Investigation of the effects of orally administered trazodone on intraocular pressure, pupil diameter, physical examination variables, and sedation level in healthy equids.
Abstract: To investigate the effects of orally administered trazodone on intraocular pressure (IOP), pupil diameter measured in the vertical plane (ie, vertical pupil diameter [VPD]), selected physical examination variables, and sedation level in healthy equids. Methods: 7 horses and 1 pony. Methods: Food was withheld for 12 hours prior to drug administration. After baseline (time 0) sedation scoring, physical examination, and measurement of IOP and VPD, equids received 1 dose (approx 6 mg/kg) of trazodone orally. Examination and measurement procedures were repeated 0.5, 1, 2, 4, 8, 12, and 24 hours after drug administration. Blood samples were collected at each time point for analysis of plasma trazodone concentrations. Repeated-measures analysis was used to compare examination results between downstream time points and baseline. Results: 7 of 8 equids had mild sedation from 0.5 to 8 hours after treatment; compared with baseline values, mean IOP was significantly lower from 0.5 hours to 8 hours, mean VPD was significantly smaller at 0.5 hours, and mean rectal temperature was significantly lower from 1 to 8 hours after drug administration. Adverse effects (signs of excitement in 1 equid and sweating in 4) were self-limiting and considered minor. Mean maximum plasma concentration of trazodone was 1,493 ng/mL 0.75 hours after administration, and terminal half-life of the drug was 9.96 hours. Conclusions: The described oral dose of trazadone elicited sedation with a few self-limiting adverse effects in the study sample. Drug effects on IOP and VPD may alter ocular examination findings. Further investigation is warranted prior to use of trazodone for sedation in equids, particularly those with ophthalmic conditions.
Publication Date: 2021-01-23 PubMed ID: 33480276DOI: 10.2460/ajvr.82.2.138Google Scholar: Lookup
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- Journal Article
Summary
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The research article investigates how the oral administration of trazodone impacts the eye pressure, pupil size, certain physical examination aspects and sedation level in healthy equids.
Research Design
- The study involved seven horses and one pony to examine the effects of trazodone on various parameters.
- Prior to the administration of the drug, the horses were prevented from eating for 12 hours. Afterwards, the researchers conducted a baseline measurement that included sedation scoring, physical examination, intraocular pressure (IOP), and vertical pupil diameter (VPD).
- Participants were given a single oral dose of trazodone, approximately 6 mg/kg. The examination and measurement procedures were repeated after 0.5, 1, 2, 4, 8, 12, and 24 hours of drug administration.
- Blood samples were collected at each time point to analyze the plasma trazodone concentrations.
- A repeated-measures analysis was employed for results comparison between baseline and various downstream time points.
Results
- Mild sedation was observed in seven out of eight horses from 0.5 to 8 hours post-treatment.
- The IOP was significantly lower from 0.5 to 8 hours as compared to the baseline values. Similarly, the VPD was notably smaller half an hour after drug administration.
- The mean rectal temperature was significantly lower from 1 to 8 hours after the oral administration of the drug.
- Adverse effects such as signs of excitement in one participant and sweating in four were noted. However, these effects were self-limiting and considered minor.
- The mean maximum plasma concentration of trazodone was 1,493 ng/mL, observed 0.75 hours after administration, and the terminal half-life of the drug was found to be 9.96 hours.
Conclusions
- The results suggested that the administered dose of trazodone induced mild sedation along with a few minor and self-limiting adverse effects.
- Drug-induced effects on IOP and VPD were designed to alter the results of ocular examination.
- The study concludes by suggesting the need for further study prior to the use of trazodone for sedation in equids, specifically those with eye conditions.
Cite This Article
APA
Moss AL, Hritz RL, Hector RC, Wotman KL.
(2021).
Investigation of the effects of orally administered trazodone on intraocular pressure, pupil diameter, physical examination variables, and sedation level in healthy equids.
Am J Vet Res, 82(2), 138-143.
https://doi.org/10.2460/ajvr.82.2.138 Publication
Researcher Affiliations
MeSH Terms
- Animals
- Horses
- Intraocular Pressure
- Physical Examination
- Pupil
- Tonometry, Ocular
- Trazodone / pharmacology
Citations
This article has been cited 2 times.- Hobbs K, Luethy D, Davis J, Mallicote M, Torcivia C, Kulp J, Stefanovski D, Futterman C, Cooper F, van Eps A. The effects of orally administered trazodone on ambulation and recumbency in healthy horses. J Vet Intern Med 2023 Sep-Oct;37(5):1899-1906.
- Joseph EJ, Love L, Mayakis M, Varner K. Preanesthetic Administration of Trazodone Does Not Impact Anesthetic Recovery Scores in Horses. Animals (Basel) 2025 Oct 6;15(19).
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