- Last Update On : 2013-02-03
Vancomycin is a bactericidal glycopeptide antibiotic with activity against most Gram positive bacteria. It is particularly effective against methicillin-resistant Staphylococcus aureus and other multi-drug resistant organisms. Vancomycin has a plasma half-life of 4 to 6 hours. Glomerular filtration eliminates 90% of an intravenous dose over 24 hours, without biochemical modification. Renal failure vastly prolongs the plasma half-life. Peak serum levels normally range from 20 to 40 ug/mL, while therapeutic trough levels range from 5 to 10 ug/mL.
Some confusion exists regarding optimum therapeutic drug monitoring of vancomycin. Adequate trough levels, but not peak levels, correlate with efficacy. Most standard dosing regimens result in trough levels that are within the therapeutic range. Ototoxicity and nephrotoxicity rarely complicate vancomycin therapy when it is administered alone. Ototoxicity does not correlate with peak or trough levels. Nephrotoxicity may be associated with trough concentrations of 10 ug/mL or higher. Thus, many hospitals, including the hospitals in the Saint Luke’s Health System, recommend monitoring only trough levels in most patients. If trough levels are in the therapeutic range, it is very unlikely that peak levels would be above 40 ug/mL.
Trough levels are recommended prior to the fourth dose and at least weekly thereafter in the following groups of patients:
- Patients receiving aminoglycosides with vancomycin
- Anephric patients receiving dialysis
- Patients receiving higher than usual doses
- Patients with changing renal function
- Patients with altered volume of distribution
- Patients with congestive heart failure
- Patients on long term therapy
- Patients not responding to therapy
Hospitals have documented a gradual increase in the prevalence of vancomycin resistant enterococci (VRE) since the mid -1990’s. Nationwide, almost 15% of enterococci isolated from patients in intensive care units are vancomycin resistant. Even more worrisome is the recent emergence of vancomycin resistance in methicillin resistant Staphylococcus aureus. These trends have led to recommendations to restrict vancomycin use unless it is absolutely necessary.
Trough levels should be drawn immediately preceding the next dose. Specimen requirement is one plain red top tube of blood.