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Exposure to Subcutaneously Administered Butorphanol in Horses Pre-Treated With Detomidine or Detomidine-Vatinoxan.
Abstract: The aim of the study was to determine the exposure to subcutaneously administered butorphanol in horses pre-treated with intravenous (IV) detomidine, with or without vatinoxan, a peripherally selective alpha-adrenoceptor antagonist. Five healthy, adult horses received three IV treatments 7 days apart, in a randomized, cross-over design: detomidine 20 μg/kg (DET-B), detomidine 20 μg/kg with vatinoxan 200 μg/kg (DETVAT-B) and saline (S-B), all followed by 0.1 mg/kg of butorphanol administered subcutaneously 30 min later. Venous samples were collected between 10 and 270 min after butorphanol administration. Butorphanol concentrations in plasma were analyzed with liquid chromatography coupled with triple quadruple mass spectrometry. Data were analyzed with non-compartmental methods. The observed areas under plasma butorphanol concentration-time curves were 8104 ± 2590, 7042 ± 2628 and 5996 ± 1670 ng·min/mL for DET-B, DETVAT-B and S-B, respectively. There were no significant differences between treatments. Pre-treatment with detomidine, with or without vatinoxan, did not significantly affect the exposure to subcutaneously administered butorphanol in this study.
© 2026 The Author(s). Journal of Veterinary Pharmacology and Therapeutics published by John Wiley & Sons Ltd.
Publication Date: 2026-01-31 PubMed ID: 41618690DOI: 10.1111/jvp.70051Google 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
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.
Exposure to subcutaneously administered butorphanol in horses was examined to see if pre-treatment with intravenous detomidine, alone or combined with vatinoxan, affects butorphanol’s plasma concentration and overall drug exposure.
Study Objective and Design
- Purpose: To determine if pre-treatment with detomidine, an alpha-2 adrenergic agonist, or detomidine combined with vatinoxan, an alpha-adrenoceptor antagonist, affects the plasma exposure of butorphanol administered subcutaneously (SC) in horses.
- Design: Randomized, cross-over study involving five healthy adult horses.
- Treatments: Each horse received three intravenous (IV) treatments, 7 days apart:
- DET-B: Detomidine (20 μg/kg) followed 30 minutes later by butorphanol (0.1 mg/kg SC)
- DETVAT-B: Detomidine (20 μg/kg) combined with vatinoxan (200 μg/kg) followed by butorphanol (0.1 mg/kg SC)
- S-B: Saline (control) followed by butorphanol (0.1 mg/kg SC)
Methods of Data Collection and Analysis
- Blood Sampling: Venous blood samples were collected from 10 minutes to 270 minutes after butorphanol administration to measure plasma drug concentrations over time.
- Measurement Technique: Plasma butorphanol concentrations were analyzed using liquid chromatography coupled with triple quadruple mass spectrometry (LC-MS/MS), a sensitive and specific method for drug quantification.
- Data Analysis: Non-compartmental pharmacokinetic methods were used to determine the area under the plasma concentration-time curve (AUC), representing overall drug exposure.
Results
- Butorphanol Exposure:
- Area Under Curve (AUC) values were:
- DET-B: 8104 ± 2590 ng·min/mL
- DETVAT-B: 7042 ± 2628 ng·min/mL
- S-B: 5996 ± 1670 ng·min/mL
- Despite numerical differences, statistical analysis found no significant differences in butorphanol exposure among the three treatment groups.
- Area Under Curve (AUC) values were:
- Interpretation: Pre-treatment with detomidine, regardless of vatinoxan co-administration, did not significantly alter butorphanol absorption or systemic exposure following subcutaneous administration.
Significance and Context
- Implications for Clinical Practice:
- Detomidine is commonly used as a sedative in equine medicine, sometimes combined with butorphanol for analgesia.
- Understanding drug interactions affecting absorption and bioavailability is critical to dosing and efficacy.
- This study suggests that detomidine, with or without vatinoxan, does not interfere with the pharmacokinetics of SC butorphanol, supporting safe combined use without dose adjustment for butorphanol.
- Role of Vatinoxan:
- Vatinoxan is a peripherally selective alpha-adrenoceptor antagonist that can reduce some peripheral side effects of alpha-2 agonists.
- The study explored whether it influences butorphanol kinetics, which it did not significantly do.
Limitations and Considerations
- Sample Size: Only five horses were tested, limiting the statistical power and generalizability.
- Single Dose and Timeframe: Only one dose of butorphanol and sampling up to 270 minutes were studied; longer-term kinetics remain unknown.
- Pharmacodynamic Effects: The study focused on pharmacokinetics without reporting on clinical sedation or analgesia outcomes.
Conclusion
- Pre-treatment with IV detomidine, with or without vatinoxan, does not significantly affect the plasma exposure to subsequently administered SC butorphanol in horses.
- This supports the concurrent clinical use of these drugs without expected pharmacokinetic interactions altering butorphanol availability.
Cite This Article
APA
Honkavaara JM, Karikoski NP, Palvas L, Pypendop BH, Rinne VM, Raekallio MR.
(2026).
Exposure to Subcutaneously Administered Butorphanol in Horses Pre-Treated With Detomidine or Detomidine-Vatinoxan.
J Vet Pharmacol Ther.
https://doi.org/10.1111/jvp.70051 Publication
Researcher Affiliations
- Department of Equine and Small Animal Medicine, Faculty of Veterinary Medicine, University of Helsinki, Finland, Helsinki, Finland.
- Department of Equine and Small Animal Medicine, Faculty of Veterinary Medicine, University of Helsinki, Finland, Helsinki, Finland.
- Department of Equine and Small Animal Medicine, Faculty of Veterinary Medicine, University of Helsinki, Finland, Helsinki, Finland.
- Department of Surgical and Radiological Sciences, School of Veterinary Medicine, University of California, Davis, Davis, California, USA.
- Admescope (Symeres Finland OY), Oulu, Finland.
- Department of Equine and Small Animal Medicine, Faculty of Veterinary Medicine, University of Helsinki, Finland, Helsinki, Finland.
Grant Funding
- The Finnish Veterinary Foundation
- Vetcare
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