Effect of experimentally induced synovitis on amikacin concentrations after intravenous regional limb perfusion.
Authors: Beccar-Varela Axel M, Epstein Kira L, White Catherine L
Journal: Veterinary surgery : VS
Summary
# Editorial Summary: Synovitis Effects on Amikacin Delivery via IVRLP Intravenous regional limb perfusion (IVRLP) is a cornerstone technique for delivering antibiotics directly to joint infections, yet the pharmacokinetics of these drugs may differ substantially depending on joint pathology. Beccar-Varela and colleagues conducted a randomised crossover trial in eight horses, experimentally inducing radiocarpal synovitis in one limb whilst keeping the contralateral joint as a control, then performing IVRLP with amikacin (5 mg/kg in 60 mL) under tourniquet occlusion and sampling synovial fluid over 48 hours. Peak amikacin concentrations arrived significantly faster in inflamed joints (all five horses reached maximal levels by 30 minutes) compared to normal joints (only one of five by 30 minutes; most requiring one hour), and the inflamed joints achieved markedly higher peak concentrations (mean 144.5 μg/mL versus 60.0 μg/mL in normal joints). Critically, only the synovitic joints achieved the recommended therapeutic threshold of an 8:1 concentration-to-minimum inhibitory concentration ratio in most cases, suggesting that acute joint inflammation may actually enhance antibiotic penetration and efficacy during perfusion. These findings carry important implications for timing and dosing decisions in IVRLP protocols, particularly when treating acute septic arthritis where the inflammatory environment may paradoxically facilitate more effective drug delivery than in chronic or degenerative joint conditions.
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Practical Takeaways
- •Inflamed joints achieve higher antibiotic concentrations during regional limb perfusion, potentially improving treatment efficacy for septic arthritis compared to treating clinically normal joints
- •The altered pharmacokinetics in inflamed joints may mean standard IVRLP protocols achieve therapeutic drug ratios in diseased but not healthy joints
- •Consider that joint inflammation itself may enhance drug delivery and therapeutic outcomes when performing IVRLP for septic arthritis cases
Key Findings
- •Inflamed joints reached maximal amikacin concentration faster (30 min) compared to normal joints (mostly 1 hour; P=0.0161)
- •Maximum amikacin concentration was 2.4× higher in synovitis joints (144.48 μg/mL) versus normal joints (60.02 μg/mL; P=0.0301)
- •Therapeutic target C(max):MIC ratio of 8 was achieved in 60% of inflamed joints but 0% of normal joints after IVRLP