In vitro elution studies of amikacin and cefazolin from polymethylmethacrylate.
OBJECTIVE
To compare the in vitro elution characteristics of amikacin and cefazolin from polymethylmethacrylate (PMMA) alone and in combination.


METHODS
A prospective, controlled, experimental study.


METHODS
Three aliquots of 6 g sterile PMMA were measured and to them added (1) 750 mg amikacin; (2) 1050 mg cefazolin; and (3) 750 mg amikacin and 1050 mg cefazolin. Ten beads of each antimicrobial/PMMA combination were placed in 5 mL phosphate-buffered saline (PBS) at pH 7.4 and room temperature with constant agitation. PBS was sampled at 15 time points between 1 hour and 30 days. Amikacin concentrations were determined by fluorescence polarization immunoassay and cefazolin concentrations by high-performance liquid chromatography.


RESULTS
Amikacin and cefazolin eluted at concentrations greater than 8 and 4 times, respectively, above the minimum inhibitory concentration (MIC) for susceptible bacteria over 30 days. Co-elution of the antibiotics resulted in a greater rate and proportion of antibiotic eluted. Concentrations of amikacin and cefazolin in the co-eluted fluid were not maintained sufficiently above the MIC for selected bacteria over 30 days.


CONCLUSIONS
PMMA beads of only amikacin or cefazolin-eluted concentrations greater than the MIC for selected bacteria for 30 days. Co-elution of the antibiotics at the selected doses resulted in a significantly shorter duration of elution and may not be effective for treatment of wound infection.


CONCLUSIONS
Co-elution of amikacin and cefazolin from PMMA at the selected doses cannot be recommended for sustained treatment of infection.
Phillips
Heidi
H
Allegheny Veterinary Emergency Trauma and Specialty, Monroeville, PA 15146, USA. sxn2005@comcast.net
Boothe
Dawn M
DM
Shofer
Frances
F
Davidson
Jeffrey S
JS
Bennett
R Avery
RA
D000583:Amikacin / Q000737:chemistry / Q000494:pharmacology*; D000818:Animals; D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology*; D001178:Arthroplasty / Q000295:instrumentation / Q000662:veterinary*; D001419:Bacteria / Q000187:drug effects; D001843:Bone Cements / Q000737:chemistry*; D002437:Cefazolin / Q000737:chemistry / Q000494:pharmacology*; D008826:Microbial Sensitivity Tests; D019904:Polymethyl Methacrylate / Q000737:chemistry*; D011446:Prospective Studies; D013530:Surgical Wound Infection / Q000517:prevention & control / Q000662:veterinary
D000900:Anti-Bacterial Agents; D001843:Bone Cements; D000583:Amikacin; D019904:Polymethyl Methacrylate; D002437:Cefazolin