Diffusion of ertapenem into bone and synovial tissues

• Published in: Journal of antimicrobial chemotherapy Vol. 60; no. 4; pp. 893 - 896
• Main Authors: Boselli, E., Breilh, D., Djabarouti, S., Bel, J. C., Saux, M. C., Allaouchiche, B.
• Format: Journal Article
• Language: English
• Published: Oxford Oxford University Press 01-10-2007; Oxford Publishing Limited (England)
• Subjects: Adult; Aged; Anti-Bacterial Agents - pharmacokinetics; Antibiotics; Antibiotics. Antiinfectious agents. Antiparasitic agents; Bacteria; Bacteria, Aerobic - drug effects; Bacteria, Anaerobic - drug effects; beta-Lactams - administration & dosage; beta-Lactams - pharmacokinetics; Biological and medical sciences; Bone and Bones - chemistry; bone infection; Bones; Chromatography, High Pressure Liquid; diffusion; Female; Humans; Infections; Joint replacement surgery; Male; Medical sciences; Microbial Sensitivity Tests; pharmacokinetics; Pharmacology. Drug treatments; Serum - chemistry; Synovial Fluid - chemistry; Time Factors; Tissues; pharmacokinetics; bone infection; diffusion; Infection; Carbapenem derivatives; Antibiotic; Synovial membrane; β-Lactams; Bone; Antibacterial agent; Diffusion; Pharmacokinetics; Ertapenem
• ISSN: 0305-7453; 1460-2091
• DOI: 10.1093/jac/dkm296

Objectives The degree of penetration of an antibiotic into the infected site is an important criterion for therapeutic success. Ertapenem is a new carbapenem, exhibiting activity against most Gram-positive and Gram-negative aerobic and anaerobic bacteria commonly recovered from community-acquired infections. However, no studies concerning its diffusion into bone and synovial tissue are available. Our objective was to quantify ertapenem bone and synovial tissue penetration and to compare our data with the MIC90s for causative pathogens. Patients and methods In an open-label study, 18 patients who were undergoing elective total hip replacement received a single, parenteral, 1 g dose of ertapenem. One serum, one cortical and cancellous bone and one synovial tissue sample was collected per patient a median [interquartile range (IQR)] of 1.6 (1.5–1.7), 12.4 (11.9–13.1) or 23.8 h (22.6–25.2) later and analysed by HPLC. Results The median (IQR) serum concentrations of ertapenem were 70.1 (56.1–75.9), 10.0 (9.1–11.2) and 2.6 mg/L (2.3–3.0), respectively, at the different time points. The median (IQR) cancellous bone tissue concentrations were 13.2 (10.2–14.8), 1.9 (1.7–2.1) and 0.6 µg/g (0.4–0.6) at the different time points, corresponding to a median (IQR) tissue/serum penetration ratio of 0.19 (0.18–0.23). The median (IQR) cortical bone tissue concentrations were 8.0 (6.5–9.5), 1.3 (1.2–1.3) and 0.3 µg/g (0.3–0.4) at the different time points, corresponding to a median (IQR) tissue/serum penetration ratio of 0.13 (0.12–0.14). The median (IQR) synovial tissue concentrations were 26.2 µg/g (22.7–28.4), 4.0 mg/L (3.7–4.4) and 1.0 mg/L (0.9–1.2) at the different time points, corresponding to a median (IQR) tissue/serum penetration ratio of 0.41 (0.39–0.42). Conclusions The concentrations after an ertapenem 1 g dose achieved in cancellous and cortical bone tissue and in synovial tissue were greater than the MIC90s for most aerobic organisms for 24 h, and for 12 to 24 h for anaerobic bacteria in healthy volunteers undergoing total hip replacement.