Title: Prediction of pharmacokinetic profiles of ampicillin sodium, gentamicin sulfate, and combination ampicillin sodium-gentamicin sulfate in serum and synovia of healthy horses.

Authors: Bowman, K F; Dix, L P; Riond, J L; Riviere, J E

Published In Am J Vet Res, (1986 Jul)

Abstract: Pharmacokinetics of ampicillin sodium (11 mg/kg), gentamicin sulfate (2.2 mg/kg), and combination ampicillin sodium-gentamicin sulfate were determined for serum and synovia of healthy horses given single-dose IV injection and were not found to be different from those from other reports; however, a prolonged terminal gamma-phase for gentamicin (8,498 +/- 1,842 minutes) in serum of horses was found to exist. Pharmacokinetic interaction between combination ampicillin sodium-gentamicin sulfate was not observed int he serum or synovia. Prediction of ampicillin sodium or gentamicin sulfate concentrations in synovia, based on serum-based pharmacokinetics, cannot be accomplished solely upon analysis of peripheral-compartment pharmacokinetics. However, once equilibrium is achieved between synovia and extracellular fluid in the peripheral compartment, the decrease in drug concentrations in synovia parallels that in serum. Therefore, after 6 hours, synovial concentrations of gentamicin sulfate can be predicted based on peripheral-compartment pharmacokinetics, using an appropriate correction factor. The significance of these findings need to be correlated with clinical conditions so that a pharmacostatistical model for the prediction of synovial concentrations of drug(s) during treatment of horses with septic arthritis can be developed.

PubMed ID: 3740631

MeSH Terms: Ampicillin/blood; Ampicillin/metabolism*; Ampicillin/therapeutic use; Animals; Drug Interactions; Drug Therapy, Combination; Female; Gentamicins/blood; Gentamicins/metabolism*; Gentamicins/therapeutic use; Horses; Kinetics; Synovial Fluid/metabolism*