[Clinical experience of sisomicin sulfate by intravenous drip infusion for the treatment of infection complicated by malignant disease]

Sisomicin sulfate (SISO) was used for the treatment of infections complicated by malignant diseases in 10 cases; 4 cases with suspicious sepsis, 2 with pneumonia, 2 with urinary tract infection, 1 with renal abscess and 1 with cholecystitis. SISO was administered by intravenous drip infusion at daily dose from 100 to 150 mg for 6 to 12 days, concomitantly with other antibiotics. Clinical results were as follows; Good in 2, fair in 5, poor in 3 cases. As to the side effects of SISO, cylindruria with aggravation of microscopic hematuria and elevations of GOT, GPT and A1-P were observed each one of them, respectively. The relationship to the SISO, however, was not clear. In view of the above results, the drip infusion of SISO may be useful for the treatment of serious infection complicated by malignant diseases.

[A pharmacokinetic investigation of sisomicin administered intramuscularly to children]

For the purpose of studying the pharmacokinetic profile of sisomicin (SISO) and the proper conditions for its administration to children, SISO was administered intramuscularly to 10 infants aged less than 1 year, 16 young children and 18 school children at doses of 1.0, 1.5 and 2.0 mg/kg and its serum and urine levels were determined by bioassay. The mean peak levels of SISO in serum appeared at 1/4 hour in the infants, irrespective of the dose; the mean peak levels were 2.27, 3.05 and 4.83 micrograms/ml after the 1.0, 1.5 and 2.0 mg/kg doses, respectively. In the young children, the mean peak levels appeared at 1/4 hour after the 1.0 mg/kg dose and at 1/2 hour after both the 1.5 mg/kg and 2.0 mg/kg doses. The mean peak levels were 2.82, 3.80 and 6.43 micrograms/ml, respectively. In the school children, the mean peak levels appeared at 1/2 hour after all the doses and were 4.34, 5.31 and 6.87 micrograms/ml, respectively. The mean peak levels were in the order of school children greater than young children greater than infants and were dose-dependent. In the infants, the mean urinary recovery was 43.7% for the 1.0 mg/kg dose and 31.2% for the 1.5 mg/kg dose; in the young children, 50.5, 35.9 and 65.6% for the 1.0, 1.5 and 2.0 mg/kg doses, respectively; and in the school children, 54.2, 50.2 and 56.7%. Using the observed serum levels, the pharmacokinetic parameters were calculated according to the one-compartment open model theory. (1) The mean elimination rate constants (K) were calculated at 0.60, 0.67 and 0.56 hr-1 for the infants, young children and school children, respectively. There were found no great differences among the above 3 age groups. The mean absorption rate constants (ka) were 18.5, 7.6 and 5.9 hr-1 and the apparent volumes of distribution per kg body weight, Vd (L/kg), 0.44, 0.26 and 0.22 L/kg, respectively. These 2 parameters were significantly greater in the infants than in the young children and school children. The maximum serum concentration (Cmax) and the time when the concentration reaches a maximum (Tmax) were substantially in agreement with the observed values. The half-lives (T1/2) were 1.16, 1.03 and 1.23 hours for infants, young children and school children, respectively, and did not differ significantly among the 3 groups. A serum level simulation curve constructed by plotting the mean values for K, ka and Vd did not reveal any substantial deviation from the observed values.(ABSTRACT TRUNCATED AT 400 WORDS)

[Aerosol administration of dibekacin--the sputum concentration]

Serum concentrations of dibekacin (DKB), sisomicin (SISO) and gentamicin (GM) were measured in 3 rabbits after intratracheal administration through the transtracheal teflon tube. The peak serum levels (average) were 106 micrograms/ml (administrated 100 mg DKB for injection), 148 micrograms/ml (administrated 100 mg DKB solution), 166 micrograms/ml (administrated 100 mg SISO solution) and 80 micrograms/ml (administrated 80 mg GM solution). Serum concentrations and urine excretions of DKB were measured in 3 volunteers after aerosol administration using ultrasonic nebulizer. The peak serum levels (average) were 4.6 micrograms/ml (administrated 100 mg DKB for injection) and 3.1 micrograms/ml (administrated 100 mg DKB solution). The urine excretions (average) were 3.7 mg and 4.3 mg respectively during 6 hours. Before and after administration of DKB aerosol the spirogram and flow-volume curve were examined in the volunteers. But the examinations showed no changes. Sputum concentrations were measured in 1 patient with chronic bronchobronchiolitis after administration of DKB aerosols using the ultrasonic nebulizer. The highest sputum concentration was acquired immediately after nebulization and the sputum levels decreased gradually while time passed. Six patients with the lower respiratory tract infections were treated with DKB aerosol therapy and the utility rate was 80%.

[Simulation of the pharmacokinetics of aminoglycosides in the kidneys: single and continuous intake of sisomicin and gentamicin by rats]

The pharmacokinetics of sisomicin and gentamicin in the cortical and medullary layers of the kidneys was studied on rats. The antibiotics were administered daily in doses of 12.5 and 25 mg/kg a day. The levels of the antibiotics in the cortical layer were much higher than those in the medullary layer. The use of a twice as higher dose in the first case resulted in a less than a two-fold increase in the drug concentration, while in the second case the increase was more than two-fold. Prognosis of the pharmacokinetics of aminoglycosides used for 8-16 days was achieved with the help of the constants of the two-compartmental model. It was shown that the actual levels of sisomicin and gentamicin in the kidney medullary layer did not significantly differ from the estimated ones and the levels of the drugs in the cortical layer were much lower than the predicted ones. The distorted linearity of the aminoglycoside pharmacokinetics must be mainly due to saturation of the cortical layer with the drugs.

[Pharmacokinetic prediction of the efficacy of using sisomicin in wound infections]

The pharmacokinetics of sisomicin in the blood, infection foci and urine of patients with wound infections was studied comparatively. Higher blood levels of the antibiotic after intravenous injection as compared to those after intramuscular injection provided its more intensive penetration into the tissues of the wound edges and bottom. After intravenous injection the sisomicin concentration in the tissues was sufficient for inhibition of the strains of Staphylococcus, E. coli and Ps. aeruginosa detected in the patients, while after intramuscular injection the antibiotic levels were sufficient only for inhibition of the first two causative agents. Comparison of the data on the sisomicin pharmacokinetics in the blood and tissues of the wounds provided the characteristics of the level of the drug penetration into the focus of the infection ("therapeutic availability"). Since the levels of sisomicin in the blood and infection foci were highly variable in different individuals. It is recommended that the antibiotic be used under the control of its concentrations in patients. It was shown that the data on the sisomicin renal excretion might be used for the purposes of the pharmacokinetic control.

[Pharmacokinetic basis for using tobramycin and sisomicin in treating pyelonephritis of the transplanted kidney]

The pharmacokinetics of tobramycin and sisomicin in patients after kidney transplantations was studied. A significant variability of the pharmacokinetic parameters of tobramycin and sisomicin under conditions of the changing function of the kidney transplant was shown. This required individual control of the drug serum levels in such patients. Linear correlation between the exponent (beta) and the clearance of endogenous creatinine was observed. On the basis of this correlation a nomogram providing a decrease in the percentage of the errors in determining the dosage intervals was plotted.

[Studies on the combination action of sisomicin, gentamicin and piperacillin, cefmetazole against Pseudomonas aeruginosa and Serratia marcescens]

The combined actions of sisomicin (SISO), gentamicin (GM) and piperacillin (PIPC), cefmetazole (CMZ) against Pseudomonas aeruginosa E-2 and Serratia marcescens T-55 were studied. The following results were obtained. 1. The combinations of SISO-PIPC, SISO-CMZ, GM-PIPC and GM-CMZ using the checker board dilution method on P. aeruginosa E-2 and S. marcescens T-55 were found to have a synergistic effect and the minimum FIC index values were 0.38 in all combinations. 2. With the killing kinetic method, all combinations tested showed a synergistic effect. 3. A synergistic effect of the combinations of SISO-PIPC, SISO-CMZ, GM-PIPC and GM-CMZ was observed in the protective effect on experimental P. aeruginosa E-2 and S. marcescens T-55 infections in mice.

[Build up of a given concentration of tobramycin and sisomycin in the blood of young children by the intravenous infusion of the antibiotics according to a calculated regimen]

Three regimens for intravenous infusion of tobramycin and sisomicin in doses of 1.33 and 1 mg/kg, respectively were analysed theoretically with the use of the constants of a two-compartmental model characterizing the tobramycin pharmacokinetics in adults. The regimen implied administration of the antibiotics by means of a 12-hour infusion. The second regimen consisted of a jet injection of the initial dose simultaneously with the beginning of the maintenance infusion. The third regimen consisted of a rapid initial infusion followed by a slow maintenance infusion. It was shown that maintenance of the drug concentration at the required levels, i.e. 2-8 microgram/ml for tobramycin and 2-61 microgram/ml for sisomicin was most safely provided by the regimen of the subsequent infusions. This regimen was tried clinically in the treatment of 17 children aged 2 months to 2.5 years with severe forms of acute pneumonia. The rate of the 25-minute initial infusion of tobramycin was 22.2 microgram/kg . min and that of the subsequent 2.7-hour maintenance infusion was 4.85 microgram/kg . min, the total dose being 1.33 mg/kg. The rate of the 20-minute initial infusion of sisomicin was 21.7 microgram/kg . min and that of the subsequent 2.4-hour maintenance infusion was 3.88 microgram/kg . min, the total dose being 1 mg/kg. It was shown that the levels of both the antibiotics in the blood serum of the patients were within the required ranges.

[Pharmacokinetics of a cefotetan and an aminoglycoside preparation in combined administration. 2. Absorption and exercise of cefotetan and sisomicin in dogs when the two are given together]

Cefotetan (20 mg/kg i.v.) and sisomicin (10 mg/kg i.m.) were administered alone or in combination to Beagle dogs. The mean plasma concentrations of cefotetan administered in combination with sisomicin at the above dosages were 98.0 microgram/ml at 5 minutes, 45.7 microgram/ml at 30 minutes and 3.46 microgram/ml at 4 hours. These plasma concentrations of cefotetan were similar to those of cefotetan administered alone to the corresponding dogs. The calculated plasma half-lives (T 1/2 beta) of cefotetan were 53.9 minutes in combination with sisomicin and 57.4 minutes alone. The excretion of cefotetan in dog urine were 52.4% and 50.2% of the dose after administration in combination with sisomicin and alone, respectively, during 24 hours. The results indicate that there were no significant differences in the pharmacokinetics of cefotetan alone or in combination with sisomicin in dogs. The maximum concentrations of sisomicin in dogs administered in combination with cefotetan were 20.2 microgram/ml at 30 minutes after dosing. The concentrations of 11.7 microgram/ml at 2 hours and 3.13 microgram/ml at 4 hours of administration were maintained in plasma. The calculated plasma half-lives of sisomicin were 68.8 minutes in combination with cefotetan and 86.4 minutes alone. The urinary rcoveries of sisomicin were 79.3% and 76.1% in combination with cefotetan and alone, respectively, during 24 hours. There were no significant differences in the pharmacokinetics of sisomicin alone and in combination with cefotetan in dogs.

[Pharmacokinetics of cefotetan and an aminoglycoside preparation in combined administration. 1. Individual quantification of cefotetan and sisomicin by bioassay and their absorption, distribution, and excretion in rats when given together]

The beta-lactam and aminoglycoside groups of antibiotics are often used in combination. This paper reports a bioassay method for each of cefotetan and sisomicin concentration in body fluids, and pharmacokinetics of both drugs following intravenous administration of cefotetan and intramuscular administration of sisomicin alone and in combination to rats. As to cefotetan determination, a previously reported bioassay method was modified by increasing the NaCl concentration in the sensitivity test agar from 0 to 6%, using Bacillus subtilis ATCC 6633 as the test organism. To assay for sisomicin in the presence of cefotetan, Pseudomonas aeruginosa ATCC 8689, resistant to the beta-lactam antibiotic, was used. Cefotetan (20 mg/kg intravenous) and sisomicin (10 mg/kg intramuscular) were administered concomitantly to rats. The mean plasma concentrations of cefotetan and sisomicin were 16.3 microgram/ml and 16.1 microgram/ml, at 30 minutes after administration respectively. The concentrations were declined to 2.20 microgram/ml for cefotetan and 2.53 microgram/ml for sisomicin at 90 minutes after dosing administration. The calculated plasma half-lives (T 1/2 beta) were 21.3 minutes for cefotetan and 22.2 minutes for sisomicin. The plasma and tissue concentrations of cefotetan administered in combination with sisomicin were nearly the same as those of cefotetan alone. Urinary excretion of cefotetan and sisomicin in the concomitant administration was carried out in rats. Recoveries in urine were 45.9% of the dose for cefotetan and 85.6% of the dose for sisomicin for a period of 24 hours. When each drug was administered alone to rats, cefotetan and sisomicin were recovered 49.8% and 81.6%, respectively, of the dose in the 24-hour urine.

Empiric antibiotic treatment of infections in myelosuppressed cancer patients. Preliminary results

A prospective, randomized study was performed to compare the efficacy and safety of mezlocillin plus sisomicin (Regimen A) and cefamandole plus tobramycin (Regimen B). Sixty-one episodes of documented infections were treated in 49 adult myelosuppressed cancer patients. About two-thirds of the patients treated with either regimen responded to this antibacterial therapy. The patients failing to respond to the initial therapy were treated with additional antibiotics, either with the empiric Regimen C (cefotaxime plus amikacin plus azlocillin) or with antibiotics selected on the basis of bacteriological results (Regimen D). With these schedules, the over-all response rate was increased to about 90%. The data suggest that febrile granulocytopenic cancer patients may profit from this empiric and sequential antibiotic treatment.

Combined action of decreasing concentrations of azlocillin and sisomicin on Pseudomonas aeruginosa as assessed in a dynamic in vitro model

The effect of decreasing concentrations of azlocillin and sisomicin on Pseudomonas aeruginosa was examined. Logarithmically growing bacterial cultures were incubated in an ultrafiltration cell, and after adding the antibiotics, the culture medium was diluted every 20 min without any decrease in cell density. The turn-over of medium resulted in the elimination of azlocillin with a half-life of 75 min. This simulated serum kinetics in vivo. When testing sisomicin, small amounts of this agent were added during every dilution step to achieve a half-life of 120 min. Growth conditions were comparable in all experiments. The simultaneous combination of azlocillin and sisomicin resulted in strong synergism as assessed by higher killing rates and more prolonged growth inhibition of surviving bacteria. Comparable results were observed when both drugs were added at intervals of 40 min. When applied at intervals of 120 min, the combined effect of azlocillin and sisomicin was reduced, but still superior to the effect of double the concentration of each compound alone. Thus, neither pre-treatment with azlocillin nor with sisomicin impaired the antibacterial activity of the combination partner. This seems to be of clinical importance since the agents may be administered at different times during combined therapy.

[Elaboration of the procedures for the pharmacokinetic interpretation of aminoglycoside nephrotoxicity: the experimental evaluation of the safety of repeated gentamycin administration]

Nephrotoxicity and pharmacokinetics of gentamicin were studied on rats treated with the antibiotic for 30 days in doses of 6.25, 12.5 and 25 mg/kg administered daily. The pharmacokinetics of gentamicin and the time course of changes in the urea nitrogen levels of the blood serum were studied after the 1st, 5th, 8th and 30th injection. The analysis of the respective curves was used for calculation of the average integral values of the concentrations of the antibiotic (C) and urea nitrogen (E). After that the average integral values of these parameters ((CAVG and EAVG respectively) within the whole treatment couse with the use of every dose were calculated in the same way by using the curves of the dynamics of C and E changing. Comparison of the diagrams of E dependence on C for gentamicin and sisomycin showed that nephrotoxicity of sisomycin was 1.48 times higher than that of gentamicin.

Pharmacokinetic study of sisomicin in humans

Detailed analyses of the pharmacokinetics of sisomicin administered at doses of 25, 50 and 100 mg intravenously and intramuscularly to healthy volunteers established that the drug is handled by a two-compartment open model system with a disposition (elimination) half-life of 2.6 hr. The kinetic estimates over this dose range are linear and independent of dose and were verified by a 60-min infusion experiment in which dose and the maximum serum concentration achieved (5 microgram/ml) were predicted correctly. Sisomicin was rapidly distributed to the tissue compartment, and equilibrium between the central and the tissue compartment was established by 30 min after dosing. Renal clearance (55 ml/min) of sisomicin was about 30% less than total body clearance (78 ml/min). Total urinary excretion of sisomicin during a 24-hr period following drug administration was about 70% of the dose. The disposition kinetics of sisomicin following intramuscular administration are similar to those obtained following rapid intravenous administration. Intramuscular bioavailability of sisomicin for the doses of 25, 50, and 100 mg was greater than 95%. Based on these results, various initial loading infusion doses and maintenance infusion rates were calculated to provide specific desired peak and steady-state serum sisomicin concentrations rapidly. The purpose was not to expose patients to potentially toxic high peak concentrations of drug while maintaining these concentrations during the current therapeutic dosing intervals of 8 to 12 hr.

[Sisomicin pharmacokinetics in rat tissues in single and long-term administration]

The pharmacokinetics of sisomicin administered intramuscularly to rats in daily doses of 12.5 and 25 mg/kg for 30 days was studied. After a single administration of the drug in the above doses the highest and the lowest levels of sisomicin were observed in the kidney cortical layer and liver, respectively. The antibiotic level in the tissues rose with an increase in the antibiotic dose and duration of the drug use. The two-fold rise in the dose resulted in an elevation in the sisomicin level in the kidney cortical layer by 1.7 times, in the medullary layer by 3 times, and in the blood serum, lungs and spleen by 2.3, 1.2 and 1.5 times, respectively. After treatment with a dose of 25 mg/kg for 8 days the antibiotic level in all tissues studied was higher than that after the first administration of the drug: in the cortical and medullary layers of the kidneys by 5-7 times and in the blood serum and other tissues by 1.2-2 times. When sisomicin was used repeatedly in any dose, stabilization of or some decrease in the mean integral concentration of the antibiotic in the kidney cortical layer and a continuous increase of this value with respect to the medullary layer (up to the 30th day) were noted. The difference between the antibiotic levels in the kidney layers after the repeated administration of the drug was less pronounced than that after a single administration of the drug. The cumulation index of sisomicin in the kidney cortical layer persisted at the same level and that in the medullary layer gradually increased. In this connection it is concluded that correlation between the sisomicin nephrotoxic effect and the level of the antibiotic in the kidney cortical layer is more pronounced than that in the medullary layer.

[Treatment of severe febrile neutropenia (author's transl)]

Random allocation of 22 patients with benign and malignant diseases with neutrophil counts of up to 1 X 10(9)/l blood and probably infection-caused fever of more than 38 degrees C to intravenous treatment with one of the following antibiotic combinations was performed: carbenicillin (6 g/m(2) . 6 h) plus sisomicin (45 g/m2 . 6 h) or mezlocillin (3 g/m2 . 6 h) plus sisomicin (45 g/m2 . 6 h). Both combinations were tolerated equally well. Patients became afebrile in 16 out of 23 treatment periods. Seven out of 11 patients responded to carbenicillin - sisomicin, and 9 out of 12 to mezlocillin - sisomicin. Mezlocillin thus leads to equal success of treatment in febrile neutropenia as the double dose of carbenicillin when both antibiotics are combined with the same aminoglycoside.

[Pharmacokinetic basis of the nephrotoxic action of sisomycin. The pharmacokinetics of sisomycin in single and multiple administrations to rats]

The pharmacokinetics of sisomicin was studied on Wistar rats. The antibiotic was used in single or repeated doses of 12.5 and 25 mg/kg. The kinetic data of the antibiotic titration in blood serum within 1 and 24 hours of intramuscular administration of the drug were formalized with the use of a linear two-compartment model. The average values of the elimination constant and the constants of sisomycin transfer from the central compartment into the peripheral one were 0.64, 0.34 and 0.13 hours-1 respectively. The value of the apparent distribution volume in the central compartment was 0.38 ml/kg and that of the stationary and kinetic distribution volumes was 1.37 and 3.06 1/kg respectively. The value of the general clearance was 0.24 1/(kg.hour) and that of the sisomicin half-life was 8.7 hours. Comparison of the antibiotic levels estimated with a model and actually measured in the blood after repeated administrations revealed the drug cumulation. When the antibiotic was used in a dose of 25 mg/kg daily, its cumulation was observed earlier (by the 5th--8th day) than on its use in a dose of 12.5 mg/kg (by the 30th day). Irrespective of the dose, sisomicin cumulation was accompanied by prolongation of the antibiotic half-life in the rats.