In Vitro Elution and Antibacterial Activity of Clindamycin, Amikacin, and Vancomycin from R-gel Polymer

In vitro elution of amikacin from four hydrogel preparations: A pilot study

OBJECTIVE

To determine in vitro elution of amikacin from poloxamer 407 NF, 1% carboxymethylcellulose (CMC), 3% CMC, 5% CMC, and control (sterile water).

STUDY DESIGN

Descriptive in vitro.

SAMPLE POPULATION

Triplicate samples from each experimental group.

METHODS

Amikacin solution was prepared in poloxamer 407 NF, 1% CMC, 3% CMC, 5% CMC, or sterile water. Then, 1 ml of phosphate-buffered saline (PBS) was added to each of three aliquots per base and the samples were incubated at 37°C. PBS was removed and replaced at 1, 4, 8, 12, 24, 48, 72, 96, 120, 144, 168, 192, 216, and 240 hours and amikacin concentration was measured.

RESULTS

The highest median concentration of amikacin in the eluent of poloxamer 407 NF, 3% CMC, and 5% CMC was observed at 48 hours: 3300, 3030, and 2190 μg/ml, respectively. The highest median concentration of amikacin in the eluent of 1% CMC and sterile water were observed at 1 hour: 13300 and 15600 μg/ml, respectively. Median eluent concentration of amikacin exceeded 2000 μg/ml (the reported minimum inhibitory concentration [MIC] of certain biofilm-producing methicillin-resistant Staphylococcus pseudintermedius) from 24 to 96 hours for poloxamer 407 NF, 24-72 hours for 3% CMC, 48-72 hours for 5% CMC, 1-4 hours for 1% CMC, and 1-4 hours for sterile water.

CONCLUSION

Amikacin elution from tested substances reached or exceeded target MIC during the 240 hours tested.

CLINICAL SIGNIFICANCE

Hydrogel-amikacin solutions may be useful topical treatment options for some infected wounds. In vivo safety and efficacy should be evaluated.

In vitro elution of amikacin and Dispersin B from a polymer hydrogel

OBJECTIVE

To characterize the in vitro elution of amikacin and Dispersin B (β-N-acetylglucosaminidase) in a degradable hydrogel.

STUDY DESIGN

In vitro, prospective study.

METHODS

Amikacin (group A; 40 mg/mL), Dispersin B (group D; 70 μg/mL), or combined amikacin and Dispersin B (group AD; 40 mg/mL and 70 μg/mL, respectively) were added to a hydrogel. Ten aliquots per group were incubated in phosphate-buffered saline that was exchanged at 1, 4, 8, 12, and 24 hours and then once daily for 10 days. Eluted amikacin and Dispersin B were quantitated by using an amikacin reagent kit and a Dispersin B enzyme-linked immunosorbent assay kit, respectively. Time point drug concentrations were compared between groups by using repeated-measures analysis of variance, and total drug elution was compared by using an area under the curve calculation.

RESULTS

Amikacin alone, Dispersin B alone, and amikacin and Dispersin B combined together underwent rapid elution in the first 24 hours, followed by a gradual decrease over 10 days. The concentration of Dispersin B eluted in group D was higher at 1 day and lower from day 5 to day 10 compared with that in group AD. The concentration of amikacin eluted in group A was higher at 1, 4, and 8 hours and on day 10 and lower on day 1 compared with that in group AD. The total elution of amikacin was greater from group AD compared with that from group A (P = .02).

CONCLUSION

Combining amikacin and Dispersin B had an affect on the total elution of amikacin but not Dispersin B.

CLINICAL SIGNIFICANCE

The combination of amikacin and Dispersin B in a degradable hydrogel could allow local treatment of complex infections without the requirement for multiple invasive procedures.

A review of local antibiotic implants and applications to veterinary orthopaedic surgery

In the face of increasing incidence of multidrug resistant implant infections, local antibiotic modalities are receiving increased attention for both infection prophylaxis and treatment. Local antibiotic therapy that achieves very high antibiotic drug concentrations at the site of the implant may represent an avenue for treatment of biofilmforming bacterial pathogens. Randomized controlled trials in human patients have demonstrated an infection risk reduction when antibiotic-impregnated cement is used for infection prophylaxis in implanted joint prostheses, and when a gentamicin-impregnated collagen sponge is used for infection prophylaxis in midline sternotomy. The other modalities discussed have for the most part yet to be evaluated in randomized controlled trials in veterinary or human patients. In general, the in vivo pharmacokinetics and appropriate dosing profiles for local antibiotic modalities have yet to be elucidated. Toxicity is possible, and attention to the dose applied is warranted.