Elution of antimicrobials from a cross-linked dextran gel: In vivo quantification.

The research investigates a new method of delivering antimicrobial medication to horses using a biodegradable gel. The study aimed to determine how antimicrobial medications were released from the gel once implanted under the skin of a horse and to understand its effects on wound healing.

Research Methodology

• The study involved the placing of antimicrobial-impregnated cross-linked dextran gel under the skin in the necks of 11 horses. The study used three types of antimicrobial medications – amikacin, vancomycin and a combination of amikacin/clindamycin.
• A total of 6 replicates were performed on each horse with a resting period of 3 months between experiments.
• Small probes were inserted at different points around the incision, where the gel-antimicrobial medication was placed. These probes identified the amount of antimicrobial medication in the interstitial fluid of the wounds over a period of 10 days.
• Blood was drawn from all 11 horses on the day of the operation and then again on the first and seventh day post-operation.
• The concentration of the used antimicrobials was ascertained using fluorescence polarisation immunoassay for amikacin and vancomycin, and high-performance liquid chromatography for clindamycin.
• At the end of the study, a biopsy was performed on the incisions to understand the effect of the antimicrobial medication and the dextran gel on wound healing.

Findings

• Maximum concentration of amikacin was detected 4 hours after administration and for vancomycin and the combination gel, it was 8 hours.
• The amount of antimicrobial medication that remains over the minimum inhibitory concentration (MIC) for the targeted microorganism lasted for up to 10 days for vancomycin, 9 days for amikacin, and 8 days for clindamycin post-implantation.
• Concentrations of amikacin and vancomycin in the bloodstream were too low to be detected, whereas the concentrations of clindamycin were 0.52 µg/ml at 24 hours and 0.63 µg/ml at 7 days.
• There was no significant difference in wound healing between the treatment and control incisions, indicating that the use of the gel and antimicrobial medication did not affect wound healing negatively.

Conclusion

The research concludes that the antimicrobial-impregnated cross-linked dextran gel is a safe and effective localized delivery method for antimicrobial medication in the treatment of infection in horses.