[Studies on tobramycin by the intravenous drip infusion method]

Fundamental and clinical efficacy evaluation has been made in the study on the therapy with intravenous drip infusion of tobramycin (TOB) which is one of the aminoglycoside antibiotics and which has been recently approved of intravenous administration. The fundamental evaluations were made with intravenous drip infusion of 60 mg of TOB for 1 hour and that of 120 mg of TOB for 2 hours to 4 healthy adult volunteers on crossover method. Follow-up determinations were made for comparison on its concentrations in blood and urine samples which were collected both at intervals thereafter, using 2 assay methods of the bioassay and the EMIT methods. The maximum blood level of TOB based on the intravenous drip infusion of 60 mg for 1 hour was 5.9 micrograms/ml and 4.6 micrograms/ml by the bioassay and the EMIT methods at the end of intravenous drip infusion, respectively, and 0.3 micrograms/ml and 0.4 micrograms/ml, respectively, at 6 hours after the drip infusion. The T 1/2 value was 1.81 hours with bioassay and 2.41 hours with the EMIT method. The maximum blood level of TOB through drip infusion method of 120 mg of TOB for 2 hours was 7.5 micrograms/ml by bioassay and 5.8 micrograms/ml by EMIT method. The T 1/2 value was 1.87 hours and 1.99 hours, respectively. The recovery rate of TOB from urine until 24 hours after the administration was 83.0% and 94.4% with the doses of 60 mg and 120 mg, respectively, which were determined only with the bioassay. The correlation coefficient between the agar well method and the EMIT method was 0.963 and 0.972 in the groups of intravenous drip infusion of 60 mg for 1 hour and 120 mg for 2 hours, respectively, showing proximity to each other. TOB was kept administered with a daily dose of 120 mg at a time to 11 cases and at 2 times to 1 case with chronic complicated infections of urinary tracts (comprising 9 cases with chronic complicated cystitis, 2 with chronic complicated pyelonephritis, and 1 with acute epididymitis). Of the 12 patients, 8 could meet the criteria for evaluation of drug efficacy and 6 of them proved to be effective, while 2 were ineffective. The efficacy rate was so high as 75%. The rate of disappearance of bacteria was 80.0%, which was very high. No side effect was specifically found out, except 1 case showing slight rise in S-GOT.