Aminoglycoside redistribution phenomenon after hemodialysis: netilmicin and tobramycin

The serum concentration time profile of netilmicin and tobramycin before, during, and after hemodialysis was assessed in 5 noninfected adult chronic hemodialysis patients. The pharmacokinetic profile was biexponential for both agents in the pre-hemodialysis period. The total body clearance of netilmicin was significantly greater than that of tobramycin (5.32 +/- 0.75 ml/min vs 3.66 +/- 1.00 ml/min; p less than 0.05). The hemodialysis clearances of netilmicin and tobramycin were similar (60.8 +/- 16.6 ml/min and 54.7 +/- 18.8 ml/min, respectively). Netilmicin and tobramycin serum concentrations increased significantly 10 minutes after cessation of hemodialysis and maximally rebounded to 38.3 +/- 16.2% and 18.3 +/- 3.0% at 1.7 +/- 0.3 hours and 1.9 +/- 0.7 hours, respectively. This phenomenon may be a primary contributor to the marked variability observed in the clinical pharmacokinetics of these agents in hemodialysis patients. These data suggest that clinical serum concentrations should not be drawn until two hours after hemodialysis.