The ectoenzyme E-NPP3 negatively regulates ATP-dependent chronic allergic responses by basophils and mast cells.

Crosslinking of the immunoglobulin receptor FcεRI activates basophils and mast cells to induce immediate and chronic allergic inflammation. However, it remains unclear how the chronic allergic inflammation is regulated. Here, we showed that ecto-nucleotide pyrophosphatase-phosphodiesterase 3 (E-NPP3), also known as CD203c, rapidly induced by FcεRI crosslinking, negatively regulated chronic allergic inflammation. Basophil and mast cell numbers increased in Enpp3(-/-) mice with augmented serum ATP concentrations. Enpp3(-/-) mice were highly sensitive to chronic allergic pathologies, which was reduced by ATP blockade. FcεRI crosslinking induced ATP secretion from basophils and mast cells, and ATP activated both cells. ATP clearance was impaired in Enpp3(-/-) cells. Enpp3(-/-)P2rx7(-/-) mice showed decreased responses to FcεRI crosslinking. Thus, ATP released by FcεRI crosslinking stimulates basophils and mast cells for further activation causing allergic inflammation. E-NPP3 decreases ATP concentration and suppresses basophil and mast cell activity.

Lymphangioleiomyoma of the Uterus and Pelvic Lymph Nodes: A Report of 3 Cases, Including the Potentially Earliest Manifestation of Extrapulmonary Lymphangioleiomyomatosis.

We present 3 cases of extrapulmonary lymphangioleiomyomatosis (LAM) identified incidentally in the uterine corpus and pelvic nodes resected for other reasons. One patient, a 47-yr-old female with corpus cancer, underwent a total hysterectomy and nodal dissection; the other 2 patients, aged 44 and 49 yr, underwent simple hysterectomy for corpus leiomyomas. None of the patients had evidence of tuberous sclerosis complex or any significant lesions in other organs. An area of spindle cell proliferation, intimately associated with dilated and tortuous lymphatic vessels, was found in the myometrium of all 3 patients, and nodal involvement with spindle cell proliferation was observed in the patient with corpus cancer. The spindle cells had faintly eosinophilic cytoplasm and a bland appearance. They were immunoreactive for α-SMA, gp100 (HMB45), and Melan-A. Tumor cell clusters lined with a single layer of lymphatic endothelium were floating in the lymphatic vessel lumen. These lesions were diagnosed as lymphangioleiomyoma in the uterine corpus and associated lymph nodes. Two of the cases seemed to be the earliest manifestations of extrapulmonary LAM, and the other case represents early-phase metastasis of LAM from the uterus. The present cases support the speculation that the uterus is the primary source of LAM cells.

CYP7A1 expression in hepatocytes is retained with upregulated fibroblast growth factor 19 in pediatric biliary atresia.

AIM: Bile acid biosynthesis is strictly regulated under physiological conditions. The expression of fibroblast growth factor (FGF) 19 is induced when bile acids bind to the farnesoid X receptor in the intestinal epithelium. Fibroblast growth factor 19 is then transported by the portal flow, causing transcriptional inhibition of cytochrome P450, family 7, subfamily A, polypeptide 1 (CYP7A1), a key enzyme in bile acid biosynthesis, through the extracellular signal-regulated kinase (ERK) pathway. However, the regulatory mechanisms of these signaling pathways in hepatocytes under chronic cholestasis remain unclear. We investigated the regulation of these signaling pathways in patients with biliary atresia (BA). METHODS: We analyzed the regulation of molecules in these signaling pathways using liver and serum samples from eight BA children and four non-cholestatic disease controls. RESULTS: CYP7A1 mRNA expression was not inhibited in BA microdissected hepatocyte-enriched tissue (HET) despite high serum bile acid concentrations. The FGF19 protein was synthesized in BA HET, and its serum concentration was elevated. Fibroblast growth factor receptor 4 was phosphorylated in BA livers. However, ERK phosphorylation was significantly reduced. We examined SPRY2 expression to determine how the ERK pathway was inactivated downstream of the FGF receptor; the expression was significantly increased in BA HET. CONCLUSIONS: This is the first study to measure the CYP7A1 mRNA levels in human BA HET. Fibroblast growth factor 19 was increased in BA hepatocytes. By focusing on its regulation in hepatocytes, we showed that the FGF19 pathway did not suppress bile acid synthesis, probably due to an altered mechanism involving upregulated SPRY2 in BA patients.

Ecto-nucleoside triphosphate diphosphohydrolase 7 controls Th17 cell responses through regulation of luminal ATP in the small intestine.

Extracellular ATP is released from live cells in controlled conditions, as well as dying cells in inflammatory conditions, and, thereby, regulates T cell responses, including Th17 cell induction. The level of extracellular ATP is closely regulated by ATP hydrolyzing enzymes, such as ecto-nucleoside triphosphate diphosphohydrolases (ENTPDases). ENTPDase1/CD39, which is expressed in immune cells, was shown to regulate immune responses by downregulating the ATP level. In this study, we analyzed the immunomodulatory function of ENTPDase7, which is preferentially expressed in epithelial cells in the small intestine. The targeted deletion of Entpd7 encoding ENTPDase7 in mice resulted in increased ATP levels in the small intestinal lumen. The number of Th17 cells was selectively increased in the small intestinal lamina propria in Entpd7(-/-) mice. Th17 cells were decreased by oral administration of antibiotics or the ATP antagonist in Entpd7(-/-) mice, indicating that commensal microbiota-dependent ATP release mediates the enhanced Th17 cell development in the small intestinal lamina propria of Entpd7(-/-) mice. In accordance with the increased number of small intestinal Th17 cells, Entpd7(-/-) mice were resistant to oral infection with Citrobacter rodentium. Entpd7(-/-) mice suffered from severe experimental autoimmune encephalomyelitis, which was associated with increased numbers of CD4(+) T cells producing both IL-17 and IFN-γ. Taken together, these findings demonstrate that ENTPDase7 controls the luminal ATP level and, thereby, regulates Th17 cell development in the small intestine.

Gas chromatography-electron ionization-mass spectrometry quantitation of valproic acid and gabapentin, using dried plasma spots, for therapeutic drug monitoring in in-home medical care.

A simple and sensitive gas chromatography-electron ionization-mass spectrometry (GC-EI-MS) method using dried plasma spot testing cards was developed for determination of valproic acid and gabapentin concentrations in human plasma from patients receiving in-home medical care. We have proposed that a simple, easy and dry sampling method is suitable for in-home medical patients for therapeutic drug monitoring. Therefore, in the present study, we used recently developed commercially available easy handling cards: Whatman FTA DMPK-A and Bond Elut DMS. In-home medical care patients can collect plasma using these simple kits. The spots of plasma on the cards were extracted into methanol and then evaporated to dryness. The residues were trimethylsilylated using N-methyl-N-trimethylsilyltrifluoroacetamide. For GC-EI-MS analysis, the calibration curves on both cards were linear from 10 to 200 µg/mL for valproic acid, and from 0.5 to 10 µg/mL for gabapentin. Intra- and interday precisions in plasma were both ≤13.0% (coefficient of variation), and the accuracy was between 87.9 and 112% for both cards within the calibration curves. The limits of quantification were 10 µg/mL for valproic acid and 0.5 µg/mL for gabapentin on both cards. We believe that the present method will be useful for in-home medical care.

Penetration of meropenem into human pancreatic juice.

This study examined the penetration of meropenem into pancreatic juice in patients who had undergone hepato-biliary-pancreatic surgery. The patients received a 0.5-h infusion of 500 mg meropenem. The observed maximum concentration (mean ± standard deviation, n = 5) was 39.1 ± 11.2 µg/ml at 0.5 h in plasma and 2.12 ± 0.73 µg/ml at 1.10 ± 0.14 h in pancreatic juice. The pancreatic juice/plasma ratio was 0.06 ± 0.02. The area under the drug concentration-time curve was 73.0 ± 37.5 µg•h/ml in plasma and 4.24 ± 2.77 µg•h/ml in pancreatic juice. The pancreatic juice/plasma ratio was 0.06 ± 0.01. The mean drug-exposure times above 0.125 µg/ml and 0.25 µg/ml (the minimum inhibitory concentrations (MIC) for common pathogens) in pancreatic juice were 99.4% and 87.3%, respectively, for 500 mg meropenem 3 times daily. This commonly used regimen for pancreatitis achieved the drug-exposure time target (40% of the time above the MIC) at the action site, despite the low penetrability of meropenem.

Impact of cow's milk allergy on enterocolitis associated with Hirschsprung's disease.

PURPOSE: To investigate the impact of cow's milk allergy (CMA) on infants with Hirschsprung's disease (HD). METHODS: Twenty-four patients, who developed gastrointestinal symptoms before the age of 60 days and underwent surgery for HD in the period between January 2003 and December 2012, were enrolled in this study. They were divided into two groups based on CMA-related findings: stimulation index of lymphocyte stimulation test >300 % and the presence of eosinophilic infiltration in the resected colon. Ten patients were determined specimen as not having CMA (Group A), because they did not satisfy any of the criteria. The remaining 14 were determined as having possible CMA (Group B), because they satisfied either or both findings. Patient background characteristics, pre- and postoperative clinical history, and laboratory data were compared between Groups A and B. RESULTS: Pre- and postoperative enterocolitis did not occur in Group A patients. Postoperative enterocolitis was more frequent in Group B than in Group A (p = 0.04). Other clinical and laboratory data did not show significant difference between the two groups. CONCLUSION: CMA is a possible risk factor for postoperative enterocolitis in patients with HD.

Development and validation of a GC-EI-MS method with reduced adsorption loss for the quantification of olanzapine in human plasma.

A simple and sensitive GC-EI-MS method using solvent extraction and evaporation was developed for the determination of olanzapine concentrations in plasma samples. Because olanzapine and promazine, which was used as the internal standard (IS), are nitrogenous bases, they can adsorb to the weakly acidic silanol groups on the surfaces of glass centrifuge tubes during solvent extraction and evaporation. Silylation of the glass tubes, addition of triethylamine (TEA), and use of a sample solution with a basic pH could prevent adsorption loss. The extraction method involved mixing plasma (500 µL) in a silylated glass tube with a promazine solution (2 µg/mL, 25 µL) in methanol containing 1% TEA. After addition of aqueous sodium carbonate (0.5 mol/L, pH 11.1, 1 mL) and extraction into 3 mL of dichloromethane/n-hexane (1:1, v/v) containing 1% TEA, the organic phase was evaporated to dryness in a silylated glass tube. The residue was dissolved in ethyl acetate containing 1% TEA (50 µL). For GC-EI-MS analysis, the calibration curves of olanzapine in human plasma were linear from 0.5 to 100 ng/mL. Intra- and interday precisions in plasma were both less than 7.36% (coefficient of variation), and the accuracy was between 94.6 and 110% for solutions with concentrations greater than 0.5 ng/mL. The limit of quantification was 0.5 ng/mL in plasma. The assay was applied to therapeutic drug monitoring in samples from three schizophrenic patients.

Humoral immunity is involved in the development of pericentral fibrosis after pediatric live donor liver transplantation.

Although LT can be successful for treating end-stage liver disease in children, some patients develop fibrosis around the central vein area (PCF). This raises the possibility that PCF could lead to later cirrhosis and graft failure. Here, we report a retrospective immunohistochemical study of 28 patients who received a live donor liver transplant. We assessed the incidence and etiology of PCF using CD3, CD20, HLA-DR, and C4d-specific antibodies. Histological evidence of PCF was found in 13 cases (46.4%), of which 11 (84.6%) had experienced ACR and/or CP events post-transplant. Immunohistochemical evaluation revealed significantly stronger staining with these antibodies in the central vein area in PCF, especially for CD20 and C4d. This implies humoral immunopathology and suggests involvement of humoral immunity in the development of PCF. These results further imply that suppression of cellular immunity alone is insufficient to prevent PCF. We therefore suggest that suppression of both humoral and cellular immunity in combination would be required for prevention of PCF.

Clinical pharmacokinetics of meropenem and biapenem in bile and dosing considerations for biliary tract infections based on site-specific pharmacodynamic target attainment.

The present study investigated the pharmacokinetics of meropenem and biapenem in bile and estimated their pharmacodynamic target attainment at the site. Meropenem (0.5 g) or biapenem (0.3 g) was administered to surgery patients (n = 8 for each drug). Venous blood samples and hepatobiliary tract bile samples were obtained at the end of infusion (0.5 h) and for up to 5 h thereafter. Drug concentrations in plasma and bile were analyzed pharmacokinetically and used for a Monte Carlo simulation to predict the probability of attaining the pharmacodynamic target (40% of the time above the MIC). Both drugs penetrated similarly into bile, with mean bile/plasma ratios of 0.24 to 0.25 (maximum drug concentration) and 0.30 to 0.38 (area under the drug concentration-time curve). The usual regimens of meropenem (0.5 g every 8 h [q8h]) and biapenem (0.3 g q8h) (0.5-h infusions) achieved similar target attainment probabilities in bile (≥ 90%) against Escherichia coli, Klebsiella pneumoniae, and Enterobacter cloacae isolates. However, against Pseudomonas aeruginosa isolates, meropenem at 1 g q8h and biapenem at 0.6 g q8h were required for values of 80.7% and 71.9%, respectively. The biliary pharmacodynamic-based breakpoint (the highest MIC at which the target attainment probability in bile was ≥ 90%) was 1 mg/liter for 0.5 g q8h and 2 mg/liter for 1 g q8h for meropenem and 0.5 mg/liter for 0.3 g q8h and 1 mg/liter for 0.6 g q8h for biapenem. These results help to define the clinical pharmacokinetics of the two carbapenems in bile while also helping to rationalize and optimize the dosing regimens for biliary tract infections based on site-specific pharmacodynamic target attainment.

Modification of yeast characteristics by soy peptides: cultivation with soy peptides represses the formation of lipid bodies.

We have previously reported that the cultivation of yeast cells with soy peptides can improve the tolerance of yeast to freeze-thaw stress (Izawa et al. Appl Microbiol Biotechnol 75:533-538, 2007), indicating that soy peptides can modify the characteristics of yeast cells. To gain a greater understanding of the potencies of soy peptides, we further investigated the effects of cultivation with soy peptides on yeast physiology and found that soy peptides repress the formation of lipid bodies (also called lipid droplets or lipid particles), in which neutral lipids are accumulated. Compared with casein peptone, bacto peptone, yeast nitrogen base, and free amino acid mixtures having the same amino acid composition as soy peptides, cultivation with soy peptides caused decreased levels of mRNAs of neutral lipid synthesis-related genes, such as DGA1, and repressed the formation of lipid bodies and accumulation of triacylglycerol. These results indicate that soy peptides affect the lipid metabolism in yeast cells, and also demonstrate a potentiality of edible natural ingredients as modifiers of the characteristics of food microorganisms.

Vacuolar morphology of Saccharomyces cerevisiae during the process of wine making and Japanese sake brewing.

Although ethanol and osmotic stress affect the vacuolar morphology of Saccharomyces cerevisiae, little information is available about changes in vacuolar morphology during the processes of wine making and Japanese sake (rice wine) brewing. Here, we elucidated changes in the morphology of yeast vacuoles using Zrc1p-GFP, a vacuolar membrane protein, so as to better understand yeast physiology during the brewing process. Wine yeast cells (OC-2 and EC1118) contained highly fragmented vacuoles in the sake mash (moromi) as well as in the grape must. Although sake yeast cells (Kyokai no. 9 and no. 10) also contained highly fragmented vacuoles during the wine-making process, they showed quite a distinct vacuolar morphology during sake brewing. Since the environment surrounding sake yeast cells in the sake mash did not differ much from that surrounding wine yeast cells, the difference in vacuolar morphology during sake brewing between wine yeast and sake yeast was likely caused by innate characters.

Population pharmacokinetics and pharmacodynamics of meropenem in Japanese pediatric patients.

The aims of this study were to develop a population pharmacokinetic model for meropenem in Japanese pediatric patients, and to use this model to assess the pharmacodynamics of meropenem regimens against common bacterial populations. Pharmacokinetic data were pooled from nine separate studies (229 plasma samples and 61 urine samples from 40 infected children), modeled using the NONMEM program, and used for a pharmacodynamic simulation to estimate the probabilities of attaining the bactericidal target (40% of the time above the MIC for the bacterium). In the final population pharmacokinetic model, body weight (BW, kg) was the most significant covariate: Cl(r) (l/h) = 0.254 x BW, Cl(nr) (l/h) = 3.45, V (c) (l) = 0.272 x BW, Q (l/h) = 1.65, and V (p) (l) = 0.228 x BW, where Cl(r) and Cl(nr) are the renal and non-renal clearances, V (p) and V (c) are the volumes of distribution of the central and peripheral compartments, and Q is the intercompartmental (central-peripheral) clearance. In most typical patients (BW = 10, 20, and 30 kg), the approved regimens of 10-40 mg/kg, three times a day (0.5-h infusions), achieved a target attainment probability of >80% against Escherichia coli, Streptococcus pneumoniae, methicillin-susceptible Staphylococcus aureus, Haemophilus influenzae, and Pseudomonas aeruginosa isolates. The results of this study provide a better understanding of the pharmacokinetics and pharmacodynamics of meropenem in Japanese pediatric patients.

Pharmacokinetic­pharmacodynamic target attainment analysis of meropenem in Japanese adult patients.

This study was a pharmacokinetic (PK)-pharmacodynamic (PD) target attainment analysis of meropenem in Japanese adult patients. Plasma drug concentration data (265 samples from 42 patients) were used for population PK modeling and Monte Carlo simulation to assess the probability of attaining the PK-PD target (40% of the time above the MIC for the bacterium). The final population PK model identified creatinine clearance (Cl(cr), ml/min) and body weight (BW, kg) as the most significant covariates: Cl (l/h) = 0.0905 × Cl(cr) + 2.03, V(c)(l) = 0.199 9 BW, Q (l/h) = 4.02, and V(p) (l) = 4.55, where Cl is the clearance, Vc and Vp are the volumes of distribution of the central and peripheral compartments, respectively, and Q is the intercompartmental clearance. The Monte Carlo simulation developed the PK-PD breakpoints (the highest MIC values at which the probabilities of target attainment in plasma are 80% or more) for meropenem regimens, the values of which varied with the Cl(cr) and BW of the patient. The simulation also demonstrated that 0.25 g every 12 h (0.5-h infusion) achieved a target attainment probability of 82.4-100% against Escherichia coli, methicillin-susceptible Staphylococcus aureus, Haemophilus influenzae, and Streptococcus pneumoniae isolates. However, against Pseudomonas aeruginosa isolates, 0.5 g every 8 h or 1 g every 8 h was required to achieve 80% or more probability in most typical patients. These results provide a PK-PD-based strategy for tailoring a meropenem regimen according to Clcr and BW of a Japanese adult patient and susceptibility of the causative bacteria.

Assessment of micafungin regimens by pharmacokinetic-pharmacodynamic analysis: a dosing strategy for Aspergillus infections.

OBJECTIVES: A pharmacokinetic (PK)-pharmacodynamic (PD) analysis was conducted to assess various micafungin regimens for Candida and Aspergillus infections, as appropriate regimens have not been established, especially for Aspergillus infections. METHODS: Plasma drug concentrations (48 samples from 10 adult patients with haematological malignancies) were determined chromatographically, and used for population PK modelling and Monte Carlo simulation to evaluate the ability of regimens (1 h infusions) to attain genus-dependent PK-PD targets, namely fungistatic and fungicidal targets against Candida spp. [area under the plasma unbound (1%) drug concentration-time curve over 24 h/MIC (fAUC/MIC) = 10 and 20] and an effective concentration target against Aspergillus spp. (plasma unbound drug concentration = 0.05 mg/L). RESULTS: Mean (variance) values for two-compartment PK model parameters were: clearance, 0.762 L/h (15.4%); volume of central compartment, 9.25 L (24.6%); intercompartmental clearance, 7.02 L/h (fixed); and volume of peripheral compartment, 8.86 L (71.8%). The Monte Carlo simulation demonstrated that 50 mg once daily and 100 mg once daily for the fungistatic and fungicidal targets achieved a >95% probability of target attainment against Candida spp. To achieve such probability against Aspergillus spp., 250 mg once daily or 100 mg twice daily was required. CONCLUSIONS: These results rationalize the approved micafungin dosages for Candida infections (50 mg once daily for prophylaxis and 100-150 mg once daily for treatment), and on the basis of these results we propose a PK-PD-based dosing strategy for Aspergillus infections. A regimen of 200-250 mg/day should be initiated to ensure the likelihood of a favourable outcome. The regimen can be optimized by decreasing the dosing interval.

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.

Heat shock and ethanol stress provoke distinctly different responses in 3'-processing and nuclear export of HSP mRNA in Saccharomyces cerevisiae.

Under conditions of heat shock at 42 degrees C, mRNAs of HSP (heat shock protein) genes are exported out of the nucleus, whereas bulk poly(A)(+) (polyadenylated) mRNA shows a nuclear accumulation in Saccharomyces cerevisiae. Such a selective mRNA export seems an efficacious strategy of yeast cells to adapt rapidly to stress. Although ethanol stress (10%, v/v) as well as heat shock blocks the export of bulk poly(A)(+) mRNA, the differences and/or similarity between heat shock and ethanol stress in the mechanisms of selective mRNA export still remain to be clarified. We found that ethanol stress induced transcriptional activation of a subset of yeast HSP genes; however, intriguingly, most such transcripts remained in the nucleus in a hyperadenylated state and, as a consequence, were not translated into HSPs. Elimination of ethanol resulted in a rapid shortening of the poly(A) tails of HSP mRNAs, loss of their nuclear retention, and the coincidental synthesis of the respective HSPs. Since HSP mRNAs are selectively exported from the nucleus in heat-shocked cells, yeast cells respond differently to ethanol stress and heat shock in the 3'-processing and transport of HSP mRNAs. Furthermore, these results also suggest that hyperadenylation and nuclear retention of mRNAs might be used as a means to control eukaryotic gene expression under stressed conditions.

Population pharmacokinetic modeling and pharmacodynamic assessment of cefozopran in pediatric patients.

The aims of this study were to develop a population pharmacokinetic model for cefozopran in pediatric patients, and to use this model to evaluate the pharmacodynamics of cefozopran regimens against common bacterial populations. Plasma drug concentration data (110 samples from 31 pediatric patients) were modeled using the NONMEM program. The mean estimate and interindividual variance of the model were used in a Monte Carlo simulation to estimate the probabilities of attaining the bactericidal target for cefozopran (the time which the drug concentration remains above the minimum inhibitory concentration for the bacterium is 70% of the dosing interval). A two-compartment model fitted the data and body weight (BW, kg) was the most significant covariate. The final model was: Cl (l/h) = 0.674 x BW0.538, Vc (l) = 0.00233 x BW2.25 + 1.85, Q (l/h) = 1.46, and Vp (l) = 0.0964 x BW, where Cl is the clearance, Vc, and Vp are the volumes of distribution of the central and peripheral compartments, and Q is the intercompartmental clearance. The approved regimens of 20- or 40-mg/kg four times a day (0.5-h infusions), which were more effective than the corresponding three times a day-regimens, provided sufficient bactericidal effects on common bacterial populations (Escherichia coli, Streptococcus pneumoniae, Haemophilus influenzae, and Pseudomonas aeruginosa) in most typical patients. These results better define the pharmacokinetics of cefozopran and help in the choice of appropriate regimens for pediatric patients.

Optimized dosage and frequency of cefozopran for patients with febrile neutropenia based on population pharmacokinetic and pharmacodynamic analysis.

OBJECTIVES: To establish a cefozopran (a fourth-generation cephem) population pharmacokinetic model using patient data and use it to explore alternative dosage regimens that could optimize the currently used dosing regimen to achieve higher likelihood of pharmacodynamic exposure against pathogenic bacteria. METHODS: We conducted a prospective clinical trial of cefozopran for haematological patients with febrile neutropenia (FN). Twenty-two patients (30 episodes) were selected to receive intravenous cefozopran every 8 h on a daily basis. We gathered concentration data and performed the NONMEM program. The Monte Carlo simulation was performed to assess the pharmacodynamic exposure based on the population pharmacokinetics and MIC. RESULTS: The NONMEM program demonstrated that a two-compartment model provided a best fit for the data, that is, CL of 4.62 (L/h), V1 of 10.3 (L), Q of 4.47 (L/h), and V2 of 4.48 (L). On the basis of the Japanese national surveillance findings for Pseudomonas aeruginosa, methicillin-sensitive Staphylococcus aureus, coagulase-negative Staphylococcus, viridans group streptococci, Escherichia coli and Klebsiella pneumoniae, Monte Carlo simulation data showed that probability of target attainment(T>MIC = 70%) is 67% to 97% for dosing every 8 h, and 48% to 88% for dosing every 12 h. For the patients in whom the efficacy of cefozopran could be evaluated, 17 of 22 patients (77.2%) survived the episode of FN without requiring further antibacterial treatment. CONCLUSIONS: Our study proved that Monte Carlo simulation based on population pharmacokinetics can determine optimized dosage and method. The optimal regimen for this cephem was found to be three times daily.

Pharmacodynamic assessment of doripenem in peritoneal fluid against Gram-negative organisms: use of population pharmacokinetic modeling and Monte Carlo simulation.

This study aimed to assess the peritoneal pharmacodynamics of intravenous doripenem using population pharmacokinetic modeling and Monte Carlo simulation. Drug concentrations in peritoneal fluid (PF) and serum from 11 laparotomy patients and MIC distributions against clinical isolates in Japan for 4 Gram-negative organisms were used. The probabilities of attaining the pharmacodynamic target (40% T > MIC) were greater in PF than in serum. To achieve a > or =90% probability of target attainment in PF, 0.25 g tid and 0.5 g tid (0.5-h infusions) had to be sufficient against Escherichia coli, Klebsiella spp., and Enterobacter cloacae; however, 1 g tid (0.5-h infusion) was required against Pseudomonas aeruginosa. Prolonged (4-h) infusion regimens resulted in increase of the target attainment probabilities in PF for P. aeruginosa. These results should help to achieve a better understanding of the peritoneal pharmacodynamics of doripenem while also helping to rationalize and optimize the dosing regimen for intra-abdominal infections.