Relationship between the clinical efficacy and AUC/MIC of intravenous ciprofloxacin in Japanese patients with intraabdominal infections

The efficacy of fluoroquinolones (FQs) correlates with the pharmacokinetic/pharmacodynamic (PK–PD) parameter, AUC/MIC. To our knowledge, however, no prospective studies have reported the relationship between FQ efficacy and PK–PD parameters in intraabdominal infection; therefore, we prospectively investigated the relationship between the efficacy of intravenous ciprofloxacin (CPFX IV) and PK–PD parameters. The study included 16 patients diagnosed with peritonitis between 2006 and 2008: 14 patients infected with a single organism and 2 patients infected with more than one organism. Each patient was treated with CPFX IV (300 mg twice daily). The response rate was 56 % (9 responders and 7 non-responders). Non-responders were infected with Escherichia coli, Pseudomonas aeruginosa, and Bacteroides fragilis (6 patients were infected with a single organism and 1 with more than one organism). Plasma drug concentrations were measured 1 h and 2 or 4 h after administration of CPFX IV. AUC for 24 h (AUC_0–24)/MIC values was calculated. The range of AUC_0–24/MIC values in responders [95.3–3628.4 (geometric mean, 521.6)] was significantly different from that in non-responders [7.0–45.2 (geometric mean, 16.5)] (p = 0.001). The target AUC/MIC value of CPFX IV would be considered to be 45–95 in patients with peritonitis.