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Pharmacokinetics of boldenone and stanozolol and the results of quantification of anabolic and androgenic steroids in race horses and nonrace horses
Author(s) -
SOMA L. R.,
UBOH C. E.,
GUAN F.,
MCDONNELL S.,
PACK J.
Publication year - 2007
Publication title -
journal of veterinary pharmacology and therapeutics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.527
H-Index - 60
eISSN - 1365-2885
pISSN - 0140-7783
DOI - 10.1111/j.1365-2885.2007.00824.x
Subject(s) - stanozolol , chemistry , nandrolone , anabolic steroid , anabolism , pharmacokinetics , testosterone (patch) , endocrinology , medicine , chromatography , horse , biochemistry , biology , paleontology
Anabolic steroids (ABS) boldenone (BL; 1.1 mg/kg) and stanozolol (ST; 0.55 mg/kg) were administered i.m. to horses and the plasma samples collected up to 64 days. Anabolic steroids and androgenic steroids (ANS) in plasma were quantified using liquid chromatography‐tandem mass spectrometry (LC‐MS/MS). The limit of detection of all analytes was 25 pg/mL. The median absorption ( t 1/2∂ ) and elimination ( t 1/2 e ) half‐lives for BL were 8.5 h and 123.0 h, respectively, and the area under the plasma concentration–time curve () was 274.8 ng·h/mL. The median t 1/2 e for ST was 82.1 h and the was 700.1 ng·h/mL. Peak mean () plasma concentrations ( C max ) for BL and ST were 1127.8 and 4118.2 pg/mL, respectively. Quantifiable concentrations of ABS and ANS were found in 61.7% of the 988 plasma samples tested from race tracks. In 17.3% of the plasma samples two or more ABS or ANS were quantifiable. Testosterone (TES) concentrations mean () in racing and nonracing intact males were 241.3 ± 61.3 and 490.4 ± 35.1 pg/mL, respectively. TES was not quantified in nonracing geldings and female horses, but was in racing females and geldings. Plasma concentrations of endogenous 19‐nortestosterone (nandrolone; NA) from racing and nonracing males were 50.2 ± 5.5 and 71.8 ± 4.6 pg/mL, respectively.