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Equine veterinary journal2021; 53(6); 1250-1256; doi: 10.1111/evj.13418

Systemic detectability of dexamethasone and prednisolone after eye drop application in horses.

Abstract: Equine sport agencies list steroids as prohibited substances for competing horses. Objective: The objective of this study was to investigate if the controlled substances dexamethasone and prednisolone are detectable in equine serum and urine samples during and after treatment with eye drops and if this can generate a positive doping test. Methods: Prospective cohort study. Methods: The study cohort included 11 horses. One eye of the horses was treated with either dexamethasone (Maxitrol 0.1%, n = 5 eyes) or prednisolone (Pred forte 1%, n = 6 eyes) eye drops 3 times daily for 14 days. Dexamethasone and prednisolone concentrations were determined in serum and urine at day 0 (negative control), 1, 7, 14, 15, 17 and 21 using liquid chromatography-tandem mass spectrometry. Blood samples were collected within 2 hours post application. Urine samples were collected during spontaneous urination. Results: All serum samples (range: 0.7-43 ng/mL, mean 2.1 ng/mL) and urine samples (range 1.2-5 ng/mL, mean 0.8 ng/mL) showed measurable amounts of dexamethasone during the course of treatment. Concentrations in both serum and urine samples were below limit of detection (LOD) 24 hours after the last dexamethasone treatment (day 15). All serum samples (range 1.1-32.5 ng/mL, mean 6.4 ng/mL) and urine samples (range 3.7-19 ng/mL, mean 4.6 ng/mL) were positive for prednisolone during treatment. Urine samples were below LOD on day 15; serum samples on day 21. Conclusions: Dexamethasone and prednisolone eye drops can induce detectable drug levels in serum and urine samples of horses after a 14-day treatment plan. This can lead to a positive doping result. All samples tested negative (below LOD of the analytical method) for dexamethasone one day and for prednisolone one week after treatment cessation.
Publication Date: 2021-01-28 PubMed ID: 33421187DOI: 10.1111/evj.13418Google Scholar: Lookup
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  • Journal Article

Summary

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This research article investigates the detectability of the steroids dexamethasone and prednisolone in horse serum and urine after eye drop application and if it can result in a positive doping test. After a 14-day treatment period, both steroids were still detectable, which could lead to positive doping results. For dexamethasone, it became undetectable one day after finishing treatment; for prednisolone, it took a week to become undetectable.

Study Methodology

  • In this prospective cohort study, dexamethasone and prednisolone were applied as eye drops to 11 horses. One eye of each horse was treated with either steroids three times a day for a period of 14 days.
  • Dexamethasone was applied to 5 eyes and prednisolone to 6 eyes. The steroids concentrations were measured in serum and urine samples at various intervals (day 0, 1, 7, 14, 15, 17, and 21) using a method known as liquid chromatography-tandem mass spectrometry. Blood samples were collected within 2 hours post application of the steroids, while urine samples were collected during spontaneous urination.

Results of the Study

  • All Serum and urine samples showed the presence of dexamethasone during the course of treatment with a mean measurement of 2.1ng/mL and 0.8ng/mL respectively. Similarly, all samples were positive for prednisolone during the treatment, with mean results of 6.4ng/mL and 4.6ng/mL in serum and urine samples respectively.
  • The serum and urine concentrations of both steroids dropped below the detectability limit after the 14-day treatment period. Dexamethasone became undetectable in both serum and urine samples 24 hours post-treatment, whereas prednisolone took seven days post-treatment to become undetectable in the serum samples and one day after treatment to become undetectable in urine samples.

Conclusions

  • The study concluded that dexamethasone and prednisolone, when applied as eye drops to horses, can be detected in the serum and urine samples. Consequently, it can lead to a positive doping result, which could pose a challenge for equine sports agencies that classify these steroids as prohibited substances.
  • Notably, all samples tested negative for dexamethasone a day after stopping the treatment and for prednisolone a week after ending treatment. This finding indicates the period during which the drugs remain detectable in the body post-treatment.

Cite This Article

APA
Stucki M, Voegel CD, Binz TM, Kraemer T, Lavaud A, Voelter K. (2021). Systemic detectability of dexamethasone and prednisolone after eye drop application in horses. Equine Vet J, 53(6), 1250-1256. https://doi.org/10.1111/evj.13418

Publication

ISSN: 2042-3306
NlmUniqueID: 0173320
Country: United States
Language: English
Volume: 53
Issue: 6
Pages: 1250-1256

Researcher Affiliations

Stucki, Michael
  • Veterinary Ophthalmology, Equine Clinic, Vetsuisse Faculty Zurich, Zurich, Switzerland.
Voegel, Clarissa D
  • Zurich Institute of Forensic Medicine, Center for Forensic Hair Analytics, University of Zurich, Zurich, Switzerland.
Binz, Tina M
  • Zurich Institute of Forensic Medicine, Center for Forensic Hair Analytics, University of Zurich, Zurich, Switzerland.
Kraemer, Thomas
  • Zurich Institute of Forensic Medicine, Center for Forensic Hair Analytics, University of Zurich, Zurich, Switzerland.
Lavaud, Arnold
  • Veterinary Ophthalmology, Equine Clinic, Vetsuisse Faculty Zurich, Zurich, Switzerland.
Voelter, Katrin
  • Veterinary Ophthalmology, Equine Clinic, Vetsuisse Faculty Zurich, Zurich, Switzerland.

MeSH Terms

  • Animals
  • Dexamethasone
  • Doping in Sports
  • Horses
  • Ophthalmic Solutions
  • Prednisolone
  • Prospective Studies

Grant Funding

  • PR 2017/02 / Stiftung pro Pferd

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Citations

This article has been cited 1 times.
  1. Keen B, Cawley A, Reedy B, Fu S. Metabolomics in clinical and forensic toxicology, sports anti-doping and veterinary residues. Drug Test Anal 2022 May;14(5):794-807.
    doi: 10.1002/dta.3245pubmed: 35194967google scholar: lookup