QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Résumé Extracto Full Text PDF Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Articles Ahead of Print [Order Reprint] Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Pai, M. P Articles by Allen, S. E Search for Related Content PubMed PubMed Citation Articles by Pai, M. P Articles by Allen, S. E

Using Vancomycin Concentrations for Dosing Daptomycin in a Morbidly Obese Patient with Renal Insufficiency

Assistant Professor, College of Pharmacy, University of New Mexico, Albuquerque, NM

Renee-Claude Mercier, PharmD

Associate Professor, College of Pharmacy, University of New Mexico

Sarah E Allen, MD

Clinical Associate Professor, School of Medicine, University of New Mexico

Reprints: Dr. Pai, College of Pharmacy, University of New Mexico, MSC09 5360, Albuquerque, NM 87131-0001, fax 505/272-6749, apai{at}salud.unm.edu

OBJECTIVE: To report a case in which vancomycin clearance was used to determine the daptomycin dosing interval in a morbidly obese patient with renal impairment.

CASE SUMMARY: A 46-year-old man (209 kg; 178 cm) failed a 42 day course of vancomycin therapy for treatment of a methicillin-resistant Staphylococcus aureus-infected wound and cellulitis. The median trough vancomycin concentration was 12.6 µg/mL (range 7.3-24.1) through his course of therapy. Estimation of creatinine clearance (Cl_cr) was confounded in this clinical scenario, given the patient's weight and a lack of valid equations in this patient population. Daptomycin was administered empirically at 6 mg/kg dosed every 48 hours based on estimated clearance from measured vancomycin concentrations. Steady-state plasma concentrations of daptomycin were determined, and the daptomycin half-life in this patient was more accurately estimated using vancomycin clearance as a surrogate. In addition, a 4 mg/kg dose of daptomycin would have been sufficient based on plasma concentrations. The patient demonstrated rapid clinical improvement and remained free of cellulitis for 6 months after completion of daptomycin and a 12 week course of trimethoprim/sulfamethoxazole.

DISCUSSION: The dosing interval of daptomycin is adjusted based on Cl_cr. However, estimation of Cl_cr is difficult in morbidly obese patients with renal impairment, given a lack of valid equations. In this clinical scenario, vancomycin concentrations were used to estimate Cl_cr and served as a surrogate measure to determine the daptomycin dosing interval. Measured daptomycin concentrations validated this approach and confirmed the inadequacy of commonly used Cl_cr equations.

CONCLUSIONS: In this clinical scenario, vancomycin concentrations more accurately estimated Cl_cr, thereby facilitating determination of the daptomycin dosing interval.

Key Words: daptomycin, morbid obesity, renal impairment, vancomycin

Published Online, February 28, 2006. www.theannals.com, DOI 10.1345/aph.1G509

This article has been cited by other articles:

				R. E. Warren Daptomycin in endocarditis and bacteraemia: a British perspective J. Antimicrob. Chemother., November 1, 2008; 62(suppl_3): iii25 - iii33. [Abstract] [Full Text] [PDF]

				M. P. Pai, J. P. Norenberg, T. Anderson, D. W. Goade, K. A. Rodvold, R. A. Telepak, and R.-C. Mercier Influence of Morbid Obesity on the Single-Dose Pharmacokinetics of Daptomycin Antimicrob. Agents Chemother., August 1, 2007; 51(8): 2741 - 2747. [Abstract] [Full Text] [PDF]