Abstract
In order to ensure the welfare of performance horses and riders as well as the integrity of the sport, the use of both therapeutic and illegal agents in horse racing is tightly regulated. While Dehydroepiandrosterone (DHEA) is not specifically banned from administration to racehorses in the United States and no screening limit or threshold concentration exists, the metabolic conversion of DHEA to testosterone make its presence in nutritional supplements a regulatory concern. The recommended regulatory threshold for total testosterone in urine is 55 and 20ng/mL for mares and geldings, respectively. In plasma, screening and confirmation limits for free testosterone (mares and geldings), of no greater than 0.1 and 0.025ng/mL, respectively are recommended. DHEA was administered orally, as part of a nutritional supplement, to 8 exercised female thoroughbred horses and plasma and urine samples collected at pre-determined times post administration. Using liquid chromatography-mass spectrometry (LC-MS), plasma and urine samples were analyzed for DHEA, DHEA-sulfate, testosterone, testosterone-sulfate, pregnenolone, androstenedione, and androstenediol. DHEA was rapidly absorbed with maximal plasma concentrations reaching 52.0±43.8ng/mL and 32.1±12.9ng/mL for DHEA and DHEA sulfate, respectively. Free testosterone was not detected in plasma or urine samples at any time. Maximum sulfate conjugated testosterone plasma concentrations were 0.98±1.09ng/mL. Plasma testosterone-sulfate concentrations did not fall below 0.1ng/mL and urine testosterone-sulfate below 55ng/mL until 24-36h post DHEA administration. Urine testosterone sulfate concentrations remained slightly above baseline levels at 48h for most of the horses studied.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 39-47 |
| Number of pages | 9 |
| Journal | Drug Testing and Analysis |
| Volume | 7 |
| Issue number | 1 |
| DOIs | |
| State | Published - Jan 1 2015 |
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Keywords
- DHEA
- Horse
- Metabolism
- Testosterone
ASJC Scopus subject areas
- Analytical Chemistry
- Environmental Chemistry
- Pharmaceutical Science
- Spectroscopy
Cite this
Disposition and metabolic profile of the weak androgen Dehydroepiandrosterone (DHEA) following administration as part of a nutritional supplement to exercised horses. / Knych, Heather K; Arthur, Rick; Stanley, Scott D; Mckemie, D. S.
In: Drug Testing and Analysis, Vol. 7, No. 1, 01.01.2015, p. 39-47.Research output: Contribution to journal › Article
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TY - JOUR
T1 - Disposition and metabolic profile of the weak androgen Dehydroepiandrosterone (DHEA) following administration as part of a nutritional supplement to exercised horses
AU - Knych, Heather K
AU - Arthur, Rick
AU - Stanley, Scott D
AU - Mckemie, D. S.
PY - 2015/1/1
Y1 - 2015/1/1
N2 - In order to ensure the welfare of performance horses and riders as well as the integrity of the sport, the use of both therapeutic and illegal agents in horse racing is tightly regulated. While Dehydroepiandrosterone (DHEA) is not specifically banned from administration to racehorses in the United States and no screening limit or threshold concentration exists, the metabolic conversion of DHEA to testosterone make its presence in nutritional supplements a regulatory concern. The recommended regulatory threshold for total testosterone in urine is 55 and 20ng/mL for mares and geldings, respectively. In plasma, screening and confirmation limits for free testosterone (mares and geldings), of no greater than 0.1 and 0.025ng/mL, respectively are recommended. DHEA was administered orally, as part of a nutritional supplement, to 8 exercised female thoroughbred horses and plasma and urine samples collected at pre-determined times post administration. Using liquid chromatography-mass spectrometry (LC-MS), plasma and urine samples were analyzed for DHEA, DHEA-sulfate, testosterone, testosterone-sulfate, pregnenolone, androstenedione, and androstenediol. DHEA was rapidly absorbed with maximal plasma concentrations reaching 52.0±43.8ng/mL and 32.1±12.9ng/mL for DHEA and DHEA sulfate, respectively. Free testosterone was not detected in plasma or urine samples at any time. Maximum sulfate conjugated testosterone plasma concentrations were 0.98±1.09ng/mL. Plasma testosterone-sulfate concentrations did not fall below 0.1ng/mL and urine testosterone-sulfate below 55ng/mL until 24-36h post DHEA administration. Urine testosterone sulfate concentrations remained slightly above baseline levels at 48h for most of the horses studied.
AB - In order to ensure the welfare of performance horses and riders as well as the integrity of the sport, the use of both therapeutic and illegal agents in horse racing is tightly regulated. While Dehydroepiandrosterone (DHEA) is not specifically banned from administration to racehorses in the United States and no screening limit or threshold concentration exists, the metabolic conversion of DHEA to testosterone make its presence in nutritional supplements a regulatory concern. The recommended regulatory threshold for total testosterone in urine is 55 and 20ng/mL for mares and geldings, respectively. In plasma, screening and confirmation limits for free testosterone (mares and geldings), of no greater than 0.1 and 0.025ng/mL, respectively are recommended. DHEA was administered orally, as part of a nutritional supplement, to 8 exercised female thoroughbred horses and plasma and urine samples collected at pre-determined times post administration. Using liquid chromatography-mass spectrometry (LC-MS), plasma and urine samples were analyzed for DHEA, DHEA-sulfate, testosterone, testosterone-sulfate, pregnenolone, androstenedione, and androstenediol. DHEA was rapidly absorbed with maximal plasma concentrations reaching 52.0±43.8ng/mL and 32.1±12.9ng/mL for DHEA and DHEA sulfate, respectively. Free testosterone was not detected in plasma or urine samples at any time. Maximum sulfate conjugated testosterone plasma concentrations were 0.98±1.09ng/mL. Plasma testosterone-sulfate concentrations did not fall below 0.1ng/mL and urine testosterone-sulfate below 55ng/mL until 24-36h post DHEA administration. Urine testosterone sulfate concentrations remained slightly above baseline levels at 48h for most of the horses studied.
KW - DHEA
KW - Horse
KW - Metabolism
KW - Testosterone
UR - http://www.scopus.com/inward/record.url?scp=84922667779&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84922667779&partnerID=8YFLogxK
U2 - 10.1002/dta.1716
DO - 10.1002/dta.1716
M3 - Article
C2 - 25242721
AN - SCOPUS:84922667779
VL - 7
SP - 39
EP - 47
JO - Drug Testing and Analysis
JF - Drug Testing and Analysis
SN - 1942-7603
IS - 1
ER -