Research strategies and frontier technology advances in intracerebral pharmacokinetics / 中国药理学通报

The establishment of the cerebral pharmacokinetic model aims to truly reflect the disposition and course of action of drugs entering brain tissues, to ensure that brain-targeted drugs reach effective intracerebral concentrations, while preventing neurological damage from non-brain-targeted drugs, and to greatly improve effectiveness and safety. With the rapid development of research strategies and analytical techniques in the field of pharmacokinetics, intracerebral pharmacokinetic techniques have evolved from traditional brain tissue homogenization and cerebrospinal fluid extraction to in situ in vivo analysis techniques, from invasive techniques to non-invasive imaging techniques, and from the macroscopic tissue level to the microscopic cellular/subcellular level. A variety of pharmacokinetic research methods in brain are complementing each other and becoming increasingly perfect, gradually forming a comprehensive " subcellular-cellular-tissue" pharmacokinetic research system in brain, laying the foundation for elucidating the dynamic changes of drugs in brain and predicting the course of action of drugs in brain. This paper reviews the evolution and development of pharmacokinetic research strategies in brain, evaluates the advantages and limitations of various techniques and methods, and provides a reference for predicting the pharmacodynamic and toxic effects of drugs in brain tissues.

The influence of sepsis on antimicrobials tissue penetration: The use of microdialysis technique to access free drug distribution

Abstract Sepsis is described as a life-threatening organ dysfunction caused by a host's response to infection, leading to an unbalance in body homeostasis. It is one of the leading causes of death in developed countries. Considering that in critically ill patients, such as those with sepsis, plasma concentrations do not necessarily reflect tissue concentrations, one way to assess tissue concentrations is through the microdialysis technique, which allows direct measurements of free drug at the site of action. This review was carried out after searching the Pubmed, Scielo and Web of Science databases, using the following descriptors: (microdialysis AND (sepsis OR septic shock OR severe sepsis OR septicemia)) OR (microdialysis AND (sepsis OR septic shock OR severe sepsis) OR septicemia) AND (antimicrobial OR antibiotic OR antifungal)). The physiological changes generated by sepsis may imply changes in pharmacokinetic parameters, such as in clearance, which may be reduced in these patients and in volume of distribution, which presents an expansion, mainly due to edema. Both events contribute to a high inter- individual variability in tissue penetration of antimicrobials which is generally observed in patients with sepsis.

Comparative study on brain pharmacokinetics of Buyang Huanwu Decoction in normal and cerebral ischemia rats using brain microdialysis combined with LC-MS/MS / 中草药·英文版

Objective: To conduct a comparative study on the brain pharmacokinetics of seven ingredients (i. e. senkyunolide A, ferulic acid, formononetin, calycosin, ononin, calycosin-O-β-D-glucopyranoside, and paeoniflorin), which were the compounds of Buyang Huanwu Decoction (BHD), in normal and cerebral ischemia rats administrated intragastrically with BHD. Methods: The samples of normal and permanent middle cerebral artery occlusion (pMCAO) rats were collected by using brain microdialysis technique. The concentrations of seven ingredients were determined by the HPLC-MS/MS method. After the BHD were administrated intragastrically to the rats for seven consecutive days, brain microdialysis probes were inserted into the hippocampus of rats, and then the brain microdialysates were collected at 20 min time intervals for 5 h. The separation of the seven ingredients and internal standard (IS) was carried out on an ACQUITY UPLC BEH C

Free interstitial levels of metformin in the liver of healthy and diabetic Wistar rats

Abstract In the present study, free interstitial levels reached by metformin in the liver were investigated in control and diabetic rats by microdialysis. Firstly, a bioanalytical method using an HPLC-UV system to determine the drug concentration in microdialysis samples was validated. The blood glucose levels and biochemical parameters were investigated in control and diabetic animals. Following that, both groups received a dose of 50 mg/kg of metformin iv bolus and the free interstitial levels reached in the liver were assessed by microdialysis. The method was validated according to FDA guidelines being suitable to quantify free concentrations of metformin in the liver of control and diabetics rats. Free exposure to metformin was similar in control and diabetic animals: AUC0-∞ 118.50 ± 40.18 vs 112.93 ± 50.25 µg.h/mL, respectively. The half-life in tissue was similar to that described in the literature for plasma. Hence diabetes induced by streptozotocin after administration of nicotinamide in our study did not damage the renal and hepatic function of the animals. The levels reached in the liver were 1.6 times higher than the free plasma concentrations, demonstrating higher liver penetration of metformin. This is the first investigation in liver interstitial concentration of metformin in control and diabetic rats

The mechanism of Shuyu capsules in treating premenstrual dysphoric disorder caused by liver qi depression based on microdialysis technology from the aspect of Glu-GABA metabolic pathway / 国际中医中药杂志

Objective:To explore the mechanism of premenstrual dysphoric disorder (PMDD) caused by liver-qi depression from the aspect of Glu-GABA metabolic pathways.Methods:Thirty-six rats with similar open field scores and regular estrus cycles were divided into blank group, model group, fluoxetine group, Shuyu capsule group, saikosaponin group and inhibitor group according to the random number table method, with 6 rats in each group. Stereotactic hippocampus surgery was performed during the first estrous cycle reception period after the estrus cycle was determined. In the non-receiving period of the third and fourth estrus cycles, the restraint model was constructed, and from the first day of the modeling, rats of the fluoxetine group were given fluoxetine capsules 2.67 mg/kg, while rats of the Shuyu capsule group and saikosaponin group were given Shuyu capsules 0.408 g/kg and saikosaponin 0.72 mg/kg once a day for 5 consecutive days. Rats in the inhibitor group were injected with 20 μl L-malic acid with 5 mmol/L concentration, which is an inhibitor of glutamate decarboxylase (GAD), in the hippocampus on the last day of modeling. After the administration, weighed the rats and carried out open field experiments. During the second and fivth estrus cycles of rats, the extracellular fluid of the hippocampus was collected by microdialysis technology, and the content of Glu and GABA in the dialysate was detected by HPLC-FLD. Results:After 5 days of administration, compared with the model group, the body weight of rats in the Shuyu capsule group, the inhibitor group and the fluoxetine group increased ( P<0.05), and the total score of the open field experiment decreased ( P<0.05); compared with the model group, during the receiving period of the five estrus cycle, the Glu level of the Shuyu capsule group and the inhibitor group decreased ( P<0.05); In the non-receiving period of the fifth estrus cycle, the Shuyu capsule group, Glu level of the fluoxetine group and the saikosaponin group increased, GABA level of Shuyu capsule group, inhibitor group and fluoxetine group decreased ( P<0.05), Glu/GABA level of Shuyu capsule group, fluoxetine group and inhibitor group (1.49 ± 0.13, 1.32 ± 0.33, 3.92 ± 0.79 vs. 0.35 ± 0.48) was higher than that of the model group ( P<0.05). Conclusion:The therapeutic mechanism of Shuyu capsule in the treatment of PMDD caused by liver Qi depression rats may be ascribed to inhibiting GAD from Glu-GABA metabolic pathway.

Advances in microdialysis-coupled microfluidics for body fluid monitoring / 中华检验医学杂志

Microdialysis is a novel technique for rapid and continuous sampling of body fluid in the extracellular space, especially for some hard-to-obtain samples, e.g. cerebrospinal fluid, interstitial fluid. Microfluidic technology plays a significant role in body fluid analysis because of its miniaturization, high-throughput, and automation, offering a feasible method for rapid and low-cost biochemical analysis. In clinical practice, body fluid analysis is often required to be fast and/or capable of long-termly monitoring certain biomarkers. However, current technologies are insufficient to meet this requirement. The combination of microdialysis and microfluidic technologies could provide a new perspective to solve this problem.

Microdialysis combined with metabonomics in exploring metabolic disturbance of adjuvant arthritis rats and intervention effect of Achyranthes bidentata saponins / 中国药理学通报

Aim To use microdialysis technology combined with ultra-high performance liquid chromatography tandem quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF/MS) technology to study the effect of Achyranthes bidentata saponins (ABS) on rheumatoid arthritis (RA) and its mechanisms. Methods SD rats were randomly divided into adjuvant arthritis (AA) model group, blank control group and ABS administration group. AA rat model was induced by Freund's complete adjuvant. UPLC-Q-TOF/MS was used to collect joint cavity microdialysis fluid sample information of each group of rats. Results On 6th day after administration of ABS, an inhibitory effect on the paw swelling, improved the arthritis score (P < 0. 05), and better the pathological morphology of the synovial tissues were found in AA rats. Nineteen potential biomarkers were discovered and identified. Pathway enrichment analysis revealed that they mainly involved purine metabolism, pyrimidine metabolism, fatty acid biosynthesis and steroid hormone biosynthesis pathway. Conclusions Microdialysis combined with metabolomics can reveal the metabolic mechanism of ABS intervention on RA, laying a foundation for further study of the mechanism of ABS.

Regulatory effect and mechanism of novel sedative hypnotic compound YZG-331 on glutamate and its receptor / 药学学报

This study investigated the effect of a novel adenosine derivative YZG-331 on the glutamate (Glu) content and its receptor N-methyl-D-aspartate receptor (NMDAR) in mouse frontal cortex. All procedures in this research were approved by the Institutional Animal Care and Use Committee of the Institute of Materia Medica, Chinese Academy of Medical Sciences. High performance liquid chromatography (HPLC) was used to detect the Glu contents in the mouse frontal cortex tissue homogenate and extracellular fluid which were collected by brain microdialysis method. Western blot and co-immunoprecipitation methods were used to detect the expressions of NMDAR in cell membranes and endosomes, as well as the expression levels of endocytosis-related proteins and their interaction. The results showed that there was no significant change in Glu content in the dialysates from mouse frontal cortex within 0-0.5 h period and 0.5-1 h period after intragastric administration of YZG-331 (40 mg·kg-1). Compare to the control group, the Glu content in mouse frontal cortex homogenates has no significant statistical differences after 15 minutes of administration of compound YZG-331. YZG-331 significantly decreased the expressions of NMDAR subunits NR1 and NR2B in the mouse frontal cortex cell membrane, meanwhile significantly increased the expressions of NR1 and NR2B proteins in the frontal cortex endosomes. It also increased the phosphorylation levels of NMDAR subunit NR2B in the frontal cortex. In addition, the result of co-immunoprecipitation which used NR2B as bait protein showed that the expression of postsynaptic density-95 (PSD95) in NR2B and PSD95 immunoprecipitation complexes in mouse frontal cortex tissues was significantly reduced. These results indicate that YZG-331 does not affect the Glu content in mouse frontal cortex, but it weakens the interaction between NR2B and PSD95 by increasing the phosphorylation level of NR2B in the mouse frontal cortex. Therefore, it reduces the membrane stability of NMDAR and promotes NMDAR's endocytosis, which leading to the decrease of excitotary transmission. It may be one of the mechanisms of YZG-331 to exert sedative and hypnotic effects.

Comparative of pharmacokinetic of moxifloxacin in the plasma and lung tissues of pneumonia rats and normal rats / 药学实践杂志

Objective To compare the pharmacokinetics of moxifloxacin (MXF) administered orally in the plasma and lung tissues of rats with pneumonia infected by Streptococcus pneumoniae (S.p) and normal rats. Methods To establish a model of Streptococcus pneumoniae pneumonia rats and normal rats. Moxifloxacin was administered by intragastric administration at 42 mg/kg. Microdialysis technique was used to sample the blood and lung tissues of pneumonia rats and normal rats to determine the free drug concentration of moxifloxacin in each sample, calculate the pharmacokinetic parameters, and compare the pharmacokinetics of oral moxifloxacin in pneumonia rats and normal rats. Results The t1/2 of moxifloxacin in the blood of normal rats and pneumonia rats were (5.27±4.38) h, (2.15±0.07) h (P>0.05), and Cmax were (4.94±0.98) μg/ml, respectively, (4.83±0.05) μg/ml (P>0.05), Clast_obs/Cmax were 0.02±0.03, 0.27±0.04 (P<0.05), AUC0-t were (22.33±2.02)μg/ml·h, (12.88±1.19)μg /ml·h (P<0.05), CL/F are (1.79±0.11)(mg/kg)/(μg/ml)·h, (2.49±0.26)(mg/kg)/(μg/ml)·h (P<0.05); Cmax of lung tissue of normal rats and pneumonia rats were (1.42±0.05) μg/ml, (4.84±0.02) μg/ml (P<0.05), t1/2 are (1.9±0.63)h, (3.39±0.79)h (P>0.05), AUMC are (11.93±5.14)μg/ml·h2, (107.01±25.39)μg/ml·h2 (P<0.05), AUC0-t are (3.06±1.0) 7μg/ml·h, (13.16±0.53)μg/ml·h (P<0.01). Conclusions ① Under the 400 mg/d dose condition, after intragastric administration of moxifloxacin, the concentration of free drugs in the blood and lung tissues is higher, far exceeding the minimum inhibitory concentration (MIC) and anti-drug resistance concentration (MPC), can effectively remove Streptococcus pneumoniae. ②The free concentration of moxifloxacin in the lung tissue of rats infected with Streptococcus pneumoniae is always higher than that of normal rats, and the Cmax is about 3.4 times that of normal rats. The penetration rate of moxifloxacin in lung tissue of pneumonia rats is significantly higher than that of normal rats.

Microdialysis sampling and HPLC-MS/MS quantification of sinomenine, ligustrazine, gabapentin, paracetamol, pregabalin and amitriptyline in rat blood and brain extracellular fluid / 药学学报

The treatment plan for chronic pain often proceeds from a single drug to drug combination therapy. Sinomenine and ligustrazine, natural alkaline substances derived from traditional Chinese medicines, are expected to provide a new choice for combination analgesic therapy strategies. Here we establish a microdialysis sampling and HPLC-MS/MS quantification method for sinomenine, ligustrazine, gabapentin, paracetamol, pregabalin and amitriptyline in rat blood and brain extracellular fluid. Blood and brain microdialysis probes were implanted in the jugular vein toward the right atrium and left corpus striatum zone (AP +0.2 mm, ML 3.0 mm, DV 3.5 mm) in rats. The blood and brain microdialysis probes were perfused with citric acid buffer solution and Ringer's solution, respectively. Blood and brain extracellular fluid microdialysate were collected at intervals of 20 min at a perfusion rate of 1.5 μL·min-1, and continuously collected for 24 h after administration. The liquid chromatographic separation used a C18-reversed phase chromatographic column (HSS T3 2.5 μm, 2.1 mm×50 mm), the mobile phase was methanol/water (containing 0.05‰ formic acid), and gradient elution was carried out at a flow rate of 0.3 mL·min-1. Mass spectrometric detection used an electrospray ion source, positive ion mode and multi-reaction monitoring method. The selected quantitative ions for sinomenine, ligustrazine, gabapentin, paracetamol, pregabalin, amitriptyline and internal standard naloxone were 330/181, 137/80, 172/154, 152/110, 160/142, 278/233 and 328/310 respectively. The specificity, linear range, matrix effect, accuracy, precision, stability and probe recovery were investigated and confirmed to be suitable for the determination of the above drugs in rat blood and brain extracellular fluid microdialysate. The calculated in vivo recovery of microdialysis probes ranged from 19.38% to 25.88%. After intravenous administration of sinomenine (50 mg·kg-1), ligustrazine (50 mg·kg-1), gabapentin (50 mg·kg-1), paracetamol (50 mg·kg-1), pregabalin (50 mg·kg-1) and amitriptyline (40 mg·kg-1) to rats, the peak concentration in the blood microdialysate was in the range of 0.2-10 μg·mL-1. Drug concentrations could also be detected in brain extracellular fluid microdialysate, however with lower levels (peak concentration: 0.1-6 μg·mL-1) than those of blood microdialysates at each time point. In conclusion, this method can be applied to microdialysis sampling and quantification of sinomenine, ligustrazine, gabapentin, paracetamol, pregabalin and amitriptyline in rats. The method will promote research in identifying herb-drug pharmacokinetic interactions, as well as safety concerns in combination-therapy strategies.

Microdialysis recovery of cefradine in vitro / 药学实践杂志

Objective To determine the in vitro recovery rate and influencing factors of cefradine microdialysis. Methods Two different methods (loss method, gain method) of microdialysis concentration and LC-MS/MS were used to determine the in vitro recovery rate of cefradine. The effect of flow rate and concentration of the perfusate on the recovery rate were investigated. To explore the feasibility of microdialysis technology for pharmacokinetic studies in cefradine. Results The LC-MS/MS analysis method was linear in the required range and the method was sensitive and reliable. There was no significant difference in the recovery rate measured by gain or loss method. Under the same conditions, the in vitro recovery of the probe decreased with increasing flow rate, independent of the drug concentration around the probe. Conclusion Microdialysis technique could be used to study the pharmacokinetics of cefradine, and loss method could be used to determine the in vivo recovery rate and pharmacokinetics of cefradine on microdialysis.

Determination of recovery rate of levofloxacin microdialysis probe by high-performance liquid chromatography / 第二军医大学学报

Objective To investigate the in vitro and in vivo relative recovery rates of levofloxacin from microdialysis probes. Methods High-performance liquid chromatography (HPLC) was established for determination of levofloxacin concentrations. Column was Kromasil C18 (150 mm×4.6 mm, 5 μm), the mobile phase consisted of acetonitrile and 10 mmol/L of potassium dihydrogen phosphate solution (15:85), with column temperature being 30 °C, detection wavelength being 294 nm, and injection volume being 10 μL. The relative recovery rates of vascular microdialysis probes in vitro were measured by dialysis and reverse dialysis. The effects of drug concentration and flow rate on probe deliveries were investigated. The in vivo recovery rates of the probe in the jugular vein and prostate were measured by reverse dialysis, and the stability of 12 h recovery rate in vivo was investigated. Results When the concentration of levofloxacin was 0.1-50.0 μg/mL, the linear relationship was good in the HPLC analysis (r = 0.998 7), and its specificity was good. The precision and accuracy of high-, medium-, low-concentration quality control samples, and lower limit of quantitation all met the analysis requirements. In the in vitro relative recovery experiments, there was no statistical difference between the recovery rate and reverse recovery rate of the vascular microdialysis probes (P>0.05). Drug concentrations did not affect in vitro recovery rate. The recovery rate decreased with the increase of flow rate. In vivo, the relative recovery rate of the probe was (48.46±1.94)% in the jugular vein and (13.23±1.44)% in the prostate. The relative recovery rates were stable during 12 h. Conclusion The established HPLC can be used for the determination of levofloxacin microdialysis probe. Reverse dialysis can be used to detect the relative recovery rate of levofloxacin microdialysis probe in vivo.

Metabonomics research strategy based on microdialysis technique / 中国中药杂志

Metabonomics is the branch of systems biology. It has been widely used in the fields of diagnostic markers discovery, disease prognosis, drug action mechanism, drug efficacy and toxicity evaluation, traditional Chinese medicine syndromes differentiation. There are shortcomings in the conventional metabonomics research. Microdialysis technology is a new type of biosampling technology, and metabonomics research based on microdialysis technology is in the ascendant. In view of the particularity of microdialysis technology and its great differences from traditional sampling and pretreatment methods, the metabonomics process based on microdialysis technology has certain similarities with traditional metabonomics research, and its basic process has some particularity. Advantages and basic strategies of metabonomics research by microdialysis technology are systematically summarized for researchers' reference.

Combination of In Vivo ¹²³IFP-CIT SPECT and Microdialysis Reveals an Antipsychotic Drug Haloperidol-induced Synaptic Dopamine Availability in the Rat Midbrain and Striatum

Synaptic dopamine (DA) is mainly regulated by the presynaptic DA transporter (DAT). Single-photon emission computerized tomography (SPECT) with the DAT radiotracer [¹²³I]FP-CIT assesses changes in synaptic DA availability when endogenous DA displaces [¹²³I]FP-CIT or competes for DAT. Here, we investigated the effects of haloperidol (HAL) and clozapine (CLZ) on [¹²³I]FP-CIT binding in the rat striatum and midbrain to assess the utility of [¹²³I]FP-CIT SPECT to quantify changes in synaptic DA availability. Rats underwent [¹²³I]FP-CIT SPECT after intraperitoneal administration of normal saline (vehicle), HAL (1 and 7 mg/kg), CLZ (10 and 54 mg/kg) and bupropion (BUP, a DAT blocker, 20 and 100 mg/kg). In the striatum and midbrain, percent differences in the nondisplaceable binding potential (BP(ND)) of [¹²³I]FP-CIT compared to the vehicle were calculated for the various drugs and doses. In another experiment, changes in endogenous striatal DA concentration were measured by in vivo microdialysis under the conditions used in the SPECT study. BUP dose-dependently occupied DAT at considerable levels. Compared to the vehicle, HAL decreased [¹²³I]FP-CIT BP(ND) in the striatum (−25.29% and −2.27% for 1 and 7 mg/kg, respectively) and to a greater degree in the midbrain (−58.74% and −49.64% for 1 and 7 mg/kg, respectively), whereas the CLZ-treated group showed a decrease in the midbrain (−38.60% and −40.38% for 10 and 54 mg/kg, respectively) but an increase in the striatum (18.85% and 38.64% for 10 and 54 mg/kg, respectively). Antipsychotic-induced changes in endogenous striatal DA concentrations varied across drugs and doses. The data demonstrate that [¹²³I]FP-CIT SPECT may be a useful preclinical technique for detecting increases in synaptic DA availability in the midbrain and striatum in response to HAL, with results comparable to those of in vivo microdialysis.

Protective Effect of Dandeng Tongnao Capsule (DDTN) on Cerebral Ischemia Reperfusion Rats / 中国药学杂志

OBJECTIVE: To observe the protective effects of Dandeng Tongnao capsule (DDTN) on cerebral ischemia reperfusion injury in rat and explore its mechanism so as to reevaluation the clinical efficacy of DDTN. METHODS: Middle cerebral artery occlusion (MCAO) model in rats was established using filament method and reperfusion was processed with filament removed 2 h later. Therefore, the MCAO models were established to observe the effect of DDTN-L group (0.21 g•kg-1) and DDTN-H group (0.84 g•kg-1) on infract volume via TTC staining. Regional cerebral blood flow(rCBF) of corpus striatum of the side of cerebral infraction was measured by using laser doppler flow (LDF). Pathological changes of neuron in hippocampuses were observed via hematoxylin and eosin (HE) staining and transmission electron microscopy (TEM).The changes of amino acid in cerebral ischemia were detected by microdialysis system. The level of Ca2+ was evaluated by flow cytometer (FCM). RESULTS: The results showed that the cerebral blood flow increased and infract volume reduced at 7, 14 d in DDTN group. Analysis of HE staining and TEM scan suggested that DDTN (0.21, 0.84 g•kg-1) remarkably alleviated neuronal injury of hippocampal CA1 area during I/R. The contents of Ca2+ and excitatory amino acids were significantly decreased in DDTN group. CONCLUSION: DDTN could prevent cerebral injury of MCAO rats via decreasing the intracellular Ca2+ concentration, and inhibiting the release of excitatory amino acids.

Monitoring unbound warfarin in drug combination therapy by pharmacokinetics and fluorospectrometry / 中草药·英文版

Objective: Monitoring the unbound drug concentration in blood in combination therapy is necessary, because its concentration determines the efficacy of drug therapy. This study was designed to explore the effect of Dan Hong Injection (DHI) on the unbound warfarin using two approaches including an in vivo pharmacokinetic and in vitro fluorescence studies. Methods: The effect of DHI on the pharmacokinetic properties of the unbound warfarin was investigated by a microdialysis sampling method coupled with LC–MS/MS. The effect of DHI and salvianolic acid B (SaB) on warfarin binding with bovine serum albumin (BSA) was conducted by fluorescence spectrometry. Results: The AUC0-tn of warfarin with DHI group was higher than that of warfarin alone group. The result showed that DHI could increase the concentration of unbound warfarin in rat blood, which may be due to the competition between warfarin and DHI as well as its components binding to serum albumin. The competition process was demonstrated by fluorescence study. Conclusion: Combination therapy of DHI with warfarin could enhance the release profile of warfarin from serum protein.

Pharmacokinetics and pharmacodynamics study of Panax notoginseng saponins in mice with Parkinson’s disease by using UPLC-MS/MS combined with microdialysis / 中草药

Objective: To investigate the changes in the content of notoginsenoside R1 (R1), ginsenoside Rg1(Rg1) and amino acid neurotransmitters in brain micro dialysate after the treatment with Panax notoginseng saponins (PNS) solution in Parkinson’s disease (PD) model mice induced by 1-methylmethyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Methods: Mice were injected intraperitoneally with MPTP to induce PD mice model. After intravenous injection of PNS solution, brain micro dialysate was collected by microdialysis technique. The sample was divided into two parts, one was subjected to pharmacokinetic study of R1 and Rg1 by UPLC-MS/MS, and the other part for pharmacodynamics study which was done by pre-column derivatization of the amino acids and HPLC-FLD analysis. Results: After iv administration of PNS to the mice, the maximum CSF concentration was (35.48 ± 24.4) ng/mL for R1 and (75.61 ± 41.35) ng/mL for Rg1. The time to reach maximum concentration was found 1.75 h both for R1 and Rg1. The AUC value of R1 and Rg1 were (100.12 ± 84.29) ng∙h/mL and (218.84 ± 144.73) ng∙h/mL, respectively. Moreover, the levels of aspartic acid and glutamic acid were reduced, and glycine, taurine and γ-aminobutyric acid levels were increased in PD model mice treated with PNS in comparison with model group. Conclusion: PNS can enter the brain through the blood brain barrier (BBB) to some extent, and regulate the imbalance of amino acid level in PD model mice, so as to display the neuroprotective effect and its therapeutic value.

Metabonomics study of MCAO rats based on microdialysis technique combined with UPLC-Q/TOF-MS / 中草药

Objective: To study the brain striatum metabolomics characteristics of middle cerebral artery occlusion (MCAO) rats. Methods: The middle cerebral artery was occluded by monofilament to establish the MCAO rat model. The microdialysis probe was implanted into the striatum, and the brain microdialysis samples were collected under awake and free activity condition and were measured by UPLC-Q/TOF-MS in positive and negative ion mode respectively. Multivariate statistics were used to establish the metabobomics model. Results: Brain-targeted metabolomics studies based on microdialysis samples were successfully performed. Metabolomics models could clearly distinguish normal and model rats, and seven differential metabolites were identified. Conclusion: The brain metabolism characteristics of MCAO rats had changed significantly. The metabolomics research based on microdialysis technology enriches the research methods of metabolomics.

Establishment of skin and joint micro-dialysis sampling method of triptolide in vivo by HPLC-MS/MS / 中国中药杂志

To detect the concentration of triptolide in skin and joint after percutaneous administration,an HPLC-MS/MS method and skin and joint micro-dialysis( MD) method of triptolide were established in this study. The separation was achieved on triple quadrupole( AB QTRAP4500) and phenomenex-C18( 4. 6 mm×150 mm,5 μm,luna) column with acetonitrile-water with 0. 1% formic acid( 65 ∶35) as the mobile phase at a flow rate of 0. 7 m L·min-1. An electrospray ionization( ESI) source was applied and operated in the positive multiple reaction monitoring( MRM) mode. The fragment ion for triptolide was m/z 361. 1→145. 0. The effects of different perfusion [Ringer's,PBS( p H 7. 4),30% ethanol saline]drug concentrations and flow rates on the recovery rate,as well as the relationship between the recovery rate and the loss rate were determined by incremental( dialysis) and reduction( retrodialysis) methods.The reduction method was applied in the in vivo study to investigate and determine the stability of the probe recovery rate in 10 h. The results of HPLC-MS/MS detection method conformed to the requirements of biological samples. The perfusion fluid was 30% ethanol saline. The recovery rate of skin and joint probes in vitro of triptolide increased within the flow rate of 0. 5-2. 5 μL·min-1. In order to increase the timeliness of data and the accuracy,the flow rate was determined to be 1 μL·min-1,and the sample interval was determined to be 0. 5 h. The recovery rate of triptolide in skin and joint probes in vitro and the loss rate were stable and equal despite of change of triptolide concentration within 10-200 μg·L-1. This indicated that the effect of drug concentration on the MD probe recovery rate was small,and the recovery rate could be replaced by the loss rate. The loss rate in vivo using MD method was measured at 10 h,indicating that the transfer rate of triptolide was stable within 10 h. The established method of triptolide in MD and HPLC-MS/MS can be applied to investigate the kinetic in skin and joint after percutaneous administration of triptolide.

Pharmacokinetics of skin and blood of Tripterygium wilfordii and Paeonia lactiflora micro-emulsion gel based on micro-dialysis technology / 中国中药杂志

To further investigate the metabolism of Tripterygium wilfordii and Paeonia lactiflora micro-emulsion gel in vivo,an LCMS/MS method was established for the determination of triptolide and paeoniflorin in T. wilfordii and P. lactiflora micro-emulsion gel.The extracorporeal recovery rate of blood probe was measured by concentration difference methods( incremental method and decremental method). Meanwhile,the skin and blood micro-dialysis methods of tripterine and paeoniflorin were established,and the pharmacokinetics of T. wilfordii microemulsion gel in skin and blood was studied by micro-dialysis combined with LC-MS/MS quantitative analysis. The results showed that the established method for the determination of triptolide and paeoniflorin in T. wilfordii microemulsion gel was well linear within the required range,and the specificity,recovery rate and degree of precision of the chromatography all conformed to the research requirements of micro-dialysis samples. The stability of freeze-thawing and the residual effect all conformed to the criteria of biological sample methodology. The probe recovery rates measured by incremental method and decremental method were almost consistent with the extracorporeal recovery rate test. The recovery rates of paeoniflorin in skin and blood micro-dialysis were( 30. 60±1. 09) % and( 28. 01± 1. 75) %,respectively. And the recovery rates of skin and blood micro-dialysis were( 26. 79 ± 2. 78) % and( 25. 39±1. 86) %,respectively. The intraday recovery rate of probes was stable within 11 h. The results of pharmacokinetic study showed that the Cmaxvalues of triptolide in skin and blood were( 148. 03±41. 51) and( 76. 77±15. 27) μg·L-1,respectively. And the Tmaxvalues were( 2. 33±0. 29) and( 3. 00± 0) h,respectively. The AUC0-11 hvalues were( 2 814. 05± 1 070. 37) and( 1 580. 63±208. 27) μg·h·L-1,respectively. The MRT0-11 hvalues were( 4. 20± 0. 33) and( 4. 54± 0. 34) h,respectively. The T1/2 values were( 4. 61±4. 11) and( 1. 07± 0. 13) h,respectively. The Cmaxvalues of paeoniflorin in skin and blood were( 991. 88 ± 152. 22) and( 407. 02±120. 06) μg·L-1,respectively. The Tmaxvalues were( 2. 00±0) h and( 2. 83±0. 29) h,respectively. The AUC0-11 hvalues were( 18 430. 27±3 289. 35) and( 6 338. 59 ± 1 659. 32) μg·h·L-1,respectively. The MRT0-11 hvalues were( 4. 29 ± 0. 16) and( 4. 00±0. 05) h,respectively. The T1/2 values were( 2. 16±0. 43) and( 1. 78±0. 48) h,respectively. The results suggested that micro-emulsion gel played a role in forming skin reservoir through percutaneous penetration. It not only could improve drug transdermal efficiency,but also control the sustained release of drug and form a long-term effect.