Vancomycin dosing in morbidly obese patients

Abstract

Doses required to achieve desired vancomycin concentrations are similar in morbidly obese and normal weight patients when TBW is used as a dosing weight for the obese (approximately 30 mg x kg(-1) x d(-1)). Shorter dosage intervals may be needed when dosing morbidly obese patients so that steady-state trough concentrations remain above 5 microg x ml(-1) in this population. Because of the large amount of variation in required doses, vancomycin serum concentrations should be obtained in morbidly obese patients to ensure that adequate doses are being administered. Dosage requirements for morbidly obese patients with renal dysfunction require further study.

Challenges of Treating a 466-Kilogram Man With Acute Kidney Injury

“…Unfortunately, few anti-microbial or other drug dosing guidelines exist for moderately obese individuals, much less for those with super obesity (8). Our patient's vancomycin volume of distribution (131.1 L) was somewhat lower than the urea volume of distribution as calculated using the conventional total body water (0.6 * weight(kg)), Watson (9), or Hume-Meyer formulas (10), though it was consistent with previous findings in obese subjects (11)(12)(13). This discrepancy highlights the limitations of available formulas and suggests that drug dosing strategies may not be substantially different between the obese and super obese.…”

Vancomycin Dosing in Critically Ill Patients: Robust Methods for Improved Continuous-Infusion Regimens

“…Data supporting the strong relationship between vancomycin volume of distribution and TBW have been described in various vancomycin pharmacokinetic studies, particularly in obese patients (1). Data supporting the importance of renal function on vancomycin clearance are also prominent (25).…”

A Review of the Toxicologic Implications of Obesity

“…These drugs include vancomycin, daptomycin, carboplatin, low-molecular-weight heparins, and cimetidine; their clearance correlates with creatinine clearance [92]. Clearance of vancomycin increased from 77 mL/min in non-obese patients to 197 mL/min in obese patients; this discrepancy appeared to be directly correlated with total body weight (1.13 vs 1.19 mL/min/kg, respectively) [114]. Studies of daptomycin have found conflicting effects of obesity on drug clearance; however, this may be due to the relatively small (n=7-12) and heterogeneous study groups [115,116].…”