[Apramycin blood concentrations and distribution in the body of calves after different methods of administration].

The serum concentrations of apramycin in calves were studied after i/v application at the rate of 20 mg/kg body mass, after i/m injection at 20-40 mg/kg b. m., and after oral administration (with milk) at 40 mg/kg b. m. in terms of establishing certain pharmacokinetic parameters. It was found that at i/v route of application the concentrations of the antibiotic ranged above 2 micrograms/cm3 within the interval from the 15th min up to the 8h hour. The time of half-distribution (t1/2 alpha) was 0.28 h, while the biologic half-life of half-elimination (t1/2 beta) was 2.31 h. After muscular application of apramycin at 20 and 40 mg/kg it was rapidly adsorbed at the site of injection; the maximum concentrations were 99 micrograms/cm3 and 202 micrograms/cm3, resp., from the first to the second hour. Levels above 2 micrograms/cm3 were found in the blood serum in the course of 8 to 10 hours when the antibiotic was applied at 20 mg/kg b. m., and they have persisted for more than 12 hours when it was administered at the rate of 40 mg/kg. The biologic half-life (t1/2 beta) was 1.63 h and 1.97 h, respectively. Following the oral administration of the antibiotic at 40 mg/kg subtherapeutic levels were established up to the 24 th hour, with the exception of the interval of the 6 th to 8 th when the concentrations were below the minimum therapeutic one (2 micrograms/cm3).(ABSTRACT TRUNCATED AT 250 WORDS)