title: In vitro elution studies of amikacin and cefazolin from polymethylmethacrylate.
abstract: 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.
authors.affiliation: Allegheny Veterinary Emergency Trauma and Specialty, Monroeville, PA 15146, USA. sxn2005@comcast.net
authors.forename: Heidi
authors.initials: H
authors.lastname: Phillips
authors.forename: Dawn M
authors.initials: DM
authors.lastname: Boothe
authors.forename: Frances
authors.initials: F
authors.lastname: Shofer
authors.forename: Jeffrey S
authors.initials: JS
authors.lastname: Davidson
authors.forename: R Avery
authors.initials: RA
authors.lastname: Bennett
mesh_terms: 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
chemical_list: D000900:Anti-Bacterial Agents; D001843:Bone Cements; D000583:Amikacin; D019904:Polymethyl Methacrylate; D002437:Cefazolin