Prospective Trial of a Novel Nomogram to Achieve Updated Vancomycin Trough Concentrations

Purpose. To determine if the use of a novel vancomycin nomogram predicts dosing regimens that achieve target trough concentrations equal to or more accurate than dosing regimens calculated using traditional pharmacokinetic calculations, evaluate the incidence of subtherapeutic and supratherapeutic troughs, and assess pharmacist's impressions of the nomogram. Methods. Prospective, open-label study in 473 patients who had a new order for vancomycin and were >18 years of age and ≤120？kg. Patients were randomized to the active group, dosed using the nomogram, or to the control group, dosed using traditional pharmacokinetic calculations already in place at our institution. Results. Patients dosed via nomogram were within the appropriate trough range in 44% of cases compared to 33% in the control group ( ). Vancomycin troughs less than 10？mcg/mL were significantly decreased with the use of nomogram ( ). Incidence of supratherapeutic troughs, greater than 20？mcg/mL, was not significantly different between groups ( ), and pharmacists agreed that the nomogram was easy to use and saved their time. Conclusions. A novel vancomycin nomogram was prospectively validated and found to be more effective than traditional pharmacokinetic dosing. The nomogram is being implemented as the standard dosing protocol at our institution. 1. Introduction Vancomycin is a glycopeptide antibiotic used to treat infections caused by gram-positive organisms, most commonly methicillin-resistant Staphylococcus aureus (MRSA). It is used for a variety of infections including cellulitis, pneumonia, sepsis, and endocarditis [1]. Due to potential side effects such as nephrotoxicity, ototoxicity, and the potential for bacterial resistance with low troughs, vancomycin concentrations are routinely monitored to ensure appropriate dosing. Previously, appropriate trough concentrations were considered to be between 5–15？mcg/mL [2, 3]. However, due to the emergence of vancomycin resistance, recommended trough concentrations have increased. In 2009, the American Society of Health-System Pharmacists/Infectious Diseases Society of America/Society of Infectious Diseases Pharmacists published a consensus statement, updating the guidelines for appropriate vancomycin trough concentrations [2]. These guidelines recommend that troughs should remain above 10？mcg/mL at all times to limit treatment failures and resistance. For patients being treated for severe infections such as, bacteremia, endocarditis, meningitis, MRSA pneumonia, osteomyelitis, or sepsis, trough concentrations should be maintained between 15