Pharmacokinetics, pharmacodynamics, and local tolerance at injection site of penicillin and gentamicin administered by intravenous regional limb perfusion in standing horses: comparison between weightbearing and flexed limbs.
Authors: Guillot Marguerite, Mespoulhes-Rivière Céline, Bousquet-Mélou Alain, Lacroix Marlène Z, Roques Béatrice B, Lallemand Elodie A
Journal: BMC veterinary research
Summary
# Editorial Summary: Antibiotic Delivery via Intravenous Regional Limb Perfusion in Standing Horses Intravenous regional limb perfusion (IVRLP) offers a targeted approach to treating distal limb infections in horses by delivering high local antibiotic concentrations whilst minimising systemic exposure, yet optimal administration protocols remain unclear. Researchers conducted a crossover study in six horses comparing sodium benzylpenicillin (7,333 IU/kg) and gentamicin (2.2 mg/kg) delivered via IVRLP in both weightbearing and flexed limb positions, with serial synovial and blood sampling to determine pharmacokinetic parameters and tissue tolerance. Gentamicin achieved considerably higher synovial concentrations than penicillin across both limb positions, whilst flexed limb positioning produced superior drug distribution to synovial fluid compared with weightbearing limbs; local tolerance at injection sites was acceptable for both antibiotics, though minor inflammation was noted in some cases. Pharmacokinetic/pharmacodynamic modelling predicted reliable efficacy against common equine pathogens (MICs ≤4 µg/mL for gentamicin and ≤0.5 IU/mL for penicillin), suggesting both antibiotics remain viable IVRLP choices depending on target organism. For practitioners, these findings support flexing the limb during IVRLP administration to optimise synovial penetration and indicate that gentamicin may offer superior concentration profiles for resistant infections, whilst penicillin maintains adequate efficacy against susceptible pathogens with potentially lower cost implications.
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Practical Takeaways
- •When performing IVRLP for distal limb infections, consider flexing the limb to improve drug delivery to synovial tissues and reduce local tissue irritation at the injection site
- •Gentamicin may offer more predictable efficacy across common bacterial pathogens than penicillin when using IVRLP, based on superior AUC/MIC ratios
- •Monitor injection sites carefully during IVRLP procedures, as flexed positioning appears to cause less inflammation than weightbearing positioning
Key Findings
- •Sodium benzylpenicillin (NaBP) achieved higher synovial concentrations when administered to flexed limbs compared to weightbearing limbs during IVRLP
- •Gentamicin demonstrated superior pharmacokinetic/pharmacodynamic parameters with AUC/MIC ratios adequate for most bacterial susceptibility profiles using IVRLP
- •Flexed limb positioning during IVRLP reduced inflammation at injection sites compared to weightbearing positioning
- •Both antibiotics achieved therapeutic concentrations in synovial fluid within the timeframe required for effective infection treatment