PREPARATION, CHARACTERIZATION AND GENTAMICIN SULFATE RELEASE INVESTIGATION OF BIPHASIC INJECTABLE CALCIUM PHOSPHATE BONE CEMENT

A calcium phosphate cement containing an antibiotic can be used for filling bone defects and to ensure local antibiotherapy. Therefore, in the present research, cement paste were prepared by combining cement liquids comprised of 4 wt.% Na2HPO4 with cement powders that consisted of beta-tricalcium phosphate (beta-TCP) and monocalcium phosphate monohydrate (MCPM). Gentamicin sulfate was also loaded on the cements and its in vitro release was evaluated over a period of time. The cement setting times were compared before and after drug addition. According to results, the initial and final setting times of samples came down after drug addition, reached to 5 and 15 min, respectively. Compressive strength of the drug-loaded samples aged in PBS measured about 30-40 MPa and showed it did not vary significantly with the period of aging until 36 days (p<0.05). pH values of the PBS solution containing samples descended gradually until reached to an equilibrium pH. Phase analysis of the samples with X-ray analysis (XRD) indicated the presence of monetite and beta-TCP in all samples. Microstructure of the fracture surface showed that the cement particles tended to form a highly integrated microporous structure. Extrusion curves of cement paste indicating that it can be delivered through a surgical gun in small non-load bearing bone defects. Finally, the results showed it reached its maximum level (35% of the initial value of the drug) on day 15, suggesting no irreversible binding occurred between the cement paste and the antibiotic of Gentamicin sulfate.