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Osaka, JapanTomonori Arita - Graduate School of Engineering, Osaka City University - Osaka, JapanAkira Tachibana - Graduate School of Engineering, Osaka City University - Osaka, JapanToshizumi Tanabe - Graduate School of Engineering, Osaka City University - Osaka, JapanHironobu Oonishi - H. Oonishi Memorial Joint Replacement Institute, Tominaga Hospital -Osaka, Japan*Email: mizokawa-ns@umin.ac.jp[INTRODICTION] : Since 1985, not resorbable crystalline osteoconductive hydroxyapatite(HA) granules were interposed on the interface between bone and bone cement at thecementation (Interface Bioactive Bone Cement : IBBC) of total hip arthoplasty (THA) toprevent generation of connective tissue and osteolysis for the longevity of cemented THA. Toprevent the patients from infection, we are planning to use b-tricalcium phosphate (Beta-TCP)impregnated with antibiotics along with HA granules. However, there have been no reports onthe loading and release of antibiotics from fine granules of Beta-TCP. Here, we haveinvestigated the loading of antibiotics on Beta-TCP and their release in vivo.[MATERIALS AND METHODS] : Beta-TCP was impregnated with antibiotics such asflomoxef sodium (F), vancomycin hydrochloride (V) cefotiam dihydrochloride (C) andcefozopran hydrochloride (CE) under normal or reduced pressure. After washing with PBSthree times, Beta-TCP loaded with the antibiotic was placed in PBS. An aliquot of solution wassampled at appropriate time intervals and the amount of the released antibiotic was estimatedbased on the anti-bacterial activity.[RESULTS AND DISCUSSION] : When drug loading was done by dropping the antibioticsolution to Beta-TCP granules, the amount of antibiotic released from 20 mg of HA was 8 µgfor F, 0 µg for V, 6 µg for C and 520 µg for CE. Their release completed within 24 hrs. Whenthe antibiotic loading was done under reduced pressure, 20 mg of Beta-TCP was loaded with 40µg of F, 130 µg of V and 25 µg of C, but the released amount was 16 µg for F, 8 µg for V and0 µg for C. Each drug was released within 10 hrs. Meanwhile, 8000 µg of CE was loaded on 20mg of Beta-TCP and its release continued for 6 days. When Beta-TCP loaded with C or CEwas placed in 0.25 MEDTA to dissolve Beta-TCP gradually, the release of C and CE sustainedover 14 days along with the dissolution of Beta-TCP. The release of C from Beta-TCPcontinued over 19 days in EDTA. The released amount of C and CE were 116 µg and 7100 µg,respectively. Thus, CE seemed the most suitable for our purpose in terms of the loaded amountand releasing behavior. However, CE as well as C showed the eminent sustained release inEDTA solution. Since Beta-TCP shows bioabsoption, it is expected to be efficient antibioticscarrier. It is worthy to use adequate sizes of Beta-TCP granules impregnated with antibiotics incombination with osteoconductive HA in IBBC for the protection of the infection after jointreplacement, especially in revision surgery after infection.[REFERENCES] : Oonishi H. et al: THA with hydroxyapatite granules at cement-boneinterface, 15-to 20-year result. Clin Orhtop Relat Res. 2008; 466:373-379.Saturday, October 9, 2010, 14:00-14:40Session A21: Knee Arthroplastyfile:///E|/ISTA2010-Abstracts.htm[12/7/2011 3:15:47 PM]