Dosing of antibacterial agents in obese adults: does one size fit all?

Obesity is a global pandemic affecting 33% of adults in the United States. Obese persons receiving cefazolin or fluconazole have been shown to have worse outcomes with suboptimal dosing. Studies evaluating the safety of colistin, daptomycin, and vancomycin have shown increased weight or obesity may potentially increase toxicity. Many antimicrobials lack pharmacokinetic data to support dose individuation in obese persons, due in part to the lack of obese patients in drug development studies. A one size fits all approach to dose optimization for obese patients is not likely. Current expert opinion suggests some antimicrobials (i.e. vancomycin) be dosed according to total body weight, whereas others (i.e. aminoglycosides) require adjusted body weight for dose calculations. Yet other antimicrobials are reported to need no dose adjustment, largely based on studies using body mass index groups. Therefore, each drug should be individually evaluated to determine the proper dose for obese persons.