Why & How to Monitor Vancomycin Troughs?

Vancomycin is a glycopeptide antibiotic, typically used for treatment of MRSA. Traditionally it is recommended to get trough doses to assess efficiency.

Typically, we aim for Vancomycin trough levels between 10-20µg/mL (15-20 µg/mL for more severe infections).

WHY NOT MEASURE PEAKS?  Vancomycin displays time-dependent bactericidal activity when above the minimum inhibitory concentration (MIC), not dose-dependent. Hence, there is little evidence to support the measurement of target peak concentrations. It is actually the trough levels that are better correlated with therapeutic efficacy and potential side affects such as nephrotoxicity.

WHEN TO MEASURE? Typically measured in patients with invasive disease (i.e bacteremia) or at increased risk of nephrotoxicity (i.e CKD or concurrent aminoglycoside use).

HOW TO MEASURE? Trough concentrations should be measured within 30 minutes prior to infusion of the fourth dose or fifth dose. Why? This is when the drug (in fact all drugs) will reach steady state. NOTE: Can be measured before 3rd dose in patients which renal impairment and risk of toxicity may be greater.

*Patient on oral Vancomycin do not require trough measurements!

REFERENCES

1. Clinical practice guidelines by the infectious diseases society of America for the treatment of methicillin-resistant Staphylococcus aureus infections in adults and children.AULiu C, Bayer A, Cosgrove SE, Daum RS, Fridkin SK, Gorwitz RJ, Kaplan SL, Karchmer AW, Levine DP, Murray BE, J Rybak M, Talan DA, Chambers HF, Infectious Diseases Society of America. Clin Infect Dis. 2011;52(3):e18.
2. Jennifer H Martin, Ross Norris, Michael Barras, Jason Roberts, Ray Morris, Matthew Doogue, and Graham RD Jones. Therapeutic Monitoring of Vancomycin in Adult Patients: A Consensus Review of the American Society of Health-System Pharmacists, the Infectious Diseases Society of America, and the Society of Infectious Diseases Pharmacists. Clin Biochem Rev. 2010 Feb; 31(1): 21–24.