[Control of serum levels of tobramycin and amikacin during clinical routine treatment conditions (author's transl)].

576 serum levels at peak and before the next dosage (end level) were determined during clinical treatment conditions using radioimmunoassay in 131 patients treated with tobramycin or amikacin because of life-threatening infections. Only 42.8% of tobramycin serum peak levels were within the therapeutic range. 3.6% were potentially toxic, however, 53.6% were in a subtherapeutic range. After amikacin administration only 25% of serum peak levels were in a subtherapeutic range. 54.2% were therapeutic and 20.8% were potentially toxic. The main reason for increased peak and end serum levels was diminished renal function. Infusion treatment with more than 3 1/24 hrs lowered serum peak levels of tobramycin by 38% and of amikacin by 31%. Single doses of 80 mg of tobramycin lead to subtherapeutic concentrations too frequently, whereas single doses of 500 mg of amikacin too frequently lead to potentially toxic serum levels. Control of serum levels during aminoglycoside treatment is recommended particularly in patients at risk with life-threatening infections.