[Preparation of plastic nano-hydroxyapatite/poly (3-hydroxybutyrate-hydroxyvalerate)-polymethyl lene glycol gentamicin drug delivery system].

Objective: To develop the plastic nano-hydroxyapatite (nano-HA)/poly (3-hydroxybutyrate-hydroxyvalerate)-polyethylene glycol (PHBV-PEG) gentamicin (GM) drug delivery system (DDS) (nano-HA/PHBV-PEG-GM-DDS) for treating osteomyelitis and find its releasing character in vivo.

Methods: The plastic nano-HA/PHBV-PEG-GM-DDS was prepared using nano-HA as the core carrier of GM, nano-HA with PHBV and PEG as coating and plastic fibrin glue(FG) as microsphere scaffold. The morphological features of nano-HA, drug loaded nano-HA and drug loaded nano-HA/PHBV-PEG microsphere were examined by electron microscope. The GM concentration it blood, cortex bone and cancellous bone was detected at 12 different time points by the method of K-B after the plastic nano-HA/PHBV-PEG-GM-DDS was implanted into the femora of 36 rabbits. Its GM releasing character was assayed in vivo.

Results: Nano-HA was similar to a blackjack, and its length was less than 60 nm. Drug loaded nano-HA appeared natural crystal condensate, of which surface adsorbed massive GM. The average grain diameter was 200.5 nm. Drug loaded nano-HA/PHBV-PEG microsphere had a shrinkable porous structure, of which surface configuration was consistent. The average grain diameter was 34.5 microm. The GM concentration and the antibacterial annulus was in the linear correlation. The correlation coefficient was 0.998. In cortex and cancellous bone tissue, the GM concentration was about 95.50 +/- 16.50 microg/ml and 80.20 +/- 13.80 microg/ml from the plastic nano-HA/PHBV-PEG-GM-DDS on the 1st day, then decreased gradually. After 56 days of operation, the GM concentration still exceeded the minimum inhibitory concentration for the staphylococcus aureus, but the peak level of serum GM concentration was under the nephrotoxicity concentration.

Conclusion: Plastic nano-HA/PHBV-PEG-GM-DDS was a good drug delivery system with sustained antibiotic effect in vivo. It was an effective method for the treatment of osteomyelitis.