EXPERIMENTAL AND CLINICAL STUDIES ON A NEW ANTIBIOTIC, AMIKACIN

Abstract

Amikacin is a new antibiotic which belongs to aminoglycosides. Present study clarified the followings.
1) Antimicrobiological activity : Minimum inhibitory concentrations (MIC) of amikacin were investigated comparing with MICs of gentamicin. Sixhundred and twenty one strains isolated from the clinical materials (91 pyogenic Staphylococci, 51β-Streptococci, 57 Enterococci, 14 Shigella, 102 E. coli, 111 Klebsiella aerogenes, 12 Enterobacter aerogenes, 30 Enterobacter cloacae, 22 Proteus vulgaris, 29 Proteus mirabilis, 27 Morganella, 58 Pseudomonas aeruginosa) and 17 standard strains stocked in our laboratory were used in this test.
Antimicrobiological activity of amikacin was inferior to GM and the MIC of amikacin was 2 to 4 fold higher than that of GM. Antimicrobiological activity of aminoglycosides to Pseudomonas aeruginosa was assessed as the following order; TOB-DKB-GM-Amikacin-LVM.
2) Absorption and excretion : In 4 healthy adult volunteers who were intramuscularly given 100 mg of amikacin, the peak level in blood was 7.2 to 9.8 μg/ml at half to one hour after injection. When 200 mg were given, it became 11.5 to 12.5 μg/ml. The concentration at 6 hours after injection was 1.1 μg/ml and 3.25 μg/ml respectively on average. Urinary recovery rate for 6 hours was 67.8% on average.
3) Distribution in the organs : The highest concentration was seen in the kidney. The order of concentration in the organs was clarified as kidney-serum-lung-liver in the experimental animal (rats).
4) Concentration in the sputum; To a case expectorated the purulent sputa of 50-80 ml every day, 200 mg of amikacin was given intramuscularly, b.i.d. The maximum concentration in sputum to blood was 0.2.
5) Clinical evaluation : Two hundreds mg of amikacin were given intramuscularly, b.i.d., to 12 pa-tients with respiratory infectious diseases (bacterial pneumonia, lung abscess and bronchiectasis with infection, 6, 5, 1 case respectively) for 6 to 13 days. It was beneficial in 50% of the cases. Advanced reaction was not seen in the viewpoints of signs and symptoms, blood-chemistry and urine-analysis.