Abstract
Gentamicin (GM) was studied for on its antibacterial activity, absorption, and excretion, effect on the kidney and clinical effects. The results obtained are as follows:
1. Antibacterial activity: The susceptibility of E. colt, Klebsiella, Proteus mirabilis to GM was almost the same between the periods of 1964-1966 and 1972-1974: No tendency of increase of resistance by year was noted. However, against Pseudomonas aeruginosa, strains showing sensitibity to a concentration of more than 25mcg/ml were isolated in 12.7%, in the latter period (1972-1974), as compared with the former period (1964-1966), which was 0%.
2. Blood levels: The peak level of GM in blood was obtained at 30 minutes after intramuscular injection to a healthy human. The peak level was 7.6mcg/ml with 40mg dose, 8.7mcg/ml with 60mg and 10.6mcg/ml with 80mg, showing a dose-responding curve. The half-life of GM absorption was 1.1 hours with 40 mg dose, 1.3 hours with 60mg and 1.6 hours with 80mg, showing also a doserelated tendency.
3. Urinary levels: The peak level of GM in urine, about 200mcg/ml, was noted in 0-2 hours after intramuscular injection of GM to a healthy human. The urinary recovery was about 44% in 6 hours.
4. Effect on the kidney: The effects of GM on the kidney were studied in rats administering 20mg/kg once a day for 21 days consecutively. The results obtained are a slight increase (20mg/dl) in BUN and a slight decrease (2,600mosm/kg H2O) in urinary osmotic pressure; and urea lysozyme showed tendency to increase from the third day, the same as with kanamycin. Meanwhile, in the histopathological findings of the kidney tissue, the vacuolar degeneration and flattening of renal tubules were noted. Similar findings were obtained with kanamycin in a similar type of experiment. These results indicate that nephrotoxicity of GM is considered to be approximately the same as that of kanamycin.
5. Clinical results: GM was injected into 22 patients with various infectious diseases (respiratorytract infections 7, liver abscess 1, urinary-tract infections 14). Excellent efficacy was noted in 7 patients, good in 13 and no effect in 2. The effective rate was 90.9%. No serious side effect was noted in this clinical trial.
