Clinical Therapeutic Drug Monitoring Research Articles

A sensitive HPLC-UV method for quantifying vancomycin in biological matrices: Application to pharmacokinetic and biodistribution studies in rat plasma, skin and lymph nodes

Vancomycin (VCN) is an antibiotic used in the treatment of methicillin-resistant Staphylococcus aureus (MRSA)-derived infections. As it has a relatively narrow therapeutic window, it is imperative to develop a sensitive and reliable analytical method for drug monitoring and pharmacokinetic purposes. In the present study, quick sample preparations and a sensitive high-performance liquid chromatography method using UV detection (HPLC-UV) have been developed and validated. The analytical method for detection and quantification of VCN in rat plasma, skin and lymph node samples was validated based on the Food and Drug Administration (FDA) and European Medicine Agency (EMEA) bioanalytical method validation guidelines. The optimised plasma sample preparation involved a simple protein precipitation step, with extraction recovery of 100.3 ± 0.92 %. VCN in all biological matrices was analysed in a HPLC-UV system (215 nm) using a Cortecs® C18 column (4.6 × 150 mm, 2.7 μm particle size) fitted with a guard cartridge set at 20 °C. Reverse phase HPLC under gradient conditions, with mobile phase consisting of 20 mM phosphate buffer containing 0.5 % v/v of triethylamine and a mixture of methanol – acetonitrile (70:30, v/v), and runtime of 12 min/sample was employed. The calibration standards used for plasma ranged between 0.1−50 μg/ml, while in the skin and lymph node matrices, standards ranged between 0.05−50 μg/ml with correlation coefficients (R2) of ≥ 0.9995 for all matrices. The method was selective, sensitive, accurate and precise for detecting and quantifying VCN in the biological matrices used. The validated method was successfully utilised in the detection of VCN in a pharmacokinetic and organ biodistribution study carried out in rats following oral and IV bolus administration of the drug. This validated bioanalytical method offers a wide range of potential applications in clinical therapeutic drug monitoring, pharmacokinetics and toxicology.

Applicability of ninhydrin as a fluorescent reagent for estimation of teicoplanin in human plasma using salting-out assisted liquid-liquid extraction technique.

The applicability of ninhydrin, a widely used derivatizing reagent, for determination of teicoplanin (TEIC) in its pure form, pharmaceutical vials, and in human plasma was investigated. The presented spectrofluorimetric method was based on a condensation reaction between ninhydrin and the primary amine group existing in TEIC (in the presence of phenylacetaldehyde) to produce a highly fluorescent product detected at 460 nm (λex ,390 nm). Calibration plots were constructed in the concentration range 60-600 ng mL-1 with a good correlation coefficient of 0.9998 and a low detection limit of 10.84 ng mL-1 . The method was subjected to a bioanalytical validation study according to US-FDA recommendations. The proposed method was applied for analysis of TEIC in commercial vials with high recovery result 101.88 ± 1.11%. In addition, the method was utilized efficiently for detection of TEIC in human plasma using salting-out assisted liquid-liquid extraction technique (SALLE) with a recovery range from 96.71 ± 1.08% to 97.71 ± 0.86%. SALLE is an effective approach used for extraction of TEIC from human plasma without interferences using ammonium sulphate. The proposed method is highly recommended to monitor TEIC in clinical laboratory samples and therapeutic drug monitoring systems.

A simple and rapid LC-MS/MS method for the simultaneous determination of eight antipsychotics in human serum, and its application to therapeutic drug monitoring

A simple and rapid liquid chromatography/tandem mass spectrometry (LC-MS/MS) method was developed and used to determine eight antipsychotics (aripiprazole, clozapine, haloperidol, olanzapine, paliperidone, quetiapine, risperidone, and ziprasidone) in human serum for practical clinical usage. Stable isotope-labeled internal standards were used for all drugs to compensate for method variability, including matrix effects, ion extraction and ionization variations. Samples were prepared by simple protein precipitation with methanol. Chromatographic separation was accomplished in less than 3.3 min on a KINTEX C18 column (50 mm × 3.0 mm, 5 μm) using a gradient elution of 2 mM aqueous ammonium formate and methanol at a flow rate of 0.5 mL/min. Quantification was performed by multiple reaction monitoring (MRM) in the positive mode. The method was fully validated according to the latest recommendations of international guidelines. The correlation coefficients of calibration curves were all greater than 0.9945. Internal standard-normalized matrix effects ranged from 96.3% to 115%, and extraction recoveries were between 88.1% and 107%. Coefficients of variation ranged from 1.82 − 13.5% for intra-day precision, 5.69–14.7% for inter-day precision, and the relative error for accuracy did not exceed ± 13.5% for any analyte. The method was successfully applied to routine clinical therapeutic drug monitoring for 2,173 samples.

Bayesian estimation of pharmacokinetic parameters: an important component to include in the teaching of clinical pharmacokinetics and therapeutic drug monitoring.

Bayesian estimation of pharmacokinetic parameters (PKP), as discussed in this review, provides a powerful approach towards the individualization of dosing regimens. The method was first described by Lewis Sheiner and colleagues and it is well suited in clinical environs where few blood fluid measures of drugs are available in the clinic. This makes it a valuable tool in the effective implementation of therapeutic drug monitoring. The principle behind the method is Bayes theorem, which incorporates elements of variability in a priori-known population estimates and variability in the pharmacokinetic parameters, and known errors intrinsic to the assay method used to estimate the blood fluid drug concentrations. This manuscript reviews the Bayesian method. The literature was scanned using Pubmed to provide background into the Bayesian method. An Add-in for Excel program was used to show the ability of the method to estimate PKP using sparse blood fluid concentration vs time data. Using a computer program, the method was able to find reasonable estimates of individual pharmacokinetic parameters, assessed by comparing the estimated data to the true PKP. Education of students in clinical pharmacokinetics is incomplete without some mention and instruction of the Bayesian forecasting method. For a complete understanding, a computer program is needed to demonstrate its utility.

UPLC–MS/MS method for the simultaneous quantification of bictegravir and 13 others antiretroviral drugs plus cobicistat and ritonavir boosters in human plasma

A sensitive and rapid ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method has been developed and validated for 14 antiretroviral drugs and 2 boosters in human plasma. Plasma (100 μL) was precipitated with a solution of acetonitrile containing labelled internal standards. The compounds were separated with a total chromatic run time of 6 min using an Acclaim TM RSLC 120 C18 column (2.1 × 100 mm, 2.2 μm). The method was fully validated according to the European Medecines Agency guidelines. Linearity of all analytes concentrations was validated up to 5000 ng/mL. Lower limits of quantification were ranged from 2.5 ng/mL to 10 ng/mL according to compounds. Intra-day and inter-day precision ranged from 0.2% to 8.9% and accuracies were below 13%. This UPLC-MS/MS method can be applied to clinical pharmacology research and therapeutic drug monitoring in patients living with HIV.

A novel molecularly imprinted polymer decorated by CQDs@HBNNS nanocomposite and UiO-66-NH2 for ultra-selective electrochemical sensing of Oxaliplatin in biological samples

A platform equipped with a well-designed synthetic interface, as a universal sensor, is required to detect highly selective and sensitive anticancer drugs in complex matrices of different biological samples. In this study, we developed a novel electrochemical sensor based on the combination of molecularly imprinted method with the 3D-framework UiO-66-NH2 as excellent target molecule recognizer on the surface of a glassy carbon electrode modified with carbon quantum dots incorporated hexagonal boron nitride nanosheets (CQDs@HBNNS/UiO-66-NH2 /MIP/GCE) for ultraselective detection of trace levels of Oxaliplatin (OXA) as an anticancer drug. The increased efficiency and sensitivity of the proposed MIP sensor was obtained due to the use of UiO-66-NH2 with high porosity structure which effectively increased the number of binding sites and specific surface area as well as CQDs@HBNNS nanocomposite (CQDs@HBNNS-NCs) with ideal electric conductivity and synergistic effects to facilitate the electron transfer process. During MIP preparation, optimal conditions were achieved by using experimental design, based on a standard orthogonal array, and different electrodes were characterized by scanning electron microscopy and cyclic voltammetry. Electrochemical responses of imprinted sensor displayed two dynamic linear ranges from 1.0 to 20.0 nM and 20.0 to 250.0 nM with a detection limit of 0.37 nM. In addition, superior anti-interfering ability of the designed MIP sensor toward OXA detection in the presence of interferents at high concentration especially other Pt-based anticancer drugs as well as reproducibility and stability of it proved that the CQDs@HBNNS/UiO-66-NH2 /MIP/GCE could be extensively applied in the clinical therapeutic drug monitoring.

Development and validation of an integrated LC-MS/MS assay for therapeutic drug monitoring of five PARP-inhibitors

An liquid chromatography-mass spectrometry (LC-MS/MS) assay was developed for the combined analysis of the five poly (ADP-ribose) polymerase (PARP) inhibitors niraparib, olaparib, rucaparib talazoparib and veliparib. A simple and fast sample pre-treatment method was used by protein precipitating of plasma samples with acetonitrile and dilution of the supernatant with formic acid (0.1% v/v in water). This was followed by chromatographic separation on a reversed-phase UPLC BEH C18 column and detection with a triple quadrupole mass spectrometer operating in the positive mode. A simplified validation procedure specifically designed for bioanalytical methods for clinical therapeutic drug monitoring (TDM) purposes, was applied. This included assessment of the calibration model, accuracy and precision, lower limit of quantification (LLOQ), specificity and selectivity, carry-over and stability. The validated range was 30–3000 ng/mL for niraparib, 100–10,000 ng/mL for olaparib, 50–5000 ng/mL for rucaparib, 0.5–50 ng/mL for talazoparib and 50–5000 for veliparib. All results were within the criteria of the US Food and Drug Administration (FDA) guidance and European Medicines Agency (EMA) guidelines on method validation. The assay has been successfully implemented in our laboratory.

Determination of voriconazole in human plasma by liquid chromatography-tandem mass spectrometry and its application in therapeutic drug monitoring in Chinese patients.

ObjectiveTo develop a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the quantification of voriconazole in human plasma, and to evaluate its application in clinical therapeutic drug monitoring.MethodPlasma samples were obtained from Chinese patients receiving voriconazole, precipitated with methanol (using fluconazole as an internal standard), and then subjected to LC-MS/MS using an SB C18 column with a methanol and water mobile phase at a flow rate of 0.4 mL/minute. Quantification was performed by multiple-reaction monitoring using the precursor and product ion pair m/z 350–280.9 for voriconazole and m/z 307–219.9 for fluconazole.ResultsThe calibration curve was linear over a range of 0.1–10.0 µg/mL (R2 = 0.9995). The inter-day and intra-day relative standard deviations were <7.68% and <8.97%, respectively. Extraction recovery, matrix effect, and stability were also validated. Sixty-eight plasma samples from 42 patients were analyzed, and the voriconazole concentrations in 25 samples (36.8%) were outside the optimal range of 1.5–4.5 µg/mL.ConclusionsWe developed a simple and accurate method of drug monitoring, which could improve the efficacy and prevent adverse reactions of voriconazole.

Development and validation of a volumetric absorptive microsampling- liquid chromatography mass spectrometry method for the analysis of cefepime in human whole blood: Application to pediatric pharmacokinetic study

Cefepime is a fourth-generation cephalosporin antibiotic with an extended spectrum of activity against many Gram-positive and Gram-negative bacteria. There is a growing need to develop sensitive, small volume assays, along with less invasive sample collection to facilitate pediatric pharmacokinetic clinical trials and therapeutic drug monitoring. The volumetric absorptive microsampling (VAMS™) approach provides an accurate and precise collection of a fixed volume of blood (10 μL), reducing or eliminating the volumetric blood hematocrit assay-bias associated with the dried blood spotting technique. We developed a high-performance liquid chromatographic method with tandem mass spectrometry detection for quantification of cefepime. Sample extraction from VAMS™ devices, followed by reversed-phase chromatographic separation and selective detection using tandem mass spectrometry with a 4 min runtime per sample was employed. Standard curves were linear between 0.1–100 μg/mL for cefepime. Intra- and inter-day accuracies were within 95.4–113% and precision (CV) was < 15 % based on a 3-day validation study. Recoveries ranged from 40.8 to 62.1% and the matrix effect was within 89.5–96.7% for cefepime. Cefepime was stable in human whole blood under assay conditions (3 h at room temperature, 24 h in autosampler post-extraction). Cefepime was also stable for at least 1 week (7 days) at 4 °C, 1 month (39 days) at −20 °C and 3 months (91 days) at −78 °C as dried microsamples. This assay provides an efficient quantitation of cefepime and was successfully implemented for the analysis of whole blood microsamples in a pediatric clinical trial.

Ultrahigh-throughput absolute quantitative analysis of linezolid in human plasma by direct analysis in real time mass spectrometry without chromatographic separation and its application to a pharmacokinetic study.

Therapeutic drug monitoring (TDM) is necessary in the clinical management of linezolid to improve its efficacy and reduce the risk of time- and dose-dependent toxicity. A novel and ultrahigh-throughput analytical method for the determination of linezolid in human plasma was developed based on direct analysis in real-time tandem mass spectrometry (DART-MS/MS) without chromatographic separation. After solid-phase extraction with Waters Oasis HLB, the linezolid and internal standard linezolid-d3 were detected by positive ion electrospray ionization followed by multiple reaction monitoring (MRM) of the transition at m/z 338.1 → 296.2 and 341.2 → 297.3, respectively. The use of DART-MS obviates the need for chromatographic separation and allowed determination of linezolid in a total run time of only 24s per sample. The method was linear in the concentration range 0.20-25μgmL-1 with intraday and interday precision <14.5% and accuracy ranging from -3.85% to 12.7%. The method was successfully applied to a pharmacokinetic study of linezolid in healthy male volunteers after oral administration of a 600mg tablet. DART-MS/MS provides a rapid and sensitive method for the determination of linezolid that does not require chromatographic separation. It is eminently suitable to meet the high-throughput challenge of clinical TDM. Graphical abstract.

Mo1892 – Non-Medical Reverse Switch Between the Originator Infliximab and Its Biosimilar in Patients with Inflammatory Bowel Disease: Clinical Outcomes and Therapeutic Drug Monitoring

Mo1892 – Non-Medical Reverse Switch Between the Originator Infliximab and Its Biosimilar in Patients with Inflammatory Bowel Disease: Clinical Outcomes and Therapeutic Drug Monitoring

An ultra-performance liquid chromatography-tandem mass spectrometry method to quantify vancomycin in human serum by minimizing the degradation product and matrix interference.

Aim: This study aimed to develop and validate a method for better therapeutic monitoring of vancomycin serum concentration. Methods & results: An ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed and validated to minimize the interference of crystalline degradation product and matrix. It was compared with chemiluminescence microparticle immunoassay (CMIA)and ultra-performance liquid chromatography with ultraviolet detection (UPLC-UV) in the performance of testing normal, on-dialysis and hemolytic serum samples. For on-dialysis samples, a moderate correlation (r=0.534) was observed between UPLC-UV and UPLC-MS/MS. In testing hemolytic samples, ten (10/85, 11.8%) samples were overestimated by CMIA method. Conclusion: Vancomycin concentration determined by CMIA, UPLC-UV was more affected by various panels of serum samples than UPLC-MS/MS assay, suggesting that UPLC-MS/MS is a more reliable and promising tool for clinical vancomycin therapeutic drug monitoring.

Molecularly imprinted polymer decorated 3D-framework of functionalized multi-walled carbon nanotubes for ultrasensitive electrochemical sensing of Norfloxacin in pharmaceutical formulations and rat plasma

In this work, a 3D-framework of functionalized multi-walled carbon nanotubes (fMWCNTs) decorated with molecularly imprinted polymer (MIP), has been fabricated to achieve fast and ultrasensitive electrochemical molecular sensing. The cavity networks of MIP layer from Norfloxacin (NFX) molecules offers simultaneous identification and quantification of NFX; and thus, ensures its high selectivity. The porous structure of fMWCNT 3D-framwork effectively increases the specific surface area, and the copolymer of fMWCNTs and MIP shows synergistic effect for electrocatalytic reaction of NFX at the modified sensor. Under optimized conditions, the fabricated sensors show wide linear detection ranges of 0.003-0.391 μM and 0.391–3.125 μM, low limit of determination (LOD) of 1.58 nM, and excellent selectivity in discriminating NFX according to its structural analogues and possible interferences. Precise and fast quantification of NFX in pharmaceutical formulations (Yunnan Baiyao and Ouyi Pharmaceutical) and rat plasma samples (N = 4) suggests its simplicity and reliability. The recoveries from pharmaceutical formulations ranged from 97.36 to 109.58% with the precisions (relative standard deviations, RSD, n = 3) of 1.74–3.41%; and the recoveries from rat plasma samples ranged from 83.00 to 115.67% with RSDs (n = 3) of 0.45–10.30%. Considering the advantages of easy fabrication, and selective and sensitive detection, such sensors with different types of MIPs would be widely applied in the fields of pharmaceutical analysis, and environmental and clinical therapeutic drug monitoring.

P409 Non-medical reverse switch between the originator infliximab and its biosimilar in patients with inflammatory bowel disease: clinical outcomes and therapeutic drug monitoring

P409 Non-medical reverse switch between the originator infliximab and its biosimilar in patients with inflammatory bowel disease: clinical outcomes and therapeutic drug monitoring

An LC-MS/MS Method for Absolute Quantification of Nivolumab in Human Plasma: Application to Clinical Therapeutic Drug Monitoring.

Nivolumab is a fully humanized IgG4 monoclonal antibody that targets the programmed death-1 (PD-1) receptor, disrupting PD-1-mediated signaling and restoring antitumor immunity. The objective of this study was to develop a nivolumab quantification method using liquid chromatography-tandem mass spectrometry (LC-MS/MS) and to evaluate its application in clinical therapeutic drug monitoring. Nivolumab was purified from human plasma using rProtein A resin and then digested with trypsin. The ASGITFSNSGMHWVR peptide (multiple reaction monitoring transition: m/z 550.6→661.4) was detected as a surrogate peptide of nivolumab by triple quadrupole mass spectrometry. Plasma samples (126) were collected from 14 patients with non-small cell lung cancer who were undergoing clinical dosing regimen with nivolumab. The pharmacokinetic data were analyzed using Phoenix NLME software (Version 7.0, Certara, St. Louis, MO) based on a previously reported population pharmacokinetics (PPK) model of nivolumab. Nivolumab was selectively detected in human plasma and the linear range was 5-200 mcg/mL (R = 0.99). The accuracy and intraday and interday imprecision were within ±15% of the quality control values of 5 (lower limit of quantification), 10 (low), 80 (medium), and 160 (high) mcg/mL. The nivolumab concentrations measured using LC-MS/MS were consistent with those of previously reported PPK models, and the pharmacokinetic parameters could be adequately predicted from a single trough concentration using a Bayesian approach. An absolute quantification method for nivolumab using LC-MS/MS was successfully developed and validated. Combined with PPK analysis, this method should be useful for the therapeutic drug monitoring of nivolumab in clinical practice.

Research of optimal dosing regimens and therapeutic drug monitoring for vancomycin by clinical pharmacists: analysis of 7-year data

To investigate the effectiveness and safety of clinical pharmacists-directed vancomycin dosing and therapeutic drug monitoring (TDM), and to promote the individualized medication of vancomycin. Information of hospitalized patients treated by vancomycin admitted to Ruijin Hospital Affiliated to Shanghai Jiao Tong University School of Medicine from January 2011 to October 2017 was collected retrospectively during study period, the patients were divided into pharmacists intervention and non-pharmacists intervention groups according to pharmacist-directed vancomycin dosing guideline or not. The individualized dosing regimen of vancomycin for the patients in pharmacists intervention group was guided by clinical pharmacists, this guideline was that pharmacists offered the TDM guidance, made the individualized dosage regimen of vancomycin, etc., which based on the patients' pathophysiology, condition, and the adjustments of increased dose or 24-hour continuous infusion vancomycin were made for patients if the steady-state trough concentrations fell below the target level. Vancomycin dosage was made for patients in the non-pharmacists intervention group by physicians only based on vancomycin instructions or clinical experience. The vancomycin dosing, TDM, microorganism culture, renal function, 30-day mortality rate, and length of hospital stay were recorded. The appropriateness of TDM for vancomycin was defined as a blood collection within 1 hour of the next scheduled dose after steady state achieved. The rationality of the initial dosing regimen was determined based on the vancomycin application guidelines issued by Infectious Diseases Society of America (IDSA) in 2009. A total of 258 patients were enrolled, and there were 158 patients in the non-pharmacists intervention group and 100 in pharmacists intervention group. The appropriateness of TDM for vancomycin in pharmacists intervention group was significantly improved as compared with that in non-pharmacists intervention group [87.0% (87/100) vs. 69.6% (110/158), P < 0.01], the percentage of first trough serum concentrations drawn on day 3 after steady state achieved was significantly increased [51.0% (51/100) vs. 37.3% (53/142), P < 0.05]. Compared with the non-pharmacists intervention group, the percentages of patients who received appropriate initial dosing and attained the initial target therapeutic range in pharmacists intervention group were significantly increased [87.4% (76/87) vs. 68.2% (75/110), 51.7% (45/87) vs. 30.9% (34/110), both P < 0.01], the percentage of patients whose vancomycin dosing regimen was adjusted based on TDM results was also significantly increased [54.0% (47/87) vs. 15.5% (17/110), P < 0.01], the rate of vancomycin serum concentrations reaching the standard was increased [70.1% (61/87) vs. 32.7% (36/110), P < 0.01], and a lower number of patients in sub- or supra-therapeutic range was observed in pharmacists intervention group [27.6% (24/87) vs. 46.4% (51/110), 2.3% (2/87) vs. 20.9% (23/110), both P < 0.01]. In addition, a lower incidence of vancomycin-induced acute kidney injury (AKI) was observed in pharmacists intervention group as compared with that in non-pharmacists intervention group [0 (0/87) vs. 6.4% (7/110), P < 0.01]. No significant difference was observed in the microorganism culture, 30-day mortality rate or length of hospital stay between the two groups. Among the 87 patients in pharmacists intervention group, the vancomycin dosing was adjusted for 42 patients who did not attain the target therapeutic range, increasing the dose of vancomycin was made for 22 patients, 24-hour continuous infusion was made for 20 patients. Compared with the only increasing vancomycin dose group, vancomycin continuous infusion for 24 hours could significantly increase the serum trough concentration (mg/L: 18.0±6.7 vs. 12.5±5.8, P < 0.05), and reduce daily dosage (mg/kg: 27.1±7.1 vs. 36.6±9.2, P < 0.01). The implementation of a pharmacist-directed vancomycin dosing guideline based on TDM optimized vancomycin dosing regimen, improved the accuracy and timeliness of TDM for vancomycin, achieved a higher percentage of levels within the therapeutic range, and a lower incidence of vancomycin-induced AKI.

AntiEpileptic drug Monitoring in PREgnancy (EMPiRE): a double-blind randomised trial on effectiveness and acceptability of monitoring strategies.

Pregnant women with epilepsy on antiepileptic drugs (AEDs) may experience a reduction in serum AED levels. This has the potential to worsen seizure control. To determine if, in pregnant women with epilepsy on AEDs, additional therapeutic drug monitoring reduces seizure deterioration compared with clinical features monitoring after a reduction in serum AED levels. A double-blind, randomised trial nested within a cohort study was conducted and a qualitative study of acceptability of the two strategies was undertaken. Stratified block randomisation with a 1 : 1 allocation method was carried out. Fifty obstetric and epilepsy clinics in secondary and tertiary care units in the UK. Pregnant women with epilepsy on one or more of the following AEDs: lamotrigine, carbamazepine, phenytoin or levetiracetam. Women with a ≥ 25% decrease in serum AED level from baseline were randomised to therapeutic drug monitoring or clinical features monitoring strategies. In the therapeutic drug monitoring group, clinicians had access to clinical findings and monthly serum AED levels to guide AED dosage adjustment for seizure control. In the clinical features monitoring group, AED dosage adjustment was based only on clinical features. Primary outcome - seizure deterioration, defined as time to first seizure and to all seizures after randomisation per woman until 6 weeks post partum. Secondary outcomes - pregnancy complications in mother and offspring, maternal quality of life, seizure rates in cohorts with stable serum AED level, AED dose exposure and adverse events related to AEDs. Analysis of time to first and to all seizures after randomisation was performed using a Cox proportional hazards model, and multivariate failure time analysis by the Andersen-Gill model. The effects were reported as hazard ratios (HRs) with 95% confidence intervals (CIs). Secondary outcomes were reported as mean differences (MDs) or odds ratios. A total of 130 women were randomised to the therapeutic drug monitoring group and 133 to the clinical features monitoring group; 294 women did not have a reduction in serum AED level. A total of 127 women in the therapeutic drug monitoring group and 130 women in the clinical features monitoring group (98% of complete data) were included in the primary analysis. There were no significant differences in the time to first seizure (HR 0.82, 95% CI 0.55 to 1.2) or timing of all seizures after randomisation (HR 1.3, 95% CI 0.7 to 2.5) between both trial groups. In comparison with the group with stable serum AED levels, there were no significant increases in seizures in the clinical features monitoring (odds ratio 0.93, 95% CI 0.56 to 1.5) or therapeutic drug monitoring group (odds ratio 0.93, 95% CI 0.56 to 1.5) associated with a reduction in serum AED levels. Maternal and neonatal outcomes were similar in both groups, except for higher cord blood levels of lamotrigine (MD 0.55 mg/l, 95% CI 0.11 to 1 mg/l) or levetiracetam (MD 7.8 mg/l, 95% CI 0.86 to 14.8 mg/l) in the therapeutic drug monitoring group than in the clinical features monitoring group. There were no differences between the groups on daily AED exposure or quality of life. An increase in exposure to lamotrigine, levetiracetam and carbamazepine significantly increased the cord blood levels of the AEDs, but not maternal or fetal complications. Women with epilepsy perceived the need for weighing up their increased vulnerability to seizures during pregnancy against the side effects of AEDs. Fewer women than the original target were recruited. There is no evidence to suggest that regular monitoring of serum AED levels in pregnancy improves seizure control or affects maternal or fetal outcomes. Further evaluation of the risks of seizure deterioration for various threshold levels of reduction in AEDs and the long-term neurodevelopment of infants born to mothers in both randomised groups is needed. An individualised prediction model will help to identify those women who need close monitoring in pregnancy. Current Controlled Trials ISRCTN01253916. This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 22, No. 23. See the NIHR Journals Library website for further project information.

A new concept of efficient therapeutic drug monitoring using the high-resolution continuum source absorption spectrometry and the surface enhanced Raman spectroscopy

In this study, a new therapeutic drug monitoring approach has been tested based on the combination of CaF molecular absorption using high-resolution continuum source absorption spectrometry (HR-CSAS) and surface enhanced Raman spectroscopy (SERS). HR-CSAS with mini graphite tube was successfully tested for clinical therapeutic drug monitoring of the fluorine-containing drug capecitabine in sweat samples of cancer patients: It showed advantageous features of high selectivity (no interference from Cl), high sensitivity (characteristic mass of 0.1 ng at CaF 583.069 nm), low sample consumption (down to 30 nL) and fast measurement (no sample pretreatment and less than 1 min of responding time) in tracing the fluorine signal out of capecitabine. However, this technique has the disadvantage of the total loss of the drug's structure information after burning the sample at very high temperature. Therefore, a new concept of combining HR-CSAS with a non-destructive spectroscopic method (SERS) was proposed for the sensitive sensing and specific identification of capecitabine. We tested and succeed in obtaining the molecular characteristics of the metabolite of capecitabine (named 5-fluorouracil) by the non-destructive SERS technique. With the results shown in this work, it is demonstrated that the combined spectroscopic technique of HR-CSAS and SERS will be very useful in efficient therapeutic drug monitoring in the future.

Quantification of the next-generation oral anti-tumor drugs dabrafenib, trametinib, vemurafenib, cobimetinib, pazopanib, regorafenib and two metabolites in human plasma by liquid chromatography-tandem mass spectrometry

A sensitive and selective method of high performance liquid chromatography (HPLC) coupled to tandem mass spectrometry (MS/MS) has been developed for the simultaneous quantification of six anticancer protein kinase inhibitors (PKIs), dabrafenib, trametinib, vemurafenib, cobimetinib, pazopanib, regorafenib, and two active metabolites (regorafenib-M2 and regorafenib-M5) in human plasma. Plasma protein precipitation with methanol enables the sample extraction of 100 μL aliquot of plasma. Analytes are detected by electrospray triple-stage quadrupole mass spectrometry and quantified using the calibration curves with stable isotope-labeled internal standards. The method was validated based on FDA recommendations, including assessment of extraction yield (74–104%), matrix effects, analytical recovery (94–104%) with low variability (<15%). The method is sensitive (lower limits of quantification within 1 to 200 ng/mL), accurate (intra- and inter-assay bias: −0.3% to +12.7%, and −3.2% to +6.3%, respectively) and precise (intra- and inter-assay CVs within 0.7–7.3% and 2.5–8.0%, respectively) over the clinically relevant concentration range (upper limits of quantification 500 to 100,000 ng/mL). This method is applied in our laboratory for both clinical research programs and routine therapeutic drug monitoring service of PKIs.

High-sensitive electrochemical sensor for determination of Norfloxacin and its metabolism using MWCNT-CPE/pRGO-ANSA/Au

In this work, a high-sensitive electrochemical sensor of Norfloxacin (NFX) has been developed using a composite electrode of MWCNT-CPE/pRGO-ANSA/Au. MWCNT-CPE is the multi-walled carbon nanotubes (MWCNT) – carbon paste electrode (CPE). pRGO-ANSA means the partially reduced graphene oxide (pRGO) – 6-aminonaphthalene-2-sulphonic acid (ANSA) hybrid nanomaterials. Au represents gold nanoparticles. The electrochemical sensing of NFX was investigated by cyclic voltammetry (CV), linear sweep voltammetry (LSV) and differential pulse voltammetry (DPV). Experimental results show that the combination of MWCNT-CPE/pRGO-ANSA/Au offers high electrical conductivity, large surface area and excellent electrocatalytic activity, being beneficial for electrochemical sensing performance. The calibration curves of NFX exhibit linear response in the NFX concentration range of 0.03–1.0 and 1.0–50.0μM, with the limit of detection (LOD) of 0.016μM (S/N=3). The fabricated sensors were successfully applied for detecting the presence of NFX in pharmaceutical formulations and rat plasma samples. The measured results were comparable with those obtained using ultrahigh performance liquid chromatography (UHPLC), indicating its high potential for applications in pharmaceutical analysis and clinical therapeutic drug monitoring.