Optimal dosing of cefotaxime and desacetylcefotaxime for critically ill paediatric patients. Can we use microsampling?

OBJECTIVES: To describe the population pharmacokinetics of cefotaxime and desacetylcefotaxime in critically ill paediatric patients and provide dosing recommendations. We also sought to evaluate the use of capillary microsampling to facilitate data-rich blood sampling. METHODS: Patients were recruited into a pharmacokinetic study, with cefotaxime and desacetylcefotaxime concentrations from plasma samples collected at 0, 0.5, 2, 4 and 6 h used to develop a population pharmacokinetic model using Pmetrics. Monte Carlo dosing simulations were tested using a range of estimated glomerular filtration rates (60, 100, 170 and 200 mL/min/1.73 m2) and body weights (4, 10, 15, 20 and 40 kg) to achieve pharmacokinetic/pharmacodynamic (PK/PD) targets, including 100% ƒT>MIC with an MIC breakpoint of 1 mg/L. RESULTS: Thirty-six patients (0.2-12 years) provided 160 conventional samples for inclusion in the model. The pharmacokinetics of cefotaxime and desacetylcefotaxime were best described using one-compartmental model with first-order elimination. The clearance and volume of distribution for cefotaxime were 12.8 L/h and 39.4 L, respectively. The clearance for desacetylcefotaxime was 10.5 L/h. Standard dosing of 50 mg/kg q6h was only able to achieve the PK/PD target of 100% ƒT>MIC in patients >10 kg and with impaired renal function or patients of 40 kg with normal renal function. CONCLUSIONS: Dosing recommendations support the use of extended or continuous infusion to achieve cefotaxime exposure suitable for bacterial killing in critically ill paediatric patients, including those with severe or deep-seated infection. An external validation of capillary microsampling demonstrated skin-prick sampling can facilitate data-rich pharmacokinetic studies.

Potential of biomarkers during pharmacological therapy setting for postmenopausal osteoporosis: a systematic review.

BACKGROUND: Biochemical markers of bone turnover (BTMs), such as the bone alkaline phosphatase (bALP), procollagen type I N propeptide (PINP), serum cross-linked C-telopeptides of type I collagen (bCTx), and urinary cross-linked N-telopeptides of type I collagen (NTx), are used to manage therapy monitoring in osteoporotic patients. This systematic review analyzed the potential of these BMTs in predicting the clinical outcomes in terms of BMD, t-score, rate of fractures, and adverse events during the therapy setting in postmenopausal osteoporosis. METHODS: All randomized clinical trials (RCTs) reporting data on biomarkers for postmenopausal osteoporosis were accessed. Only articles reporting quantitative data on the level of biomarkers at baseline and on the outcomes of interest at the last follow-up were eligible. RESULTS: A total of 36,706 patients were retrieved. Greater values of bALP were associated with a greater rate of vertebral (P = 0.001) and non-vertebral fractures (P = 0.0001). Greater values of NTx at baseline were associated with a greater rate of adverse events at the last follow-up (P = 0.02). Greater values of CTx at baseline were associated with a greater rate of adverse events leading to discontinuation (P = 0.04), gastrointestinal adverse events (P = 0.0001), musculoskeletal adverse events (P = 0.04), and mortality (P = 0.04). Greater values of PINP at baseline were associated with greater rates of gastrointestinal adverse events (P = 0.02) at the last follow-up. CONCLUSION: The present analysis supports the adoption of BMTs during pharmacological therapy setting of patients suffering from osteoporosis. LEVEL OF EVIDENCE: I, systematic review of RCTs.

Development and validation of a UHPLC-MS/MS method to measure cefotaxime and metabolite desacetylcefotaxime in blood plasma: a pilot study suitable for capillary microsampling in critically ill children.

Critical illness has been shown to affect the pharmacokinetics of antibiotics, which can lead to ineffective antibiotic exposure and the potential emergence of resistant bacteria. The lack of studies describing antibiotic pharmacokinetics in critically ill children has led to significant off-label dosing. This is, in part, due to the ethical and physiological challenges of removing frequent, large-volume samples from children. Capillary microsampling facilitates the collection of small volumes of blood samples to conduct clinical pharmacokinetic studies. A sensitive, rapid, and accurate ultra-high-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) bioanalytical method to measure cefotaxime and desacetylcefotaxime in 2.8 µL of plasma was developed and validated. Plasma samples were treated with acetonitrile and analytes were separated using a Kinetex C8 (100 × 2.1 mm) column. The chromatographic separation was established using a gradient method, with the mobile phases consisting of acetonitrile and ammonium acetate. An electrospray ionization source interface operated in a positive mode for the multiple reaction monitoring MS/MS analysis of cefotaxime, desacetylcefotaxime, and deuterated cefotaxime (internal standard). The bioanalytical method using microsample volumes met requirements for method validation for both analytes. Cefotaxime had precision within ± 7.3% and accuracy within ± 5% (concentration range of 0.5 to 500 mg/L). Desacetylcefotaxime had precision within ± 9.5% and accuracy within ± 3.5% (concentration range of 0.2 to 10 mg/L). The bioanalytical method was applied for the quantification of cefotaxime and its metabolite to 20 capillary microsamples collected at five time points in one dosing interval from five critically ill children.

Expression levels of blood platelet and C-reactive protein in patients with severely pneumonic and their predictive values for efficacy.

This paper aims to detect the expression levels of blood platelet (PLT) and C-reactive protein (CRP) in severely pneumonic patients and analyze their correlation. For this purpose, eighty-one severely pneumonic patients were retrospectively selected as an observation group and 106 healthy people as a control group. Pretreatment and post-treatment expression levels of PLT and CRP, their predictive values for efficacy, and correlation of PLT, CRP, and PSI scores in observation group after treatment were analyzed. Before treatment, the expression level of PLT in the observation group was higher than the control group (P< 0.05). In the observation group, the expression level of PLT after treatment was significantly lower than that before treatment (P< 0.05). Before treatment, the expression level of CRP in the observation group was higher than the control group (P< 0.05). In the observation group 1) the pretreatment PLT expression level was higher than that in the control group; 2) the post-treatment PLT expression level was significantly lower than that in the pretreatment one; 3) the pretreatment CRP expression level was higher than that in the control group; and 4) the post-treatment CRP expression level was significantly lower than the pretreatment one (All P-values< 0.05). Based upon the efficacy, the observation group was divided into an effective group and an invalid group. The post-treatment expression levels of PLT and CRP in the effective group were lower than those in the invalid group (P< 0.05). Based upon the ROC curve, the area under curves (AUC) of PLT, CRP, and joint detection were 0.843, 0.864, and 0.886, respectively. When the cut-off point was > 0.579, the best specificity and sensitivity were 98.44 and 70.59%, respectively. According to the Pearson test, positive correlations existed between PLT and CRP, between PLT and PSI scores, and between CRP and PSI scores. In conclusion, the expression levels of PLT and CRP in severely pneumonic patients might be used to evaluate the efficacy and conducive to detection of the disease, which have high application values in clinic.

Large-Scale Cognitive GWAS Meta-Analysis Reveals Tissue-Specific Neural Expression and Potential Nootropic Drug Targets.

Here, we present a large (n = 107,207) genome-wide association study (GWAS) of general cognitive ability ("g"), further enhanced by combining results with a large-scale GWAS of educational attainment. We identified 70 independent genomic loci associated with general cognitive ability. Results showed significant enrichment for genes causing Mendelian disorders with an intellectual disability phenotype. Competitive pathway analysis implicated the biological processes of neurogenesis and synaptic regulation, as well as the gene targets of two pharmacologic agents: cinnarizine, a T-type calcium channel blocker, and LY97241, a potassium channel inhibitor. Transcriptome-wide and epigenome-wide analysis revealed that the implicated loci were enriched for genes expressed across all brain regions (most strongly in the cerebellum). Enrichment was exclusive to genes expressed in neurons but not oligodendrocytes or astrocytes. Finally, we report genetic correlations between cognitive ability and disparate phenotypes including psychiatric disorders, several autoimmune disorders, longevity, and maternal age at first birth.

Pilot Study of the Pharmacokinetics of Cefotaxime in Critically Ill Patients with Acute Kidney Injury Treated with Continuous Renal Replacement Therapy.

The objective of this study was to describe the pharmacokinetics of cefotaxime (CTX) in critically ill patients with acute kidney injury (AKI) when treated with continuous renal replacement therapy (CRRT) in the intensive care unit (ICU). This single-center prospective observational pilot study was performed among ICU-patients with AKI receiving ≥48 h concomitant CRRT and CTX. CTX was administered intravenously 1,000 mg (bolus) every 6 h for 4 days. CRRT was performed as continuous venovenous hemofiltration (CVVH). Plasma concentrations of CTX and its active metabolite desacetylcefotaxime (DAC) were measured during CVVH treatment. CTX plasma levels and patient data were used to construct concentration-time curves. By using this data, the duration of plasma levels above 4 mg/liter (four times the MIC) was calculated and analyzed. Twenty-seven patients were included. The median CTX peak level was 55 mg/liter (range, 19 to 98 mg/liter), the median CTX trough level was 12 mg/liter (range, 0.8 to 37 mg/liter), and the median DAC plasma level was 15 mg/liter (range, 1.5 to 48 mg/liter). Five patients (19%) had CTX plasma levels below 4 mg/liter at certain time points during treatment. In at least 83% of the time any patient was treated with CTX, the CTX plasma level stayed above 4 mg/liter. A dosing regimen of 1,000 mg of CTX given four times daily is likely to achieve adequate plasma levels in patients with AKI treated with CVVH. Dose reduction might be a risk for suboptimal treatment.

Application of acetone acetals as water scavengers and derivatization agents prior to the gas chromatographic analysis of polar residual solvents in aqueous samples.

The sensitivity of gas chromatography (GC) combined with the full evaporation technique (FET) for the analysis of aqueous samples is limited due to the maximum tolerable sample volume in a headspace vial. Using an acetone acetal as water scavenger prior to FET-GC analysis proved to be a useful and versatile tool for the analysis of high boiling analytes in aqueous samples. 2,2-Dimethoxypropane (DMP) was used in this case resulting in methanol and acetone as reaction products with water. These solvents are relatively volatile and were easily removed by evaporation enabling sample enrichment leading to 10-fold improvement in sensitivity compared to the standard 10µL FET sample volumes for a selection of typical high boiling polar residual solvents in water. This could be improved even further if more sample is used. The method was applied for the determination of residual NMP in an aqueous solution of a cefotaxime analogue and proved to be considerably better than conventional static headspace (sHS) and the standard FET approach. The methodology was also applied to determine trace amounts of ethylene glycol (EG) in aqueous samples like contact lens fluids, where scavenging of the water would avoid laborious extraction prior to derivatization. During this experiment it was revealed that DMP reacts quantitatively with EG to form 2,2-dimethyl-1,3-dioxolane (2,2-DD) under the proposed reaction conditions. The relatively high volatility (bp 93°C) of 2,2-DD makes it possible to perform analysis of EG using the sHS methodology making additional derivatization reactions superfluous.

[Cefodizime increases peripheral blood CD4/CD8 and Th1/Th2 ratios in senile patients with bacterial pneumonia].

OBJECTIVE: To explore the influence of cefodizime on CD4/CD8 and T helper 1(Th1)/Th2 cell ratios in peripheral blood of the senile patients with bacterial pneumonia. METHODS: Sixty-three senile patients with bacterial pneumonia were enrolled and divided into two groups randomly. Patients in the control group (n=31) were given intravenous infusion of ceftriaxone sodium, and patients in the observation group (n=32) were given intravenous infusion of cefodizime. The fasting venous blood was taken before and after treatment to detect CD4/CD8 and Th1/Th2 cell ratios with flow cytometry. At the same time, the serum interleukin-2 (IL-2), interferon γ (IFN-γ), IL-4 and IL-10 contents were also detected with ELISA. RESULTS: Before treatment, there was no significant difference in the above indexes between the two groups. After treatment, CD4⁺ cells and Th1 cells of the observation group increased while Th2 cells decreased; as a result, the CD4/CD8 and Th1/Th2 cell ratios of the observation group were significantly higher than those of the control group. At the same time, serum IL-2 and IFN-γ contents of the observation group were significantly higher than those of the control group, while serum IL-4 and IL-10 contents were significantly lower than those of the control group. CONCLUSION: Cefodizime can improve the cellular immune function and rectify CD4/CD8 and Th1/Th2 imbalance in peripheral blood of the senile patients with bacterial pneumonia.

Probing the interaction of cefodizime with human serum albumin using multi-spectroscopic and molecular docking techniques.

To know the interaction of cefodizime (CEF) with human serum albumin (HSA), techniques of different spectroscopies and molecular modeling were used. The inner filter effects were eliminated to get accurate binding parameters. Steady state fluorescence suggested a static type for CEF-HSA interaction, and the complex formation had a high affinity of 10(5) L mol(-1). On the basis of the thermodynamic results and site marker competitive experiments, it was considered that CEF was bound to site I (subdomain IIA) of HSA mainly by hydrogen bonds and van der Waals force. The calculated binding distance (r) indicated that the non-radioactive energy transfer came into being in the interaction between CEF and HSA. Furthermore, molecular modeling was applied to further define that CEF interacted with the Trp214, Lys199, Phe211, Leu238 residues of HSA. In addition, three-dimensional fluorescence and circular dichroism (CD) results showed that the binding of CEF can cause conformational and some microenvironmental changes of HSA. This paper provides reasonable models helping us further understand the transportation and distribution of CEF when it spreads into human blood serum which is of great importance in pharmacology and pharmacodynamics.

BioDMET: a physiologically based pharmacokinetic simulation tool for assessing proposed solutions to complex biological problems.

We developed a detailed, whole-body physiologically based pharmacokinetic (PBPK) modeling tool for calculating the distribution of pharmaceutical agents in the various tissues and organs of a human or animal as a function of time. Ordinary differential equations (ODEs) represent the circulation of body fluids through organs and tissues at the macroscopic level, and the biological transport mechanisms and biotransformations within cells and their organelles at the molecular scale. Each major organ in the body is modeled as composed of one or more tissues. Tissues are made up of cells and fluid spaces. The model accounts for the circulation of arterial and venous blood as well as lymph. Since its development was fueled by the need to accurately predict the pharmacokinetic properties of imaging agents, BioDMET is more complex than most PBPK models. The anatomical details of the model are important for the imaging simulation endpoints. Model complexity has also been crucial for quickly adapting the tool to different problems without the need to generate a new model for every problem. When simpler models are preferred, the non-critical compartments can be dynamically collapsed to reduce unnecessary complexity. BioDMET has been used for imaging feasibility calculations in oncology, neurology, cardiology, and diabetes. For this purpose, the time concentration data generated by the model is inputted into a physics-based image simulator to establish imageability criteria. These are then used to define agent and physiology property ranges required for successful imaging. BioDMET has lately been adapted to aid the development of antimicrobial therapeutics. Given a range of built-in features and its inherent flexibility to customization, the model can be used to study a variety of pharmacokinetic and pharmacodynamic problems such as the effects of inter-individual differences and disease-states on drug pharmacokinetics and pharmacodynamics, dosing optimization, and inter-species scaling. While developing a tool to aid imaging agent and drug development, we aimed at accelerating the acceptance and broad use of PBPK modeling by providing a free mechanistic PBPK software that is user friendly, easy to adapt to a wide range of problems even by non-programmers, provided with ready-to-use parameterized models and benchmarking data collected from the peer-reviewed literature.

Effects of cefodizime on chemokines of liver tissues in mice with immunological hepatic injury.

BACKGROUND: Chronic hepatic inflammation is characterized by the accumulation of lymphocytes as a consequence of increased recruitment from the blood and retention within the tissue at sites of infection. CXC chemokine ligand 16 (CXCL16) mRNA has been detected in both inflamed and normal liver tissues and is strongly upregulated in the injured liver tissues in a murine model. The aim of this study was to investigate the effect of cefodizime on CXCL16 mRNA of liver tissues in mice with immunological hepatic injury. METHODS: The murine model of immunological hepatic injury was induced by Bacillus Calmette Guerin and Lipoposaccharide. The mice with immunological hepatic injury were randomly assigned to the model group, the cefodizime group and the ceftriaxone group. The three groups were continuously given agents for seven days and CXCL16 mRNA of liver tissue was determined and contrasted with the control group treated by normal saline. Reverse transcription-polymerase chain reaction was used to assay CXCL16 mRNA levels in liver tissues. RESULTS: The expressions of CXCL16 mRNA were significantly higher in the model group and the ceftriaxone group than in the control group and the cefodizime group (P < 0.05), indicating the mice in the model group and the ceftriaxone group were immunodeficient. There was no statistical difference in the expressions of CXCL16 mRNA between the control group and the cefodizime group. Similarly, no statistical difference in the expressions of CXCL16 mRNA between the model group and the ceftriaxone group was detected (P > 0.05). CONCLUSION: Cefodizime effectively reduces the infiltration of lymphocytes into liver tissues and alleviates the liver damage by decreasing CXCL16 mRNA in liver tissues in mice with immunological hepatic injury.

Pharmacokinetics of cefotaxime and desacetylcefotaxime in infants during extracorporeal membrane oxygenation.

Extracorporeal membrane oxygenation (ECMO) is used to temporarily sustain cardiac and respiratory function in critically ill infants but can cause pharmacokinetic changes necessitating dose modifications. Cefotaxime (CTX) is used to prevent and treat infections during ECMO, but the current dose regimen is based on pharmacokinetic data obtained for non-ECMO patients. The objective of this study was to validate the standard dose regimen of 50 mg/kg of body weight twice a day (postnatal age [PNA], <1 week), 50 mg/kg three times a day (PNA, 1 to 4 weeks), or 37.5 mg/kg four times a day (PNA, >4 weeks). We included 37 neonates on ECMO, with a median (range) PNA of 3.3 (0.67 to 199) days and a median (range) body weight of 3.5 (2.0 to 6.2) kg at the onset of ECMO. Median (range) ECMO duration was 108 (16 to 374) h. Plasma samples were taken during routine care, and pharmacokinetic analysis of CTX and its active metabolite, desacetylcefotaxime (DACT), was done using nonlinear mixed-effects modeling (NONMEM). A one-compartment pharmacokinetic model for CTX and DACT adequately described the data. During ECMO, CTX clearance (CL(CTX)) was 0.36 liter/h (range, 0.19 to 0.75 liter/h), the volume of distribution of CTX (V(CTX)) was 1.82 liters (0.73 to 3.02 liters), CL(DACT) was 1.46 liters/h (0.48 to 5.93 liters/h), and V(DACT) was 11.0 liters (2.32 to 28.0 liters). Elimination half-lives for CTX and DACT were 3.5 h (1.6 to 6.8 h) and 5.4 h (0.8 to 14 h). Peak CTX concentration was 98.0 mg/liter (33.2 to 286 mg/liter). DACT concentration varied between 0 and 38.2 mg/liter, with a median of 10 mg/liter in the first 12 h postdose. Overall, CTX concentrations were above the MIC of 8 mg/liter over the entire dose interval. Only 1 of the 37 patients had a sub-MIC concentration for over 50% of the dose interval. In conclusion, the standard cefotaxime dose regimen provides sufficiently long periods of supra-MIC concentrations to provide adequate treatment of infants on ECMO.

Microemulsion and mixed micelle for oral administration as new drug formulations for highly hydrophilic drugs.

Microemulsions (MEs) and mixed micelles (MMs) have been used as new drug formulations for high hydrophilic drugs such as cefpirom and cefodizim for oral administration. Cefpirom and cefodizim are neither actively nor passively transported across cell membranes. Up to date, they can be only administrated intravenously (i.v.) or intramuscularly (i.m.). The rabbit (Chinchilla) in vivo model was used in the present work to investigate ways of overcoming the poor oral absorption of these cephalosporins. The cephalosporins at 100mg/kg were formulated in MEs and MMs and administered intraduodenally (i.d.). Very low bioavailability (2.5-3.0%) was observed, if cefpirom or cefodizim i.d. were applied without colloidal vehicle. However, the addition of the cephalosporins to ME or MM is shown to be highly effective in increasing the bioavailability values (up to 64% absolute bioavailability) of the model drugs. In conclusion, MEs and MMs improve essentially the oral bioavailability of the high hydrophilic drugs.

Preparation, physicochemical characterization and biological evaluation of cefodizime metal ion complexes.

OBJECTIVES: Cefodizime is a broad spectrum cephalosporin belonging to the third generation agents. In this study, attention has been paid to the preparation, physicochemical characterization and biological evaluation of new Cu2+, Zn2+, Fe3+, Co2+ and Al3+ complexes of cefodizime. METHODS: The stoichiometrics and the mode of bonding of the complexes were deduced from their elemental and metal analysis, electrical conductivity measurements, UV-vis, infrared and Raman spectroscopic investigations. Study of the stoichiometry of these complexes referred to the formation of 1 : 1 ratios of metal to ligand. Antimicrobial activity of the complexes was determined using two strains of Gram-positive (Bacillus subtilis and Proteus vulgaris) and two strains of Gram-negative (Escherichia coli W3110 and Pseudomonas putida) bacteria. The minimal inhibitory concentration was determined as the lowest concentration inhibiting bacterial growth on solid Luria Bertani medium. KEY FINDINGS: The spectra gave evidence as to the position of binding. In addition, the aqueous solubility of cefodizime was strongly reduced by complexation. CONCLUSIONS: The antibacterial activity of cefodizime was not affected by complexation with Al3+ but it was reduced by complexation with the other tested metal ions against the bacteria under study.

Evaluation of cefotaxime and desacetylcefotaxime concentrations in cord blood after intrapartum prophylaxis with cefotaxime.

Preterm premature rupture of the membranes is associated with a high risk of neonatal sepsis. An increase in the incidence of early-onset neonatal sepsis due to ampicillin-resistant Escherichia coli in premature infants has been observed in the past few years. Intrapartum prophylaxis with ampicillin has proven to be efficient for the prevention of early neonatal sepsis due to group B streptococci. To date, there is no strategy for the prevention of early neonatal sepsis due to ampicillin-resistant E. coli. Our aim was to investigate whether a standardized dosage regimen of intrapartum cefotaxime could provide concentrations in the cord blood greater than the cefotaxime MIC(90) for E. coli. Seven pregnant women hospitalized with preterm premature rupture of the membranes and colonized with ampicillin-resistant isolates of the family Enterobacteriaceae were included. Cefotaxime was given intravenously during delivery, as follows: 2 g at the onset of labor and then 1 g every 4 h until delivery. Blood specimens were collected from the mother 30 min after the first injection and just before the second injection, and at birth, blood specimens were simultaneously collected from the mother and the umbilical cord. The concentrations of cefotaxime in the cord blood ranged from 0.5 to 8.5 mg/liter. The MIC(90) of cefotaxime for E. coli strains (0.125 mg/liter) was achieved in all cases. This preliminary study supports the use of cefotaxime for intrapartum prophylaxis in women colonized with ampicillin-resistant isolates of Enterobacteriaceae. The effectiveness of this regimen for the prevention of neonatal sepsis needs to be evaluated with a larger population.

Implications of current recommendations for third-generation cephalosporin use in the WHO Western Pacific Region following the emergence of multiresistant gonococci.

To ascertain recommendations for the treatment of gonorrhoea in the WHO Western Pacific Region (WPR) following the emergence of "cephalosporin-resistant" Neisseria gonorrhoeae and to relate these to clinical and laboratory measures directed towards disease and antibiotic resistance control. WHO WPR Gonococcal Antimicrobial Resistance Programme members provided data on the type, dose and source of third-generation cephalosporins recommended for the treatment of gonorrhoea. Ceftriaxone was recommended more widely (11/15 respondents) than cefixime (five centres). No cephalosporins were recommended in three jurisdictions. One other oral (ceftibuten) and injectable (cefodizime) agent was recommended. Uniform (400 mg) doses of cefixime were recommended but ceftriaxone regimens ranged between 125 mg and 1 g, with nine of 11 respondents using a 250 mg dose. Both generic and proprietary preparations were widely used. Third-generation cephalosporins are widely recommended for the treatment of gonorrhoea in the WPR, with injectable ceftriaxone more extensively so than oral cefixime and in an expanded dose range. Few other cephalosporins were recommended. Current knowledge suggests that the trend towards ceftriaxone treatment in higher doses may decrease the impact of the circulation of "cephalosporin-resistant" gonococci in the WPR. These recommendations represent public sector practice only and of themselves are unlikely to contain the further spread of "cephalosporin-resistant" gonococci because of the general clinical use of cephalosporins. Optimisation of strategies for laboratory detection of third-generation cephalosporin resistance can be simplified in the WPR because of the restricted spectrum of cephalosporins recommended. Additional efforts are urgently required for both disease and antibiotic resistance control in gonorrhoea.

Plasma and peritoneal concentration following continuous infusion of cefotaxime in patients with secondary peritonitis.

OBJECTIVES: The aim of this study was to determine the steady-state plasma and peritoneal concentrations of cefotaxime and its metabolite desacetyl-cefotaxime administered by continuous infusion to critically ill patients with secondary peritonitis. PATIENTS AND METHODS: In 11 patients, a continuous infusion of 4 g/24 h of cefotaxime following a bolus of 2 g was evaluated. Plasma and peritoneal levels of cefotaxime and desacetyl-cefotaxime were measured at steady state on days 2 and 3 (plasma) and on day 3 (peritoneal) by HPLC. Results are expressed as means +/- SD. RESULTS: Total and unbound plasma levels of cefotaxime were 24.0 +/- 21.5 and 20.3 +/- 19.8 mg/L on day 2 and 22.1 +/- 20.7 and 18.9 +/- 19.2 mg/L on day 3, respectively. Total and unbound levels of cefotaxime in the peritoneal fluids were 16.2 +/- 11.5 and 14.3 +/- 10.4 mg/L, respectively. The unbound fraction of plasma cefotaxime was 81.8 +/- 5.9% on day 2 and 82.6 +/- 7.7% on day 3, and the unbound fraction at the peritoneal site was 87.0 +/- 5.5% on day 3. Total and unbound plasma levels of desacetyl-cefotaxime were 9.0 +/- 8.1 and 8.4 +/- 8.1 mg/L on day 2 and 7.6 +/- 7.6 and 7.2 +/- 7.6 mg/L on day 3, respectively. Total and unbound levels of desacetyl-cefotaxime in the peritoneal fluids were 11.9 +/- 11.5 and 10.9 +/- 10.8 mg/L, respectively. The MICs for the enterobacteria recovered ranged from 0.016 to 0.25 mg/L. CONCLUSIONS: Continuous infusion of 4 g/24 h of cefotaxime provided a peritoneal concentration >5x MIC for the recovered Enterobacteriaceae and the susceptibility breakpoint of cefotaxime for facultative Gram-negative bacilli.

Microanalysis of beta-lactam antibiotics and vancomycin in plasma for pharmacokinetic studies in neonates.

Rational dosing of antibiotics in neonates should be based on pharmacokinetic (PK) parameters assessed in specific populations. PK studies of neonates are hampered by the limited total plasma volume, which restricts the sample volume and sampling frequency. Available drug assay methods require large sample volumes and are labor-intensive or time-consuming. The objective of this study was to develop a rapid ultra-performance liquid chromatographic method with tandem mass spectrometry detection for simultaneous quantification of amoxicillin, meropenem, cefazolin, cefotaxime, deacetylcefotaxime, ceftriaxone, and vancomycin in 50 microl of plasma. Cleanup consisted of protein precipitation with cold acetonitrile (1:4) and solvent evaporation before reversed-phase chromatographic separation and detection using electrospray ionization tandem mass spectrometry. Standard curves were prepared over a large dynamic range with adequate limits of quantitation. Intra- and interrun accuracy and precision were within 100% +/- 15% and 15%, respectively, with acceptable matrix effects. Coefficients of variation for matrix effects and recovery were <10% over six batches of plasma. Stability in plasma and aqueous stocks was generally sufficient, but stability of meropenem and ceftriaxone in extracts could limit autosampler capacity. The instrument run time was approximately 3.50 min per sample. Method applicability was demonstrated with plasma samples from an extracorporeal membrane oxygenation-treated neonate. Different beta-lactam antibiotics can be added to this method with additional ion transitions. Using ultra-performance liquid chromatography mass spectrometry, this method allows simple and reliable quantification of multiple antibiotics in 50 microl of plasma for PK studies of neonates.

Inhibitory effects of Cefazolin and Cefodizime on the activity of mushroom tyrosinase.

Tyrosinase (EC 1.14.18.1) catalyzes both the hydroxylation of tyrosine into o-diphenols and the oxidation of o-diphenols into o-quinones that form brown or black pigments. In the present paper, the effects of Cefazolin and Cefodizime on the activity of mushroom tyrosniase have been studied. The results showed that the Cephalosporin antibacterial drugs (Cefazolin and Cefodizime) could inhibit both monophenolase activity and diphenolase activity of the enzyme. For the monophenolase activity, Both Cefazolin and Cefodizime could lengthen the lag time and decrease the steady-state activities, and the IC(50) values were estimated as 7.0 mM and 0.13 mM for monophenolase activity, respectively. For the diphenolase activity, the inhibitory capacity of Cefodizime was obviously stronger than that of Cefazolin, and the IC(50) values were estimated as 0.02 mM and 0.21 mM, respectively. Kinetic analyses showed that inhibition by both compounds was reversible and their mechanisms were competitive and mixed-type, respectively. Their inhibition constants were also determined and compared. The research may offer a lead for designing and synthesizing novel and effective tyrosinase inhibitors and also under the application field of Cephalosporins.