Influence of hydroxyapatite pore geometry on tigecycline release kinetics

Calcium hydroxyapatite (CHA), as one of the most important ceramic materials in bone tissue engineering, was used as a delivery system for tigecycline, a potential antibiotic in treatment of osteomyelitis. Tigecycline, in a solid state, was mixed with CHA powder and the obtained mixture was compressed into tablets. The release of tigecycline from these tablets in a pH 7.4 phosphate-buffered saline solution was measured by a UV–vis spectrophotometer at 37 °C. The total dose of tigecycline was released for 5 to 30 days, depending on the applied pressure and drug concentration. A new drug release mechanism that determines the relationship between pore sizes and drug release rate is proposed. It explains and quantifies the drug release kinetics based on pore sizes and pore size distribution.