Related Experiment Video
Updated: May 18, 2026
A Novel Method to Determine the Longitudinal Antibacterial Activity of Drug-Eluting Materials
Published on: March 3, 2023
Elution of antimicrobials from a cross-linked dextran gel: In vivo quantification
S K Hart1, J G Barrett, J A Brown
1Marion duPont Scott Equine Medical Center, Virginia-Maryland Regional College of Veterinary Medicine, Virginia Tech, Leesburg, Virginia, USA.
Reasons For Performing Study:
Use of a novel, biodegradable, antimicrobial-impregnated gel provides an alternative method of local treatment of infections in horses.
Objectives:
To determine in vivo elution of antimicrobial medications from antimicrobial-impregnated cross-linked dextran gel and to evaluate the effect on wound healing when implanted subcutaneously in horses.
Methods:
Amikacin-, vancomycin- or amikacin/clindamycin-impregnated gel was placed subcutaneously in 11 horses' necks, using 6 replicates with a 3 month washout between experiments. Capillary ultrafiltration probes for collection of interstitial fluid were placed 0 cm and 1.5 cm from the gel-filled incisions. Samples were collected at 0, 4, 8 and 12 h, and on Days 1-10. Blood was collected on Days 0, 1 and 7. Amikacin and vancomycin samples were analysed via fluorescence polarisation immunoassay, and clindamycin samples via high-performance liquid chromatography. Histology of biopsy samples was performed at the completion of the study. Differences in mean histomorphological scores between groups were assessed using Wilcoxon's signed ranks test.
Results:
Maximum antimicrobial concentrations were detected at 4 h (amikacin), and 8 h (vancomycin, and amikacin and clindamycin from the combination gel). Mean ± s.d. peak concentrations for amikacin, vancomycin, amikacin (amikacin/clindamycin) and clindamycin were 6133 ± 1461, 7286 ± 2769, 3948 ± 317 and 985 ± 960, respectively. Median number of days for which antimicrobial concentration remained above minimum inhibitory concentration for target microorganisms at implantation was ≥10 days for vancomycin, 9 days (± 1) for amikacin and 8 days (± 1) for clindamycin. Mean plasma amikacin and vancomycin concentrations were lower than detectable limits; mean serum clindamycin concentrations were 0.52 µg/ml and 0.63 µg/ml at 24 h and 7 days, respectively. There were no significant differences in histomorphological scores between treatment and control incisions (P≥0.22).
Conclusions And Potential Relevance:
Cross-linked dextran gel is a safe, effective alternative local antimicrobial delivery method.
