Drug testing and analysis2026; doi: 10.1002/dta.70132

Detection of Cyclosporine in Horse Hair After Ocular Implant Administration.

Lam, IPY
·
So, YM
·
Kwok, WH
·
Yau, W
·
Wong, COL
·
Smalley, SGR
·
Forbes, BS
·
Chow, DWY
·
Ho, ENM

Abstract: This study describes the detection and temporal distribution of cyclosporine in equine hair following ocular implant administration in a Thoroughbred gelding. Mane hair samples were collected at 172- and 217-day post-implantation and analysed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) after alkaline hydrolysis and liquid-liquid extraction. The method achieved an estimated limit of detection of 0.1 pg/mg. Cyclosporine was detected in hair at both sampling time points, with segmental analysis revealing distribution patterns consistent with systemic exposure and incorporation during hair growth. Peak concentrations were observed in distal segments corresponding to the period of implantation, whereas proximal segments in the later sample were below the detection limit, indicating declining exposure over time. To our knowledge, this study provides the first evidence of an exogenous peptide drug being incorporated into equine hair. The prolonged detectability of cyclosporine in hair highlights its potential as a complementary matrix for long-term monitoring of peptide drug exposure in equine sports.

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Publication Date: 2026-08-07 PubMed ID: 42568208DOI: 10.1002/dta.70132Google Scholar: Lookup

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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.

Overview

This research investigated the presence and distribution of the drug cyclosporine in horse hair after it was administered via an ocular implant.
The study found cyclosporine in hair samples several months post-treatment, suggesting hair analysis can be used for long-term drug monitoring in horses.

Introduction and Purpose

The goal was to detect cyclosporine, a peptide drug, in equine hair after it was delivered through an eye implant.
The focus was on understanding how the drug is incorporated into the hair over time and its potential for long-term detection.
This is important in equine sports where drug monitoring is essential to ensure fair competition and animal welfare.

Methodology

Subjects: A single Thoroughbred gelding horse received an ocular implant releasing cyclosporine.
Sample Collection: Mane hair samples were collected twice—at 172 days and 217 days after implantation.
Sample Preparation: Hair underwent alkaline hydrolysis to break down the hair matrix and liquid-liquid extraction to isolate cyclosporine.
Analysis: Cyclosporine levels were measured using liquid chromatography-tandem mass spectrometry (LC-MS/MS), a sensitive analytical technique.
Sensitivity: The method could detect as low as 0.1 picograms of cyclosporine per milligram of hair, indicating very high sensitivity.

Findings

Cyclosporine was detected in the hair samples at both time points, confirming it gets incorporated into hair following systemic exposure.
Segmental analysis (dividing hair into parts representing growth periods) showed that peak drug concentrations were found in hair segments grown during the active phase of implantation.
More recent hair segments (proximal to the scalp) collected in the later sampling were below detection limits, indicating reduced drug exposure over time as the implant released less drug or was depleted.

Significance

This is the first evidence of an exogenous peptide drug like cyclosporine being incorporated into horse hair.
Since hair grows sequentially and incorporates substances during its formation, it serves as a timeline record of drug exposure.
The prolonged detectability of cyclosporine suggests hair analysis could complement blood or urine tests for long-term monitoring in horses.
This monitoring could enhance drug testing regimes in equine sports, ensuring better regulation of prohibited substances over extended periods.

Conclusion

Cyclosporine can be detected long after administration through ocular implants by analyzing horse hair.
Hair analysis offers a non-invasive, retrospective means to monitor peptide drug exposure over time in horses.
This approach may improve anti-doping efforts in equine sports by providing a longer detection window compared to traditional biological matrices.

Cite This Article

APA

Lam IPY, So YM, Kwok WH, Yau W, Wong COL, Smalley SGR, Forbes BS, Chow DWY, Ho ENM. (2026). Detection of Cyclosporine in Horse Hair After Ocular Implant Administration. Drug Test Anal. https://doi.org/10.1002/dta.70132

Publication

Drug testing and analysis

ISSN: 1942-7611

NlmUniqueID: 101483449

Country: England

Language: English

Researcher Affiliations

Lam, Ian P Y

Racing Laboratory, The Hong Kong Jockey Club, Sha Tin, Hong Kong, China.

So, Yat-Ming

Racing Laboratory, The Hong Kong Jockey Club, Sha Tin, Hong Kong, China.

Kwok, Wai Him

Racing Laboratory, The Hong Kong Jockey Club, Sha Tin, Hong Kong, China.

Yau, Wapi

Racing Laboratory, The Hong Kong Jockey Club, Sha Tin, Hong Kong, China.

Wong, Celia O L

Racing Laboratory, The Hong Kong Jockey Club, Sha Tin, Hong Kong, China.

Smalley, Samuel G R

Veterinary Clinical Services, The Hong Kong Jockey Club, Sha Tin, Hong Kong, China.

Forbes, Bronte S

Veterinary Regulation, Welfare and Biosecurity Policy, The Hong Kong Jockey Club, Sha Tin, Hong Kong, China.

Chow, Derek W Y

Veterinary Specialty Hospital, Wan Chai, Hong Kong, China.

Ho, Emmie N M

Racing Laboratory, The Hong Kong Jockey Club, Sha Tin, Hong Kong, China.

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