Background: Polymethyl Methacrylate (PMMA) bone cement is the clinical gold standard
biomaterial for local antibiotic therapy in osteomyelitis. However, it releases 50% of the antibiotic
within the first three days. It generates excessive heat during polymerization and is non-biodegradable.
It must be removed by another operation. The best-known alternative for PMMA is hydroxyapatite.
Objectives: The present patented work is focused on synthesizing the biodegradable hydroxyapatite in
nano form for slow and sustained release of antibiotics and studying the release kinetics of antibiotics.
Methods: Nano-hydroxyapatite was synthesized by co-precipitation method and characterized by particle
size analyser, transmission electron microscopy, fourier transform infrared spectroscopy and energy
dispersive X-Ray analysis. Antibiotic loaded nano-hydroxyapatite was prepared as 7 mm beads.
The efficiency of drug-loaded nano-hydroxyapatite beads against osteomyelitic isolates was evaluated
by well diffusion assay. Zero-order, first order, second order, Higuchi model, Korsmeyer-Peppas and
Gompertz models were fit into the release kinetics of antibiotics from hydroxyapatite.
Results: Average size of nano-hydroxyapatite was 5 nm. The bactericidal activity exhibited by antibiotic-
loaded micro-sized hydroxyapatite was therapeutic until 10 days only, whereas antibiotic-loaded
nano-hydroxyapatite was therapeutic until 8 weeks. This confirms the burst release of antibiotics from
micro-sized hydroxyapatite beads. In contrast, the release was slow and sustained up to 8 weeks from
nano-hydroxyapatite. Korsmeyer-Peppas model fits into the release kinetics of antibiotics from nanohydroxyapatite.
Conclusion: Nano-hydroxyapatite with a Ca/P ratio of 1.78 is suitable for the slow and sustained delivery
of antibiotics for 8 weeks.