Application of microdialysis to cancellous bone tissue for measurement of gentamicin levels

Objectives: Knowledge concerning the distribution of antibiotics in bone tissue is valuable for pharmacokinetic and clinical use. Unfortunately, appropriate techniques are difficult to apply. We introduced microdialysis catheters to cancellous bone tissue for the investigation of gentamicin levels and compared the pharmacokinetics measured with values obtained from bone samples. Methods: After two microdialysis catheters had been inserted into cancellous bone, eight pigs received an intravenous bolus of 240 mg of gentamicin. Microdialysates and bone samples were obtained over a period of 6 h and drug concentrations were measured. Results: The area under the curves of the two microdialysates and bone samples were 1569, 1721 and 1533 mg·min/L (ANOVA, P=0.81). Reproducibility of the measurements from the microdialysates was defined as the mean ratio of AUC6/catheter no. 1/AUC6/catheter no. 2. This ratio was 1.02. Conclusions: Microdialysis is a suitable, relatively non-invasive and reproducible technique for dynamic and quantitative measurement of gentamicin levels in experimental research.