Comprehensive Guidance for Antibiotic Dosing in Obese Adults

Pharmacotherapy. 2017 Nov;37(11):1415-1431. doi: 10.1002/phar.2023. Epub 2017 Oct 30.


Physiologic alterations seen in obesity commonly impact the pharmacokinetics (PK) and pharmacodynamics (PD) of antibiotics and may result in suboptimal dosing in this expanding but understudied population. Much of the published clinical and PK evidence to date consists of small patient populations and are retrospective with, not infrequently, heterogeneous results that in some cases are contradictory. In the last 10 years, additional antimicrobial PK/PD and clinical data encompassing prolonged infusion strategies and examination of critically ill populations have emerged to inform antimicrobial dosing in obesity. In this narrative review, we critically review literature on dosing, PK, and possible dosing strategies in obese adults. We searched PubMed, Scopus, and the Cochrane Library using Medical Subject Headings including anti-infectives, specific antimicrobial names, obese, pharmacokinetics, and others. We reviewed articles, cross-referenced select cited references, and when applicable, referenced drug databases and package inserts to develop dosing recommendations. We provide an overall critical review of the available data regarding PK and dosing issues including dosing recommendations in both critically ill and noncritically ill patients with significant obesity. We developed dosing recommendations for 34 antimicrobials based on 121 articles of the 2336 identified by the search strategy. Although 11 of these do not appear to require dose adjustment, obesity-specific dosing guidance is provided for the remaining 23 antimicrobials. Additional studies are needed to better understand and resolve discrepant published results regarding the PK of antibiotics to establish optimal dosing strategies in obese adults. Alternative dosing strategies, such as extended infusions, should be considered for time-dependent antibiotics (e.g., β-lactams) in obese patients to achieve PD targets reliably. Therapeutic drug monitoring across the spectrum of antimicrobials is of increasing importance in this and other populations to ensure optimized dosing.

Keywords: antibiotic; antimicrobial; critically ill; dosing; obesity; pharmacokinetics.

Publication types

  • Review

MeSH terms

  • Adult
  • Anti-Bacterial Agents / administration & dosage*
  • Anti-Bacterial Agents / pharmacokinetics
  • Anti-Bacterial Agents / pharmacology
  • Critical Illness
  • Dose-Response Relationship, Drug
  • Drug Monitoring / methods*
  • Humans
  • Obesity / complications*
  • Time Factors


  • Anti-Bacterial Agents