Influence of glomerular filtration rate on the clearance of vancomycin administered by continuous infusion in burn patients

The relationship between clearance of vancomycin administered by continuous infusion and the glomerular filtration rate (GFR) estimated by creatinine clearance (CL(Cr)) was investigated in a large cohort of burn patients. Individual vancomycin clearance (CL(Van)) was estimated from the ratio between the rate of infusion and the plasma concentration at steady state for 70 patients (149 samples). The average value of CL(Van) (7.03+/-3.79 L/h) was higher than normal values in non-burn patients. A significant relationship between CL(Van) versus CL(Cr) was found (r=0.506; P<0.001): CL(Van) (L/h)=0.0205CL(Cr)(mL/min)+3.47. From this result, a simple formula is proposed to adapt vancomycin dosage: rate of vancomycin continuous infusion (g/day)=[0.0205CL(Cr) (mL/min)+3.47] x [target vancomycin concentration at steady state (mg/L)] x (24/1000). The limits of the predictive performance of this formula are discussed, since factors other than GFR can affect vancomycin elimination. This formula could help clinicians to define the optimum vancomycin dosage, particularly in patients with disturbed renal function.