Predictability of serum concentrations of aminoglycosides after haemodialysis

The study was undertaken to look for a correlation between the measured elimination rate constants (k) of aminoglycosides and creatinine during haemodialysis. The pharmacokinetics of aminoglycosides were studied during 44 courses of haemodialysis in 21 patients. The measured k of gentamicin and tobramycin from the start until 30 min after the end of haemodialysis (mean 0.18 h-1; t1/2 = 3 h 51 min) was significantly correlated with the measured k of creatinine (mean 0.13 h-1; t1/2 = 5 h, 20 min), and also with the gentamicin and tobramycin k during haemodialysis (mean 0.20 h-1, t1/2 = 3 h, 28 min), as predicted by a computer program. Thus, serum concentrations of aminoglycosides 30 min after haemodialysis can be estimated by simple regression equations. However, because the measured and predicted values may diverge considerably in the individual patient, monitoring of aminoglycoside concentrations in serum after haemodialysis remains necessary.