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Antimicrobial dosing adjusted for weight led to cost savings
WASHINGTON, D.C. — Researchers from the University of Michigan Hospitals have developed a guideline for weight-based antimicrobial dosing in obese patients that resulted in significant cost savings, according to a presentation here.
“The Food and Drug Administration does not recognize obesity as a special population and does not require pharmaceutical companies to perform studies specific to obese patients,” the researchers wrote in an abstract. “However, an increasing number of post-approval studies in obese patients are being published, which demonstrates utilizing actual body weight when calculating weight-based antimicrobial dosing is associated with increased serum concentrations or toxicity in morbidly obese patients compared to normal weight patients, primarily as a result of decreased drug penetration into adipose tissue compared to other tissues.”
Based on an evaluation of current literature, Jerod Nagel, PharmD, a clinical specialist in infectious diseases at the University of Michigan Hospitals and Health System, along with Anna Kempke, PharmD, a PGY1 pharmacy resident, and colleagues implemented a dosing guideline for obese patients, which recommends using ideal body weight, adjusted body weight or actual body weight when calculating an antibiotic dosing regimen for a total of seven agents. These include IV acyclovir, colistin, daptomycin (Cubicin, Cubist), foscarnet, IV ganciclovir, IV trimethoprim-sulfamethoxazole and voriconazole.
Jerod Nagel
A cost analysis of complying with the guideline recommendations included the average wholesale price of antimicrobials.
In 1 year, 1,121 doses were administered to obese patients. Compliance with the guideline recommendations occurred in 68% of all doses administered, which led to a cost savings of $97,886. Adjusted doses of daptomycin and voriconazole based on weight constituted the bulk of the savings; with full guideline compliance, dose adjustments with these antimicrobials could potential save an additional $29,733, according to the researchers.
“This project focused on guideline compliance and cost savings, and lacked the sample size to evaluate efficacy and toxicity,” Nagel told Infectious Disease News. “The level of evidence for antimicrobial dosing varies greatly for the drugs included in our guideline, and appropriate dosing in morbidly obese patients should weigh the risks and benefits on a case-by-case basis. The goal of this guideline was not to achieve 100% compliance, as there will be extenuating cases that require alternative dosing, but increase prescriber awareness about the differences in antimicrobial pharmacodynamics in obese patients and provide general dosing recommendations.” — John Schoen
Jerod Nagel, PharmD can be reached at nageljl@med.umich.edu.
For more information:
Nagel JL. Abstract K-331. Presented at: Interscience Conference on Antimicrobial Agents and Chemotherapy; Sept. 5-9, 2014; Washington, D.C.
Disclosure: The researchers report no relevant financial disclosures.