Effect of Dose on Intra-Articular Amikacin Sulfate Concentrations Following Intravenous Regional Limb Perfusion in Horses.

The study investigates how two different doses of amikacin sulfate – one a 2g dose and the other a 3g dose – given through intravenous regional limb perfusion (IVRLP) affect the concentration levels of the antibiotic in a horse’s joint fluid. The aim was to identify which dose was more efficient in reaching and maintaining target levels for combating bacterial infections present in common horse orthopedic conditions.

Research Methodology

• This study was a randomized crossover experiment involving six adult horses.
• The horses were given IVRLP with 2g and 3g amikacin via the cephalic vein in alternating limbs. This process was done under a tourniquet application for 20 minutes with at least 14 days as a washout period.
• Amikacin concentrations in the synovial fluid collected from the horse’s middle carpal and metacarpophalangeal joints were measured at the 25-minute mark as well as at 24, 36, and 48 hours after IVRLP.
• The Minimum Inhibitory Concentrations (MIC) from equine bacterial isolates were determined and their efficiency to reach targeted amikacin concentrations were compared.

Research Findings

• The study found that, overall, the synovial fluid in the horse’s middle carpal joint had a higher concentration of amikacin after the IVRLP with the 3g dose as compared to the 2g dose.
• However, no significant difference in amikacin concentration was observed in the metacarpophalangeal joint between the 2g and 3g doses.
• Target amikacin concentrations for bacteria such as Staphylococcus aureus and coagulase-negative staphylococci were achieved in both joints at 25 minutes after IVRLP with both doses.
• The 3g dose helped achieve target amikacin concentrations for fighting Escherichia coli and Actinobacillus spp. in the middle carpal joint at the 25-minute mark. However, the target concentrations were not reached for Enterococcus spp., Pseudomonas spp., or Streptococcus equi ssp. zooepidemicus, even with the larger 3g dose.

Conclusions of the Research

• The findings suggest that a 3g amikacin dose may not be necessary for the majority of distal limb injuries in horses. The 3g dose should be reserved for bacterial isolates with an MIC higher than what can be achieved with a 2g dose.
• The study also suggests that daily IVRLP may be necessary based on the results observed.