Netilmicin and gentamicin multidose kinetics in normal subjects

Multidose netilmicin and gentamicin kinetics were studied in 20 healthy subjects who received 1.7 mg/kg gentamicin (n = 10) or netilmicin (n = 10) as a 20-min infusion every 8 hr for 10 days (28 doses) during a randomized, double-blind comparative trial designed to study adverse effects and kinetics of netilmicin and gentamicin. Multidose kinetics were of the same order for gentamicin and netilmicin with the exception of the terminal plasma t 1 2 (94 and 156 hr) and the volume of distribution at steady state (450 and 1072 ml/kg). Mean peak plasma concentrations of netilmicin were slightly lower than gentamicin. Percentage of the dose eliminated in urine did not differ for the two aminoglycosides. Aminoglycoside was detectable in plasma and continued to be eliminated in urine for at least 6 days after the final dose. The plasma concentration-time profiles for both netilmicin and gentamicin were well fitted with the sum of three exponential terms; urinary excretion rates-time plots showed biexponential decay. None of the subjects had any auditory, vestibular, or renal toxicity. Although the data confirm a deep tissue compartment, they suggest that the kinetic processes involved may be more complex than previously supposed.