A Phase 1 Study To Assess the Pharmacokinetics of Intravenous Plazomicin in Adult Subjects with Varying Degrees of Renal Function

Plazomicin is an FDA-approved aminoglycoside for the treatment of complicated urinary tract infections. In this open-label study, 24 adults with normal renal function or mild, moderate, or severe renal impairment (n = 6 per group) received a single 7.5-mg/kg of body weight dose of plazomicin as a 30-min intravenous infusion. Total clearance declined with renal impairment, resulting in 1.98-fold and 4.42-fold higher plazomicin exposures, as measured by the area under the concentration-time curve from 0 h to infinity, in subjects with moderate and severe impairment, respectively, than in subjects with normal renal function. (This study has been registered at ClinicalTrials.gov under identifier NCT01462136.).

Distribution and serum concentration of sisomicin released from fibrin glue-sealed dacron graft in the rat and human

We investigated whether or not fibrin glue (FG) used as a sealant in vascular prostheses to prevent leakage might be useful as a carrier of antibiotics for the prevention of local graft infection. Sisomicin (SISO) was incorporated into fibrin glue (SISO-FG) and evaluated as to its safety and pharmacokinetics. SISO (1.75 mg) -FG Dacron grafts were implanted subcutaneously in the anterior abdominal region of Sprague-Dawley rats, and then the changes in SISO concentrations in the serum and in the tissue around the implantation sites were compared with those same sites in rats that had had intravenous injection of SISO (1.75 mg). The serum SISO concentrations were significantly lower in the SISO-FG Dacron graft group than they were in the intravenous injection group. However, until 4 h after implantation the SISO concentrations in the tissues around the implantation sites were significantly higher in the SISO-FG Dacron group than they were in the iv injection group, and the peak concentrations during that time were 5.8 times higher for the SISO-FG Dacron group than they were for the intravenous injection group. The ratio of the area under the tissue concentration time curve of SISO (AUC tissue) after implantation of the SISO-FG Dacron graft to that after intravenous injection of SISO was 13.08. Therefore, FG was considered to control the release of SISO into the serum and to maintain a high SISO concentration in the tissue around the implantation site. Clinically, SISO (45 mg) -FG was applied directly to the Dacron grafts implanted in 10 patients who underwent prosthetic vascular reconstruction. No graft infection was observed in any of the patients who received SISO-FG Dacron grafts. The mean serum concentration of SISO was 0.65+/-0.17 microg/mL after 1 h and 0.33+/- 0.21 microg/mL after 3 h. The results of these clinical applications are in close correlation with those of the animal experiment and suggest that FG is useful as a carrier of SISO, allowing its controlled release for the prevention of local infection.

Aqueous kinetics of sisomicin sulphate

Sisomicin sulphate is a new-generation aminoglycoside with a broad spectrum of antimicrobial activity that includes Pseudomonas aeruginosa. It is superior to gentamicin against indole-negative Proteus and some resistant strains of Pseudomonas. The ocular pharmacokinetics of sisomicin have not been explored. We used the agar diffusion technique of microbial assay to determine the aqueous penetration and bioavailability of a subconjunctivally placed standard dose of 20 mg/0.4 ml of sisomicin sulphate in 20 human volunteers undergoing elective cataract surgery. A peak concentration of 16.4 mg/l was found in the aqueous humour 78 minutes after injection, which is 65 times the minimum inhibitory concentration for Pseudomonas. The antibiotic was bioavailable up to 1203 minutes after injection in a concentration of 0.9 mg/l, which easily covers the minimum inhibitory concentration of Staphylococcus aureus and Pseudomonas. The antibiotic disappears from the aqueous humour at the 1434 minute interval (approximately 24 hours). The elimination half-life (t1/2 of sisomicin was determined to be 5.16 hours (K = 0.134/hour) and the aqueous clearance was 2.87 microliters/min.

[Pharmacokinetic monitoring of aminoglycoside therapy: an optimal method of administration of individualized doses of gentamicin and sisomicin]

One of the most promising approaches to design the optimal schedule for TDM provides a single determination of a drug content in the blood specimen being collected at the "ideal" sampling time equaled to the inverse value of the elimination rate constant. Three versions of the one-point method when the specimen was collected at the "ideal" time point (3 h after a single i.m. drug administration), as well as at the times of "maximum" (1 h after injection) and "minimum" (6 h after injection) concentrations were compared by the retrospective analysis of the routine TDM data obtained with HPLC-techniques in 47 patients treated with gentamicin or sisomicin. As optimal individualized doses were considered ones calculated on the base of three subsequent determinations of the aminoglycoside concentrations, i.e. 1, 3 and 6 h after injection, and the estimation of individual clearance values (Cli). The optimal doses (DCl) were calculated according to equation DCl = Dp.Cli/Clp, where Dp and Clp are population values of the dose (1 mg/kg) and Cl 72.4 ml/(h.kg), respectively. The approximate values of the individual doses (D) were calculated according to equation D = Dp.Cp/Ci, where Ci is the individual drug serum concentration 1, 3 or 6 h after administration and Cp is the corresponded population value (4.8, 1.9 and 0.8 mg/l, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

[Ways of increasing the effectiveness of antibacterial therapy in newborns]

Ways for increasing antibiotic therapy efficacy in newborns are discussed. They are the following: consideration of the structure of the antibiotic use, improvement of infection diagnosis, the use of computers in epidemiological supervision of antibiotic resistance, the use of "old" antibiotics in new dosage forms, pharmacokinetic monitoring. The data on the frequency of the antibiotic use in newborns in maternity hospitals, at home and in neonatal departments as well as on diagnosis and treatment of chlamydiosis in newborns are presented. Requirements to the computer programs on control of antibiotic resistance are described. With the account of the requirements an original epidemiological program for personal computers was developed. The results of the pharmacokinetic monitoring of the use of sisomicin and amikacin are presented as well.

Quantitative analysis of antimicrobial effect kinetics in an in vitro dynamic model

Variants of the available methods for estimating antimicrobial effect kinetics in an in vitro dynamic model were analyzed. Two integral parameters characterizing antimicrobial effect duration (TE) and intensity (IE) are suggested to define and analyze the concentration-effect relationships in these models, irrespective of the method of recording. TE is defined by the time from the moment of antibiotic administration to the movement when the bacterial count again reaches its initial level. IE is defined by the area between the microbial growth curves in the presence and absence of an antibiotic. TE and IE were used to quantify the antimicrobial effects of sisomicin on Pseudomonas aeruginosa 58, Escherichia coli 93, and Klebsiella pneumoniae 5056, simulating the pharmacokinetic profiles of the drugs observed following intramuscular administration in therapeutic doses, including the variability of aminoglycoside concentrations in human blood.

[Individual schedule of administration of aminoglycosides with reference to anatomo-physiological and pathological factors]

Potentiality of designing individual dosage of sisomicin and gentamicin in regard to "patient factors" was estimated. 62 adult patients with various pulmonary diseases at the background of volemic disorders of diverse degrees were treated with the aminoglycosides under monitoring of their blood levels. Concentrations of sisomicin and gentamicin in serum 1, 3 and 6 hours after their single administration in a dose of 1 mg/kg were determined by HELC. The antibiotic pharmacokinetics was characterized by pronounced individual variability. The ratio of the difference between the upper and lower confidence limits to the average values of the steady-state volume of distribution, the total clearance and the mean residence time amounted to 70, 60 and 57 per cent respectively. To elucidate the cause of the variability multiple correlation analysis of the pharmacokinetic parameters by the "patient factors" was performed. The highest coefficient of the multiple correlation (r = 0.690) defined relation between the aminoglycoside concentration 1 hour after the injection and the hematocrit, globular volume and phase of the volemic disorders which was expressed in coded variables. The coefficient of the multiple correlation between the total clearance and the body surface area, concentrations of creatinine and urea in serum, hematocrit, circulating blood volume and the phase of the volemic disorders was equal to 0.439. Therefore, the consideration of the above factors allowed to explain only 20 per cent of the observed individual variability of the pharmacokinetic parameters. In this connection mediated prediction of total clearance and subsequently individual dosage of the aminoglycosides by the "patient factors" was expedient only until the primary data on the pharmacokinetic monitoring were obtained.

[Pharmacokinetic monitoring of antibiotic therapy]

The general strategy in optimization of antibiotic dosage regimens included development of population or common regimens for an "average" patient (the 1st approximation), subpopulation regimens for patients of certain categories on the basis of interactions between the pharmacokinetic parameters and "patient factors" (the 2nd approximation) and individual regimens on the basis of the data of the pharmacokinetic monitoring (the 3rd approximation). Characteristics of every of the approximations in antibiotic therapy of adults and children were analyzed. Out of the peculiarities of the strategy use in pediatrics+ and micropediatrics+ the following should be indicated: (1) pharmacokinetic heterogeneity of the population requiring grouping of the patients and consequently development of subpopulation dosage regimens omitting stage I, (2) possible development of dosage regimens on the basis of the ration between the pharmacokinetic parameters or immediate drug concentration values and the "patient factors" not only in chronic but also in transitory impairment of some functions and (3) the necessity of considering systematic changes in "pharmacokinetic status" of every child during individualization of the dosage regimens by the data of the pharmacokinetic monitoring.

[Correlation of dose-antimicrobial effect in modeling in vitro pharmacokinetic profiles of normal and impaired elimination of antibiotics]

Relationships between concentration and antimicrobial effect (AME) of sisomicin (SMN) and cefotaxime (CTX) were established by simulating their pharmacokinetic profiles in an in vitro dynamic model. The AME duration (TE, time shift between the curves of bacteria heat output in the presence and absence of the antibiotics) or intensity (IE, area between the above curves) for both the antibiotics depended in the same way on the area under the concentration/time curve (AUC, mimicing of intravenous administration of the antibiotics in various doses). At low and moderate values of the AUC the dependences of IE or TE vs the AUC (the bacteriostatic phase of the AME development) were of the sigmoid shape while at high values of the AUC there was a marked increase in IE or TE (the bactericidal phase). The patterns of the IE or TE vs AUC curves in impaired antibiotic elimination were analogous. At the same time the IE or TE vs AUC curves for both the antibiotics under simulation of normal elimination (T 1/2, SMN-2.1 h, T 1/2, CTX-1.2 h) and impaired one (T 1/2, SMN-8.3 h, T 1/2, CTX-4.6 h) did not match. In the first case the AMESMN was on the whole higher and the AMECTX was lower than in the second case. Therefore, in patients with renal failure the efficient concentration of the aminoglycoside in blood can be higher and that of the cephalosporin on the contrary can be lower than the normal.

A dynamic model for in-vitro evaluation of antimicrobial action by simulation of the pharmacokinetic profiles of antibiotics

The general principles of in-vitro simulation of drug pharmacokinetic profiles for linear one-, two- and multi-compartment models are described. An in-vitro dynamic model constructed on the basis of these, incorporating a novel filtration unit to provide efficient filtration of drugs at constant inoculum size, was used to study the antimicrobial action of sisomicin on Escherichia coli A 20363, in conditions simulating the pharmacokinetic profile observed in humans after a single intramuscular dose of 1 mg/kg.

Pre-column derivatization of sisomicin with o-phthalaldehyde-beta-mercaptopropionic acid and its application to sensitive high-performance liquid chromatographic determination with fluorimetric detection

The stability of the o-phthalaldehyde (OPA) derivatives of sisomicin obtained using beta-mercaptopropionic acid was investigated by reversed-phase high-performance liquid chromatography. One of the fluorescent derivatives of sisomicin was stable at least for 6 h in 50% methanol under the optimal conditions used (OPA concentration, pH and temperature). When plasma samples spiked with sisomicin were analysed, the response was linear in the calibration range 136-900 pg of sisomicin per injected volume (40 microliters). As little as 0.06 micrograms of sisomicin per 1 ml of plasma could be detected with signal-to-noise ratio greater than or equal to 2. For plasma samples spiked with 0.2 micrograms/ml sisomicin, the recovery was 97.1 +/- 6.6% (mean +/- S.D., n = 5) with a within-run coefficient of variation of 6.8% and a day-to-day coefficient of variation of 7.2%. The method was also applied to plasma samples from rabbit after a subcutaneous injection of 1 mg/kg sisomicin.

[Dependence of the antimicrobial effect on the antibiotic concentration in modelling pharmacokinetic profiles in vitro: a comparison of 2 regimens for the single intravenous administration of sisomicin]

Kinetics of sisomicin antimicrobial effect on E. coli was studied in an in vitro dynamic model. Pharmacokinetic profiles observed in blood of humans treated with different polar dosing schedules i. e. bolus administration and continuous infusion were simulated. The first set of the experiments included simulating the profiles observed at short-term maintenance (0.25-20 min) of relatively high antibiotic levels after bolus administration (Cmax = 0.125-10 micrograms/ml). The second set included simulating the profiles observed at long-term maintenance (1-15 hours) of relatively low antibiotic levels after infusion (Cmax = 0.125-1.75 micrograms/ml). Changes in the viable count in the dynamic model were estimated microcolorimetrically with BioActivity Monitor LKB 2277-202. The use of the recently developed parameters of antimicrobial effect intensity IE and duration TE provided determination of relationship between IE or TE and logarithm of the area under the concentration-time curve (lg AUC). Its own IE (or TE) vs lg AUC curve including 4 phases corresponded to every administration schedule i. e. bolus and infusion. The 1st and 3rd phases reflected weak changes in IE or TE at significant increasing of the AUC and the 2nd and 4th phases reflected a marked increase in IE or TE at insignificant changing of the AUC.(ABSTRACT TRUNCATED AT 250 WORDS)