title: Pharmacokinetics of boldenone and stanozolol and the results of quantification of anabolic and androgenic steroids in race horses and nonrace horses.
abstract: 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 (t1/2 partial differential) and elimination (t1/2e) half-lives for BL were 8.5 h and 123.0 h, respectively, and the area under the plasma concentration-time curve (AUCho) was 274.8 ng.h/mL. The median t1/2e for ST was 82.1 h and the was 700.1 ng.h/mL. Peak mean (X+/-SD) plasma concentrations (Cmax) 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 (X+/-SE) 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.
authors.affiliation: School of Veterinary Medicine, New Bolton Center Campus, University of Pennsylvania, Kennett Square, PA 19348, USA. soma@vet.upenn.edu
authors.forename: L R
authors.initials: LR
authors.lastname: Soma
authors.forename: C E
authors.initials: CE
authors.lastname: Uboh
authors.forename: F
authors.initials: F
authors.lastname: Guan
authors.forename: S
authors.initials: S
authors.lastname: McDonnell
authors.forename: J
authors.initials: J
authors.lastname: Pack
mesh_terms: D045930:Anabolic Agents / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D000728:Androgens / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D000818:Animals; D019540:Area Under Curve; D004300:Doping in Sports; D005260:Female; D006736:Horses / Q000378:metabolism*; D007273:Injections, Intramuscular / Q000662:veterinary; D008297:Male; D010805:Physical Conditioning, Animal; D015203:Reproducibility of Results; D013197:Stanozolol / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D013739:Testosterone / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000097:blood / Q000493:pharmacokinetics
chemical_list: D045930:Anabolic Agents; D000728:Androgens; D013739:Testosterone; D013197:Stanozolol; C013915:boldenone