title: Pharmacokinetics of intra-articular, intravenous, and intramuscular administration of triamcinolone acetonide and its effect on endogenous plasma hydrocortisone and cortisone concentrations in horses.
abstract: OBJECTIVE
  To compare pharmacokinetics of triamcinolone acetonide (TA) following i.v., intra-articular (i.a.), and i.m. administration and determine its effect on plasma concentrations of hydrocortisone and cortisone.
  
  
  METHODS
  6 Thoroughbreds.
  
  
  METHODS
  TA (0.04 mg/kg) was administered i.v., i.m., or i.a., and plasma TA, hydrocortisone, and cortisone concentrations were determined.
  
  
  RESULTS
  I.v. administration of TA was fitted to a 2-compartment model. Median distribution half-life was 0.50 hours (range, 0.24 to 0.67 hours); elimination half-life was 6.1 hours (range, 5.0 to 6.4 hours). Transfer half-life of TA from joint to plasma was 5.2 hours (range, 0.49 to 73 hours); elimination half-life was 23.8 hours (range, 18.9 to 32.2 hours). Maximum plasma concentration following i.a. administration was 2.0 ng/mL (range, 0.94 to 2.5 ng/mL), and was attained at 10 hours (range, 8 to 12 hours). Maximum plasma concentration following i.m. administration was 0.34 ng/mL (range, 0.20 to 0.48 ng/mL) and was attained at 13.0 hours (range, 12 to 16 hours); concentration was still quantifiable at 360 hours. Hydrocortisone plasma concentrations were significantly different from baseline within 0.75, 2, and 1 hours after i.v., i.a., and i.m. administration, respectively, and remained significantly different from baseline at 96 and 264 hours for i.v. and i.a. administration. Following i.m. administration of TA, plasma concentrations of hydrocortisone did not recover to baseline concentrations by 360 hours.
  
  
  CONCLUSIONS
  Pharmacokinetics of TA and related changes in hydrocortisone were described following i.v., i.a., and i.m. administration. A single administration of TA has profound effects on secretion of endogenous hydrocortisone.
authors: Department of Clinical Studies-New Bolton Center, School of Veterinary Medicine, University of Pennsylvania, Kennett Square, PA 19348, USA. soma@vet.upenn.edu
authors: Lawrence R
authors: LR
authors: Soma
authors: Cornelius E
authors: CE
authors: Uboh
authors: Yowen
authors: Y
authors: You
authors: Fuyu
authors: F
authors: Guan
authors: Raymond C
authors: RC
authors: Boston
mesh_terms: D000818:Animals; D000893:Anti-Inflammatory Agents / Q000008:administration & dosage* / Q000097:blood / Q000493:pharmacokinetics* / Q000494:pharmacology; D001786:Blood Glucose / Q000032:analysis; D003348:Cortisone / Q000097:blood*; D005260:Female; D005938:Glucocorticoids / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics; D006207:Half-Life; D006736:Horses / Q000097:blood*; D006854:Hydrocortisone / Q000097:blood*; D007270:Injections, Intra-Articular / Q000662:veterinary; D007273:Injections, Intramuscular / Q000662:veterinary; D007275:Injections, Intravenous / Q000662:veterinary; D008297:Male; D014222:Triamcinolone Acetonide / Q000008:administration & dosage* / Q000097:blood / Q000493:pharmacokinetics*
chemical_list: D000893:Anti-Inflammatory Agents; D001786:Blood Glucose; D005938:Glucocorticoids; D014222:Triamcinolone Acetonide; D003348:Cortisone; D006854:Hydrocortisone