Vancomycin Administration by Continuous Infusion
I am a house pharmacist in Malaysia currently doing a clinical pharmacy rotation in the ICU. I have a few patients started on vancomycin continuous infusion instead of the conventional intermittent infusion. Theoretically, the pharmacokinetic/pharmacodynamic profile of vancomycin would seem to support this regimen. Are there any available guidelines on this? What serum drug concentration do I aim for?

Olivia Wong, BPharm

Intermittent administration continues to be the most common mode of vancomycin administration. Administration by continuous infusion has been evaluated recently as an alternative method of vancomycin administration. The rationale behind continuous-infusion administration of vancomycin is rooted in the concept that vancomycin exhibits concentration-independent bactericidal activity, which implies that maintaining trough serum concentrations above the minimum inhibitory concentration (MIC) or minimum bactericidal concentration (MBC) of a pathogen may be the most important determinant of outcome. Continuous infusion would avoid the seemingly superfluous high peak concentrations, as a peak-efficacy relationship has not been established for vancomycin, while allowing for the maintenance of a steady serum concentration at a desired concentration above the MIC or MBC.

Established guidelines for the desired steady-state serum concentration of vancomycin maintained during continuous infusion do not exist. The published literature commonly has employed a dose of 30 mg/kg or 2 g of vancomycin administered continuously over 24 hours, yielding a steady-state concentration between 15 and 25 mcg/mL. This range is many-fold higher than the typical MICs for susceptible organisms (MICs 4 mcg/mL or less). Thus, for highly susceptible bacteria, some have postulated that a lower target steady-state concentration (approx. 10 mcg/mL) would be sufficient for optimal bacterial eradication over the 24-hour period, as demonstrated in a normal volunteer study assessing bactericidal activity of 2 dosage regimens of vancomycin given by continuous infusion. Until a clinical trial verifies that a lower target range will result in optimal clinical outcomes, the desired target range of vancomycin given by continuous infusion should remain at 15-25 mcg/mL.