Implementation of a dose calculator for vancomycin to achieve target trough levels of 15-20 microg/mL in persons undergoing hemodialysis.

ABSTRACT

UNLABELLED (See the article by Brown et al, on pages 164-166.) BACKGROUND: Vancomycin is a key antibiotic for the treatment of Gram-positive bacterial infections in patients undergoing dialysis. Vancomycin has a narrow therapeutic range. Overdosing imposes a risk of nephro- and ototoxicity, wherease underdosing predisposes to treatment failure and the emergence of drug resistance. Trough levels of 15-20 µg/mL have been identified as the optimal target trough levels. METHODS: A multivariate model called the vancomycin dose calculator (VDC) was prospectively developed and validated to permit accurate vancomycin dosing in persons undergoing hemodialysis. RESULTS: The model identified 3 simple parameters that were responsible for 94.6% of the variance observed predialysis vancomycin trough level, dry body weight, and period to the next dialysis session. Maintenance dosing was accurate in 77.9% of patients, whereas major over- and underdosing were avoided in the remaining patients. The mean measured trough level of 16.5 µg/mL was 5.6% lower than the mean predicted trough level of 17.5 µg/mL. With regard to loading doses, a fixed loading dose of 20 mg/kg led to subtherapeutic trough levels in one-half of patients. CONCLUSIONS: The VDC permits accurate vancomycin maintenance dosing based on predialysis trough level, dry body weight, and period to the next dialysis session in the majority of patients undergoing hemodialysis. Higher loading doses that accounted for the period to the next dialysis may be more appropriate than fixed loading doses used in this study.