Determination of anti‐tuberculosis drug concentration and distribution from sustained release microspheres in the vertebrae of a spinal tuberculosis rabbit model

There have been several sustained-release materials containing anti-tuberculosis drug to enhance concentration in foci of spinal tuberculosis but what map by which composite drug delivery system is released is not known. Isoniazid (INH) lactic-co-glycolic acid (PLGA) and INH hydroxyapatite (HA) microspheres were prepared, respectively. The rabbits were modeled by tuberculosis strains and sustained-release microspheres were incubated in the foci. INH concentrations in the HA group were higher than those of INH and PLGA groups at L3, L4, and L5 vertebra 2 days after the drugs were embedded (p < 0.05). INH concentrations in the HA group were higher than those of INH and PLGA groups in L3 vertebra 4 days after the drugs were embedded (p < 0.05). INH concentrations in the PLGA group were higher than those of INH and HA groups in L5 vertebra; INH concentrations of the HA group were higher than those of INH and PLGA groups in L4 vertebra 6 days after the drugs were embedded (p < 0.05). These microspheres can enhance INH concentration in the foci. Furthermore, HA microspheres elicit osteogenic effects. HA is better than PLGA in terms of infiltration, but PLGA is better than HA in terms of distribution. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:200-208, 2017.