Concentration of Marbofloxacin in equine subcutaneous tissue fluid after subcutaneous administration in encapsulated microparticles.

The study investigates the efficacy of Marbofloxacin-encapsulated microparticles for delivering sufficient antimicrobial concentrations to fight surgical-site infections in horses. This method involves embedding Marbofloxacin, an antimicrobial, within biodegradable polymer particles and then administering them subcutaneously to horses, yielding promising results for controlling persistent infections.

Introduction and Objective

• The research aims to solve the problem of controlling surgical-site infections (SSIs) at implant sites in horses which are often difficult to manage with systemic antimicrobials. This difficulty is hypothesized to stem from the antimicrobial concentrations not being high enough in and around the infected tissue.
• The objective of the study, therefore, is to examine whether higher concentrations of antibiotics can be achieved using Marbofloxacin-encapsulated microparticles (MAR-MPs).
• The premise is that these microparticles, made from the biodegradable polymer poly (lactic-co-glycolic) acid, can sustainably release Marbofloxacin (MAR), an antimicrobial agent, increasing its concentration in the targeted areas.

Methodology

• The study involved the creation of six 3- × 4-cm subcutaneous pockets in the necks of six thoroughbred horses, under sedation and local anesthesia.
• MAR-MPs containing 50 mg of Marbofloxacin were inserted into each pocket, which was then sutured.
• Subcutaneous tissue fluid was collected from one pocket per horse and analyzed using LC-MS/MS on days 1, 2, 3, 4, and 7 following the procedure.

Results

• The results indicated that from days 1 to 7, the median Marbofloxacin concentration in the subcutaneous tissue fluid ranged from 17.7 to 33.05 µg/mL, exceeding the minimum inhibitory concentration (MIC) that would inhibit the growth of 90% of the bacteria tested.
• However, the area of swelling at the site of administration was noted to be significantly larger on days 1 to 4 when compared to just after administration, highlighting potential side effects of the procedure.

Conclusion

• The study concludes that Marbofloxacin-encapsulated microparticles could be beneficial for controlling surgical-site infections in horses by delivering high antimicrobial concentrations over extended periods.
• However, the authors suggest that this method should be used with strategies to reduce side effects, evident from the significant swelling recorded post-administration of MAR-MPs.