[Investigation on the use of amikacin in the newborn].

The use of amikacin (AMK) in newborns was investigated and the results obtained are summarized as follows. 1. AMK was administered to 3 rabbits at an intramuscular dose of 6 mg/kg. Mean blood levels determined according to methods of bioassay (BIO) and fluorescent immunoassay (FIA) were 28.6 and 22.2 micrograms/ml, respectively, at 30 minutes after dosing. Then, the blood levels declined rapidly. Mean T 1/2 values obtained with the above 2 assay methods were 0.76 and 0.63 hours, respectively. 2. When AMK was administered at a dose of 5.7 mg/kg to a 64 day-old newborn by drip intravenous infusion for 30 minutes, a peak blood level was attained at the end of drip intravenous infusion, which was 20.0 micrograms/ml according to BIO and was 15.5 micrograms/ml according to FIA. The blood levels declined gradually thereafter with a T 1/2 value of 2.33 hours (BIO) or 2.03 hours (FIA). When the drug was administered at 5.3 mg/kg to a 26 day-old newborn using the same infusion method, the peak blood level obtained at the end of drip intravenous infusion was 18.0 micrograms/ml according to BIO and was 14.8 micrograms/ml according to FIA, and T 1/2 values were 4.76 and 3.68 hours, respectively. 3. As there was a close correlation between the values obtained with BIO and with FIA in both rabbits and clinical cases, with a coefficient of 0.990, and also the BIO values could be estimated using a formula of FIA value X 1.2 + 2.2, it would be possible to monitor AMK levels in the blood of patients at bedside using the FIA.(ABSTRACT TRUNCATED AT 250 WORDS)