[The pharmacokinetic studies on astromicin in rats. Intramuscular, intravenous or drip intravenous administration]

Absorption, tissue distribution and excretion of astromicin (ASTM) were studied in rats after intramuscular (i.m.), intravenous (i.v.) or drip intravenous (d.i.v.; for 15, 30 min. or 60 min.) administration at a dose of 20 mg/kg. The pharmacokinetic studies of ASTM were carried out using one-compartment open model (i.m.) or two-compartment open model (i.v. and d.i.v.). The peak values of ASTM observed in serum were 48.6 micrograms/ml (i.m.), 255.3 micrograms/ml (i.v.), 57.5 micrograms/ml (15 min. d.i.v.), 45.9 micrograms/ml (30 min. d.i.v.) and 39.1 micrograms/ml (60 min. d.i.v.). The pharmacokinetic parameters of ASTM after 15 min. d.i.v. administration were calculated as follows: Kel 0.110 min-1, T1/2 21.4 min., Vd beta 0.310 L/kg, Tmax 15.0 min., Cmax 58.6 micrograms/ml, AUC 1,991 micrograms X min/ml. ASTM was rapidly distributed into the kidneys and lungs. The peak values of ASTM in the kidneys were 156.8 micrograms/g (i.m.), 185.2 micrograms/g (i.v.), 132.9 micrograms/g (15 min. d.i.v.), 135.3 micrograms/g (30 min. d.i.v.) and 117.3 micrograms/g (60 min. d.i.v.). Urinary recovery rates of ASTM amounted to 85.5% (i.m.), 99.5% (i.v.) or 87.9% (30 min. d.i.v.). After i.m. or 30 min. d.i.v. administration of ASTM, no active metabolite was found in urine of rats.