Increased Arbekacin Clearance in Patients With Febrile Neutropenia.

BACKGROUND: Arbekacin (ABK) is used to treat infections caused by methicillin-resistant Staphylococcus aureus and is used widely for the treatment of febrile neutropenia (FN). As ABK has a narrow therapeutic concentration window, the dosage must be adjusted via therapeutic drug monitoring. However, the influence of the physiology of patients with FN on the pharmacokinetic (PK) parameters of ABK remains unclear. Therefore, we examined this influence on ABK PK parameters. METHOD: We performed a retrospective cohort study using data from patients with a hematologic malignancy who were ≥18 years and had been administered ABK. We excluded patients who did not receive therapeutic drug monitoring and had an estimated glomerular filtration rate (eGFR) of <30 mL/min, because clinically sufficient data would not be available. RESULT: Of the 99 enrolled patients, 25 did not have FN and 74 had FN. Arbekacin clearance (CLabk) was shown to correlate with eGFR in patients with FN (r = 0.32, P = 0.0062) and without FN (r = 0.50, P = 0.01). CLabk was higher in patients with FN than in those without FN. In addition, in the eGFR of <100 mL/min group (normal renal function), CLabk and CLabk/eGFR were also higher in patients with FN than in those without FN. CONCLUSIONS: CLabk was increased in patients with FN and normal renal function; therefore, we propose an increased ABK dose for patients with FN and normal renal function.

Population Pharmacokinetic Analyses for Arbekacin after Administration of ME1100 Inhalation Solution.

ME1100, an inhalation solution of arbekacin, an aminoglycoside, is being developed for the treatment of hospital-acquired and ventilator-associated bacterial pneumonia. The objective of these analyses was to develop a population pharmacokinetic model to describe the arbekacin concentration-time profile in plasma and epithelial lining fluid (ELF) following ME1100 administration. Data were obtained from a postmarketing study for an intravenous (i.v.) formulation of arbekacin, a phase 1 study of ME1100 in healthy volunteers, and a phase 1b study of ME1100 in mechanically ventilated subjects with bacterial pneumonia. Data from the postmarketing study were utilized to develop a population pharmacokinetic model following i.v. administration, and this model was subsequently utilized as the foundation for development of the model characterizing arbekacin disposition following inhalation of ME1100. The final model utilized two compartments for both plasma and ELF disposition, with movement of arbekacin between the ELF and plasma parameterized using linear first-order rate constants. A bioavailability term was included for the inhalational route of administration, which was estimated to be 19.5% for a typical subject. The model included normalized creatinine clearance (CLcrn) and weight as covariates on arbekacin clearance: CL = (weight/52.2)0.855·[(CLcrn-77)·0.0289 + 2.32]. The model simultaneously described arbekacin concentrations following both i.v. and inhaled administration and provided acceptable fits to the plasma and ELF data (r2 of 0.922 and 0.557 for observed versus fitted concentrations, respectively). The developed model will be useful for conducting future analyses to support ME1100 dose selection.

Pharmacokinetics of arbekacin in bronchial epithelial lining fluid of healthy volunteers.

INTRODUCTION: Arbekacin is a unique aminoglycoside antibiotic with anti-methicillin-resistant Staphylococcus aureus activity. The efficacy of aminoglycosides is related to their serum maximum concentration. Local concentration of antibiotics in pulmonary epithelial lining fluid, rather than its serum concentration, can help determine its clinical efficacy more precisely for treatment of respiratory infectious disease. The objective of this study was to sequentially measure arbekacin concentration in epithelial lining fluid after infusion of a single clinically available dose. METHOD: After the initial blood sampling, arbekacin was intravenously infused into 6 healthy volunteers over 1 h. Epithelial lining fluid and serum samples were collected by bronchoscopic microsampling 1, 1.5, 2, 2.5, 3, 4, 5, and 6 h after the start of 200 mg arbekacin infusion. RESULTS: Each probe sampled 10.1 ± 5.2 µl bronchial epithelial lining fluid. The sample dilution factor was 266.7 ± 157.1. Drug concentration was successfully measured in all but 2 of the epithelial lining fluid samples. The maximum concentration of arbekacin in epithelial lining fluid and serum was 10.4 ± 1.9 µg/ml and 26.0 ± 12.2 µg/ml, respectively. The ratio of the maximum drug concentration in the epithelial lining fluid to that in the serum was 0.47 ± 0.19. CONCLUSIONS: The maximum concentration of epithelial lining fluid reached levels that would effectively treat most clinical strains of methicillin-resistant S. aureus.

Rapid quantification of the aminoglycoside arbekacin in serum using high performance liquid chromatography-tandem mass spectrometry.

BACKGROUND: This project entails the development and validation of a method for quantification of the aminoglycoside antibiotic arbekacin in serum using liquid chromatography tandem mass spectrometry (LC-MS/MS) for therapeutic drug monitoring in future clinical trials. METHODS: Following a protein precipitation with 0.3 mol/l perchloric acid containing internal standard dibekacin at a concentration of 0.6 µg/ml, human serum samples containing arbekacin were analyzed using a Hypersil Gold PFP column and a liquid chromatography system. Elution occurred with a gradient of water and acetonitrile, each containing 0.05% (v/v) trifluoroacetic acid and 0.1% (v/v) formic acid. Analytes were detected over a 3.25 minute run time using a tandem mass spectrometer with a heated electrospray-ionization (HESI) source in positive ionization mode with selected reaction monitoring (SRM). Matrix effects, carryover, linearity, recovery, precision, and limit of quantification were carefully evaluated. RESULTS: The limit of quantification for arbekacin was 0.1 µg/ml. All simple and total precision CV's were less than 6.2%. The method was linear from 0.1 µg/ml to 45.9 µg/ml (slope of 0.973). The mean recovery ranged from 94.7 to 103.8%. No matrix effects were detected. CONCLUSIONS: This developed and validated LC-MS/MS method allows for the quantification of arbekacin in serum following protein precipitation.

Successful combination therapy with vancomycin and arbekacin against infective endocarditis caused by MRSA.

Infective endocarditis caused by methicillin-resistant Staphylococcus aureus (MRSA) is a serious disease and sometimes leads to poor prognosis. We should have several therapeutic options. Arbekacin is one of the aminoglycoside antibiotics, which is more active against MRSA and less nephrotoxic than gentamicin. Here we presented a successfully treated case of severe MRSA endocarditis without any adverse effect by monitoring therapeutic level of vancomycin and arbekacin.

[Evaluation of once a day of arbekacin administration to neonates as a new object of peak concentration].

Once a day of arbekacin (ABK) administrations based on a new object of peak concentration setting on 9-20 microg/mL were performed to 14 neonates. The gestational ages were 27.3 +/- 4.2 weeks. As to the preparing initial dosage, Therapeutic Drug Monitoring Program soft was used. Mean daily dose of 6.2 +/- 0.4 mg/kg bodyweight was administered every 24 to 48 h by 30 min intravenous infusion. Mean serum peak concentrations of ABK and those of trough concentrations were 15.2 +/- 4.3 microg/mL and 2.0 +/- 1.4 microg/mL respectively. The relationship between the measured values (y) and predicted values (x) showed the regression equation y = 0.969 + 0.931x (R2 = 0.769, n = 35), which suggested the usefulness of the dosage design. Overall clinical effectiveness was 78.9% (11/14). There were no obvious adverse effects including abnormal auto auditory brainstem responses and serum creatinine increase. Effectiveness rate and no adverse effects suggested that once a day of ABK therapy in neonate including extremely preterm infant was preferable regimen.

Pharmacokinetics and pharmacodynamics of once-daily arbekacin during continuous venovenous hemodiafiltration in critically ill patients.

This study examined the pharmacokinetics of arbekacin during continuous venovenous hemodiafiltration (CVVHDF) and assessed the pharmacodynamics to consider arbekacin dosage adaptation in CVVHDF. Arbekacin was administered by 0.5-h infusion once daily, using a polymethyl methacrylate membrane hemofilter, to three critically ill patients undergoing CVVHDF; the flow rates were 0.8 l/h for the filtrate and 0.6 l/h for the dialysate. The drug concentrations in plasma and in the filtrate-dialysate were determined using a fluorescence polarization immunoassay and analyzed pharmacokinetically. The average sieving coefficient of arbekacin was 0.739 and the average drug clearance by CVVHDF was 1.03 l/h. A pharmacokinetic model with three compartments (1, central; 2, peripheral; 3, filtrate-dialysate side hemofilter) accurately reflected the concentration-time data for both plasma and filtrate-dialysate. The pharmacokinetic model assessed the pharmacodynamic profile of arbekacin once-daily regimens (0.5-h infusions) at filtrate-dialysate flow rates of 1.4 and 2.8 l/h, and demonstrated that only the 150-mg and 200-mg regimens achieved an effective target range for C(max) (9-20 microg/ml), suggesting that empirical dosages lower than the usual 150-200 mg should be avoided in patients undergoing CVVHDF. The minimum regimens needed to achieve an effective pharmacodynamic target for the free C(max)/MIC ratio (>8) were 75 mg for an MIC of 0.5 microg/ml, 200 mg for an MIC of 2 microg/ml, and 400 mg for an MIC of 4 microg/ml. These results will help us to better understand the pharmacokinetics of arbekacin during CVVHDF, while also helping in the selection of the appropriate arbekacin regimens, based on a pharmacodynamic assessment, for patients receiving this renal replacement therapy.

[Analysis of factors affecting long-term administration of anti-methicillin resistant Staphylococcus aureus (MRSA) drugs].

In this study, we aimed to determine an index of anti-MRSA drugs for long-term treatment. We examined adult patients to whom the anti-MRSA drugs arbekacin sulfate (ABK), vancomycin hydrochloride (VCM), and teicoplanine (TEIC) had been administered in the St. Marianna University School of Medicine, Yokohama City Seibu Hospital, for 1, year. The number of patients treated for>or==14 days was 22 (31%) among 71 patients. Immunosuppressive agent positivity (p=0.07), albumin (ALB) level of or==10 mg/dl (p=0.01),%STAB >or==15% (p=0.11), and the period until the blood drug level is measured (p=0.06) were analyzed with respect to the differences between both groups by univariate analysis. An ALB level of

Artificial neural network modeling to predict the plasma concentration of aminoglycosides in burn patients.

The goal was to use an artificial neural network model to predict the plasma concentration of aminoglycosides in burn patients and identify patients whose plasma antibiotic concentration would be sub-therapeutic based on the patients' physiological data and taking into account burn severity. Physiological data and some indicators of burn severity were collected from 30 burn patients who received arbekacin. A three-layer artificial neural network with five neurons in the hidden layer was used to predict the plasma concentration of arbekacin. Linear modeling for prediction of plasma concentration and logistic regression modeling for the classification of patients were also used and the predictive performance was compared to results from the artificial neural network model. Dose, body mass index, serum creatinine concentration and amount of parenteral fluid were selected as covariates for the plasma concentration of arbekacin. Area of burn after skin graft was a good covariate for indicating burn severity. Predictive performance of the artificial neural network model including burn severity was much better than linear modeling and logistic regression analysis. An artificial neural network model should be helpful for the prediction of plasma concentration using patients' physiological data, and burn severity should be included for improved prediction in burn patients. Because the relationship between burn severity and plasma concentration of aminoglycosides is thought to be nonlinear, it is not surprising that the artificial neural network model showed better predictive performance compared to the linear or logistic regression models.

Population pharmacokinetics of arbekacin, vancomycin, and panipenem in neonates.

Immature renal function in neonates requires antibiotic dosage adjustment. Population pharmacokinetic studies were performed to determine the optimal dosage regimens for three types of antibiotics: an aminoglycoside, arbekacin; a glycopeptide, vancomycin; and a carbapenem, panipenem. Eighty-three neonates received arbekacin (n = 41), vancomycin (n = 19), or panipenem (n = 23). The postconceptional ages (PCAs) were 24.1 to 48.4 weeks, and the body weights (BWs) ranged from 458 to 5,200 g. A one-compartment open model with first-order elimination was applied and evaluated with a nonlinear mixed-effect model for population pharmacokinetic analysis. In the fitting process, the fixed effects significantly related to clearance (CL) were PCA, postnatal age, gestational age, BW, and serum creatinine level; and the fixed effect significantly related to the volume of distribution (V) was BW. The final formulas for the population pharmacokinetic parameters are as follows: CL(arbekacin) = 0.0238 x BW/serum creatinine level for PCAs of <33 weeks and CL(arbekacin) = 0.0367 x BW/serum creatinine level for PCAs of > or = 33 weeks, V(arbekacin) = 0.54 liters/kg, CL(vancomycin) = 0.0250 x BW/serum creatinine level for PCAs of <34 weeks and CL(vancomycin) = 0.0323 x BW/serum creatinine level for PCAs of > or = 34 weeks, V(vancomycin) = 0.66 liters/kg, CL(panipenem) = 0.0832 for PCAs of <33 weeks and CL(panipenem) = 0.179 x BW for PCAs of > or = 33 weeks, and V(panipenem) = 0.53 liters/kg. When the CL of each drug was evaluated by the nonlinear mixed-effect model, we found that the mean CL for subjects with PCAs of <33 to 34 weeks was significantly smaller than those with PCAs of > or = 33 to 34 weeks, and CL showed an exponential increase with PCA. Many antibiotics are excreted by glomerular filtration, and maturation of glomerular filtration is the most important factor for estimation of antibiotic clearance. Clinicians should consider PCA, serum creatinine level, BW, and chemical features when determining the initial antibiotic dosing regimen for neonates.

Pharmacokinetics and dosing of arbekacin in preterm and term newborn infants.

BACKGROUND: The objective of the present study was to determine pharmacokinetic variables and to characterize a new initial dosing regimen of arbekacin (ABK) for preterm and term newborn infants. PATIENTS AND METHODS: Subjects were 40 infants treated with ABK in a tertiary care neonatal unit over a period of 18 months. At birth, the infants were 23 5/7-40 0/7 weeks and weighed 530-3428 g. Serum ABK concentration was measured at two points in a course of treatment. Data were analyzed by a one-compartment model to obtain volume of distribution (Vd) and clearance (CL) of ABK. These variables were correlated with the patients' demographic and laboratory data. The new initial dosing regimen was determined based on these data. RESULTS: Sixty pairs of blood samples were taken from the infants. They were divided into three groups: preterm early (PE), gestational age (GA) < 37 weeks and postnatal age (PNA) < 28 days; preterm late (PL), GA < 37 weeks and PNA >or= 28 days; and term (T), GA >or= 37 weeks and PNA < 28 days. The Vd was 0.50 +/- 0.02, 0.48 +/- 0.04, and 0.43 +/- 0.03 L/kg, and CL was 0.59 +/- 0.04, 1.12 +/- 0.10, and 0.78 +/- 0.09 mL/min per kg (mean +/- SEM) in PE, PL, and T, respectively. The new dosing regimen is 5 mg/kg every 48 h, 5 mg/kg every 24 h, and 4 mg/kg every 24 h for PE, PL, and T, respectively. CONCLUSIONS: With the new dosing regimen, more infants achieved serum ABK levels within the optimal range than the conventional one.

Prediction of plasma levels of aminoglycoside antibiotic in patients with severe illness by means of an artificial neural network simulator.

PURPOSE: The purpose of this work was to predict plasma peak and trough levels of an aminoglycoside antibiotic in patients with severe illness in an intensive care unit by a novel approach. Plasma levels were predicted based on the values of 15 physiological measurements using an artificial neural network (ANN) simulator. METHOD: A data set of 15 physiological measurements for 30 patients was used to develop the model. The ANN structure consisted of three layers: an input layer comprised of 15 processing elements, a hidden layer comprised of 10 processing elements with a sigmoid function as an activation function, and an output layer of two processing elements (peak and trough levels). The weight between neurons was trained according to the delta rule back-propagation of errors algorithm. Predicted values were obtained by "leave-one-out" experiments by both ANN and multiple linear regression analysis (MLRA). RESULTS: The correlation coefficients between observed and predicted values obtained by ANN prediction using standardized data sets were r=0.825 and r=0.854 for peak and trough levels, respectively. The correlation coefficients obtained by MLRA were r=0. 037 and r=0.276 for peak and trough levels, respectively. These results indicate that ANN shows better performance in prediction of aminoglycoside plasma levels from patients' physiological measurements than MLRA. CONCLUSIONS: Prediction of plasma levels of antibiotic in patients with severe illness by ANN was superior to the standard statistical method. Standardization of input data was found to be important for better prediction. ANN has some advantages over standard statistical methods, as it can recognize complex relationships in the data.

Toxicokinetic approach for evaluating respiratory depression effect of aminoglycoside antibiotics: species differences in drug susceptibility.

The respiratory depression effect of aminoglycoside antibiotics was studied by a toxicokinetic approach, and species differences in drug susceptibility were elucidated based on plasma concentrations. An allometric relationship was obtained between total body clearance of arbekacin, a novel aminoglycoside antibiotic, and animal body weight. The power was 0.714, less than unity, which means smaller animals have higher ability to eliminate the drug from the body and need higher doses to attain a certain steady-state plasma concentration. When the infusion rate of arbekacin was altered, the total dose required to cause the toxicologic endpoint for respiratory depression (60 per cent loss of respiratory rates) changed greatly, but the plasma concentration of arbekacin at the toxicologic endpoint remained at almost a constant level. The concentration at the toxicologic endpoint was similar for all of the animal species examined and was 650-950 micrograms ml-1, even though the total dose required to cause the toxicologic endpoint varied greatly among the animal species. These findings suggest that the toxicologic effect compartment for respiratory depression is indistinguishable from the plasma compartment, and that species differences in the total dose are due to differences in pharmacokinetics of the drug, mainly in the total body clearance, but not to differences in intrinsic susceptibility to the drug.

[Pharmacokinetics of arbekacin in healthy volunteers and patients with renal insufficiency].

Pharmacokinetics of arbekacin (HBK), a new aminoglycoside, was studied. Serum concentrations and urinary excretion were determined after single intravenous drip infusion of 100 mg HBK for 1 hour to healthy volunteers and patients with renal insufficiency of various kinds. The drug concentration was determined with bioassay, fluorescence polarization immunoassay (FPIA) and high-performance liquid chromatography (HPLC). Pharmacokinetic analysis was made in accordance with the two-compartment open model, and 24-hour endogenous creatinine clearance (Ccr) was used as the renal function index. In all cases peak serum levels were detected 1 hour after administration, and similar values were noted regardless of subjects' proficiencies of renal function. However, the serum clearance during beta-phase tended to be prolonged parallel with the degree of renal insufficiency. The excretion of HBK into urine was prolonged and cumulative recovery tended to be decreased in association with the decreased valued of Ccr.

[Pharmacokinetics of habekacin in patients with chronic renal insufficiency]. / Pharmacocinétique de l'habékacine chez les malades atteints d'insuffisance rénale chronique.

Pharmacokinetics of habekacin, a new semisynthetic aminoglycoside antibiotic were investigated in six healthy subjects and twenty-five uraemic patients (six of whom were on hemodialysis) after a single 3 mg/kg Im or IV administration. After the IM injection, the peak serum levels were higher and the times to peak levels were longer in patients with renal impairment than in healthy subjects. Elimination serum half-life increased in relation to the degree of renal impairment, from 2 h in normal subjects to 32 h in patients with creatinine clearance below 10 ml/min. Renal impairment did not significantly modify the apparent volume of distribution. After a single 3 mg/kg dose as one hour-IV infusion in six hemodialysis patients, elimination half-life averaged 48 h and 5 h, out of and on a 4 to 5 hour-hemodialysis session, respectively. Habekacin pharmacokinetic parameters appeared to be similar to those of the other available aminoglycoside antibiotics.

[Pharmacokinetics of arbekacin in dogs. I. Serum concentration and urinary excretion].

A new aminoglycoside antibiotic, arbekacin (HBK) was intramuscularly and intravenously administered to dogs in order to study its pharmacokinetics in comparison to amikacin (AMK). The results obtained are summarized as follows. Serum concentrations of HBK were well correlated with dose levels. The dose-serum concentration relationship with HBK was similar to other aminoglycoside antibiotics. Biological half-lives of HBK and AMK were both about 1 hour in dogs. This was also similar to other aminoglycoside antibiotics. There was no significant difference in peak serum concentrations between 1 hour intravenous infusion and intramuscular injection of HBK at 2 mg/kg in dogs. Repetitive administration of HBK to dogs at 2 mg/kg twice a day for 14 days did not affect its serum concentration and biological half-life. Urinary excretion of HBK in dogs in 24 hours after administration accounted for about 80-90%.

[Rapid microdetermination of 2 aminoglycosides by high-performance liquid chromatography in the plasma, bile and urine. Correlation of high-performance liquid chromatography and fluorescence polarization for plasma assays]. / Microdétermination rapide de deux aminosides par chromatographie liquide haute performance dans le plasma, la bile et l'urine. Corrélation chromatographie liquide haute performance-polarisation de fluorescence pour les dosages plasmatiques.

An HPLC method for determination of dibekacin and amikacin in various biological samples is described. A step gradient elution and fluorescence detection carried out through an on line post column derivatization system with OPT is used. The chromatographic conditions allow simple and rapid preparation, so that a result can be obtained within twenty minutes. The small volume required (150 microliters) and the rapid sample clean-up are advantageous for routine use even in pediatric patients. The good sensitivity (dibekacin: 0,44 mumol/l - amikacin: 0,35 mumol/l), reproducibility and specificity indicate it to be suitable for pharmacokinetic studies. Results obtained from HPLC were in excellent agreement with those of FPIA for both dibekacin and amikacin (r greater than or equal to 0,98).

In-vitro interaction between dibekacin and penicillins.

The in-vitro inactivation kinetics of dibekacin by three semi-synthetic penicillins (carbenicillin, ampicillin and ticarcillin) were studied taking into account the influence of certain factors such as time, the concentration of the semi-synthetic penicillin in the sample and the reaction medium used in the inactivation process. For a dibekacin/beta lactam concentration ratio of 1/100, the maximum percentage of inactivation of dibekacin was obtained for ticarcillin (99%), followed by carbenicillin (90%) and finally by ampicillin (65%) over a period of 45 h. For carbenicillin and ampicillin a linear relationship was established between the inactivation constant (Ki) and the concentration of these penicillins in the sample. It was also found that under the same experimental conditions the inactivation percentage in human serum was smaller than that observed in buffered solution, pH = 7.4. It was observed that the degree of inactivation of dibekacin and gentamicin was similar under the experimental conditions employed in this study.