Present address: National Institute for Food and Drug Control, Division of Antibiotics, Chongwen District, Beijing 100050, China
Pharmacokinetics of dexamethasone following intra-articular, intravenous, intramuscular, and oral administration in horses and its effects on endogenous hydrocortisone
Article first published online: 28 MAY 2012
© 2012 Blackwell Publishing Ltd
Journal of Veterinary Pharmacology and Therapeutics
Volume 36, Issue 2, pages 181–191, April 2013
How to Cite
SOMA, L. R., UBOH, C. E., LIU, Y., LI, X., ROBINSON, M. A., BOSTON, R. C. and COLAHAN, P. T. (2013), Pharmacokinetics of dexamethasone following intra-articular, intravenous, intramuscular, and oral administration in horses and its effects on endogenous hydrocortisone. Journal of Veterinary Pharmacology and Therapeutics, 36: 181–191. doi: 10.1111/j.1365-2885.2012.01412.x
Supported by the Pennsylvania Horse and Harness Racing Commissions and in part by the Racing and Medication Testing Consortium, Pennsylvania Horsemen’s Benevolent and Protective Association, Pennsylvania Harness Horsemen Association, and Meadows Standardbred Owners Association.
- Issue published online: 8 MAR 2013
- Article first published online: 28 MAY 2012
- (Paper received 10 January 2012; accepted for publication 16 April 2012)
Soma, L. R., Uboh, C. E., Liu, Y., Li, X., Robinson, M .A., Boston, R. C., Colahan, P. T. Pharmacokinetics of dexamethasone following intra-articular, intravenous, intramuscular, and oral administration in horses and its effects on endogenous hydrocortisone. J. vet. Pharmacol. Therap. 36, 181–191.
This study investigated and compared the pharmacokinetics of intra-articular (IA) administration of dexamethasone sodium phosphate (DSP) into three equine joints, femoropatellar (IAS), radiocarpal (IAC), and metacarpophalangeal (IAF), and the intramuscular (IM), oral (PO) and intravenous (IV) administrations. No significant differences in the pharmacokinetic estimates between the three joints were observed with the exception of maximum concentration (Cmax) and time to maximum concentration (Tmax). Median (range) Cmax for the IAC, IAF, and IAS were 16.9 (14.6–35.4), 23.4 (13.5–73.0), and 46.9 (24.0–72.1) ng/mL, respectively. The Tmax for IAC, IAF, and IAS were 1.0 (0.75–4.0), 0.62 (0.5–1.0), and 0.25 (0.08–0.25) h, respectively. Median (range) elimination half-lives for IA and IM administrations were 3.6 (3.0–4.6) h and 3.4 (2.9–3.7) h, respectively. A 3-compartment model was fitted to the plasma dexamethasone concentration–time curve following the IV administration of DSP; alpha, beta, and gamma half-lives were 0.03 (0.01–0.05), 1.8 (0.34–2.3), and 5.1 (3.3–5.6) h, respectively. Following the PO administration, the median absorption and elimination half-lives were 0.34 (0.29–1.6) and 3.4 (3.1–4.7) h, respectively. Endogenous hydrocortisone plasma concentrations declined from a baseline of 103.8 ± 29.1–3.1 ± 1.3 ng/mL at 20.0 ± 2.7 h following the administration of DSP and recovered to baseline values between 96 and 120 h for IV, IA, and IM administrations and at 72 h for the PO.