Nephrotoxicity of vancomycin in patients with normal serum creatinine

Sir, The reported rate of nephrotoxicity of vancomycin (VCM) has been 7–16%. It can reach 35% with concurrent aminoglycosides and is associated with serum concentration >40 μg/ml [ 1 ]. However, in patients with normal serum creatinine (SCr), monitoring of VCM–serum concentrations is disputable [ 2 ]. We retrospectively studied 19 patients (age 51 ± 19 years, 12 women) who had a 50% increase of their normal baseline SCr (ARF) during VCM therapy. Trough serum concentration of VCM was monitored once the ARF diagnosis was made and it was >40 μg/ml in all patients (VCMmax). Initial VCM dosing regime was unchanged up to ARF, when VCM administration was stopped. Spearman's correlations between VCMmax and age, duration of therapy (▵T), peak SCr, albumin and bilirubin were calculated. Results (mean ± SD): VCMmax, 83 ± 12 μg/ml (range 50–289); ▵T, 12 ± 9 days; baseline SCr, 1.0 ± 0.3 mg/dl; peak SCr, 3.6 ± 2.1 mg/dl; albumin, 2.1 ± 0.6 g/dl; bilirubin, 3.8 ± 7.2 mg/dl. Oliguria was present in nine patients (47%) and seven (37%) needed dialysis. Twelve patients worsened and were admitted to ICU. Concurrent with VCM, eight patients (42%) received another nephrotoxic drug (amphotericin in five). All the patients had other cause for ARF besides VCM [severe sepsis in 16 (84%)]. Survivors were six (47%), and in two of them SCr did not return to baseline. There was no correlation between VCMmax and any of the evaluated parameters. In conclusion, in order to avoid nephrotoxic levels, even in patients with normal SCr, VCM–serum concentration monitoring should be started and its dose appropriately adjusted as soon as any potential factor for ARF superimposes. Conflict of interest statement . None declared.