ANTIMICROBIAL DOSING IN OBESE PATIENTS

Although the dose of some drugs is commonly adjusted for weight, weigh t-related dosage adjustments are rarely made for most antimicrobials. We reviewed the English-language literature on antimicrobial pharmacok inetics and dosing in obesity. Although there are many potential pharm acokinetic consequences of obesity, the actual effect on the pharmacok inetics and clinical efficacy of most antimicrobials is unknown. Since similar to 30% of adipose is water, an empirical approach is use of t he Devine formula to calculate ideal body weight (IBW), to which is ad ded a dosing weight correction factor (DWCF) of 0.3 times the differen ce between actual body weight (ABW) and IBW (IBW + 0.3 x [ABW-IBW]) to arrive at a weight on which to base dosage of hydrophilic antibiotics . No studies confirm this approach for beta-lactam drugs. Clinical stu dies suggest a DWCF of similar to 0.40 for aminoglycosides and 0.45 fo r quinolones. Final dosage adjustments for antimicrobials with a narro w toxic-therapeutic window should be based on serum concentrations.