Title: Vancomycin Loading in Obese Patients<br/>Author: Bryan Hayes<br/><a href='http://umem.org/profiles/faculty/369/'>[Click to email author]</a><hr/><p>
Vancomycin guidelines recommend an initial dose of 15-20 mg/kg based on actual body weight (25-30 mg/kg in critically ill patients). [1] The MRSA guidelines further recommend a max dose of 2 gm. [2]</p>
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<strong>But, what dose do you give for an obese patient that would require more than 2 gm? </strong></p>
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A new study provides some answers to this question. [3] Obese-specific, divided-load dosing achieved trough concentrations of 10 to 20 µg/mL for <u>89%</u> of obese patients within 12 hours of initial dosing and <u>97%</u> of obese patients within 24 hours of initial dosing.</p>
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<b>Application to Clinical Practice</b></p>
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Calculate the total loading dose. At my institution we use actual body weight (the study used IBW).</li>
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Divide the total dose to be given every 6 hours until load is complete. We cap each individual dose at 2 gm (the study used 1.5 gm).</li>
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Measure a trough level before the third dose.</li>
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Change to dosing frequency dictated by renal function once level moves into target range.</li>
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<strong>Caveats</strong></p>
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The study used some more specific dosing calculations based on renal function and percentage above IBW. If patient's renal function is abnormal, consultation with a pharmacist is recommended.</p>
<fieldset><legend>References</legend>
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<li>
Ryback M, et al. Therapeutic monitoring of vancomycin in adult patients: a consensus review of the American Society of Health-System Pharmacists, the Infectious Diseases Society of America, and the Society of Infectious Diseases Pharmacists. Am J Health Syst Pharm 2009;66(1):82-98. [<a href="http://www.ncbi.nlm.nih.gov/pubmed/19106348">PMID 19106348</a>]</li>
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Liu C, et al. Clinical practice guidelines by the Infectious Diseases Society of America for the treatment of methicillin-resistant Staphylococcus aureus infections in adults and children: executive summary. Clin Infect Dis 2011;52(3):285-92. [<a href="http://www.ncbi.nlm.nih.gov/pubmed/21217178">PMID 21217178</a>]</li>
<li>
Denetclaw TH, et al. Performance of a divided-load vancomycin dosing strategy for obese patients. Ann Pharmacother. 2015 May 18. [Epub ahead of print, <a href="http://www.ncbi.nlm.nih.gov/pubmed/25986008">PMID 2598600</a>]</li>
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<p>
<strong>Follow me on Twitter (<a href="https://twitter.com/PharmERToxGuy">@PharmERToxGuy</a>) or Google Plus (+bryanhayes13)</strong></p>
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