Cefotaxime kinetics in plasma and synovial fluid following intravenous administration in horses.

The research investigates the effects of three different doses of Cefotaxime, an antibiotic, on horses. The study finds that the highest dosage tested (25 mg/kg) is most effective for treating joint infections in horses.

Experimental Procedure

• Cefotaxime powder was prepared at a concentration of 100 mg/mL using sterile water. The solution was then tailored to each horse to provide doses of 15 mg/kg, 20 mg/kg, and 25 mg/kg.
• The solution was administered to each horse intravenously via a jugular vein catheter over a 10-minute period. The varying doses were given to all six experimental horses at different times.
• Both plasma and synovial fluid samples were collected from the horses to measure Cefotaxime concentrations using high-performance liquid chromatography (HPLC).

Data Analysis

• The collected data was analyzed using standard compartmental analysis techniques and the WinSAAM modeling program to determine pharmacokinetic parameters for Cefotaxime.
• The researchers found that the plasma Cefotaxime concentrations seemed to directly relate to the infused dose and decreased in parallel, suggesting the drug follows a linear kinetic process.
• The study also revealed steady declines in Cefotaxime concentrations, which suggests that the drug’s kinetics can be described using a one-compartment model, rather than being dependent on the timing of sampling post-infusion.

Antimicrobial Effectiveness

• The maximum concentration of Cefotaxime in plasma was recorded immediately after the halt of the infusion.
• The research also evaluated Minimum Inhibitory Concentrations (MIC), the lowest concentration of an antimicrobial that inhibits visible bacterial growth, for Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae. These bacteria are commonly known to cause septic arthritis in horses.
• Based on the pharmacokinetic data and bacterial MIC values, the researchers proposed a dosage regimen of 25 mg/kg of Cefotaxime administered intravenously every 6 hours as an effective treatment protocol for susceptible joint infections in adult horses.