Release of daptomycin from polymethylmethacrylate beads in a continuous flow chamber.

Because daptomycin is active against Gram-positive cocci, it may be useful in the treatment and prevention of bone and joint infections when incorporated into polymethylmethacrylate (PMMA). The release kinetics of daptomycin from PMMA were studied in a continuous flow chamber designed to simulate in vivo conditions. Three-millimeter beads containing 2.5%, 7.5%, and 15.0% daptomycin (weight daptomycin per weight PMMA) were individually placed in a chamber with 1 mL Krebs Ringer buffer flowing at 1 mL/hour. The majority of daptomycin was released in the first 24 hours. The mean peak concentrations were 13.4, 62.3, and 146.7 microg/mL; the mean AUC0-infinity were 30, 272, and 1204 h x microg/mL; and the mean percentages of daptomycin released were 6%, 18%, and 42% for the beads containing 2.5%, 7.5%, and 15.0% daptomycin, respectively. Daptomycin is released from PMMA in a continuous flow chamber at a rate similar to that previously determined by our laboratory for vancomycin.