Formulation of calcium phosphates/poly (d,l-lactide) blends containing gentamicin for bone implantation

Implants to prevent or treat osteomyelitis are described, composed of phosphate/poly(d,l-lactide) blends containing the antibiotic gentamicin. Seven formulations of implants containing 3% gentamicin sulfate (GS) were prepared at 433 MPa and 693 MPa of compression pressure. The blends contained phosphates (25% hydroxyapatite (HAP), 75% tricalcium phosphate (TCP)) and 20% dl-PLA (weight average molecular weight, M(w): 30 kD). To prolong GS release, implants were coated with PLGA (M(w):100 kD) or dl-PLA (M(w): 200 kD). Various durations of GS release from these devices were demonstrated as feasible. Release times of more than 10 weeks were attained with implants coated with dl-PLA (M(w): 200 kD), greatly exceeding the performance of the commercial formulation.