[Pharmacokinetic studies of astromicin using a constant-rate continuous intravenous infusion method].

Astromicin (ASTM) was administered intravenously to 4 healthy adult volunteers with an average body weight of 62 kg using a continuous infusion apparatus at a constant rate of 200 mg in 1 hour (Group I), 400 mg in 1 hour (Group II) and 200 mg in 2 hours (Group III). Concentrations of the drug in serum and urine were determined by high power liquid chromatography (HPLC). The mean serum concentration of the 4 subjects reached the peak of 13.32 micrograms/ml in Group I, 22.12 micrograms/ml in Group II and 9.89 micrograms/ml in Group III. The peak concentration was achieved at the end of infusion and was dose-related. After 8 hours, the concentration dropped to less than 1 micrograms/ml in all groups. The urinary recovery rate was 90% in 8 hours and 95% in 24 hours. T1/2 (beta) analyzed by the two-compartment open model was 1.64-1.72 hours. AUC infinity was also dose-related, such as 33.1 micrograms X hr/ml and 31.6 micrograms X hr/ml in Group I and Group III, and 57.6 micrograms X hr/ml in Group II. It is recommended for amikacin (AMK) that the peak serum concentration should not exceed 35 micrograms/ml and the maximum concentration before the next infusion should be less than 5 micrograms/ml. In these experiment, ASTM which is lower in toxicity than AMK did not approach 35 micrograms/ml even at the peak level with the dosage of 400 mg in 1 hour. Furthermore, the excretion of the drug was fast and the serum level of the drug became much lower than 5 micrograms/ml very quickly.(ABSTRACT TRUNCATED AT 250 WORDS)