Access to innovative drugs and the National Reimbursement Drug List in China: Changing dynamics and future trends in pricing and reimbursement.

BACKGROUND AND OBJECTIVES: Multiple reforms aimed at improving the Chinese population's health have been introduced in recent years, including several designed to improve access to innovative drugs. We sought to review current factors affecting access to innovative drugs in China and to anticipate future trends. METHODS: Targeted reviews of published literature and statistics on the Chinese healthcare system, medical insurance and reimbursement processes were conducted, as well as interviews with five Chinese experts involved in the reimbursement of innovative drugs. RESULTS: Drug reimbursement in China is becoming increasingly centralized due to the removal of provincial pathways, the establishment of the National Healthcare Security Administration and the implementation of the National Reimbursement Drug List (NRDL), which is now the main route for drug reimbursement in China. There is also an increasing number of other channels via which patients may access innovative treatments, including various types of commercial insurance and special access. Health technology assessment (HTA) and health economic evidence are becoming pivotal elements of the NRDL decision-making process. Alongside the optimization of HTA decision making, innovative risk-sharing agreements are anticipated to be increasingly leveraged in the future to optimize access to highly specialized technologies and encourage innovation while safeguarding limited healthcare funds. CONCLUSIONS: Drug public reimbursement in China continues to align more closely with approaches widely used in Europe in terms of HTA, health economics and pricing. Centralization of decision-making processes for public reimbursement of innovative drugs allows consistency in assessment and access, which optimizes the improvement of the Chinese population's health.

Secotrijugins A-D, four highly oxidized and rearranged limonoids from Trichilia sinensis and their anti-inflammatory activity.

Four undescribed highly oxidized and rearranged limonoids, secotrijugins A-D, were purified from the leaves and twigs of Trichilia sinensis. Within them, secotrijugin A was characterized as a rare 30-nortrijugin-type limonoid with an unusual cleavage of 1,14-ether bond, secotrijugins B and C represented new examples with the cleavage of δ-lactone ring D, and secotrijugin D was a rare trijugin-type limonoid with an unusual 2,6-oxygen bridge. The structures of limonoids were characterized by means of spectroscopic analysis and ECD calculations. The cellular screening revealed that secotrijugin B was the most active against LPS-stimulated NO production in BV-2 cells, which played an anti-inflammatory role by downregulating COX-2 and iNOS protein expression. The further in vivo experiments confirmed that secotrijugin B had strong in vivo anti-inflammatory effect via suppressing NO and ROS generation.

Medication therapy of high-dose methotrexate: An evidence-based practice guideline of the Division of Therapeutic Drug Monitoring, Chinese Pharmacological Society.

AIMS: A lot of medication risks related to high-dose methotrexate (HDMTX) therapy still remain to be identified and standardized. This study aims to establish an evidence-based practice guideline for individualized medication of HDMTX. METHODS: The practice guideline was launched by the Division of Therapeutic Drug Monitoring, Chinese Pharmacological Society. The guideline was developed following the WHO handbook for guideline development and the methodology of evidence-based medicine (EBM). The guideline was initially registered in the International Practice Guidelines Registry Platform (IPGRP-2017CN021). Systematic reviews were conducted to synthesize available evidence. A multicentre cross-sectional study was conducted using questionnaires to evaluate patients' perception and willingness concerning individualized medication of HDMTX. The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach was used to rate the quality of evidence and to grade the strength of recommendations. RESULTS: Multidisciplinary working groups were included in this guideline, including clinicians, pharmacists, methodologists, pharmacologists and pharmacoeconomic specialists. A total of 124 patients were involved to integrate patient values and preferences. Finally, the guideline presents 28 recommendations, regarding evaluation prior to administration (renal function, liver function, pleural effusion, comedications, genetic testing), pre-treatment and routine dosing regimen, therapeutic drug monitoring (necessity, method, timing, target concentration), leucovorin rescue (initial timing, dosage regimen and optimization), and management of toxicities. Of these, 12 are strong recommendations. CONCLUSIONS: We developed an evidence-based practice guideline with respect to HDMTX medication using a rigorous and multidisciplinary approach. This guideline provides comprehensive and practical recommendations involving the whole process of HDMTX administration to health care providers.

Simultaneous determination of paraquat and diquat in human plasma by HPLC-DAD: Its application in acute poisoning patients induced by these two herbicides.

BACKGROUND: Paraquat and diquat are widely used in agricultural production in many countries, which are very toxic to human beings. Paraquat can be detected in some diquat solution sold in the market. The blood concentration of paraquat or diquat is an important indicator for clinical diagnosis of paraquat or diquat poisoning. So, it is very meaningful to develop a method for simultaneous determination of paraquat and diquat in human plasma. OBJECTIVE: To develop and validate a HPLC-DAD method for simultaneous determination of paraquat and diquat in human plasma and to apply it in the acute poisoning patients by these two herbicides. METHODS: Paraquat and diquat were simultaneously determined by HPLC-DAD. The plasma was treated using Waters OASIS® Column and then separated on a Thermo Hypersil GOLD (250 × 4.6 mm, 5 µm) Column with the mobile phase consisted of 75 mmol/L sodium heptane sulfonate (containing 0.1 mol/L phosphoric acid, pH 3.0) and acetonitrile (87:13, v:v) at a flow rate of 1.0 mL/min. The full-wavelength scanning was 200-400 nm, and the detection wavelength of paraquat and diquat was 257nm and 310nm, respectively. 120 and 30 plasma samples from patients with paraquat and diquat poisoning were collected and analyzed by the established method. RESULTS: The standard curve for paraquat and diquat ranged from 0.05 to 20 µg/mL, and the precision of LLOQ for paraquat was 16.49%, which was required to be less than 20%. The precision of other concentrations was less than 14.14%. The recovery of paraquat and diquat was 95.38%-103.97% and 94.79%-98.40%, respectively. The results showed that paraquat and diquat were stable under various storage conditions. 120 plasma samples of paraquat poisoning patients and 30 plasma samples of diquat poisoning patients were determined by the established method. The blood concentration of paraquat ranged from 0.10 to 20.62 µg/mL, with an average of 3.61 µg/mL, while for diquat, the concentration ranged from 0 to 26.59 µg/mL, with an average of 2.00 µg/mL. Among the diquat suspected poisoning samples, 5 samples were detected not only diquat but also paraquat, and 2 samples were detected only paraquat, no diquat. CONCLUSION: The HPLC-DAD method established in this study was high throughput, high sensitivity, simple operation, and wide linear ranges. It can be used for the screening analysis and quantitative detection of paraquat and diquat in acute poisoning patients, which can provide basis for the treatment and prognosis of these two herbicides poisoning patients.

Evidence-based Guideline for Therapeutic Drug Monitoring of Vancomycin: 2020 Update by the Division of Therapeutic Drug Monitoring, Chinese Pharmacological Society.

BACKGROUND: Clinical practice guidelines or recommendations often require timely and regular updating as new evidence emerges, because this can alter the risk-benefit trade-off. The scientific process of developing and updating guidelines accompanied by adequate implementation can improve outcomes. To promote better management of patients receiving vancomycin therapy, we updated the guideline for the therapeutic drug monitoring (TDM) of vancomycin published in 2015. METHODS: Our updated recommendations complied with standards for developing trustworthy guidelines, including timeliness and rigor of the updating process, as well as the use of the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach. We also followed the methodology handbook published by the National Institute for Health and Clinical Excellence and the Spanish National Health System. RESULTS: We partially updated the 2015 guideline. Apart from adults, the updated guideline also focuses on pediatric patients and neonates requiring intravenous vancomycin therapy. The guideline recommendations involve a broadened range of patients requiring TDM, modified index of TDM (both 24-hour area under the curve and trough concentration), addition regarding the necessity and timing of repeated TDM, and initial dose for specific subpopulations. Overall, 1 recommendation was deleted and 3 recommendations were modified. Eleven new recommendations were added, and no recommendation was made for 2 clinical questions. CONCLUSIONS: We updated an evidence-based guideline regarding the TDM of vancomycin using a rigorous and multidisciplinary approach. The updated guideline provides more comprehensive recommendations to inform rational and optimized vancomycin use and is thus of greater applicability.

Bi and oxygen defects improved visible light photocatalysis with BiOBr nanosheets.

Bi metal attached BiOBr with oxygen defect (BiOBr(3)-Bi(x%, x = 10, 20, 30)) nanosheets was prepared via the hydrothermal process in this study. The different characterization techniques of x-ray diffraction, x-ray photoelectron spectrometer, electron spin resonance (ESR), field emission scanning electron microscope, and high resolution transmission electron microscope were used to distinguish the composition, crystal structure, and morphology of the samples. Under visible light irradiation, the BiOBr(3)-Bi(x%, x = 10, 20, 30) samples exhibited improved photocatalytic activity for the degradation of colored dyes (RhB) and colorless tetracycline hydrochloride. Such an improvement was ascribed to the widened visible light absorption and enhanced separation of the photogenerated electron-hole pairs because of the synergistic effect of oxygen vacancies and Bi metal with plasmon resonance effects. A possible photocatalytic mechanism of the quasi Z-scheme process was proposed on the basis of ESR measurements and radical-trapping experiments.

Simultaneous Determination of Multiple Active Components from Bushen Pills and Application in a Pharmacokinetic Study in Rats.

Bushen Pills (BSPs), as a traditional Chinese medicine (TCM), is widely used in clinic to enrich Yang, nourish Yin, stem essence, and strengthen kidneys. Two chromatographic methods, liquid chromatography-mass spectrometry (LC-MS) and liquid chromatography-tandem mass spectrometry (LC-MS/MS), were applied to analyze the multiple active components of BSPs in dosage form for quality evaluation and in rat plasma for pharmacokinetics study, respectively. Three active constituents of BSPs, including paeoniflorin (PF), berberine hydrochloride (BBR), and schizandrin (SCH), were simultaneously determined by the established LC-MS method with electrospray ionization (ESI) in positive selected ion monitoring (SIM) mode at m/z 503.1, 336.0, and 455.2. The contents of PF, BBR, and SCH were (6.112 ± 0.166) mg/g, (335.1 ± 14.95) µg/g, and (5.867 ± 0.136) µg/g in BSPs. On this basis, PF and BBR were selected as targeted analytes for the pharmacokinetic study of BSPs in rats. Memantine hydrochloride was used as an internal standard (IS), and the plasma samples were processed by liquid-liquid extraction with ethyl acetate. All the analytes were separated on a C18 reversed phase column, eluted with a mobile phase consisting of acetonitrile-formic acid (0.01%) (25 : 75, v/v), and detected by ESI in the selected ion mode with multiple reaction monitoring (MRM). The target fragment ions were m/z 525.3 ⟶ 449.5 for PF, 336.2 ⟶ 320.2 for BBR, and 180.1 ⟶ 163.1 for IS. The linear ranges of PF and BBR were 5-500 ng/mL and 0.1-20 ng/mL with good linearity (r 2 > 0.99). No obvious matrix effect was observed, and acceptable accuracy, precision, recovery, and stability were obtained. The proposed method has been successfully applied to the pharmacokinetic study of BSPs in rats after a single dose.

Serum metabolomic profiling in patients with Alzheimer disease and amnestic mild cognitive impairment by GC/MS.

The aim of this study was to characterize the serum metabolic profiles of patients with Alzheimer's disease (AD) and amnestic mild cognitive impairment (AMCI) using metabolomics based on gas chromatography-mass spectrometry (GC/MS). Serum samples were collected from patients with AD (n = 30) and AMCI (n = 32), and normal healthy controls (NOR, n = 40). Metabolite profiles were performed with GC/MS in conjunction with multivariate statistical analysis, and possible biomarker metabolites were identified. Thirty-one kinds of endogenous metabolites could be identified simultaneously. Eleven components were chosen as biomarker metabolites between AD and NOR groups, and these metabolites were closely related to seven biological pathways: arginine and proline metabolism, phenylalanine metabolism, ß-alanine metabolism, primary bile acid synthesis, glutathione metabolism, starch and sucrose metabolism, and steroid hormone biosynthesis. Meanwhile, 10 components were chosen as biomarker metabolites between AMCI and NOR groups and seven biological pathways were closely related: arginine and proline metabolism, phenylalanine metabolism, citrate cycle, alanine, aspartate and glutamate metabolism, taurine and hypotaurine metabolism, starch and sucrose metabolism, and steroid hormone biosynthesis. Our study distinguished serum metabotypes between AD, AMCI and NOR patients successfully. The implementation of this metabolomic strategy may help to develop biochemical insight into the metabolic alterations in AD/AMCI and will be helpful for the further understanding of pathogenesis.

Synonymous mutation rs2515641 affects CYP2E1 mRNA and protein expression and susceptibility to drug-induced liver injury.

Aim: To evaluate whether the synonymous mutant rs2515641 could affect cytochrome P450 2E1 (CYP2E1) expression and the response to acetaminophen (APAP) or triptolide (TP) treatment. Materials & methods: HepG2 cells were transfected with lentiviral vector containing either CYP2E1-1263C or CYP2E1-1263T. Some of these recombinant cells were then treated with APAP or TP. CYP2E1 gene expression was detected by PCR and western blot. Results:CYP2E1 gene expression decreased significantly both in mRNA and protein level after rs2515641 mutation, indicating that this polymorphism can affect both transcription and translation. Furthermore, rs2515641 mutation dramatically changes the response of CYP2E1 expression to APAP or TP treatment. Conclusion: Rs2515641 significantly changes CYP2E1 expression and function, which would be expected to affect drug disposition and response.

CYP2E1 and miRNA-378a-3p contribute to acetaminophen- or tripterygium glycosides-induced hepatotoxicity.

Increased expression of CYP2E1 may represent the main factor contributing to oxidative stress-mediated liver damage in drug-induced liver injury (DILI). However, the regulation mechanism of CYP2E1 expression is poorly described. The present study was aimed to investigate the role of CYP2E1 in acetaminophen (APAP)- or tripterygium glycosides (TG)-induced hepatotoxicity as well as the regulation of CYP2E1 and miR-378a-3p expression by APAP or TG. Rats were randomly divided and treated with APAP, TG, chlormethiazole (CMZ), APAP + CMZ and TG + CMZ, respectively, for 4 weeks. Then, blood and liver samples were collected. Serum and hepatic biochemical parameters were measured using commercial kits. Liver histopathology was tested by H&E staining. Expression levels of CYP2E1 mRNA and miR-378a-3p were detected by qRT-PCR. CYP2E1 protein expression was determined by Western blot. Our results showed that CMZ effectively restored the hepatic histopathological changes, oxidative stress biomarkers and TNF-α levels induced by APAP or TG. CYP2E1 mRNA and/or protein expression levels were dramatically increased after chronic APAP or TG treatment, while this induction was significantly reversed by CMZ co-treatment. Of note, miR-378a-3p expression levels were significantly suppressed after APAP, TG and/or CMZ treatment. These results suggested that CYP2E1 were highly induced after chronic APAP or TG treatment, which in turn play an important role in APAP- or TG-induced hepatotoxicity. These inductions of CYP2E1 expression were probably carried out by inhibition of miR-378a-3p. Our findings might provide a new molecular basis for DILI.

Pharmacokinetics and vasodilating effect study of beraprost sodium in healthy volunteers.

Currently beraprost sodium (BPS) is widely proposed to ameliorate the symptoms caused by chronic arterial occlusive disease. The objective of this study is to investigate the BPS pharmacokinetic characteristics, its vasodilating effect and the relationship between plasma concentration vs response effect. 12 healthy Chinese volunteers (6 male, 6 female) were chosen to participate in a single center, random, and open design study. After overnight fasting, BPS (dose = 40µg) was administrated orally to each volunteer. The blood samples were collected at different time points (from 0 to 5 h after administration) and BPS concentration was analyzed by LC-MS/MS method. The vasodilating effect was evaluated by detecting the skin microcirculation blood flow of volunteers' fingers with laser Doppler fluxmetry. The Cmax of BPS was (601.14 ± 214.81) pg/mL, the Tmax was (0.58 ± 0.48) h, and AUC0-t was (1020.41±214.63) pg/mL•h. BPS exhibited significant vasodilating effect since the skin microcirculation blood flow increased definitely at 0.25, 0.5, and 0.75 h (all p<0.05) after drug administration, and a positive correlation was presented between the pharmacokinetics and the vasodilating effect, which would be beneficial for guiding BPS dosage in clinical.

Analysis of phenytoin drug concentration for evaluation of clinical response, uncontrolled seizures and toxicity.

The narrow therapeutic index, non-linear pharmacokinetics and unpredictable absorption require regular therapeutic monitoring of phenytoin. The influence of genetic differences, sex, age and race on the phenytoin plasma levels and its metabolites is well recognized. This study is aimed at evaluating phenytoin plasma drug concentration and its relationship with clinical response, persistent seizures and toxicity in different gender and various age groups of Chinese epileptic patients. This knowledge will help the clinicians in adjusting the drug dosages of phenytoin in various sub-groups of epileptic patients for enhancing the safety, efficacy and minimizing the toxicity of phenytoin. A total of 48 plasma samples of epileptic patients for measuring the plasma phenytoin concentration were received. Only patients displaying persistent seizures or suspected of adverse effects were requested for drug monitoring. All these samples were analyzed for therapeutic drug monitoring with Enzyme-multiplied immunoassay technique. Surprisingly, it was found that majorities (85.5%) of samples were out of the reference range, of which 69% of samples were in sub-therapeutic levels and 16.5% of samples were above therapeutic levels. Only 14.5% of all samples had phenytoin levels in the therapeutic range. The difference in plasma concentration of phenytoin was notably altered in gender and various age groups. Careful attention must be applied to specific gender and particular age group on an individual basis in the interpretation of plasma concentration results, in order to facilitate the modification of doses and develop the best approach in treatment and to obtain the desired clinical response because multiple factors can affect the phenytoin plasma concentration. Through these results, it can be concluded that a good correlation exists between phenytoin plasma concentration and clinical response. Therefore, regular therapeutic monitoring of phenytoin and screening of HLA-A, B, C and DRB1 genotypes before prescribing phenytoin in epileptic patients is essentially required to achieve maximum clinical response and prevent the serious toxicity.

Therapeutic drug monitoring of valproic acid.

The unpredictable and unfavorable connection of dose and plasma concentration of valproic acid supports the necessity to regularly measure its plasma concentration. The present study is drug monitoring of valproic acid and comparative evaluation of therapeutic monitoring results of valproic acid for assessment of clinical response, safety and toxicity in different age and gender groups of Chinese epileptic patients. This knowledge will help the clinicians in adjusting the drug dosages of valproic acid in various sub-groups of epileptic patients for enhancing the safety and minimizing the toxicity of valproic acid. A total of 206 plasma samples (126 males and 80 females) of epileptic patients using valproic acid were requested for therapeutic drug monitoring by neurology department of Qilu Hospital. It was found that 29 % of the total samples were found in sub-therapeutic levels, 13% of the samples had toxic levels and 58% of all the samples had valproic acid levels in therapeutic range. The difference in plasma concentration of valproic acid is notably altered in gender and various age groups. However, this requires further investigation. Despite the majority of samples in the therapeutic range, there was an unfavorable clinical response. The outcomes of the current research work exposed that there was a poor correlation between the plasma concentration and clinical response. Careful attention must be applied to specific gender and particular age group on an individual basis in the interpretation of plasma concentration results, in order to facilitate the modification of doses and develop the best approach in treatment and to obtain the desired clinical response because multiple factors can affect the valproic acid plasma concentration. Through these results, it can be concluded that poor correlation exists between valproic acid plasma concentration and clinical response.

Pharmacokinetic, metabolic profiling and elimination of brusatol in rats.

Brusatol, a quassinoid isolated from the traditional Chinese medicine Brucea javanica, has been reported to be an inhibitor of Nrf2 pathway and has great potential to be developed into a novel chemotherapeutic adjuvant. However, the in vivo process of brusatol has not been comprehensively explained yet. Therefore, this paper focused on the pharmacokinetic metabolism and excretion of brusatol in rats using a simple and reproducible LC-MS/MS method. The results indicated that the plasma concentration of brusatol decreased rapidly; the average cumulative excretion rate in urine was 5.82% during 24 h, and 0.71% in bile during 12 h. High-resolution mass spectrometry was applied for the identification of metabolites; as a result, four metabolites were detected and the structure was tentatively deduced on the base of the MS2 data, Compound Discoverer 2.0 and Mass Frontier 7.0 software. Hydroxylation, hydrolysis and glucuronidation were suggested as major metabolic pathways in vivo. The in vivo process and detection of metabolites of brusatol might improve the understanding of the mechanism of its anticancer effect and provide valuable information for its safety estimation, which will be essential to the new drug development.

The Impact of Antiepileptic Drugs on Vitamin Levels in Epileptic Patients.

BACKGROUND: The impact of antiepileptics on serum vitamin levels is controversial and uncertain. With no clear conclusions on the impact of antiepileptics on serum levels of vitamins, there is a need for further clinical studies in order to ascertain the impact of old and newer antiepileptic drugs on serum levels of vitamins in epileptic patients, thus accomplishing a suitable usage of vitamins supplementation. OBJECTIVE: The intention of the present research is to confirm the hypothesis of whether or not vitamin levels are altered with antiepileptic drugs. The study also aims to reveal which vitamin levels are particularly more altered, are vitamin levels affected by gender and the type and number of antiepileptics used. METHODS: The present research was piloted in collaboration with the Department of Neurology in Qilu Hospital of Shandong University. A total of 63 serum samples of epileptic patients receiving antiepileptics as monotherapy or polytherapy were requested for analysis of nine vitamin serum levels. Total nine vitamins (B1, B2, B6, B9, B12, A, C, D and E) in epileptic patients receiving antiepileptic drugs were analyzed. The serum results of all vitamins were compiled and evaluated with SPSS. RESULTS: It was alarmingly found that serum levels of vitamin D were particularly very low in almost all (90%) epileptic patients in this study. Notably, serum levels of vitamin C and vitamin B1 were also below reference range in 72% and 46% epileptic patients, respectively. The remaining vitamins were almost in reference range for most of the patients. In our study, mean and frequency of vitamin D, C and B1 levels do not vary too much among different gender groups. The patients receiving newer antiepileptic drugs displayed a slightly increased serum vitamin D levels in comparison to the patients receiving older antiepileptic drugs. We found low vitamin D, C and B1 serum levels in patients who were on monotherapy as in comparison with patients on polytherapy. CONCLUSION: The most significant and surprising finding of this study revealed that serum vitamin D levels in particular were very low in almost all patients and in some patients' vitamin B1 serum levels were also below the reference range. More importantly, it is first time reported here that vitamin C serum levels were also below reference range in the majority of these Chinese epileptic patients. It is recommended that all these vitamins should be regularly monitored in addition to therapeutic drug monitoring of antiepileptic drugs. Additional clinical trials are required for further evaluation. It is also recommended that epileptic patients with low serum levels of these vitamins may be prescribed vitamins supplementations with antiepileptic drugs in order to control their seizures more effectively and efficiently.

Pharmacokinetics and bioequivalence study of tetramethylpyrazine phosphate tablets after single-dose administration in healthy Chinese male subjects
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BACKGROUND: Tetramethylpyrazine, isolated from Ligusticum wallichii Franch., is widely used for the treatment of cerebrovascular and cardiovascular diseases in China. OBJECTIVE: To assess and compare the pharmacokinetic characteristics and bioequivalence of two tetramethylpyrazine phosphate (TMPP) tablets in healthy Chinese male subjects. MATERIALS AND METHODS: 20 healthy male subjects were randomly divided into two groups according to a two-period crossover design test. A single oral dose of 200 mg test or reference tablets was given with a 7-day washout period under fasting conditions. Blood samples were taken at scheduled time points, and the concentration of TMPP was measured by LC-MS. Drug And Statistical Software-Version 2.0 was used to calculate the pharmacokinetic parameters and assess bioequivalence of the two formulations. RESULTS: 20 subjects were enrolled in the study, and none dropped out. The main pharmacokinetic parameters of test and reference formulations were as follows: T1/2 was (1.79 ± 0.82) hours and (1.64 ± 0.52) hours, tmax was (0.76 ± 0.37) hours and (0.94 ± 0.44) hours, Cmax was (961.14 ± 309.64) ng/mL and (1,059.09 ± 350.69) ng/mL, AUC0-12h was (1,744.69 ± 643.49) ng×h/mL and (1,726.32 ± 494.11) ng×h/mL, AUC0-∞ was (1,756.95 ± 643.63) ng×h/mL and (1,740.16 ± 504.89) ng×h/mL, respectively. The relative bioavailability of TMPP tablets was 102.4 ± 26.0%, and no serious adverse events were reported. CONCLUSION: This single-dose study in healthy Chinese male fasted subjects showed that the TMPP test and reference tablets were bioequivalent.
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A simple and economical method of gas chromatography-mass spectrometry to determine the presence of 6 pesticides in human plasma and its clinical application in patients with acute poisoning.

An economical, rapid, and sensitive method of gas chromatography-mass spectrometry (GC-MS) was developed and validated to determine the presence of six pesticides (dichlorvos, acetochlor, atrazine, chlorpyrifos, α-endosulfan, and ß-endosulfan) in human plasma. The pesticides were extracted with acetonitrile and concentrated using anhydrous sodium sulfate. Then, the target compounds were analyzed and quantified with GC-MS using borneol as an internal standard. Separation was performed on a HP-5MS capillary column (30 m × 0.25 mm × 0.25 µm) with temperature programming. Detection was accomplished under electro-spray ionization (ESI) in selected ion monitoring (SIM) mode. Under optimized conditions, satisfactory linear ranges of 0.05-10 µg/mL were obtained for all of the analyzed pesticides. The linear correlation coefficients were greater than 0.99. The average recovery was between 86.8 and 106.5%. The inter- and intra-day precision ranged from 1.7-14.5% and 4.2-13.8%, respectively. Dichlorvos was unstable in plasma both at room temperature and when frozen. The other five pesticides were stable after storage at - 20°C for 17 days and two freeze-thaw cycles. Thirty-five plasma samples from 15 patients with acute self-poisoning were analyzed using this method. Dichlorvos was found in 13 plasma samples with a mean concentration of 0.289 µg/mL, and atrazine was found in 6 with a mean concentration of 0.261 µg/mL. Acetochlor was found in one plasma sample (0.153 µg/mL). This method is simple, reliable and cost-effective. It takes little time and does not waste solvents, and it can be used to routinely detect six pesticides in patients with acute poisoning.

Comparison of New Liquid Chromatography-Mass Spectrometry Method and Enzyme-Multiplied Immunoassay Technique for Routine Therapeutic Drug Monitoring of Vancomycin in Chinese Patients.

BACKGROUND: Therapeutic drug monitoring of vancomycin is very valuable due to the good correlation between trough levels and clinical outcome. Therefore, it is important to accurately determine the concentration of vancomycin in patient plasma for adequate dose-adjustment. The objective of this study was to develop a new liquid chromatography-mass spectrometry (LC-MS) method for determination of vancomycin in patient plasma and compare the results with those obtained from enzyme-multiplied immunoassay technique (EMIT). METHODS: After extraction by simple protein precipitation, vancomycin and bergenin (internal standard) were separated on a C18 column (150×4.6 mm, 5 µm) at 40°C by gradient elution with 0.1% formic acid and acetonitrile as the mobile phase and measured by electrospray ionization source in positive selective ion monitoring mode. Seventy-nine plasma samples from patients with severe infection were analyzed by enzyme-multiplied immunoassay technique and LC-MS method. MedCalc 15.2 software with Bland-Altman analysis and Passing-Bablok regression analysis was used for statistical analysis. RESULTS: The weighted (1/x2) calibration curve of the validated LC-MS was linear within the concentration range of 0.25 - 40 µg/mL. The inter- and intra-day precisions (%RSD) were less than 10.0%. No significant matrix effect was observed in the relevant time ranges. Comparison of the two methods indicated that results of the LC-MS were close to that of EMIT with a correlation coefficient of 0.957. Upon Bland-Altman analysis, the bias amounted to 2.9 µg/mL (95% confidence intervals of -3.4 - 9.2 µg/mL). CONCLUSIONS: The established LC-MS method and EMIT were both suitable for routine TDM of vancomycin.

Bioequivalence Study of Warfarin in Healthy Chinese Volunteers With a Validated High-Performance Liquid Chromatography-Mass Spectrometry Method.

This study was designed to investigate the pharmacokinetics of an innovative film-coated warfarin sodium tablet and to compare it with the marketed sugar-coated warfarin sodium tablet in humans. A single-dose, open-label, randomized, two-way crossover study was performed in 24 healthy Chinese male volunteers. They were administered 2.5 mg of innovative film-coated warfarin sodium tablets or the marketed sugar-coated warfarin sodium tablets. Blood samples were collected at different time points after dosing for investigation of the pharmacokinetics of warfarin in human plasma. A sensitive liquid chromatography mass spectrometry method was established to determine warfarin in plasma. Drug and Statistics 2.1.1 was applied to calculate the pharmacokinetics parameters. The main pharmacokinetic parameters for film-coated and sugar-coated warfarin were the following: t½ , 103.5 ± 18.8 and 105.8 ± 21.3 hours; Tmax , 0.7 ± 0.5 and 1.3 ± 0.8 hours; Cmax , 347.8 ± 74.8 and 322.9 ± 75.7 ng/mL; AUC0∼360 , 16,024.2 ± 3713.9 and 15,586.6 ± 3477.0 ng·mL-1 ·h; AUC0∼∞ , 17,335.7 ± 4089.1 and 16,912.0 ± 3911.2 ng·mL-1 ·h, respectively. The human pharmacokinetics of film-coated and sugar-coated warfarin were slightly different. The oral absorption and bioavailability of innovative film-coated warfarin were slightly higher than those of the sugar-coated warfarin. This study is vital to clinical usage of warfarin not only because of the pharmacokinetic parameters of the 2 pharmaceutical dosage forms of warfarin but also to obtain data on the prevalence of CYP2C9 and VKORC1 genes and their influence on the concentration of warfarin.

A comparison of liquid chromatography-tandem mass spectrometry (LC-MS/MS) and enzyme-multiplied immunoassay technique (EMIT) for the determination of the cyclosporin A concentration in whole blood from Chinese patients.

Cyclosporin A (CyA) is an immunosuppressive agent widely used in clinical therapy. In the therapeutic process, the blood concentration of CyA should be monitored to avoid or prevent rejection and toxicity. The objectives of this study were to compare the correlation of liquid chromatography-tandem mass spectrometry (LC-MS/MS) and enzyme-multiplied immunoassay technique (EMIT) for the determination of the CyA concentration in human blood and to provide evidence for the rational usage of EMIT in clinical practice. Blood samples collected from 132 patients undergoing a liver or kidney transplant or patients with aplastic anemia at Qilu Hospital of Shandong University were tested using the two methods. The calibration curve was linear from 25-500 ng·mL-1 for LC-MS/MS and from 50-450 ng·mL-1 for EMIT. The inter- and intra-day RSDs were less than 15%. The CyA blood concentration according to EMIT was 3.5 ng·mL-1 more than that according to LC-MS/MS. The 95% confidence interval was -10.0~16.9 ng·mL-1. The CyA blood concentration according to the two methods did not differ significantly (p > 0.05). LC-MS/MS and EMIT were suitable methods for determining the CyA blood concentration. The two methods were closely correlated (r2 = 0.969), but the CyA blood concentration according to EMIT was slightly higher than that according to LC-MS/MS. The clinical significance of this finding needs to be further evaluated.