The degree of penetration of an
antibiotic into the
infection site is an important factor in its therapeutic efficacy, particularly in bone and joint
infections. In the present study, we examined the bone tissue penetration of
isepamicin at a dose of 15 mg/Kg, and the results were correlated to microbiologic data to estimate the clinical efficacy of
isepamicin in bone
infections. In this open-label, single-arm, noncomparative study, subjects of similar age,
body weight, height and
creatinine clearance who were undergoing elective
total hip replacement received a single, parenteral 15 mg/Kg dose of
isepamicin. Plasma and bone tissue samples were collected a mean 1.3 hours later and analyzed by a high-pressure liquid chromatography method. Twelve patients (3 men and 9 women; mean age, 73.5 years; mean
body weight, 53.5 Kg, mean
creatinine clearance, 58.5 mL/min) were enrolled. The mean +/- SD plasma concentration of
isepamicin at the time of bone removal was 43.0 +/- 10.4 microg/mL. The mean +/- SD
isepamicin concentrations were 11.6 +/- 7.1 microg/mL in cancellous bone tissue and 12.0 +/- 7.3 microg/mL in cortical bone tissue. The mean +/- SD ratios of
isepamicin concentration in bone and plasma (bone/plasma) were 0.28 +/- 0.14 for cancellous bone tissue and 0.31 +/- 0.20 for cortical bone tissue. The concentrations achieved in both cancellous and cortical bone tissue were greater than the minimum concentrations required to inhibit the growth of 90% of strains (MIC90) of most of the susceptible pathogens commonly involved in bone
infections.