This Article Full Text Full Text (PDF) Other Versions of this Article: AAC.01061-07v1 52/2/539    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Andes, D. Articles by Hou, J. Search for Related Content PubMed PubMed Citation Articles by Andes, D. Articles by Hou, J.

 Previous Article  |  Next Article 

Antimicrobial Agents and Chemotherapy, February 2008, p. 539-550, Vol. 52, No. 2
0066-4804/08/$08.00+0     doi:10.1128/AAC.01061-07
Copyright © 2008, American Society for Microbiology. All Rights Reserved.

In Vivo Pharmacodynamic Characterization of Anidulafungin in a Neutropenic Murine Candidiasis Model

Department of Medicine,¹ Department of Medical Microbiology and Immunology, University of Wisconsin, Madison, Wisconsin,² Department of Pathology, University of Iowa, Iowa City, Iowa,³ School of Pharmacy, University of Texas, Houston, Houston, Texas⁴

Received 11 August 2007/ Returned for modification 15 October 2007/ Accepted 11 November 2007

Multiple in vivo studies have characterized the pharmacodynamics of drugs from the triazole and polyene antifungal drug classes. Fewer studies have investigated these pharmacodynamic relationships for the echinocandin drug class. We used a neutropenic murine model of disseminated Candida albicans, Candida tropicalis, and Candida glabrata infection to characterize the time course of activity of the new echinocandin anidulafungin. The pharmacokinetic-pharmacodynamic (PK-PD) indices (the percentage of time that the drug concentration was above the MIC, the ratio of the area under the concentration-time curve from 0 to 24 h [AUC_0-24] to the MIC, and the ratio of the maximum serum drug concentration [C_max] to the MIC) were correlated with in vivo efficacy, as measured by organism numbers in kidney cultures after 96 h of therapy. The kinetics following intraperitoneal anidulafungin dosing in neutropenic infected mice were monitored. Peak levels and AUCs were linear over the 16-fold dose range studied. The drug elimination half-life in serum ranged from 14 to 24 h. Single-dose postantifungal-effect studies demonstrated prolonged suppression of organism regrowth after serum anidulafungin levels had fallen below the MIC. Of the four dosing intervals studied, treatment with the more widely spaced dosing regimens was most efficacious, suggesting the C_max/MIC ratio as the PK-PD index most predictive of efficacy. Nonlinear regression analysis suggested that both the C_max/MIC and AUC/MIC ratios were strongly predictive of treatment success. Studies were then conducted with 13 additional C. albicans, C. tropicalis, and C. glabrata isolates with various anidulafungin susceptibilities (MICs of anidulafungin for these strains, 0.015 to 2.0 µg/ml) to determine if similar C_max/MIC and AUC_0-24/MIC ratios for these isolates were associated with efficacy. The anidulafungin exposures associated with efficacy were similar among Candida species.

Published ahead of print on 10 December 2007.

This article has been cited by other articles:

• Pfaller, M. A., Diekema, D. J., Ostrosky-Zeichner, L., Rex, J. H., Alexander, B. D., Andes, D., Brown, S. D., Chaturvedi, V., Ghannoum, M. A., Knapp, C. C., Sheehan, D. J., Walsh, T. J. (2008). Correlation of MIC with Outcome for Candida Species Tested against Caspofungin, Anidulafungin, and Micafungin: Analysis and Proposal for Interpretive MIC Breakpoints. J. Clin. Microbiol. 46: 2620-2629 [Abstract] [Full Text]  
• Brzankalski, G. E., Najvar, L. K., Wiederhold, N. P., Bocanegra, R., Fothergill, A. W., Rinaldi, M. G., Pattterson, T. F., Graybill, J. R. (2008). Evaluation of aminocandin and caspofungin against Candida glabrata including isolates with reduced caspofungin susceptibility. J Antimicrob Chemother 0: dkn304v1-7 [Abstract] [Full Text]