Bone gentamicin concentration after intra-articular injection or regional intravenous perfusion in the horse.
Authors: Werner Laura A, Hardy Joanne, Bertone Alicia L
Journal: Veterinary surgery : VS
Summary
# Bone Gentamicin Concentration After Intra-Articular Injection or Regional Intravenous Perfusion in the Horse When treating equine osteomyelitis or septic arthritis, clinicians must achieve adequate antibiotic penetration into both bone and synovial fluid—yet the relative merits of intra-articular (IA) injection versus regional intravenous perfusion (RIP) for delivering gentamicin to these tissues remain incompletely understood. Werner and colleagues administered 1 g gentamicin to twelve healthy horses via either IA injection into the metacarpophalangeal joints or RIP through the lateral palmar veins, then measured drug concentrations in serum, synovial fluid, and bone samples over time using fluorescence polarization immunoassay. Whilst IA administration achieved significantly higher gentamicin concentrations in synovial fluid and maintained levels above the minimum inhibitory concentration (MIC) for common pathogens for over 24 hours compared with RIP, bone penetration was remarkably similar between the two approaches, with both methods maintaining therapeutic concentrations for approximately 8 hours. For practitioners, this finding is reassuring: both IA and RIP administration appear equally effective at achieving bactericidal bone concentrations, suggesting that either technique can be selected based on clinical circumstances, anatomical accessibility, and patient tolerance rather than concerns about inferior bone penetration with one method over the other.
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Practical Takeaways
- •For joint infections, choose intra-articular injection if higher local drug concentration is needed; regional intravenous perfusion achieves similar bone penetration with systemic advantages
- •Both delivery methods maintain therapeutic drug levels in bone for at least 8 hours, informing treatment intervals for osteomyelitis
- •Either method is suitable for treating osteomyelitis based on drug kinetics; choice can be guided by clinical context, access, and systemic considerations
Key Findings
- •Intra-articular administration achieved higher synovial fluid gentamicin concentrations than regional intravenous perfusion
- •Both IA and RIP methods maintained gentamicin concentrations above minimum inhibitory concentration (MIC) in synovial fluid for over 24 hours
- •Bone gentamicin concentration remained above MIC for 8 hours with both methods with no significant difference between groups
- •Neither IA nor RIP administration significantly affected serum gentamicin concentrations