in horses where drug concentrations were best described by a two‐compartment model . Additionally, dramatic differences were noted in the elimination half‐life between the current and previous studies . The beta half‐life in the current study was 2.79 ± 0.105 hours (average ± SEM) whereas in previous studies it was reported as 49.5 minutes [1] and 47 minutes [2].…”

Section: Discussioncontrasting

confidence: 99%

“…The discrepancies, both in the compartmental model chosen as well as the elimination half‐life is likely attributable to differences in the sample collection protocol as well as the analytical assay used to quantitate drug concentrations. In the current study, serum samples were collected for 96 hours post drug administration while in previous studies sample collection was terminated at 2, 3 and 24 hours following xylazine administration . The longer sampling time in the current study likely aided in the identification of the third compartment and calculation of a more representative terminal elimination half‐life as less extrapolation of the terminal portion of the curve was required.…”

Section: Discussionmentioning

confidence: 99%

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Pharmacokinetic and pharmacodynamics of xylazine administered to exercised thoroughbred horses

Knych

Stanley

McKemie

et al. 2016

Drug Testing and Analysis

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There is limited data describing xylazine serum concentrations in the horse and no reports of concentrations beyond 24 hours. The primary goal of the study reported here was to update the pharmacokinetics of xylazine following intravenous (IV) administration in order to assess the applicability of current regulatory recommendations. Pharmacodynamic parameters were determined using PK-PD modeling. Sixteen exercised adult Thoroughbred horses received a single IV dose of 200 mg of xylazine. Blood and urine samples were collected at time 0 and at various times for up to 96 hours and analyzed using liquid chromatography tandem mass spectrometry. Xylazine serum concentrations were best fit by a 3-compartment model. Mean ± SEM systemic clearance, volume of distribution at steady state, beta half-life and gamma half-life were 12.7 ± 0.735 mL/min/kg, 0.660 ± 0.053 L/kg, 2.79 ± 0.105 hours and 26.0 ± 1.9, respectively. Immediately following administration, horses appeared sedate as noted by a decrease in chin-to-ground distance, decreased locomotion and decreased heart rate (HR). Sedation lasted approximately 45 minutes. Glucose concentrations were elevated for 1-hour post administration. The EC50 (IC50) was 636.1, 702.2, 314.1 and 325.7 ng/mL for HR, atrioventricular block, chin-to-ground distance and glucose concentrations, respectively. The Emax (Imax) was 27.3 beats per minute, 47.5%, 42.4 cm and 0.28 mg/dL for HR, atrioventricular block, chin-to-ground distance and glucose concentrations, respectively. Pharmacokinetic parameters differ from previous reports and a prolonged detection time suggests that an extended withdrawal time, beyond current regulatory recommendations, is warranted to avoid inadvertent positive regulatory findings in performance horses. Copyright © 2016 John Wiley & Sons, Ltd.

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Section: Discussioncontrasting

confidence: 99%

Section: Discussioncontrasting

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Pharmacokinetic and pharmacodynamics of xylazine administered to exercised thoroughbred horses

Knych

Stanley

McKemie

et al. 2016

Drug Testing and Analysis

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“…We therefore performed the IV premedication immediately before the catheter was positioned. The time required for the catheter placement determined the loss of the xylazine’s effect, as the half-life of this drug is 15 min shorter (32 min) in mules than in horses (47 min) [5]. …”

Section: Discussionmentioning

confidence: 99%

“…Despite a number of studies available in the literature regarding anaesthesia in horses, donkeys and ponies, few studies have been conducted on mule anaesthesia [2–4]. The results of these studies have been applied to mules, resulting in inadequate anaesthesia because there are several anatomical, physiological and pharmacological differences between horses and mules [5]. Total intravenous anaesthesia (TIVA) is usually the option of choice under field conditions, and it has become a popular technique in horses because of its advantages over inhalational anaesthesia, including decreased cardiorespiratory depression [6].…”

Section: Introductionmentioning

confidence: 99%

Guaiphenesin-ketamine-xylazine infusion to maintain anesthesia in mules undergoing field castration

et al. 2017

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BackgroundIn order to determine whether a combination of guaiphenesin, ketamine and xylazine can induce safe and satisfactory anaesthesia in mules undergoing field castration, eight healthy adult intact male mules were employed. They were premedicated with intravenous (IV) xylazine (1.3 mg/kg); an additional dose of xylazine (0.3 mg/kg IV) was administered in case of inadequate depth of sedation. Anaesthesia was induced with IV thiopental (6 mg/kg). The quality of sedation and induction was recorded. Anaesthesia was maintained with an infusion of guaiphenesin (50 mg/mL), ketamine (2 mg/mL) and xylazine (1 mg/mL) (GKX). The spermatic cord of each testis was infiltrated with 5 mL of 2% lidocaine. During anaesthesia heart rate (HR), respiratory rate (RR), rectal temperature (RT) and haemoglobin oxygen saturation (SpO2) were measured every 5 min. The data were analysed with simple one-way analysis of variance (ANOVA). A P value < 0.05 was considered statistically significant. Time of anesthesia, time of surgery and time of recovery were recorded.ResultsOnly one mule required an additional dose of xylazine to achieve a satisfactory depth of sedation. Thiopental at the dose of 6 mg/kg IV resulted in smooth induction and lateral recumbency in all animals. GKX provided adequate anaesthesia to perform castration in all mules. Muscle relaxation was deemed adequate and physiological variables remained stable and within references values during the anaesthesia and did not change in response to surgical stimulation. Time (mean ± standard deviation) from the end of the infusion to sternal recumbency and time from sternal recumbency to standing were 27.7 ± 4.6 and 30.1 ± 7.7 min, respectively.ConclusionsThe combination of xylazine, thiopental and GKX provides satisfactory short-term anaesthesia in mules undergoing field castration.

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Anesthetic Management of Other Domesticated and Non‐Domesticated Equids

Chinnadurai¹,

Matthews²

2022

Equine Anesthesia and Co‐Existing Disease

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Subspecies Studies: Pharmacokinetics and Pharmacodynamics of a Single Intravenous Dose of Xylazine in Adult Mules and Adult Haflinger Horses

Cited by 13 publications

References 13 publications

Pharmacokinetic and pharmacodynamics of xylazine administered to exercised thoroughbred horses

Pharmacokinetic and pharmacodynamics of xylazine administered to exercised thoroughbred horses

Guaiphenesin-ketamine-xylazine infusion to maintain anesthesia in mules undergoing field castration

Anesthetic Management of Other Domesticated and Non‐Domesticated Equids

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