Abstract

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.

Keywords: Antibiotics, bactericidal activity, bone cement, Gompertz model, Korsmeyer-Peppas model, nano-hydroxyapatite.