Pharmacokinetics of a high dose of gentamicin administered intravenously or intramuscularly to horses.
OBJECTIVE
To evaluate pharmacokinetics of a high dose of gentamicin administered i.v. or i.m. to horses.


METHODS
Repeated-measures study.


METHODS
6 clinically normal female adult stock-type horses.


METHODS
All horses were given gentamicin (6.6 mg/kg [3 mg/lb] of body weight), i.v. and i.m., in a two-way cross-over design. Serum gentamicin concentrations were measured during a 24-hour period.


RESULTS
Plasma concentration curves were consistent with a two-compartment model. Maximum plasma gentamicin concentrations were 71.9 +/- 15.7 micrograms/ml (0 hours after injection) and 22.0 +/- 4.9 micrograms/ml (1.31 hours after injection) for the i.v. and i.m. groups, respectively. Area under the curve (AUC) was 116.6 +/- 14.5 and 116.3 +/- 14.6 micrograms.h/ml for the i.v. and i.m. groups, respectively. Elimination half-life for the IV group was 3.0 +/- 2.8 hours. Trough concentrations were < 2 micrograms/ml for > 15 and > 12 hours for the i.v. and i.m. groups, respectively. Significant changes were not detected in clinicopathologic variables before and after administration of gentamicin.


CONCLUSIONS
Administration of a high dose of gentamicin i.v. or i.m. resulted in peak plasma concentrations, AUC, and minimum trough plasma concentrations. Results indicate once-daily administration of gentamicin might be as efficacious and safe as multiple-dose daily administration in accordance with traditional low-dose regimens, similar to those used in other species.
Department of Large Animal Medicine and Surgery, College of Veterinary Medicine, Texas A&M University, College Station 77843-4461, USA.
K G
KG
Magdesian
P M
PM
Hogan
N D
ND
Cohen
G W
GW
Brumbaugh
W V
WV
Bernard
D000818:Animals; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D019540:Area Under Curve; D001682:Biological Availability; D018592:Cross-Over Studies; D005260:Female; D005839:Gentamicins / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D006207:Half-Life; D006736:Horses / Q000378:metabolism*; D007273:Injections, Intramuscular / Q000662:veterinary; D007275:Injections, Intravenous / Q000662:veterinary
D000900:Anti-Bacterial Agents; D005839:Gentamicins