Vancomycin, a glycopeptide antibiotic, is often used for the treatment of suspected/confirmed infections due to gram-positive bacteria, including methicillin-resistant Staphylococcus aureus (S aureus).1,2 Vancomycin exhibits a time-dependent bactericidal activity and the area under the serum drug concentration time curve (AUC) to minimum inhibitory concentration (MIC) ratio (AUC/MIC) has been identified as the best parameter for measuring vancomycin efficacy.3
Despite the fact that current guidelines recommend intermittent dosing of vancomycin, some experts suggest continuous infusion particularly in the critically ill (with high drug distribution and increased drug clearance).4-6
In a recently published study, the authors sought to evaluate continuous vancomycin infusion in 164 medical intensive care unit patients by comparing them to 75 patients treated with intermittent vancomycin infusion in a retrospective fashion.7
Patients in the continuous infusion arm received a median daily vancomycin dose of 960 (526-1723) mg, resulting in a median serum vancomycin concentration of 19.8 (9.8-29.4) mg/L. However, serum vancomycin levels were frequently in a subtherapeutic range on treatment days 1 (44%), 2 (29%), and 3 (23%). Renal replacement therapy had to be started significantly more often during vancomycin intermittent therapy when compared to patients in the continuous infusion group (23% vs. 7%; p =0 .007).
This study has a number of limitations. The retrospective design limits the accuracy of data collection as well as the fact that we cannot establish causality. In addition, the study was conducted in the medical intensive care unit which limits generalization of the results to other patient population in other intensive care units (i.e. surgical or neurological). Moreover, vancomycin dosing in the continuous infusion group was less than what was used in other reports.
The authors suggest that higher loading doses might be necessary to overcome the subtherapeutic drug levels that might occur on the first days of continuous infusion therapy. Prospective, randomized, controlled trials to investigate efficacy, safety, and dosing patterns of continuous vancomycin administration in critically ill patients are necessary.
1. Chua K, Howden BP. Treating Gram-positive infections: vancomycin update and the whys, wherefores and evidence base for continuous infusion of anti-Gram-positive antibiotics. Curr Opin Infect Dis 2009;22:525-34.
2. Moellering Jr RC. Vancomycin: a 50-year reassessment. Clin Infect Dis 2006;42(Suppl 1):S3-4.
3. Rybak M, Lomaestro B, Rotschafer JC, et al. 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. Am J Health Syst Pharm 2009;66:82-98.
4. Rybak MJ, Lomaestro BM, Rotschafer JC, et al. Vancomycin therapeutic guidelines: a summary of consensus recommendations from the infectious diseases Society of America, the American Society of Health-System Pharmacists, and the Society of Infectious Diseases Pharmacists. Clin Infect Dis 2009;49:325-7.
5. Roberts JA, Lipman J, Blot S, et al. Better outcomes through continuous ...