Pharmacokinetics of Vancomycin in Anuria

After a single 1-g intravenous dose of vancomycin, the mean peak concentration in the serum of 29 anephric patients was 48.3 ~g/ml. An initial rapid decline to 15 µg/ml within 3–5 hr was followed by slow elimination, with 3.5 µg/ml present after 18 days. Intermittent dialysis had no appreciable effect on drug levels in serum. The biphasic decline in serum concentrations of vancomycin indicates at least two-compartment pharmacokinetics in both anephric and normal patients. In anephric patients the elimination half-life was 7.5 days and the elimination rate constant was 0.32; these values were 8 hr and 10.25, respectively, in normal patients. On the basis of these results, the vancomycin regimen recommended for anephric patients is an initial 1-g intravenous dose followed by 500 mg every eight days. With these dosages peak concentrations are 48 µg/ml (well below reported toxic levels) and trough concentrations are 7 µg/ml (well above the minimal inhibitory concentrations for susceptible pathogens causing shunt infections).