[Netilmicin and tobramycin: comparative evaluation of pharmacokinetics, nephrotoxicity, and therapeutic efficacy in animal studies (author's transl)].

Pharmacokinetics, nephrotoxicity, and therapeutic efficacy of (2S-cis)-4-O-[3-amino-6-(aminomethyl)-3,4-dihydro-2H-pyran-2-yl]-2-deoxy-6-O-[3-deoxy-4-C-methyl-3-(methyl-amino)-beta-L-arabinopyranosyl]-N1-ethyl-D-streptamine sulfate (netilmicin) and tobramycin were investigated in rats. The excretion rates of tubular cells and of the urinary enzyme malic dehydrogenase served as parameter of nephrotoxicity. Both compounds were, similar to other aminoglycosides, tubulotoxic within the range of dosages used for human therapy. Netilmicin, however, produced less renal damage than did tobramycin in all dosages applied. Pharmacokinetic studies revealed lower renal concentrations of netilmicin after repetitive administration. Experimental chemotherapy of the chronic E. coli pyelonephritis in rats with both aminoglycosides resulted in a significant reduction of the renal bacterial counts. In spite of approximately identical serum concentration curves and in vitro activity, especially the low dosage of netilmicin led to more favourable therapeutic results than equal doses of tobramycin. These animal experiments suggest higher renal tolerance and efficacy of netilmicin.