Concentration of Marbofloxacin in equine subcutaneous tissue fluid after subcutaneous administration in encapsulated microparticles.
Authors: Mita Hiroshi, Kuroda Taisuke, Minamijima Yohei, Tamura Norihisa, Ohta Minoru
Journal: Journal of equine veterinary science
Summary
# Editorial Summary Surgical-site infections at implant locations present a persistent clinical challenge in equine practice, largely because systemic antimicrobial administration fails to achieve sufficiently high drug concentrations at the infected tissue site. Researchers investigated whether marbofloxacin-loaded microparticles made from biodegradable polymer could maintain therapeutic concentrations in subcutaneous tissue fluid when implanted directly into surgical pockets, using six Thoroughbreds with surgically created subcutaneous pockets in the neck region filled with 50 mg of the microparticle preparation. Over a seven-day monitoring period, marbofloxacin concentrations in the tissue fluid ranged from 17.7 to 33.05 µg/mL, consistently exceeding the MIC₉₀ threshold required to inhibit 90% of clinically relevant bacterial isolates—a critical finding for antimicrobial efficacy. The treatment did generate significant swelling at the implant site for the first four days post-administration, highlighting the need for careful case selection and management strategies to mitigate inflammatory responses. These encapsulated microparticles may offer farriers and veterinarians a valuable tool for controlling refractory implant-related infections by delivering high local drug concentrations over an extended period, though further investigation into minimising local tissue reactions will be essential before widespread clinical adoption.
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Practical Takeaways
- •Marbofloxacin microparticles may offer a viable local delivery strategy for controlling difficult-to-treat surgical-site infections around implants in horses by maintaining therapeutic antimicrobial concentrations for extended periods
- •Clinicians should be aware that these microparticles produce localized swelling during the first 4 days post-implantation; strategies to manage this inflammatory response should be developed before clinical use
- •This approach could reduce reliance on systemic antimicrobials for implant-associated infections, potentially decreasing systemic drug exposure while improving local control
Key Findings
- •Marbofloxacin-encapsulated microparticles achieved median tissue fluid concentrations of 17.7–33.05 µg/mL over 7 days, exceeding MIC90 for clinical bacterial isolates
- •Sustained antimicrobial release was demonstrated in vivo with biodegradable poly(lactic-co-glycolic) acid microparticles containing 50 mg marbofloxacin per subcutaneous pocket
- •Local tissue swelling at administration sites was significantly larger on days 1–4 compared to post-implantation (P < 0.05), indicating inflammatory response to microparticles