title: Association of the clinical efficacy of vancomycin with the novel pharmacokinetic parameter area under the trough level (AUTL) in elderly patients with hospital-acquired pneumonia.
abstract: OBJECTIVE
  The pharmacokinetic-pharmacodynamic parameter that best predicts the efficacy of vancomycin is the ratio of the area under the concentration versus time curve (AUC) to the minimum inhibitory concentration (MIC). A 24-h AUC (AUC24 )/MIC ratio ≥ 400 was recommended in an American consensus review, but vancomycin treatment occasionally fails despite maintenance of AUC24 /MIC ≥ 400. We evaluated the association between clinical efficacy of vancomycin and two novel pharmacokinetic parameters, the 'area under the trough level' (AUTL) and the 'area above the trough level' (AATL), in hospitalized elderly patients with methicillin-resistant Staphylococcus aureus (MRSA) pneumonia.
  
  
  METHODS
  The subjects were hospitalized elderly patients who were administered vancomycin for treatment of MRSA pneumonia between 2006 and 2012 at Sasebo Chuo Hospital (Nagasaki, Japan). Pharmacokinetic parameters of vancomycin were estimated for each patient by Bayesian analysis using population pharmacokinetic parameters for Japanese patients. Based on the patient-specific parameters thus obtained, AUC24 values were calculated as the vancomycin dosage divided by vancomycin clearance. AUTL was calculated as the trough serum concentration multiplied by 24 h, whereas AATL was calculated by subtracting AUTL from AUC24 .
  
  
  CONCLUSIONS
  Logistic regression analysis demonstrated that efficacy of vancomycin was more strongly associated with AUTL than AUC24 . The optimal cut-off value of AUTL was 331 μg∙h/mL, which means that the optimal cut-off value of the trough serum concentration was 13·8 μg/mL.
  
  
  CONCLUSIONS
  Efficacy of vancomycin was associated with AUTL, a novel pharmacokinetic parameter. Determining the target AUTL or trough concentration may enhance the efficacy of vancomycin therapy in elderly patients with MRSA pneumonia. Given that nephrotoxicity may increase with a Ctrough in excess of 15 μg/mL, this level should ideally not be exceeded.
authors.affiliation: Department of Community Pharmacy, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Fukumori
authors.affiliation: Department of Medical Pharmaceutics, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Tsuji
authors.affiliation: Department of Pharmacy, Sasebo Chuo Hospital, Sasebo, Japan.
authors.forename: A
authors.initials: A
authors.lastname: Mizoguchi
authors.affiliation: Department of Medical Pharmaceutics, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan.|Certara G.K., Minato-ku, Tokyo, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Kasai
authors.affiliation: Department of Medical Pharmaceutics, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan.|Shionogi Research Laboratories, Osaka, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Ishibashi
authors.affiliation: Department of Pharmacy, Sasebo Chuo Hospital, Sasebo, Japan.
authors.forename: N
authors.initials: N
authors.lastname: Iwamura
authors.affiliation: Department of Medical Pharmaceutics, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama, Japan.
authors.forename: H
authors.initials: H
authors.lastname: To
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000627:therapeutic use*; D019540:Area Under Curve; D001499:Bayes Theorem; D003428:Cross Infection / Q000188:drug therapy* / Q000382:microbiology; D005260:Female; D006760:Hospitalization; D006801:Humans; D007564:Japan; D016015:Logistic Models; D008297:Male; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects / Q000302:isolation & purification; D008826:Microbial Sensitivity Tests; D018410:Pneumonia, Bacterial / Q000188:drug therapy* / Q000382:microbiology; D013203:Staphylococcal Infections / Q000188:drug therapy / Q000382:microbiology; D016896:Treatment Outcome; D014640:Vancomycin / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000627:therapeutic use*
chemical_list: D000900:Anti-Bacterial Agents; D014640:Vancomycin
keywords: MRSA; pharmacokinetic parameter; therapeutic drug monitoring; vancomycin