Morphine Synovial Fluid Concentrations After Intravenous Regional Limb Perfusion in Standing Horses.
Authors: Hunter Barbara G, Parker Jill E, Wehrman Rita, Stang Bernadette, Cebra Christopher K
Journal: Veterinary surgery : VS
Summary
# Intravenous Regional Limb Perfusion with Morphine in Standing Horses Intravenous regional limb perfusion (IVRLP) is an established technique for delivering high local drug concentrations to equine joints and soft tissues, but evidence regarding morphine delivery through this route remained limited. Researchers administered 0.1 mg/kg morphine alone or combined with 1 g gentamicin to the forelimbs of six standing sedated horses, collecting synovial fluid and blood samples at five timepoints over 24 hours to quantify drug concentrations and assess safety. Peak morphine concentrations in synovial fluid (mean 3903 ng/mL) occurred within 20 minutes of perfusion, with no significant difference between morphine alone and morphine-gentamicin combinations, whilst plasma morphine remained low (11–63 ng/mL), indicating excellent local targeting; gentamicin synovial concentrations matched previously reported levels. For practitioners considering IVRLP with morphine as an analgesic adjunct for joint or soft tissue conditions, this work confirms adequate synovial penetration and good safety profile in standing horses, supporting its use as part of a multimodal pain management strategy during regional anaesthesia, though further work on clinical efficacy and optimal dosing would strengthen evidence for routine application.
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Practical Takeaways
- •IVRLP with morphine can deliver therapeutic analgesic concentrations directly to joint structures in standing horses without significant systemic drug absorption or adverse effects
- •Combining morphine with gentamicin in regional perfusion does not compromise morphine delivery, allowing concurrent antimicrobial therapy for septic arthritis
- •The 20-minute peak suggests optimal timing for joint anesthesia if performing arthroscopic procedures after IVRLP in standing patients
Key Findings
- •Peak synovial fluid morphine concentrations of 3903±4881 ng/mL were achieved 20 minutes after intravenous regional limb perfusion (IVRLP) in standing sedated horses
- •No significant difference in morphine synovial concentrations when morphine was combined with gentamicin versus morphine alone
- •Plasma morphine concentrations remained low (11-63 ng/mL peak within 2 hours), indicating minimal systemic absorption
- •IVRLP with morphine caused no clinically apparent adverse effects in standing sedated horses