title: In vitro comparison of elution characteristics of vancomycin from calcium phosphate cement and polymethylmethacrylate.
abstract: BACKGROUND
  Calcium phosphate cement [CPC (Biopex)] has been used as the drug delivery system of choice for treatment of infected joint replacement because of its good elution efficiency. The influence of CPC polymerization on the bactericidal activity of vancomycin (VCM) impregnated into CPC has not been investigated. We compared VCM concentration, bactericidal activity, and profile of eluates between CPC and polymethylmethacrylate (PMMA; Cemex RX).
  
  
  METHODS
  Test specimens consisted of a powder composite of CPC or PMMA, VCM and solvent (10:0.25:3.3 g). Each test specimen was immersed in sterile phosphate-buffered saline. Eluates obtained on days 1, 3, 7, and 14 and weeks 4, 8, and 12 were evaluated by high performance liquid chromatography (HPLC) and by microbiological assay (MBA).
  
  
  RESULTS
  The elution level of VCM from CPC/VCM on day 1 was 8.1 fold greater than that from PMMA/VCM. The detection periods of VCM from CPC/VCM and PMMA/VCM were 8 weeks and 14 days, respectively. The values of eluates from CPC/VCM and PMMA/VCM obtained by HPLC were comparable to those obtained by MBA. HPLC chromatogram showed that the elution profiles of VCM from CPC/VCM and PMMA/VCM on day 1 were very close to those of standard solutions.
  
  
  CONCLUSIONS
  CPC could release more VCM over a longer period than PMMA. The polymerization of CPC and PMMA did not alter the inhibitory activity of VCM and did not denature VCM.
authors.affiliation: Department of Orthopaedic Surgery, Kitasato University School of Medicine, Sagamihara, Kanagawa 228-8555, Japan.
authors.forename: Ken
authors.initials: K
authors.lastname: Urabe
authors.forename: Kouji
authors.initials: K
authors.lastname: Naruse
authors.forename: Hideki
authors.initials: H
authors.lastname: Hattori
authors.forename: Masahiro
authors.initials: M
authors.lastname: Hirano
authors.forename: Kentaroo
authors.initials: K
authors.lastname: Uchida
authors.forename: Kenji
authors.initials: K
authors.lastname: Onuma
authors.forename: Hwang Jung
authors.initials: HJ
authors.lastname: Park
authors.forename: Moritoshi
authors.initials: M
authors.lastname: Itoman
mesh_terms: D000900:Anti-Bacterial Agents; D001843:Bone Cements; D002130:Calcium Phosphates / Q000138:chemical synthesis*; D002851:Chromatography, High Pressure Liquid; D052978:Disk Diffusion Antimicrobial Tests; D016503:Drug Delivery Systems; D066298:In Vitro Techniques; D019904:Polymethyl Methacrylate / Q000138:chemical synthesis*; D016459:Prosthesis-Related Infections / Q000517:prevention & control; D014640:Vancomycin
chemical_list: D000900:Anti-Bacterial Agents; D001843:Bone Cements; D002130:Calcium Phosphates; D014640:Vancomycin; D019904:Polymethyl Methacrylate; C020243:calcium phosphate