Development of a rapid LC-MS/MS method for simultaneous quantification of ten commonly used antibiotic drugs in human serum

The use of TDM in clinical practice to monitor the plasma levels of antibiotics administered to critically ill patients is a well-established approach that allows for optimization of the patient's response to drug therapy, considering the characteristics of the drug, the clinical and physiological status of the patient and any peculiar of the pathogen that caused the clinical picture. In our laboratory, we have developed a single LC-MS/MS analysis for dosing the serum concentration of an antibacterial panel composed of eight antibacterial and two selective inhibitors. The method presented used a certified material furnished by a commercial company and was internally validated using the EMA guidelines. The results have shown high sensitivity, precision, and accuracy, a lower matrix effect combined with simple sample preparation and a time-saving procedure. We have evaluated the recovery rate and matrix effect by testing serum samples without pathological index and serum pools obtained from haemolysed, icteric, or lipemic samples. The assay has shown a recovery range between 94% and 101%.

One-Pot facile synthesis of fluorescent copper nanoclusters for highly selective and sensitive detection of tetracycline

Due to the excellent characteristics, fluorescent copper nanoclusters (Cu NCs) have aroused great interest in recent years. Herein, the simple prepared, environmentally friendly fluorescent Cu NCs were synthesized by using trypsin as the stabilizer and applied for the determination of tetracycline. Uniformly dispersed Try-Cu NCs were obtained with average size of 3.5 ± 0.3 nm and some excellent merits of good water solubility, UV light stability and salt stability. Emission peaks around 460.0 nm were visibly quenched by tetracycline based on static quenching mechanism and inner filter effect (IFE). Two excellent linear relationships were observed between ln(F0/F) and tetracycline concentrations in the range of 1-100 μM and 100-300 μM with limit of detection (LOD) of 0.084 μM. Meanwhile, this nanoprobe exhibited an apparent selectivity for tetracycline detection. Moreover, Try-Cu NCs were successfully employed to determine tetracycline in serum and milk samples after facile pretreatment with satisfactory recovery rates and credible standard deviation. The results suggested that this as-prepared Try-Cu NCs had excellent application prospects in the future.

Halloysite nanotubes-based hybrid silica monolithic spin tip for hydrophilic solid-phase extraction of sulbactam, cefoperazone, and cefuroxime in whole blood

In this study, we proposed a novel method utilizing polyethyleneimine (PEI)-modified halloysite nanotubes (HNTs)-based hybrid silica monolithic spin tip to analyze hydrophilic β-lactam antibiotics and β-lactamases inhibitors in whole blood samples for the first time. HNTs were incorporated directly into the hybrid silica monolith via a sol-gel method, which improved the hydrophilicity of the matrix. The as-prepared monolith was further modified with PEI by glutaraldehyde coupling reaction. It was found that the PEI-modified HNTs-based hybrid silica monolith enabled a large adsorption capacity of cefoperazone at 35.7 mg g-1. The monolithic spin tip-based purification method greatly reduced the matrix effect of whole blood samples and had a detection limit as low as 0.1 - 0.2 ng mL-1. In addition, the spiked recoveries of sulbactam, cefuroxime, and cefoperazone in blank whole blood were in the range of 89.3-105.4 % for intra-day and 90.6-103.5 % for inter-day, with low relative standard deviations of 1.3-7.2 % and 4.9-10.5 %, respectively. This study introduces a new strategy for preparing nanoparticles incorporated in a hybrid silica monolith with a high adsorption capacity. Moreover, it offers a valuable tool to monitor sulbactam, cefoperazone, and cefuroxime in whole blood from pregnant women with the final aim of guiding their administration.

Therapeutic drug monitoring of vancomycin in surgical patients using a validated HPLC method

BACKGROUND

Vancomycin is being used for the treatment of a variety of infections caused by methicillin resistant Staphylococcus aureus and methicillin susceptible Staphylococcus aureus. Therapeutic drug monitoring (TDM) is highly recommended for ensuring the safe and effective therapy with vancomycin. A reliable and cost-effective bioanalytical method is required for TDM as well as pharmacokinetic studies of vancomycin.

MATERIALS AND METHODS

A selective, sensitive, and cost effective HPLC method was developed and validated for quantification of vancomycin concentrations in human plasma. The mobile phase was a mixture of buffer (50 mM ammonium dihydrogen phosphate, pH 2.4) and acetonitrile 88 : 12 v/v. The separation was carried on C18 column (125 × 4.6 mm, particle size 5 µm) with isocratic flow rate of 0.370 mL/min at room temperature with UV detection at 215 nm. The method was validated for sensitivity, accuracy, and precision as well as stability of vancomycin in human plasma by following European Medicine Agency (EMA) guideline. Therapeutic drug monitoring of vancomycin was performed by quantifying the trough concentrations of vancomycin in 65 human plasma samples after administration of therapeutically relevant dose.

RESULTS

The developed method was sensitive enough to quantify vancomycin concentrations as low as 0.25 mg/L in human plasma. Moreover, the method was proved accurate and precise in terms of quantifying the unknown concentration of vancomycin. The evaluation of short-term, long-term, and freeze-thaw stability proved the stability of vancomycin in human plasma. The TDM of vancomycin by using this method showed that 39 (60%) samples were within the target trough concentration range (TTCR), i.e. 10 - 20 mg/L, while 23 samples (35.4%) were below the TTCR, and 3 samples (4.6%) were above this range.

CONCLUSION

The developed method is sensitive and cost effective for quantification of vancomycin in human plasma. The results of sample analysis shows that the developed method can be used reliably for TDM of vancomycin.

Spatially confined CuFe2O4 nanosphere in N/O-codoped porous carbon mimetics for triple-mode sensing of antibiotics and visual detection of neurotransmitters in biofluids

BACKGROUND

Carbon-based nanozymes have recently received enormous concern, however, there is still a huge challenge for inexpensive and large-scale synthesis of magnetic carbon-based "Two-in-One" mimics with both peroxidase (POD)-like and laccase-like activities, especially their potential applications in multi-mode sensing of antibiotics and neurotransmitters in biofluids. Although some progresses have been made in this field, the feasibility of biomass-derived carbon materials with both POD-like and laccase-like activities by polyatomic doping strategy is still unclear. In addition, multi-mode sensing platform can provide a more reliable result because of the self-validation, self-correction and mutual agreement. Nevertheless, the use of magnetic carbon-based nanozyme sensors for the multi-mode detection of antibiotics and neurotransmitters have not been investigated.

RESULTS

We herein report a shrimp shell-derived N, O-codoped porous carbon confined magnetic CuFe2O4 nanosphere with outstanding laccase-like and POD-like activities for triple-mode sensing of antibiotic d-penicillamine (D-PA) and chloramphenicol (CPL), as well as colorimetric detection of neurotransmitters in biofluids. The magnetic CuFe2O4/N, O-codoped porous carbon (MCNPC) armored mimetics was successfully fabricated using a combined in-situ coordination and high-temperature crystallization method. The synthesized MCNPC composite with superior POD-like activity can be used for colorimetric/temperature/smartphone-based triple-mode detection of D-PA and CPL in goat serum. Importantly, the MCNPC nanozyme can also be used for colorimetric analysis of dopamine and epinephrine in human urine.

SIGNIFICANCE

This work not only offered a novel strategy to large-scale, cheap synthesize magnetic carbon-based "Two-in-One" armored mimetics, but also established the highly sensitive and selective platforms for triple-mode monitoring D-PA and CPL, as well as colorimetric analysis of neurotransmitters in biofluids without any tanglesome sample pretreatment.

A comparison of aminoglycoside antibiotic serum concentrations collected by peripheral veins and peripherally inserted central catheters in adults with cystic fibrosis

BACKGROUND

People with cystic fibrosis (PwCF) are frequently hospitalized for treatment of pulmonary exacerbation. The Cystic Fibrosis Foundation Pulmonary Guidelines support the use of intravenous aminoglycosides with therapeutic drug monitoring for the treatment of pulmonary exacerbation due to Pseudomonas aeruginosa. Serum intravenous tobramycin concentrations are commonly collected by peripheral venipuncture (PV). Discomfort associated with collection of samples by PV prompts collection via PICC, but the accuracy of intravenous tobramycin serum levels collected by PICC has not been documented in adult PwCF. The primary study objective was to evaluate the difference between intravenous tobramycin serum levels collected by PV and PICC in adult PwCF.

METHODS

The authors conducted a prospective case-control study of adult PwCF admitted to University of Utah Health for a pulmonary exacerbation receiving tobramycin by a single lumen PICC. The authors compared tobramycin peak and random serum levels collected by PV and PICC using a detailed flush and waste protocol.

RESULTS

The authors analyzed a total of 19 patients with peripheral and PICC samples. The mean tobramycin peak collected by PV (27.2 mcg/mL) was similar to the mean peak collected by PICC (26.9 mcg/mL) (paired samples Wilcoxon signed-rank test, p = .94). The correlation coefficient was 0.88 (95% CI = 0.85-0.91, p < .001).

CONCLUSION

Tobramycin serum samples collected by PICC appear to be similar in value to PV collections. Collecting aminoglycoside levels by PICC rather than PV may reduce patient discomfort and improve quality of life. Additional multicenter studies are needed to confirm these results.

In vitro stability study of 10 beta-lactam antibiotics in human plasma samples

BACKGROUND AND OBJECTIVES

Beta-lactam antibiotics are reported for some of them to be subject to a rapid degradation in infusion solutions and in human blood samples. However, the current data of stability available in blood samples are limited to a few number of beta-lactam antibiotics, and the methodology of the corresponding studies may be discussed. The objective of the present study is to evaluate the stability of 10 beta-lactam antibiotics in human plasma samples.

METHODS

Stability of amoxicillin, cefazolin, cefepime, cefotaxime, cefoxitin, ceftazidime, ceftriaxone, imipenem, meropenem, and piperacillin was evaluated at low and high concentrations at 20°C, 4°C, -20°C, and -80°C for 1, 7, 60, and 90 days, respectively.

RESULTS

Amoxicillin, cefepime, meropenem, and piperacillin were the least stable antibiotics. The maximum durations allowing the stability for all the evaluated beta-lactams at both tested concentrations were estimated at 3 h, 23 h, 10 days, and 35 days at 20°C, 4°C, -20°C, and -80°C, respectively.

CONCLUSION

We recommend to transport antibiotic plasma samples in ice at 4°C and even at -20°C if these samples come from external hospitals. Ideally, plasma samples should be stored at -80°C if possible; if not, the analysis of the samples should be performed as soon as possible in the limit of 10 days after a storage at -20°C.

Fast and Sensitive Analysis of Fosfomycin in Human Plasma Microsamples Using Liquid Chromatography-Tandem Mass Spectrometry for Therapeutic Drug Monitoring

BACKGROUND

Fosfomycin is an antibiotic recently repurposed as a potential combination treatment for difficult-to-treat Gram-negative bacterial infections. The pharmacokinetic features of fosfomycin have demonstrated that different pathophysiologic alterations may affect its exposure. Therapeutic drug monitoring may improve real-time management of fosfomycin therapy in different clinical scenarios.

OBJECTIVES

To develop and validate a fast and sensitive liquid chromatography - tandem mass spectrometry method for measuring fosfomycin in human plasma microsamples (3 µL).

METHODS

Analysis was preceded by a user-friendly pre-analytical single-step process performed via a rapid chromatographic run of 2.5 minutes, followed by negative electrospray ionization and detection on a high-sensitivity triple quadrupole tandem mass spectrometer operated in the multiple reaction monitoring mode. European Medicines Agency guidelines were used to validate the specificity, sensitivity, linearity, precision, accuracy, matrix effects, extraction recovery, limits of quantification, and stability of the analytical method.

RESULTS

The new assay produced accurate (BIAS%: 0.9-9.1) and precise (coefficient of variation [CV]%: 8.1-9.5) measurements of fosfomycin over a concentration range of 1-1000 mg/L. Overall, analyte recovery was consistent (mean values: 91.2%-97.2%) at all tested concentration levels. The analyte was also stable in human plasma and the final extract under various storage conditions. The clinical applicability of the assay was confirmed through quantitation of plasma samples obtained from patients.

CONCLUSIONS

A sensitive liquid chromatography - tandem mass spectrometry method for measuring fosfomycin in plasma was developed and validated according to the European Medicines Agency criteria. Quantitation of fosfomycin in clinical plasma samples confirmed that the assay is suitable for therapeutic drug monitoring in clinical scenarios.

A high performance liquid chromatography-tandem mass spectrometry assay for therapeutic drug monitoring of 10 drug compounds commonly used for antimicrobial therapy in plasma and serum of critically ill patients: Method optimization, validation, cross-validation and clinical application

BACKGROUND AND AIMS

Intensive care antibiotic treatment faces challenges due to substantial pharmacokinetic differences in critically ill patients. Individualized antibiotic dosing guided by therapeutic drug monitoring (TDM) is considered to minimize the risk of treatment failure and toxicity. This study aimed to develop a valid method for simultaneous LC-MS/MS quantification of 10 drugs frequently used in intensive care antibiotic therapy for which TDM-guided dosing is recommended: piperacillin, meropenem, flucloxacillin, cefuroxime, vancomycin, colistin A and B, linezolid, ciprofloxacin and tazobactam.

METHODS AND RESULTS

Thorough optimization of sample preparation and chromatography resulted in a fast and simple method based on protein precipitation of 50 µL plasma or serum and gradient elution using an Acquity UPLC HSS-T3 column. Electrospray ionization-triple quadrupole mass spectrometry in dynamic multiple reaction monitoring was used for quantification, covering the therapeutic range of each drug compound. Validation following EMA and FDA recommendations, including inter-platform validation and inter-laboratory comparison, demonstrated high accuracy, precision and robustness of the new method. The assay was successfully used to monitor plasma antibiotic levels of critically ill patients (n = 35).

CONCLUSION

The established multiplex method covers major drug classes with documented dosing challenges, provides a reliable basis for the implementation of high-throughput TDM, and its application confirmed the clinical impact of TDM in a real-world setting.

Ceftazidime/avibactam serum concentration in patients on ECMO

OBJECTIVES

The use of extracorporeal membrane oxygenation (ECMO) may alter blood levels of several drugs, including antibiotics, leading to under dosing of these drugs and thus to potential treatment failure. No data exist on pharmacokinetics of new antimicrobial, in particular ceftazidime/avibactam. We therefore perform this study to evaluate ceftazidime/avibactam blood levels in ECMO patients and find factors associated with underdosing.

METHODS

Retrospective observational study of patients on ECMO having received ceftazidime/avibactam and in whom trough blood levels of ceftazidime and avibactam were available. Main outcome measurement was the number of patients with ceftazidime and avibactam blood levels above predefined cut-off values, derived from the European Committee on Antimicrobial Susceptibility Testing (EUCAST) breakpoints for Enterobacteriaceae and Pseudomonas aeruginosa, namely 8 mg/L for ceftazidime and 4 mg/L for avibactam, and explored factors associated with underdosing.

RESULTS

Twenty-three ceftazidime/avibactam trough levels were available in 14 ECMO patients, all of them having received veno-venous ECMO for SARS-CoV-2-associated pneumonia. Although ceftazidime levels were above 8 mg/L in all except one patient, nine (39%) of the avibactam dosages were below 4 mg/L. Increased renal clearance (creatinine clearance > 130 mL/min) was the main factor associated with under dosing, since 7 out of the 10 dosages below the predefined cut-offs were measured in patients with this condition.

CONCLUSIONS

In ECMO patients receiving ceftazidime/avibactam, ceftazidime and avibactam serum levels are above EUCAST breakpoints in most cases, justifying the use of normal dosing in ECMO patients. Increased renal clearance may lead to ceftazidime and avibactam under dosing.

A machine learning approach to predict daptomycin exposure from two concentrations based on Monte Carlo simulations

Daptomycin is a concentration-dependent lipopeptide antibiotic for which exposure/effect relationships have been shown. Machine learning (ML) algorithms, developed to predict the individual exposure to drugs, have shown very good performances in comparison to maximum a posteriori Bayesian estimation (MAP-BE). The aim of this work was to predict the area under the blood concentration curve (AUC) of daptomycin from two samples and a few covariates using XGBoost ML algorithm trained on Monte Carlo simulations. Five thousand one hundred fifty patients were simulated from two literature population pharmacokinetics models. Data from the first model were split into a training set (75%) and a testing set (25%). Four ML algorithms were built to learn AUC based on daptomycin blood concentration samples at pre-dose and 1 h post-dose. The XGBoost model (best ML algorithm) with the lowest root mean square error (RMSE) in a 10-fold cross-validation experiment was evaluated in both the test set and the simulations from the second population pharmacokinetic model (validation). The ML model based on the two concentrations, the differences between these concentrations, and five other covariates (sex, weight, daptomycin dose, creatinine clearance, and body temperature) yielded very good AUC estimation in the test (relative bias/RMSE = 0.43/7.69%) and validation sets (relative bias/RMSE = 4.61/6.63%). The XGBoost ML model developed allowed accurate estimation of daptomycin AUC using C0, C1h, and a few covariates and could be used for exposure estimation and dose adjustment. This ML approach can facilitate the conduct of future therapeutic drug monitoring (TDM) studies.

Subcutaneous administration of ceftazidime at 20 and 40 mg/kg produces theoretically therapeutic plasma concentrations for at least 120 hours in red-eared sliders (Trachemys scripta elegans)

OBJECTIVE

To evaluate and compare the pharmacokinetic parameters of SC ceftazidime administered at 20 and 40 mg/kg to red-eared sliders.

ANIMALS

8 adult red-eared sliders (Trachemys scripta elegans).

METHODS

In a sequential, 2-period study with a 3-week washout period between treatments, ceftazidime was administered SC to turtles at 20 and 40 mg/kg. Blood samples were collected from the subcarapacial sinus at 0, 24, 48, 72, 96, and 120 hours after ceftazidime administration. Plasma ceftazidime concentrations were quantified using reversed-phase HPLC.

RESULTS

Mean plasma half-life after 20- and 40-mg/kg dosing was 39.75 ± 8.0 hours and 33.03 ± 6.56 hours, respectively. Mean maximum plasma concentration after 20- and 40-mg/kg dosing was 71.0 ± 15.93 µg/mL and 120.0 ± 30.62 µg/mL, respectively. Mean plasma ceftazidime concentrations remained ≥ 8 µg/mL, the theoretical MIC for various reptile pathogens for all time points.

CLINICAL RELEVANCE

Results indicate that ceftazidime dosed at either 20 or 40 mg/kg produces plasma concentrations exceeding the theoretical MIC of various reptile pathogens for at least 120 hours. An ideal dosing interval could not be determined, as all plasma concentrations remained above the threshold of interest for all time points. Follow-up studies should focus on establishing a dosing interval and more rigorous monitoring for potential adverse effects.

Pharmacokinetics of amikacin after intravenous, intra-articular, and combined intravenous and intra-articular administration in healthy neonatal foals

BACKGROUND

Pharmacokinetics of amikacin administered IV to neonatal foals are described, but little data are available regarding the plasma concentrations contributed by concurrent intra-articular (IA) administration.

HYPOTHESIS/OBJECTIVES

Compare the pharmacokinetics of amikacin when the total dose is administered IV compared to being divided between IV and IA routes of administration in neonatal foals and predict the plasma concentrations from various combined IV and IA dosing regimens.

ANIMALS

Eight healthy neonatal foals.

METHODS

Foals received 3 amikacin treatment protocols: (1) IV-only (25 mg/kg q24h IV), (2) concurrent IV and IA (16.7 mg/kg q24h IV and 8.3 mg/kg q24h into 1 tarsocrural joint), and (3) IA-only (8.3 mg/kg q24h into 1 tarsocrural joint). Protocols were administered for 3 days beginning at 7, 14, and 21 days of age. Plasma concentrations ≥53 μg/mL at 30 minutes were considered therapeutic for isolates with intermediate susceptibility.

RESULTS

Foal age was a significant variable. The IV-only protocol met or exceeded the 30-minute plasma concentrations considered therapeutic (mean μg/mL [95% confidence interval, CI]) in 7- to 9-day-old (54.0 [52.2-56.9]), 14- to 16-day-old (58.1 [55.2-61.0]), and 21- to 23-day-old (66.6 [63.7-69.6]) foals. Concurrent IV and IA protocol did not reach the 30-minute concentration considered therapeutic in 7- to 9-day-old foals (46.5 [43.6-49.4]) but did in 14- to 16-day-old (62.9 [60.0-65.8]) and 21-to 23-day-old (62.6 [59.7-65.6]) foals.

CONCLUSIONS AND CLINICAL IMPORTANCE

Concurrent IV and IA administration of amikacin produces 30-minute plasma concentrations considered therapeutic in foals 14 to 23 days old, but concentrations observed in younger foals might be below those considered therapeutic for isolates with intermediate susceptibility to amikacin.

Comparison of pharmacokinetics software for therapeutic drug monitoring of piperacillin in patients with severe infections

OBJECTIVE

To evaluate the predictive performance of population pharmacokinetic models for piperacillin (PIP) available in the software MwPharm, TDMx and ID-ODs for initial dosing selection and therapeutic drug monitoring (TDM) purposes.

METHODS

This is a prospective observational study in adult patients with severe infections receiving PIP treatment. Plasma concentrations were quantified by ultra-high performance liquid chromatography coupled to tandem mass spectrometry. The differences between predicted and observed PIP concentrations were evaluated with Bland-Altman plots; additionally, the relative and absolute bias and precision of the models were determined.

RESULTS

A total of 145 PIP plasma concentrations from 42 patients were analysed. For population prediction, MwPharm showed the best predictive performance with a mean relative difference of 34.68% (95% CI -197% to 266%) and a root mean square error (RMSE) of 60.42 µg/mL; meanwhile TDMx and ID-ODs under-predicted PIP concentrations. For individual prediction, the TDMx model was found to be the most precise with a mean relative difference of 7.61% (95% CI -57.63 to 72.86%), and RMSE of 17.86 µg/mL.

CONCLUSION

Current software for TDM is a valuable tool, but it may also include different population pharmacokinetic models in patients with severe infections, and should be evaluated before performing a model-based TDM in clinical practice. Considering the heterogeneous characteristics of patients with severe infections, this study demonstrates the need for therapy personalisation for PIP to improve pharmacokinetic/pharmacodynamic target attainment.

Clinical benefits of therapeutic drug monitoring of vancomycin therapy in patients with postoperative intracerebral hemorrhage: a retrospective cohort study

OBJECTIVE

The objective of this study was to investigate the clinical efficacy and safety of conducting therapeutic drug monitoring (TDM) of vancomycin in patients with postoperative intracerebral haemorrhage.

METHODS

We conducted a retrospective analysis of 435 patients who experienced postoperative cerebral haemorrhage and were treated with vancomycin in the Department of Neurosurgery of Inner Mongolia Autonomous Region People's Hospital from January 2017 to December 2021. Patients were then matched using the propensity score matching method in a ratio of 1:1. Ninety-two pairs of cases were successfully matched, and the data before and after performing vancomycin TDM were analysed.

RESULTS

After PSM, the baseline data of the two groups were balanced. There were no significant differences in the 14-day mortality and length of hospital stay (p>0.05) between the two groups. Compared with the non-TDM group, the TDM group had a higher proportion of patients with normal white blood cells (83.7% vs 56.5%, p=0.000), neutrophil count (57.6% vs 25.0%, p=0.000) and attaining desirable reductions of 80% in procalcitonin (65.2% vs 10.9%, p=0.000) and C-reactive protein (78.3% vs 41.3%, p=0.000) levels. At US$15.82 per additional TDM, TDM significantly promoted patient outcomes, as seen in improvements in the proportion of patients attaining desirable levels of white blood cells, neutrophil count, procalcitonin and C-reactive protein.

CONCLUSIONS

Vancomycin TDM is a safe and effective approach for the treatment of patients with postoperative intracerebral haemorrhage. The empirical use of TDM of vancomycin significantly improved normal values of white blood cells and neutrophil count, achieved desirable reductions of 80% in procalcitonin and C-reactive protein, and reduced nephrotoxicity in patients with postoperative intracerebral haemorrhage.

Effect of a Declined Plasma Concentration of Valproic Acid Induced by Meropenem on the Antiepileptic Efficacy of Valproic Acid

OBJECTIVE

This study aimed to indicate whether a declined plasma concentration of valproic acid (VPA) induced by co-administration of meropenem (MEPM) could affect the antiepileptic efficacy of VPA.

METHODS

We retrospectively reviewed data of hospitalized patients who were diagnosed with status epilepticus or epilepsy between 2010 and 2019. Patients co-administered VPA and MEPM during hospitalization were screened and assigned to the exposure group, while those co-administerd VPA and other broad-spectrum antibiotics were allocated to the control group.

RESULTS

The exposure group and control group included 50 and 11 patients, respectively. With a similar dosage of VPA, the plasma concentration of VPA significantly decreased during co-administration (24.6 ± 4.3 μg/mL) compared with that before co-administration (88.8 ± 13.6 μg/mL, p < 0.0001), and it was partly recovered with the termination of co-administration (39.8 ± 13.2 μg/mL, p = 0.163) in the exposure group. The inverse probability of treatment weighting estimated the treatment efficacy via changes in seizure frequency, seizure duration, and concomitant use of antiepileptic drugs, which were not significantly different between the exposure and control groups. In the exposure group, there was no significant differences in seizure frequency between the periods of before-during and before-after (p = 0.074 and 0.153, respectively). Seizure duration during VPA-MEPM co-administration was not significantly different from that before co-administration (p = 0.291).

CONCLUSIONS

In this study, the reduced plasma concentration of VPA induced by the co-administration of MEPM did not affect the antiepileptic efficacy of VPA. This conclusion should be interpreted with caution, and more research is warranted.

TRIAL REGISTRATION

Chinese Clinical Trial Registry: ChiCTR2000034567. Registered on 10 July 2020.

Population pharmacokinetics of ciprofloxacin in newborns with early onset neonatal sepsis and suspected meningitis

BACKGROUND

Neonatal Sepsis accounts for significant proportion of neonatal mortality globally. Ciprofloxacin can be used as an effective antimicrobial against common causative agents of neonatal sepsis. However, there is only limited information about its pharmacokinetic distribution in plasma and Cerebrospinal fluid (CSF) of neonates.

METHODS

Plasma and CSF samples were taken using a sparse sampling technique from neonates who received at least one dose of intravenous ciprofloxacin. Ciprofloxacin levels were analysed using high-performance liquid chromatography (HPLC). Population pharmacokinetic analysis was conducted using a non-linear mixed-effects modelling using Pumas® (Pharmaceutical Modelling and Simulation) package (Version 2.0).

RESULTS

53 neonates were enroled in the study of whom; 9 (17%) had meningitis. The median concentration of ciprofloxacin in CSF was 1.4 (0.94-2.06) ug/ml and plasma was 2.94 (1.8-5.0) ug/ml. A one-compartment model with first-order elimination fitted the data. Body weight was found to be a significant covariate on volume of distribution (Vd). Simulations based on the final model suggest that dose of 10 mg/kg, intravenous b.d may not be able to achieve the desirable indices.

CONCLUSIONS

One compartment model with weight as a covariate explained the available data. Further studies with modified sampling strategy, larger sample size and variable dose levels are needed.

Age-associated augmented renal clearance and low BMI trigger suboptimal vancomycin trough concentrations in children with haematologic diseases: data of 1453 paediatric patients from 2017 to 2022

BACKGROUND

It is usually difficult for the trough concentration of vancomycin to reach the recommended lower limit of 10 mg/L per the label dose in the paediatric population. Moreover, children with haematologic diseases who suffer from neutropenia are more likely to have lower exposure of vancomycin, and the risk factors have been poorly explored.

METHOD

We reviewed and analysed the initial trough concentration of vancomycin and synchronous cytometry and biochemical parameters in the blood of 1453 paediatric patients with haematologic diseases over a 6 year period, from 2017 to 2022.

RESULTS

Forty-five percent of the enrolled children had vancomycin trough concentrations below 5 mg/L after receiving a dose of 40 mg/kg/day, and the multiple regression showed that age (OR = 0.881, 95% CI 0.855 to 0.909, P < 0.001), BMI (OR = 0.941, 95% CI 0.904 to 0.980, P = 0.003) and the glomerular filtration rate (OR = 1.006, 95% CI 1.004 to 1.008, P < 0.001) were independent risk factors. A total of 79.7% of the children experienced augmented renal clearance, which was closely correlated to age-associated levels of serum creatinine. The vancomycin trough concentration was higher in children with aplastic anaemia than in those with other haematologic diseases due to a higher BMI and a lower glomerular filtration rate.

CONCLUSION

Age-associated augmented renal clearance and low BMI values contributed to suboptimal trough concentrations of vancomycin in children with haematologic diseases, and the effects of long-term use of cyclosporine and glucocorticoids need to be taken into account.

Simultaneous determination of ceftazidime and pyridine in human plasma by LC-UV

A sensitive, accurate and precise liquid chromatography (LC) method for the simultaneous determination of ceftazidime and pyridine in human plasma has been developed and validated. Acetonitrile (ACN) was employed to precipitate the proteins in the plasma samples. Chromatographic separation was performed with a Kinetex® C18 (150 mm × 3 mm, 2.6 µm) column with gradient elution. Ammonium formate 20 mM and ACN were mixed in a ratio of 98:2 (v/v) for mobile phase A and 85:15 (v/v) for mobile phase B. Both were adjusted to pH 4.5 with formic acid. The flow rate was 0.4 mL/min. UV detection was performed at 254 nm. Calibration curves were linear in the range from 0.3 to 225 μg/mL for ceftazidime and from 0.2 to 10 μg/mL for pyridine with correlation coefficients ≥ 0.999. Within- and between-run precision and accuracy were satisfactory with coefficients of variation (CV) ≤ 8.0% and deviations ≤ 7.0%, respectively. The method fulfilled all validation criteria prescribed by the European Medicines Agency guidelines. Next, it has been used successfully to analyze plasma samples of patients who received ceftazidime under intermittent and continuous administration. With intermittent administration, the concentration of the antibiotics reached a peak and then dropped quickly, which may be below the minimal inhibitory concentration (MIC). With continuous administration, the concentration of the antibiotics remained stable over 24 h, certainly above the MIC. Although the same tendency in ceftazidime concentration changes over time was observed, a difference in concentration amongst the patients was noticeable. The concentration of pyridine in plasma was negligible.

Selective Spectrofluorimetric Protocol for Determination of Commonly Used Gram-negative Bactericidal Drug in Combined Pharmaceutical Dosage Forms and Human Plasma

Gram-negative bacteria cause infections such as skin infection, meningitis, and pneumonia in human being. Gram-negative bacteria are highly resistant to most availaible bactericidal drugs. One of the most commonly used Gram-negative bactericidal drug is Polymyxin B sulfate (PMS). In addition, it is used in cases of highly resistant Gram-negative bacterial infections. The widespread of PMS necessitate the development of an exceedingly sensitive and selective fluorimetric assay for its determination in pure form, different pharmaceutical dosage forms, and human plasma. The presented method is used to determine PMS in their dosage form (vials) and combined pharmaceutical formulations (skin and eye ointments) with a high degree of accuracy and selectivity. The described procedure relies on the structure of a derivative of a high degree of fluorescence called dihydropyridine, via the condensation of the amino moiety of PMS with two equivalents of acetylacetone in the presence of formaldehyde and Teorell buffer (pH = 3). The fluorescent product was measured at 471 nm (λ_ex = 402 nm). The linearity ranged from 100-3000 ng mL^-1 of PMS with an excellent r² of 0.9998. LOD and LOQ were 27.16 ng mL^-1 and 82.30 ng mL^-1, respectively. Owing to the developed method's high selectivity, it was successfully utilized for assay of PMS, in the ointment, in the presence of oxytetracycline as an active ingredient. Furthermore, the procedure applied for the estimation of parenteral PMS in human plasma with very good mean recovery 97.42 ± 1.46.

Pharmacokinetics of Vancomycin in Critically Ill Children: A Systematic Review

Background and Objective

Vancomycin is often used in the ICU for the treatment of Gram-positive bacterial infection. In critically ill children, there are pathophysiologic changes that affect the pharmacokinetics of vancomycin. A systematic review of vancomycin pharmacokinetics and pharmacodynamics in critically ill children was performed.

Methods

Pharmacokinetic studies of vancomycin in critically ill children published up to May 2021 were included in the review provided they included children aged > 1 month. Studies including neonates were excluded. A search was performed using the PubMed, Scopus, and Google Scholar databases. The Risk of Bias Assessment Tool for Systematic Reviews (ROBIS) was used to check for quality and reduce bias. Data on study characteristics, patient demographics, clinical parameters, pharmacokinetic parameters, outcomes, and study limitations were collected.

Results

Thirteen studies were included in this review. A wide variety of dosing and sampling strategies were used in the studies. Methods for estimating vancomycin pharmacokinetics, especially the area under the curve over 24 h, varied. Vancomycin doses of 20–60 mg/kg were given daily. This resulted in high variability in pharmacokinetic parameters. Vancomycin trough level was less than 15 μg/mL in most of the studies. Vancomycin clearance ranged from 0.05 to 0.38 L/h/kg. Volume of distribution ranged from 0.1 to 1.16 L/kg. Half-life was between 2.4 and 23.6 h. Patients in the study receiving continuous vancomycin infusion had AUC₂₄ < 400 µg·h/mL.

Conclusion

There is large variability in the pharmacokinetics of vancomycin among critically ill patients. Studies to assess the factors responsible for this variability in vancomycin pharmacokinetics are needed.

Simultaneous determination of moxifloxacin with NSAIDs in API, dosage and serum by reverse phase high-performance liquid chromatography: Application to in vitro drug interactions

Experimental design is a significant tool for optimization and validation for the development of HPLC methods to determine API in both human serum and pharmaceutical formulations. In this study, RP-HPLC method is developed and validated for the simultaneous determination of moxifloxacin and NSAIDs. In this experiment, Purospher STAR C18 column with optimum assay conditions (10:90, v/v, water: methanol, pH 2.75) used as mobile phase having flow rate of 1.5mL min^-1 and screened at 240 nm. The experimental results exhibit reliability through accuracy (98-102%), precision (0.011-1.85%) and linearity (R²>0.999) in range of 0.15-40μgmL^-1. The LOD and LOQ limits for moxifloxacin and NSAIDs are found to be 0.015 and 0.046 μgmL^-1 respectively. The significant outcomes conclude that the developed method for assay is effectively suitable to human serum and pharmaceutical formulations and there is no interference from excipients of tablets and serum. The proposed method is useful for drug-interaction and investigation of moxifloxacin with NSAIDs.

Initial Serum C-reactive Protein Level as a Predictor of Increasing Serum Vancomycin Concentration During Treatment

BACKGROUND

Vancomycin has a narrow therapeutic window, and an increase in its serum concentration-to-dose ratio during treatment can cause renal toxicity. Therefore, this study was aimed at finding a marker to identify patients at risk of increasing serum vancomycin during treatment.

METHODS

This was a retrospective cohort study of patients treated with vancomycin at Kanazawa University Hospital, Japan, from April 2012 to May 2015. Spearman correlation coefficients were calculated to determine the correlations between changes in vancomycin concentration-to-dose ratio and initial values or changes in laboratory data and other parameters. In addition, a multiple regression analysis was conducted.

RESULTS

One hundred ninety-nine patients for whom 2 or more points of data on therapeutic drug monitoring (TDM) of intravenous vancomycin treatment were available and did not undergo dialysis were included in the study. Changes in vancomycin concentration-to-dose ratio were associated with C-reactive protein (CRP) and sodium (Na) levels on the initial day of TDM and with changes in white blood cell count, Na, and estimated glomerular filtration rates (eGFRs). Multiple regression analysis helped identify CRP and Na levels on the initial day of TDM and change in eGFR as independent influencing variables.

CONCLUSIONS

A high serum CRP level on the initial day of TDM is an independent predictor of increasing vancomycin concentration-to-dose ratio in patients receiving intravenous vancomycin treatment, even if eGFR remains unchanged.

Investigating the need for therapeutic drug monitoring of imipenem in critically ill patients: Are we getting it right?

BACKGROUND

The drug levels and clearances of imipenem in critically ill patients are not comprehensively described in current literature, yet it is vital that adequate levels be achieved for therapeutic success.

OBJECTIVES

To determine the proportion of critically ill patients treated with imipenem/cilastatin with sub-therapeutic imipenem plasma levels, and to compare the clinical outcomes of those patients with therapeutic levels with those who had sub-therapeutic levels.

METHODS

Trough imipenem plasma levels of 68 critically ill patients from a surgical intensive care unit were measured using a validated high-performance liquid chromatography method. Imipenem trough levels were compared with the minimum inhibitory concentration (MIC) of the causative bacterial agents, based on a target value of 100% time above MIC (¦T &gt;MIC).

RESULTS

The proportion of participants with sub-therapeutic imipenem levels was 22% (95% confidence interval (CI) 13% - 34%). The 14- and 28-day mortality rates in the sub-therapeutic group were 33% and 40%, respectively, compared with 19% (p=0.293) and 26% (p=0.346), respectively, in the therapeutic group. Sub-therapeutic imipenem plasma levels are associated with adjusted hazard ratio of 1.47 (95% CI 0.55 - 3.91).

CONCLUSIONS

The lower proportion of critically ill patients with sub-therapeutic imipenem plasma levels in this study compared with previous studies may be attributed to the practice of higher dosages and the administration method of extended infusions of imipenem/cilastatin in our setting. The results demonstrate a trend of higher mortality in patients with sub-therapeutic imipenem levels, although the results were not statistically significant at this sample size.

The use of extrapolation based on modeling and simulation to support high-dose regimens of ceftaroline fosamil in pediatric patients with complicated skin and soft-tissue infections

A model-informed drug development approach was used to select ceftaroline fosamil high-dose regimens for pediatric patients with complicated skin and soft-tissue infections caused by Staphylococcus aureus with a ceftaroline minimum inhibitory concentration (MIC) of 2 or 4 mg/L. Steady-state ceftaroline concentrations were simulated using a population pharmacokinetics (PK) model for ceftaroline fosamil and ceftaroline including data from 304 pediatric subjects and 944 adults. Probability of target attainment (PTA) for various simulated pediatric high-dose regimens and renal function categories were calculated based on patients achieving 35% fT>MIC (S. aureus PK/pharmacodynamic target for 2-log10 bacterial killing). For extrapolation of efficacy, simulated exposures and PTA were compared to adults with normal renal function receiving high-dose ceftaroline fosamil (600 mg 2-h infusions every 8 h). For safety, predicted ceftaroline exposures were compared with observed pediatric and adult data. Predicted ceftaroline exposures for the approved pediatric high-dose regimens (12, 10, or 8 mg/kg by 2-h infusions every 8 h for patients aged >2 to <18 years with normal/mild, moderate, or severe renal impairment, respectively; 10 mg/kg by 2-h infusions every 8 h for patients aged ≥2 months to <2 years with normal renal function/mild impairment) were well matched to adults with normal renal function. Median predicted maximum concentration at steady state (Cmax,ss ) and area under the plasma concentration-time curve over 24 h at steady state pediatric to adult ratios were 0.907-1.33 and 0.940-1.41, respectively. PTAs (>99% and ≥81% for MICs of 2 and 4 mg/L, respectively) matched or exceeded the adult predictions. Simulated Cmax,ss values were below the maximum observed data in other indications, including a high-dose pediatric pneumonia trial, which reported no adverse events related to high exposure.

Measurement of Free Plasma Concentrations of Beta-Lactam Antibiotics: An Applicability Study in Intensive Care Unit Patients

BACKGROUND

The antibacterial effect of antibiotics is linked to the free drug concentration. This study investigated the applicability of an ultrafiltration method to determine free plasma concentrations of beta-lactam antibiotics in ICU patients.

METHODS

Eligible patients included adult ICU patients treated with ceftazidime (CAZ), meropenem (MEM), piperacillin (PIP)/tazobactam (TAZ), or flucloxacillin (FXN) by continuous infusion. Up to 2 arterial blood samples were drawn at steady state. Patients could be included more than once if they received another antibiotic. Free drug concentrations were determined by high-performance liquid chromatography with ultraviolet detection after ultrafiltration, using a method that maintained physiological conditions (pH 7.4/37°C). Total drug concentrations were determined to calculate the unbound fraction. In a post-hoc analysis, free concentrations were compared with the target value of 4× the epidemiological cut-off value (ECOFF) for Pseudomonas aeruginosa as a worst-case scenario for empirical therapy with CAZ, MEM or PIP/tazobactam and against methicillin-sensitive Staphylococcus aureus for targeted therapy with FXN.

RESULTS

Fifty different antibiotic treatment periods in 38 patients were evaluated. The concentrations of the antibiotics showed a wide range because of the fixed dosing regimen in a mixed population with variable kidney function. The mean unbound fractions (fu) of CAZ, MEM, and PIP were 102.5%, 98.4%, and 95.7%, with interpatient variability of <6%. The mean fu of FXN was 11.6%, with interpatient variability of 39%. It was observed that 2 of 12 free concentrations of CAZ, 1 of 40 concentrations of MEM, and 11 of 23 concentrations of PIP were below the applied target concentration of 4 × ECOFF for P. aeruginosa. All concentrations of FXN (9 samples from 6 patients) were >8 × ECOFF for methicillin-sensitive Staphylococcus aureus.

CONCLUSIONS

For therapeutic drug monitoring purposes, measuring total or free concentrations of CAZ, MEM, or PIP is seemingly adequate. For highly protein-bound beta-lactams such as FXN, free concentrations should be favored in ICU patients with prevalent hypoalbuminemia.

Modification and validation of liquid chromatographic method for the quantification of ciprofloxacin in human plasma and its application to a bioavailability study

A new simple, accurate, precise and sensitive liquid chromatographic method for the analysis of Ciprofloxacin in human plasma, suitable for quantification of drug was developed and validated using HPLC-UV method. The analyte was chromatographically separated from endogenous plasma components on a C-18 reversed phase column (5µm, 25cm × 0.46cm) and detected at 278nm. The sample pretreatment was carried out with acetonitrile on 200µl of plasma. The Lower limit of quantification (LLOQ) was 0.04 µg/ml with linearity in the range 0.04-4 µg/ml and coefficient of correlation value (R²)>0.995. The method was successfully validated as per current FDA guidance for necessary parameters and applied to a pilot bioavailability study conducted on six healthy volunteers with marketed Ciprofloxacin 250mg immediate release tablets. The plasma concentrations were subjected to non-compartmental analysis for calculation of pharmacokinetic parameters like C_max, T_max, AUC_o-t, AUC _0-∞ and t_½ etc. The mean values of C_max and T_max were found to be 1.35±0.09µg/ml and 1.25±0.27h respectively while for other pharmacokinetic parameters including AUC_o-t, AUC_0-∞ were found to be 5.98±0.96 μg/ml×h and 6.34±1.07μg/ml×h. The drug exhibited half-life (t_½) of 3.94±0.33h. The obtained results proved the suitability of the method for routine pharmacokinetic studies of Ciprofloxacin.

Therapeutic Drug Level Monitoring of Teicoplanin in Korean Pediatric Patients with Normal versus Impaired Renal Function

BACKGROUND

Teicoplanin is used to treat serious gram-positive infections. Optimal teicoplanin trough levels are considered to be ≥ 10 μg/mL. Despite its wide use in various clinical settings, data on teicoplanin trough level in pediatric patients are limited. Therefore, the aim of this study was to investigate the therapeutic drug level monitoring of teicoplanin in Korean pediatric patients, including those with impaired renal function.

METHODS

A retrospective study was performed in pediatric patients (age ≤ 18 years old) who received teicoplanin from September 2014 to April 2018. The regimen included a loading dose of 10 mg/kg/dose at 12 hours' interval three times in a row, and a maintenance dose of 10 mg/kg/dose commenced at 24 hours of interval after the loading dose, with a maximum of 400 mg/dose, respectively. The first therapeutic drug levels were measured. Distribution and characteristics of trough levels in patients with decreased renal function and those with bacteremia were also assessed.

RESULTS

A total of 187 trough levels were collected from 143 patients. Hematologic and oncologic diseases were the most common underlying diseases (83.2%, n = 119). One hundred eighty trough levels were first measured, and their median value was 16.2 μg/mL (range, 2.3-100 μg/mL) and the median interval between initial teicoplanin injection and 1st trough level was 96.5 hours (range 47.6-179.3 hours). Lower steady-state levels were observed in younger age group (median, 13.5 vs. 18.0 μg/mL, P = 0.038). Median trough levels were higher in patients with decreased renal functions (P < 0.001). In addition, among eight with gram-positive bacteremia, seven of them had a favorable outcome.

CONCLUSION

This study provides additive information on trough level monitoring of teicoplanin in children with impaired renal function and treatment effect in patients with gram-positive bacteremia. Careful monitoring for steady state trough levels of teicoplanin is warranted.

Association of Obesity With Maternal and Cord Blood Penicillin Levels in Women With Group B Streptococcus Colonization

OBJECTIVE

To compare maternal and cord blood penicillin concentrations in women with and without obesity who are receiving intrapartum group B streptococcus (GBS) prophylaxis.

METHODS

We performed a prospective cohort study of term women receiving intrapartum penicillin prophylaxis for GBS colonization (determined by antenatal rectovaginal culture). The following outcomes were compared between obese (body mass index [BMI] 35 or higher at delivery) and nonobese (BMI less than 30 at delivery) groups: penicillin concentration in maternal blood (after two penicillin doses) and umbilical cord blood, GBS rectovaginal colonization status on admission and after two completed doses, and neonatal GBS colonization (using a postnatal ear swab). Fifty-five women were needed to detect a 0.75 SD difference in cord blood penicillin concentrations.

RESULTS

Fifty-five women were enrolled and had all specimens collected; 49 had complete data for analysis (obese n=25, nonobese n=24). There was no difference in the median maternal penicillin concentration between groups (obese 4.2 micrograms/mL vs nonobese 4.0 micrograms/mL, P=.58). There was, however, a 60% lower median cord blood penicillin concentration in the obese compared with the nonobese group (2.7 micrograms/mL vs 6.7 micrograms/mL, respectively, P<.01), with no significant difference in time from last penicillin dose to delivery (obese 2.9 hours vs nonobese 1.7 hours, P=.07). The difference in cord blood concentrations remained significant after adjustment for nulliparity, hypertensive disorders, and time from last penicillin dose to delivery. Only 59.6% of women tested positive for GBS by rectovaginal culture on admission (obese 60.9% vs nonobese 58.3%, P=.86).

CONCLUSION

The median cord blood penicillin concentration was 60% lower in neonates born to women with obesity compared with those born to women without obesity. However, all concentrations exceeded the minimum inhibitory concentration. Maternal penicillin levels were not significantly different between groups. More than 40% of women who previously tested positive for GBS by antenatal culture tested negative for GBS on admission for delivery.

Physiologically Based Pharmacokinetic Modeling for Trimethoprim and Sulfamethoxazole in Children

OBJECTIVE

The aims of this study were to (1) determine whether opportunistically collected data can be used to develop physiologically based pharmacokinetic (PBPK) models in pediatric patients; and (2) characterize age-related maturational changes in drug disposition for the renally eliminated and hepatically metabolized antibiotic trimethoprim (TMP)-sulfamethoxazole (SMX).

METHODS

We developed separate population PBPK models for TMP and SMX in children after oral administration of the combined TMP-SMX product and used sparse and opportunistically collected plasma concentration samples to validate our pediatric model. We evaluated predictability of the pediatric PBPK model based on the number of observed pediatric data out of the 90% prediction interval. We performed dosing simulations to target organ and tissue (skin) concentrations greater than the methicillin-resistant Staphylococcus aureus (MRSA) minimum inhibitory concentration (TMP 2 mg/L; SMX 9.5 mg/L) for at least 50% of the dosing interval.

RESULTS

We found 67-87% and 71-91% of the observed data for TMP and SMX, respectively, were captured within the 90% prediction interval across five age groups, suggesting adequate fit of our model. Our model-rederived optimal dosing of TMP at the target tissue was in the range of recommended dosing for TMP-SMX in children in all age groups by current guidelines for the treatment of MRSA.

CONCLUSION

We successfully developed a pediatric PBPK model of the combination antibiotic TMP-SMX using sparse and opportunistic pediatric pharmacokinetic samples. This novel and efficient approach has the potential to expand the use of PBPK modeling in pediatric drug development.

Bath immersion pharmacokinetics of florfenicol in Nile tilapia (Oreochromis niloticus)

Drug administration by immersion can be a preferable method in certain conditions especially for treating small-sized, anorexic, or valuable fish. Pharmacokinetic information regarding bath treatment is considerably lacking in comparison to other common administration routes. The current study aimed to investigate if immersion can be an effective route to administer florfenicol (FF) for treatment in Nile tilapia. Nile tilapia reared at 28°C were immersed with FF solution at concentrations of 50, 100, 200, 500, and 500/200 (3 hr/117 hr) ppm for 120 hr and moved to drug-free freshwater for another 24 hr. The serum FF concentration in 100, 200, and 500/200 ppm groups reached steady-state at 12 hr with concentrations of 2.44, 3.04, and 5.26 µg/ml, respectively, which were about 2% of the bathing concentrations. The target therapeutic levels of 1-4 µg/ml were attained and maintained within 1-12 hr, depending on the immersion concentration and the target MIC. Serum FF reached the target with shorter time at higher bathing concentration. Following the 120-hr bath, the serum FF declined with the first-order half-life of approximately 10 hr. A minimum of 100 ppm FF is required for treatment purpose, and an initial high loading concentration followed by maintenance concentration is a plausible way to reach in vivo therapeutic level in short time. Greater than 99% of the residual FF in the bathing water could be removed within 15 min by 0.05% NaOCl. Our results indicated that bath immersion is a promising potential route for FF administration in Nile tilapia.

Validation of Multi-Residue Method for Quantification of Antibiotics and NSAIDs in Avian Scavengers by Using Small Amounts of Plasma in HPLC-MS-TOF

Pharmaceuticals are still considered emerging pollutants affecting both aquatic and terrestrial ecosystems. Scavenging bird species may be exposed to veterinary drugs when they feed on livestock carcasses provided at supplementary feeding stations, as these are often stocked with ailing and/or recently medicated animals. Because those animals may be a source of several different pharmaceutical compounds, analytical methods to evaluate residue levels and exposure potential should enable detection and quantification of as many different compounds as possible, preferably from small sample volumes. Four different extraction methods were tested to conduct HPLC-MS-TOF analysis of some of the most common veterinary drugs used in livestock in Spain. The method deemed most viable was a simple extraction, using methanol and 100 µL of plasma, that allowed quantification of seven antibiotics (tetracycline, oxytetracycline, ciprofloxacin, enrofloxacin, nalidixic acid, trimethoprim, sulfadiazine) and five nonsteroidal anti-inflammatory drugs (NSAIDs) (meloxicam, flunixin, carprofen, tolfenamic acid, phenylbutazone). The method was then applied to analysis of 29 Eurasian griffon vulture (Gyps fulvus) nestling samples, wherein enrofloxacin and tolfenamic acid were most commonly detected (69% and 20%, respectively). To our knowledge, this is the first study including NSAIDs in the exposure assessment of different classes of veterinary pharmaceuticals in live avian scavengers.

Population Pharmacokinetics and Pharmacodynamics of Norvancomycin in Children With Malignant Hematological Disease

Knowledge of pharmacokinetic (PK) behavior of norvancomycin (NVCM) in pediatric patients is lacking, which leads to empirical therapy in clinical practice. This study developed a population PK model of children aged 0-15 years; 112 opportunistic samples in total from 90 children were analyzed. The stability and prediction of the final model were evaluated by goodness-of-fit plots, nonparametric bootstrap, visual predictive check, and normalized prediction distribution errors. The PKs of NVCM in children was described by a 2-compartment model with first-order elimination along with body weight and estimated glomerular filtration rate as significant covariates on clearance. The population typical values of the PK parameters were as follows: clearance 0.12 L/kg/h, central compartment distribution volume 0.17 L/kg, peripheral compartment distribution volume 0.38 L/kg, and intercompartmental clearance 0.35 L/kg/h. Logistic analysis showed that the ratio of area under the concentration-time curve over 24 hours (AUC_0-24 ) to minimum inhibitory concentration (MIC) had the strongest correlation with clinical efficacy, and at least 80% clinical efficiency could be achieved when AUC_0-24 /MIC ≥ 221.06 was defined as the target. Monte Carlo simulation results suggested that a higher dose was required for this pediatric population in order to reach the target. The dosing regimen was optimized based on the final model. A population PK model of NVCM was first characterized in children with hematologic malignancy, and an evidence-based approach for NVCM dosage individualization was provided.

Incidence of snakebites in Can Tho Municipality, Mekong Delta, South Vietnam-Evaluation of the responsible snake species and treatment of snakebite envenoming

BACKGROUND

Data on incidence of snakebites and the responsible snake species are largely missing in Vietnam and comprehensive national guidelines for management of snakebite envenoming are not yet available. They are needed to estimate the scope of this health problem, to assess the demand for snake antivenom and to ensure the best possible treatment for snakebite victims.

METHODOLOGY/PRINCIPLE FINDINGS

A cross-sectional community-based survey was conducted from January to April 2018. Multistage cluster sampling was applied and snakebite incidence in Can Tho municipality, excluding two central districts of Can Tho city, was calculated at 48 (95%-confidence interval (CI): 20.5-99.8) snakebites per 100,000 person-years. Seven snakebite victims found during the survey reported 3 bites from green pit vipers and 4 bites from non-venomous snakes. In 2017 two treatment centres for snakebite envenoming in Can Tho city, the Military Hospital 121 and the Paediatric Hospital, received 520 admissions of snakebite victims. Two hundred sixty-seven came from Can Tho Municipality and 253 from neighbouring provinces. According to these data, the incidence of snakebites for Can Tho municipality was calculated at 21 (95%-CI: 18.5-23.7) snakebites per 100,000 person-years. Incidence was 14 (95%-CI: 12-17) snakebites per 100,000 person years in those 7 districts of the municipality which were part of the community survey. Green pit vipers were responsible for 92% of snakebite envenoming. Antivenom, antibiotics and corticosteroids were administered to 405 (90%), 379 (84%), and 310 (69%) out of 450 patients, respectively.

CONCLUSIONS

Incidence of snakebites in Can Tho Municipality is relatively low and green pit vipers are responsible for the vast majority of bites. Approximately one third of snakebite patients sought medical care in hospitals and although hospital data still underestimate the real incidence of snakebites, these statistics are valuable and can be obtained fast and inexpensively. Evaluation of patients' records indicates the need for development of guidelines for management of snakebite envenoming in Vietnam to ensure a rational use of antivenom and ancillary treatments.

Disposition and pharmacokinetics of azithromycin in serum and a lung tissue of two modified-release formulations compared with an immediate-release product on the market

The aim of this study was to determine the disposition and pharmacokinetics in serum and a lung tissue homogenate in guinea pig (Cavia porcellus) of two experimental formulations of azithromycin, those were included in a modified release polymer matrix (MRF) after oral administration. The results obtained are compared with a commercial form of immediate release. 3 groups of animals were randomly formed in groups of 7 for control and 14 for each group of modified-release formulations (MRFs) were treated with a single dose of 8mg/kg of active principle. In lung tissue, comparisons of concentration of azithromycin, showed statistically significant differences between commercial product, MRF1 and MRF2. All pharmacokinetic parameters for MRF1 and MRF2 were significantly different with the exception of C_max with respect to commercial product. The treatment of the animals with MRFs may have several benefits over treatment with azithromycin alone since could increase dosing interval for the two MRFs evaluated and reduce the frequency of application, patient stress levels and toxicological risks by accumulation of the active principle.

A statistical approach to optimizing paper spray mass spectrometry parameters

RATIONALE

Paper spray mass spectrometry (PS-MS) was used to analyze and quantify ampicillin, a hydrophilic compound and frequently utilized antibiotic. Hydrophilic molecules are difficult to analyze via PS-MS due to their strong binding affinity to paper substrates and low ionization efficiency, among other reasons.

METHODS

Solvent and paper parameters were optimized to increase the extraction of ampicillin from the paper substrate. After optimizing these key parameters, a Resolution IV 1/16 fractional factorial design with two center points was employed to screen eight different design parameters simultaneously.

RESULTS

Pore size, sample volume, and solvent volume were the most significant factors affecting average peak area under the curve (AUC) and the signal-to-blank (S/B) ratio for the 1 μg/mL ampicillin calibrant. After optimizing the key parameters, a linear calibration curve with a range of 0.2 μg/mL to 100 μg/mL was generated (R²  = 0.98) and the limit of detection (LOD) and lower limit of quantification (LLOQ) were calculated to be 0.07 μg/mL and 0.25 μg/mL, respectively.

CONCLUSIONS

The statistical optimization procedure undertaken here increased the mass spectral signal intensity by more than a factor of 40. This statistical method of screening followed by optimization experiments proved faster and more efficient, and produced more drastic improvements than typical one-factor-at-a-time experiments.

Multidrug-Resistant Staphylococcus epidermidis Ventriculostomy-Related Infection Successfully Treated by Intravenous Ceftaroline after Failure of Daptomycin Treatment

BACKGROUND

Ventriculostomy-related infection with multidrug-negative strains are challenging to treat. We report the use of new antibiotics in such a case.

CASE DESCRIPTION

We report the case of a neurosurgical intensive care unit patient who developed ventriculostomy-related infection with a multidrug-resistant Staphylococcus epidermidis. Vancomycin, recommended in such cases, was not used due to high minimal inhibitory concentrations and concerns for lack of pharmacokinetic/pharmacodynamic target attainment. Daptomycin and ceftaroline remained the only treatment options. Daptomycin was shown microbiologically ineffective after 10 treatment days, with undetectable cerebrospinal fluid (CSF) concentration. Ceftaroline, a novel beta-lactam agent to which the strain showed susceptibility, was thus used. Serum and CSF samples were assessed for antibiotic concentrations. Our results show that CSF bacterial clearance was obtained after 6 days of such treatment. Serum and CSF samplings showed low penetration ratios (2.6%-4.8%), probably due to mild inflammatory CSF profile, with CSF concentration at minimal inhibitory concentration level.

CONCLUSIONS

We observed than even in the case of mild meningeal inflammation, ceftaroline penetration in CSF, although moderate, enabled efficient bacterial clearance and clinical efficacy, in adjunction to correct ventriculoperitoneal shunt management.

A long lifetime ratiometrically luminescent tetracycline nanoprobe based on Ir(III) complex-doped and Eu3+-functionalized silicon nanoparticles

Different from fluorescent dyes-doped or carbon materials-based ratiometric tetracycline nanoprobes, herein, a new Ir(III) complex-doped and europium(III) ion (Eu³⁺)-functionalized silicon nanoparticles (Ir(III)@SiNPs-Eu³⁺) with long luminescent lifetimes was firstly fabricated for selective detection of tetracycline (TC) in complex systems through time-resolved emission spectra (TRES) measurement. In the presence of TC, the red phosphorescence of Eu³⁺ is greatly enhanced by adsorption energy transfer emission (AETE) of TC, while the strong green luminescence of Ir(III)@SiNPs is quenched by the inner filtration effect (IFE) of TC. Based on these striking emission changes, Ir(III)@SiNPs-Eu³⁺ can sensitively detect TC in the linear range of 0.01-20 μM with a detection limit of 4.9 × 10^-3 μM. Benefitting from the long lifetime of Ir(III)@SiNPs-Eu³⁺, the nanoprobe demonstrates excellent TC detection performance through TRES in high background system of 5 % human serum. Furthermore, the formed Ir(III)@SiNPs-Eu³⁺/TC complex can be used to sensitively recognize Hg²⁺ via a ratiometric luminescence mode. Notably, the cytotoxicity of Ir(III)@SiNPs-Eu³⁺ is very low and thus the sensitive monitoring the detection of Ir(III)@SiNPs-Eu³⁺ to TC and Hg²⁺ also works well in porcine renal cells, demonstrating high application potential in real samples.

Lengthening the aptamer to hybridize with a stem-loop DNA assistant probe for the electrochemical detection of kanamycin with improved sensitivity

By adding 6 thymines to lengthen the parent aptamer combined with the change of "on" and "off" induced by the target for an assistant stem-loop DNA probe (ASP-SLP-MB), a new folding-type electrochemical kanamycin (Kana) aptamer-engineering dual-probe-based sensor (sensor d) was developed. By purposefully reducing the background current and increasing the electron transfer efficiency of methylene blue (MB), the sensor obtained significantly enhanced detection sensitivity compared with non-aptamer-engineering one-probe-based sensor (sensor a). Such efficacy was validated by a big decrease from 530.6 to 210.2 nA for the background current signal and from 360 to 0.3 nM for the detection limit. In addition to the improved sensitivity, the sensor also exhibited good selectivity, anti-fouling detection performance, and potential quantitative analysis ability, showing a feasible potential practical analytical application in real-life complicated samples, for example, milk and serum. The released results prove that the aptamer-engineering method is effective in improving the analytical performance of folding-type sensors and provides a methodological guidance for the design and fabrication of other high-performance folding-type aptasensors. Graphical abstract.

Comparative LC-MS/MS and HPLC-UV Analyses of Meropenem and Piperacillin in Critically Ill Patients

BACKGROUND

Therapeutic drug monitoring (TDM) of beta-lactam antibiotics has become a valuable tool to guide dosing in critically ill patients. The main goal of the study was to compare two routinely used techniques for beta-lactam TDM in intensive care unit (ICU) patient samples, namely isotope dilution liquid chromatography tandem mass spectrometry (ID-LC-MS/MS) and high-performance liquid chromatography combined with ultra-violet detection (HPLC-UV).

METHODS

A set of 80 sera/plasma samples from ICU patients receiving therapeutic meropenem or piperacillin dosage was investigated. Sample duplicates and quality assessment samples were assayed in parallel with an in-house LC-MS/MS and a commercially available IVD HPLC-UV kit. A pharmacokinetic and pharmacodynamic (PK/PD) target with ≥ 22.5 mg/L for piperacillin and ≥ 8.0 mg/L for meropenem was used for medical assessment of trough sample (n = 40) antibiotic concentrations.

RESULTS

There was no difference between serum and Li-heparin plasmas. Concentration deviations were found for 4% of meropenem and 17% of piperacillin samples. Eliminating the influence of the systemic bias of approximately 10% for piperacillin, measurement discrepancies ≥ 25% between LC-MS/MS and HPLC-UV analyses were only observed for ≈ 4 - 6% of all samples. In the same way, identical PK/PD target attainment rates of 50 - 60% could be obtained.

CONCLUSIONS

After correction of the analytical bias for piperacillin measurements, both methods showed comparable results, also with respect to clinical decision limits. HPLC-UV analysis is an adequate TDM methodology for testing of beta-lactam antibiotics in centers where no special knowledge in LC-MS/MS based TDM is present. However, potential matrix effects, interferences, and calibration issues for both methods must be taken into account.

Pharmacokinetic modeling and simulation for dose rationale of doripenem in neonates and infants

The aims of this study were to construct a population pharmacokinetic model of doripenem in neonates and infants and to assess the dosing regimen for patients <3 months of age using Monte-Carlo pharmacokinetic/pharmacodynamic (PKPD) simulations. In the population pharmacokinetic analysis using 187 plasma concentrations from 47 neonates and infants, a two-compartment model well described plasma doripenem concentrations with the most significant covariates of chronological age and gestational age identified for the pharmacokinetics of doripenem. Monte-Carlo simulations suggested that the selected dosages for neonates and infants based on chronological age and gestational age (5 or 10 mg/kg) would provide ≥90% target attainment of 40%fT_>MIC against MIC of 2 μg/mL in all age groups. These results would be useful for understanding the PKPD characteristics of doripenem, which could provide essential information on optimal therapeutic treatment for neonates and infants.

The effect of therapeutic drug monitoring of beta-lactam and fluoroquinolones on clinical outcome in critically ill patients: the DOLPHIN trial protocol of a multi-centre randomised controlled trial

BACKGROUND

Critically ill patients undergo extensive physiological alterations that will have impact on antibiotic pharmacokinetics. Up to 60% of intensive care unit (ICU) patients meet the pharmacodynamic targets of beta-lactam antibiotics, with only 30% in fluoroquinolones. Not reaching these targets might increase the chance of therapeutic failure, resulting in increased mortality and morbidity, and antibiotic resistance. The DOLPHIN trial was designed to demonstrate the added value of therapeutic drug monitoring (TDM) of beta-lactam and fluoroquinolones in critically ill patients in the ICU.

METHODS

A multi-centre, randomised controlled trial (RCT) was designed to assess the efficacy and cost-effectiveness of model-based TDM of beta-lactam and fluoroquinolones. Four hundred fifty patients will be included within 24 months after start of inclusion. Eligible patients will be randomly allocated to either study group: the intervention group (active TDM) or the control group (non-TDM). In the intervention group dose adjustment of the study antibiotics (cefotaxime, ceftazidime, ceftriaxone, cefuroxime, amoxicillin, amoxicillin with clavulanic acid, flucloxacillin, piperacillin with tazobactam, meropenem, and ciprofloxacin) on day 1, 3, and 5 is performed based upon TDM with a Bayesian model. The primary outcome will be ICU length of stay. Other outcomes amongst all survival, disease severity, safety, quality of life after ICU discharge, and cost effectiveness will be included.

DISCUSSION

No trial has investigated the effect of early TDM of beta-lactam and fluoroquinolones on clinical outcome in critically ill patients. The findings from the DOLPHIN trial will possibly lead to new insights in clinical management of critically ill patients receiving antibiotics. In short, to TDM or not to TDM?

TRIAL REGISTRATION

EudraCT number: 2017-004677-14. Sponsor protocol name: DOLPHIN. Registered 6 March 2018 . Protocol Version 6, Protocol date: 27 November 2019.

A Dried Blood Spot Analysis for Solithromycin in Adolescents, Children, and Infants: A Short Communication

BACKGROUND

Solithromycin is a fourth-generation macrolide antibiotic with potential efficacy in pediatric community-acquired bacterial pneumonia. Pharmacokinetic (PK) studies of solithromycin in pediatric subjects are limited, therefore application of minimally invasive drug sampling techniques, such as dried blood spots (DBS), may enhance the enrollment of children in PK studies. The objectives of this study were to compare solithromycin concentrations in DBS with those in liquid plasma samples (LPS) and to quantify the effects of modeling DBS concentrations on the results of a population PK model.

METHODS

Comparability analysis was performed on matched DBS and LPS solithromycin concentrations collected from two different phase 1 clinical trials of solithromycin treatment in children (clinicaltrials.gov #NCT01966055 and #NCT02268279). Comparability of solithromycin concentrations was evaluated based on DBS:LPS ratio, median percentage prediction error, and median absolute percentage prediction error. The effect of correcting DBS concentrations for both hematocrit and protein binding was investigated. In addition, a previously published population PK model (NONMEM) was leveraged to compare parameter estimates resulting from either DBS or LPS concentrations.

RESULTS

A total of 672 paired DBS-LPS concentrations were available from 95 subjects (age: 0-17 years of age). The median (range) LPS and DBS solithromycin concentrations were 0.3 (0.01-12) mcg/mL and 0.32 (0.01-14) mcg/mL, respectively. Median percentage prediction error and median absolute percentage prediction error of raw DBS to LPS solithromycin concentrations were 5.26% and 22.95%, respectively. In addition, the majority of population PK parameter estimates resulting from modeling DBS concentrations were within 15% of those obtained from modeling LPS concentrations.

CONCLUSIONS

Solithromycin concentrations in DBS were similar to those measured in LPS and did not require correction for hematocrit or protein binding.

Multiple innate antibacterial immune defense elements are correlated in diverse ungulate species

In this study, we aimed to evaluate to what extent different assays of innate immunity reveal similar patterns of variation across ungulate species. We compared several measures of innate antibacterial immune function across seven different ungulate species using blood samples obtained from captive animals maintained in a zoological park. We measured mRNA expression of two receptors involved in innate pathogen detection, toll-like receptors 2 and 5 (TLR2 and 5), the bactericidal capacity of plasma, as well as the number of neutrophils and lymphocytes. Species examined included aoudad (Ammotragus lervia), American bison (Bison bison bison), yak (Bos grunniens), Roosevelt elk (Cervus canadensis roosevelti), fallow deer (Dama dama), sika deer (Cervus nippon), and Damara zebra (Equus quagga burchellii). Innate immunity varied among ungulate species. However, we detected strong, positive correlations between the different measures of innate immunity-specifically, TLR2 and TLR5 were correlated, and the neutrophil to lymphocyte ratio was positively associated with TLR2, TLR5, and bacterial killing ability. Our results suggest that ecoimmunological study results may be quite robust to the choice of assays, at least for antibacterial innate immunity; and that, despite the complexity of the immune system, important sources of variation in immunity in natural populations may be discoverable with comparatively simple tools.

Facile synthesis of copper(II) oxide nanospheres covered on functionalized multiwalled carbon nanotubes modified electrode as rapid electrochemical sensing platform for super-sensitive detection of antibiotic

Herein, we report a super-active electrocatalyst of copper(II) oxide nanoparticles (CuO NPs) decorated functionalized multiwalled carbon nanotubes (CuO NPs@f-MWCNTs) by the ultrasonic method. The as-synthesized CuO NPs@f-MWCNTs was characterized through the FESEM, XPS, XRD and electrochemical impedance spectroscopy (EIS). The combination of highly active CuO NPs and highly conductive f-MWCNTs film with rapid detection enables this nanohybrid to display excellent electrochemical performance towards anesthesia drug. Furthermore, the hybrid electrocatalyst modified SPCE was developed for the determination of flunitrazepam (FTM) for the first time. FTM is important anesthesia drug with high adverse effect in human body. Benefiting from the synergistic reaction of CuO NPs and f-MWCNTs, this nanohybrid exhibited high sensitivity and specificity towards FTM electro-reduction. The CuO NPs@f-MWCNTs film modified SPCE exhibits outstanding electrochemical activity including excellent reproducibility, wide linear range from 0.05 to 346.6 µM with nanomolar limit of detection for FTM detection. Further, the as-modified CuO NPs@f-MWCNTs/SPCE has been applied to determination of FTM in biological and drug samples with satisfactory recovery results, thereby showing a notable potential for extensive (bio) sensor applications.

Electrochemical Aptamer-Based Sensors for Improved Therapeutic Drug Monitoring and High-Precision, Feedback-Controlled Drug Delivery

The electrochemical aptamer-based (E-AB) sensing platform appears to be a convenient (rapid, single-step, and calibration-free) and modular approach to measure concentrations of specific molecules (irrespective of their chemical reactivity) directly in blood and even in situ in the living body. Given these attributes, the platform may thus provide significant opportunities to render therapeutic drug monitoring (the clinical practice in which dosing is adjusted in response to plasma drug measurements) as frequent and convenient as the measurement of blood sugar has become for diabetics. The ability to measure arbitrary molecules in the body in real time could even enable closed-loop feedback control over plasma drug levels in a manner analogous to the recently commercialized controlled blood sugar systems. As initial exploration of this, we describe here the selection of an aptamer against vancomycin, a narrow therapeutic window antibiotic for which therapeutic monitoring is a critical part of the standard of care, and its adaptation into an electrochemical aptamer-based (E-AB) sensor. Using this sensor, we then demonstrate: (i) rapid (seconds) and convenient (single-step and calibration-free) measurement of plasma vancomycin in finger-prick-scale samples of whole blood, (ii) high-precision measurement of subject-specific vancomycin pharmacokinetics (in a rat animal model), and (iii) high-precision, closed-loop feedback control over plasma levels of the drug (in a rat animal model). The ability to not only track (with continuous-glucose-monitor-like measurement frequency and convenience) but also actively control plasma drug levels provides an unprecedented route toward improving therapeutic drug monitoring and, more generally, the personalized, high-precision delivery of pharmacological interventions.

Effect of green tea on the gastrointestinal absorption of amoxicillin in rats

BACKGROUND

The investigation of food-drug and plant-drug interactions has become increasingly important. In case of antibiotics, it is essential to achieve and maintain a plasma concentration sufficient for the antimicrobial action. Although, on theoretical basis, the interaction of polyphenols and antibiotics may be hypothesized, experimental data are lacking to assess its clinical relevance. The aim of our study was to assess the interaction between one of the most widely used antibiotics, amoxicillin, and green tea, the most frequently consumed drink with high polyphenol content.

METHODS

The effects of green tea on the plasma level of amoxicillin was studied in an in vivo experiment in rats. The plasma level of amoxicillin was monitored by LC-MS/MS for 240 min after oral administration. The polyphenol content of green tea was determined by the Folin-Ciocalteu method.

RESULTS

The peak plasma concentration of amoxicillin significantly decreased upon its co-administration with green tea, although the AUC0-240 of the antibiotic did not decrease significantly in the group treated with amoxicillin suspended in green tea.

CONCLUSIONS

Our results suggest a potentially relevant interaction between green tea and amoxicillin, worth being further studied in humans.

Ratiometric detection of tetracycline based on gold nanocluster enhanced Eu3+ fluorescence

Tetracycline (TC), a widely-used antibiotic to treat bacterial infections, combines with Eu³⁺ to form a stable EuTC complex that has a low fluorescence (FL) yield because of Eu³⁺ coordination with water molecules. We report a simple, label-free ratiometric fluorescent platform for sensitively and selectively sensing of TC, using L-histidine caped gold nanoclusters (His-AuNCs) as a FL indicator and an enhancer of Eu³⁺ FL. The His-AuNCs were prepared via chemical reduction of Au(III) by L-histidine, which was a reducer and a protecting agent. The His-AuNCs exhibited good photostability, outstanding stability toward high ionic strengths, storage stability, and favorable optical properties. In the absence of TC, the AuNCs-Eu³⁺ system displays strong FL emission at 475 nm (F₄₇₅) from the His-AuNCs and weak FL at 620 nm from Eu³⁺ (F₆₂₀) with excitation at 375 nm. TC quenches the His-AuNC FL and greatly enhances the Eu³⁺ emission. This is attributed to an enhancement of the EuTC complex fluorescence by the His-AuNCs. Thus, a ratiometric F₆₂₀/F₄₇₅ FL signal can be used for TC detection by simply mixing AuNCs and Eu³⁺. Under the optimized conditions, the linear range from 10 nM to 60 μM and a detection limit of 4 nM (S/N = 3) for TC were obtained. The application of the assay platform for the detection of TC in environmental and biological samples was demonstrated. The sensing platform has advantages of easy preparation, rapid response, high sensitivity, and good selectivity.

Population Pharmacokinetic Modeling and Probability of Target Attainment Analyses in Asian Patients With Community-Acquired Pneumonia Treated With Ceftaroline Fosamil

Efficacy of ceftaroline fosamil, the prodrug of the active metabolite ceftaroline, was demonstrated in a phase 3 study of hospitalized Asian patients with Pneumonia Outcomes Research Team (PORT) risk class III-IV community-acquired pneumonia (NCT01371838). The objectives of the current analysis were to expand an existing ceftaroline and ceftaroline fosamil population pharmacokinetic (PK) model with data from this phase 3 study and a phase 1 study (NCT01458743) assessing ceftaroline PK in healthy Chinese volunteers and to evaluate the probability of PK/pharmacodynamic (PK/PD) target attainment (PTA) in Asian patients with community-acquired pneumonia (CAP) treated with ceftaroline fosamil. The ceftaroline plasma concentration-time course was simulated for 5000 Asian patients with CAP for different renal function subgroups using the final model. PTA was calculated for Streptococcus pneumoniae, Staphylococcus aureus, and non-extended-spectrum β-lactamase-producing Enterobacteriaceae. PTA was also evaluated for ceftaroline MIC90 values of isolates collected from Asia-Pacific surveillance studies (2012-2014) and for EUCAST and FDA/CLSI ceftaroline susceptibility break points. The final model reasonably described the ceftaroline PK. Race was not found to be a significant covariate impacting ceftaroline PK, suggesting similar ceftaroline PK in Asian and Western populations when corrected for body weight. High PTAs (90%-100%) were predicted for Asian patients with CAP treated with ceftaroline fosamil, covering MIC90 values of target CAP pathogens from the region. Similarly, >90% PTAs were predicted at EUCAST and FDA/CLSI clinical break points for these pathogens. These results support the use of the ceftaroline fosamil dosing regimens approved in Europe and the United States in Asian patients with PORT III-IV CAP.