Prediction of pharmacokinetic profiles of ampicillin sodium, gentamicin sulfate, and combination ampicillin sodium-gentamicin sulfate in serum and synovia of healthy horses.
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.
D000667:Ampicillin / Q000097:blood / Q000378:metabolism* / Q000627:therapeutic use; D000818:Animals; D004347:Drug Interactions; D004359:Drug Therapy, Combination; D005260:Female; D005839:Gentamicins / Q000097:blood / Q000378:metabolism* / Q000627:therapeutic use; D006736:Horses; D007700:Kinetics; D013582:Synovial Fluid / Q000378:metabolism*
D005839:Gentamicins; D000667:Ampicillin