Altered vancomycin pharmacokinetics in obese and morbidly obese patients: what we have learned over the past 30 years.

Vancomycin was the first glycopeptide antibiotic introduced into clinical practice. Despite the numerous benefits of vancomycin, clinicians have struggled to dose vancomycin successfully in obese patients to achieve a therapeutic concentration for optimal bacterial killing. Owing to the hydrophilicity of vancomycin and the increase in both adipose tissue and muscle mass associated with obesity, the volume of distribution of vancomycin in obese patients is likely to be altered compared with non-obese patients. In addition to an increase in body mass, obesity is associated with an increase in certain circulating proteins, which results in altered free serum vancomycin concentration. Another alteration that occurs in obesity is increased blood flow secondary to increased cardiac output and blood volume, resulting in increased vancomycin clearance in obese patients. Vancomycin pharmacokinetics in the obese population remain an area of much debate, one that requires continued research given the rising number of obese patients in both the USA and worldwide.