Using clinical data to determine vancomycin dosing parameters.

The serum concentrations and pharmacokinetic parameters produced from standard doses of vancomycin were evaluated in 22 patients. The mean (+/- SD) half-life, clearance (Cl), and volume of distribution, respectively, were 6.2 (+/- 1.9) h, 79.2 (+/- 34.3) ml/min, and 0.54 (+/- 0.23) L/kg. Geometric regression analysis was used to determine significant correlations between Cl and creatinine clearance (CrCl) (p less than 0.001). The dosing method developed is based on the pharmacokinetic parameters of vancomycin derived from our patient data and the relationship between Cl and CrCl described by the following equation, Cl = (0.674) (CrCl) + 13.45 (r = 0.703). Predictive performance measures were used to compare our dosing method with that of the Matzke nomogram. Our method was found to be less biased and more precise in regards to predicted half-life and volume of distribution, while less biased with no difference in precision in regard to predicting clearance. We plan to use this dosing method at our institution to provide a more individualized initial dosing regimen for vancomycin. Other institutions may wish to use a similar approach to design a dosing nomogram specific for their patient population.