提高微透析探针回收率方法的研究进展

微透析是将灌流取样和透析技术结合起来的研究物质动态变化的一种新型采样技术,适合于深部组织和重要器官的活体研究。微透析探针的回收率是影响微透析结果准确性的重要因素之一。微透析探针对物质的回收率通常较低,需结合灵敏的检测方法才能实现物质的定量分析,因此限制了微透析技术在科研中的应用及发展。如何提高微透析探针的回收率是亟待解决的问题,本文综述了国内外研究中提高微透析探针对物质回收率的方法,为探针回收率的提高提供一些参考。     

芒柄花素、芍药苷血液和脑在体微透析方法的建立

目的:建立芒柄花素、芍药苷血液和脑局部在体微透析方法。方法:采用增量法考察流速对芒柄花素和芍药苷回收率的影响,结合实际操作,确定流速和取样间隔;利用浓度差法(增量法和减量法)研究流速、浓度、温度对微透析探针体外回收率和损失率的影响,探讨反透析法用于探针体内回收率测定的可行性;将血液探针和脑探针分别植入大鼠颈静脉和脑纹状体,考察探针在10h内体内回收率的稳定性。结果:芒柄花素,芍药苷血液和脑探针体外回收率随着流速的增高而降低,综合考虑取样时间和取样体积,确定流速为1.5μL·min^-1,取样时间间隔为20min;在相同流速和温度下,探针增量法回收率RR与减量法损失率RL近似相等,且探针回收率与药物浓度无关,说明可用反透析法进行体内回收率的测定;在大鼠体内微透析回收率考察中,血液和脑探针10h回收率保持相对稳定,但不同探针相对回收率之间存在一定的差异性。结论:所建立的芒柄花素、芍药苷血液和脑微透析方法可用于大鼠体内和脑局部药动学研究,反透析法可作为同时研究芒柄花素,芍药苷探针体内回收率的测定方法。     

微透析取样技术在中药体内分析中的应用研究进展

本文综述了微透析取样技术在中药体内分析中的应用,介绍微透析取样技术的原理、组成、探针类型、特点,重点阐述了微透析取样技术在测定脑、血液、皮肤等组织器官中中药有效成分浓度的应用实例。表明微透析取样技术在中药药效研究中具有广阔的前景。     

基于微透析技术的苦参碱凝胶经皮给药的药动学研究

目的 建立同步测定经皮给药制剂在皮肤、血液中药动学的方法,研究苦参碱凝胶在体内的药动学行为。方法 应用经体外和体内回收率校正建立的基于微透析探针的皮肤血液双位点同步微透析系统,通过在皮肤和颈静脉植入探针,在大鼠腹部脱毛部位给予苦参碱凝胶,连续收集探针中12 h的透析液,并采用LC-MS微量检测技术测定探针透析液中的药物浓度。结果 本研究成功构建了双位点同步微透析药动学评价系统,大鼠皮肤给予苦参碱凝胶后,皮肤中的药物浓度、AUC值、半衰期均显著高于血液中药物浓度。结论 本研究建立的微透析结合LC-MS的取样及检测技术为经皮给药制剂的药动学研究提供了新的技术平台。     

微透析技术在药物代谢和药代动力学研究中的应用

本文介绍了近年来有关微透析技术在药物代谢和药动学研究领域中应用的现状入已取得重大进展。微透析技术除应用于动物模型中的研究外,在人体中的研究特别是临床应用方面亦在发展中,该项技术在药物代谢和药代动力学研究领域中有广阔应用前景,但微透析探针校正和对微透析取样获得的少量样品的分析方法是仍需要深入研究的问题。     

反向透析法用于体内经皮吸收微透析探针回收率的测定

目的考察反向透析法用于体内经皮吸收过程中微透析探针回收率校正的可行性.方法在体外试验中用零净流量法测定探针的回收率和传递率,在体内试验中用反向透析法测定探针的回收率;以小猪为试验动物,观察模型药雷公藤内酯醇软膏的体内经皮吸收过程.结果体外试验中,微透析探针的回收率为(64.29±2.34)%,回收率和传递率一致;体内经皮微透析实验中探针的回收率在实验前为(51.47±3.51)%,实验结束后为(51.96±4.97)%.雷公藤内酯醇软膏经皮吸收后,药物在皮内浓度很快达到稳态,去除药物后皮内药物浓度则迅速下降.结论反向透析法测定的探针回收率在实验过程中稳定,可以用于测定体内经皮吸收微透析探针回收率.     

钩藤碱微透析探针回收率测定及影响因素研究

目的:考察体内外微透析探针回收率的稳定性和重现性,为进一步的体内微透析试验提供依据。方法:采用增量法和减量法考察浓度、流速对探针回收率的影响。结果:微透析探针回收率受流速影响较大,基本不受浓度影响,且体内回收率稳定性良好。结论:微透析技术可用于钩藤碱的体内药代动力学研究,反透析法可作为体内研究钩藤碱探针回收率的测定方法。     

头孢拉定微透析体外回收率及影响因素的研究

目的 测定头孢拉定微透析体外回收率及影响因素。方法 采用微透析浓度差法（减量法、增量法）和液质联用技术（LC-MS/MS）测定头孢拉定的体外回收率,并考察流速、浓度对回收率的影响,以探讨微透析技术用于头孢拉定体内药动学研究的可行性。结果 所建立的方法在要求范围内线性关系良好,方法灵敏可靠。增、减量法测得的回收率无显著性差异。相同条件下,探针体外回收率随流速增大而减小,不受探针周围药物浓度的影响。结论 微透析技术可用于头孢拉定药动学研究,减量法可用于头孢拉定微透析体内回收率和药动学参数的测定。     

灌流液改性剂对环维黄杨星D微透析探针回收率的影响研究

目的考察灌流改性剂对环维黄杨星D微透析探针回收率的影响,验证使用改性灌流液条件下微透析探针体外相对回收率与相对损失率的一致性,为体内微透析研究提供实验依据。方法采用高效液相色谱法测定灌流液中环维黄杨星D含量,计算不同改性灌流液条件下微透析探针的体外相对回收率,优选合适的改性剂种类与用量,再分别采用增量法与减量法计算不同药物浓度水平下探针体外相对回收率与相对损失率,比较两者结果的一致性。结果常规灌流条件下,乙醇作为灌流液改性剂对环维黄杨星D相对回收率提高较多,优选灌流液配比为30%乙醇-林格氏液。在2.53~10.12μg·mL~(-1)内环维黄杨星D体外相对回收率和相对损失率具有高度的一致性。结论选择合适的灌流液改性剂可显著提高微透析探针相对回收率水平,对于同一根微透析探针环维黄杨星D体外相对回收率与外周液药物浓度无关,探针回收率可通过药物透过半透膜时的流失量来间接计算,结果较好地证明反透析法适合于环维黄杨星D微透析采样。     

微透析技术在药物-蛋白结合研究中的应用

目的 介绍微透析技术在药物-蛋白结合研究中的应用。方法 通过查阅近年来国内外相关文献,概述微透析技术的基本原理、特点、探针及影响探针相对回收率的主要因素,并重点介绍其在药物-蛋白结合研究中的应用。结果与结论 与平衡透析法、超滤法相比,微透析技术是一项新兴的在体或离体取样技术,在药物-蛋白结合研究中具有显著的优越性和广阔的应用前景。     

Microdialysis Sampling for the Investigation of Dermal Drug Transport

Microdialysis perfusion in vivo has the potential to be a powerful sampling technique in dermal and transdermal drug delivery studies. Characterization of a commercially available microdialysis probe in vitro considering relevant physiological parameters is a vital first step in the evaluation of microdialysis as a dermal sampling technique. In previous microdialysis studies, analyte concentration and neutrality have been implicated in altering microdialysis recovery. The recovery of a model compound 5-fluorouracil (5-FU) was investigated at several pH values and donor concentrations. The relative recovery of 5-FU by the microdialysis probe was affected by pH but not by donor concentration. To confirm further that the changing concentration and pH profile presented by the flux of 5-FU was not significantly altering microdialysis recovery, an experiment comparing direct and microdialysis sampling of a Franz diffusion cell receptor compartment was performed. Although the 5-FU concentration (0-686 ng/ml) and pH (7.40-7.24) changed substantially, the recovery of 5-FU was not adversely affected. To demonstrate the feasibility of dermal microdialysis, the flux of a commercial preparation of 5-fluorouracil was monitored utilizing a microdialysis probe implanted in excised rat skin in vitro. The results from the dermally implanted probe demonstrate the potential of the technique while establishing the limitations of the current microdialysis system.     

Assessment of in vitro and in vivo recovery of gallamine using microdialysis

The application of microdialysis technique for the investigation of pharmacokinetics and pharmacodynamics of drugs requires careful assessment of probe performance to ensure validity of the data obtained using this technique. The aim of this study was to establish and validate the microdialysis technique for investigation of the pharmacokinetics and pharmacodynamics of the neuromuscular blocker, gallamine. In vitro recovery of gallamine from the microdialysis probe when different perfusion flow rates were employed was evaluated leading to selection of a flow rate of 2 microl/min with 15-min sampling intervals for the subsequent studies. In vitro recovery of gallamine from the microdialysis probe was independent of concentration, stable over an 8-h period and reproducible. Comparable in vitro recoveries were obtained by different established approaches including recovery estimation by gain, loss and the zero-net flux (ZNF) method. Recovery by loss was used to study the in vivo recovery of gallamine from rat muscle tissue. The in vivo recovery was stable over a 5.5-h sampling period. In vitro performance of the probe subsequent to the in vivo study remained stable supporting reusage of the probe. These data highlight the importance of a systematic examination of microdialysis probe validation.     

Use of osmotic agents in microdialysis studies to improve the recovery of macromolecules

The availability of microdialysis probes with higher molecular weight cutoff membranes has made it possible to measure larger molecular weight compounds like bioactive peptides and proteins. However, the higher molecular weight membrane cutoff allows for increased fluid loss from the probe, influencing both the physiology of the tissue compartment and analyte recovery. This study examined the ability of osmotic agents like bovine serum albumin (BSA) to offset the water loss from the microdialysis probe. In the presence of BSA, water loss from the microdialysis probe was minimized. Furthermore, addition of BSA to the perfusate produced significant increases in analyte recovery. Application of this technique to the measurement of bioactive macromolecules was examined using in vitro microdialysis of tumor necrosis factor (TNF) and interleukin-1 beta (IL-1B). The results of the present study suggest osmotic agents like BSA can prevent fluid loss from the microdialysis probe and improve analyte recovery.     

Evaluation of in vivo and in vitro recovery rate of anatoxin-a through the microdialysis probe

In vivo microdialysis is a versatile sampling technique commonly employed to observe changes in neurotransmitters levels that occur in response to different treatments, being these treatments administered through a microdialysis probe implanted into a specific brain region in living animals. In previous works we have used this technique to study the effects of the drug anatoxin-a, a nicotinic acetylcholine receptor agonist, on dopamine release in striatum. The aim of the present study was to assess the recovery of anatoxin-a through the microdialysis probe. This information allows knowing the exact amount of the drug crossing the microdialysis membrane, acting on extracellular tissue. High Performance Liquid Chromatography (HPLC) with Fluorescence Detection (FLD) has been used for the analysis of anatoxin-a. We observed that the recovery of anatoxin-a was about 0.5%. Under our experimental conditions, the results suggest that anatoxin-a can be used as an important tool in the study of neuronal nicotinic receptors by in vivo microdialysis technique and also show a reliable estimation of the anatoxin-a recovery through the microdialysis probe under both in vivo and in vitro conditions.     

Validation of an ocular microdialysis technique in rabbits with permanently implanted vitreous probes: systemic and intravitreal pharmacokinetics of fluorescein

The purpose of this work is to validate a novel ocular microdialysis sampling technique in rabbits with permanently implanted vitreous probes. This objective is achieved by studying the vitreous pharmacokinetics of fluorescein following systemic and intravitreal administration. The rabbits were divided into two groups (groups I and II) based on whether or not they were allowed a recovery period following surgical implantation of probes. The integrity of the blood-retinal barrier was determined by the vitreal protein concentrations and the fluorescein permeability index. Vitreal protein concentrations returned to baseline 48 h after probe implantation and therefore experiments were conducted 72 h post-implantation of probes in rabbits where recovery period was allowed. The permeability indices for fluorescein after systemic administration in group I (without recovery period) and group II (with recovery period) indicated that the integrity of the blood-retinal barrier was maintained and were found out to be 0.55 +/- 0.27 and 0.71 +/- 0.38%, respectively, for the vitreous chamber. Following microdialysis probe implantation in the group II rabbits, the blood-retinal barrier integrity was not compromised. A novel microdialysis technique in rabbits with permanently implanted probes for studying the pharmacokinetics of posterior segment has been developed and characterized.     

Application of Microdialysis in Pharmacokinetic Studies

The objective of this review is to survey the recent literature regarding the various applications of microdialysis in pharmacokinetics. Microdialysis is a relatively new technique for sampling tissue extracellular fluid that is gaining popularity in pharmacokinetic and pharmacodynamic studies, both in experimental animals and humans. The first part of this review discusses various aspects of the technique with regard to its use in pharmacokinetic studies, such as: quantitation of the microdialysis probe relative recovery, interfacing the sampling technique with analytical instrumentation, and consideration of repeated procedures using the microdialysis probe. The remainder of the review is devoted to a survey of the recent literature concerning pharmacokinetic studies that apply the microdialysis sampling technique. While the majority of the pharmacokinetic studies that have utilized microdialysis have been done in the central nervous system, a growing number of applications are being found in a variety of peripheral tissue types, e.g. skin, muscle, adipose, eye, lung, liver, and blood, and these are considered as well. Given the rising interest in this technique, and the ongoing attempts to adapt it to pharmacokinetic studies, it is clear that microdialysis sampling will have an important place in studying drug disposition and metabolism.     

Pharmacokinetic study of ketoprofen isopropyl ester-loaded lipid microspheres in rat blood using microdialysis

A blood microdialysis technique coupled with high-performance liquid chromatography was used to investigate the pharmacokinetics of unbound ketoprofen in rats after intravenous administration of a lipid-soluble ketoprofen derivate, ketoprofen isopropyl ester (KPI), loaded into lipid microspheres (LM) and ketoprofen solution. A microdialysis probe was inserted into the jugular vein of male Wistar rats. KPI-loaded LM or ketoprofen solution (24 mg/kg, i.v.) was then administrated via a femoral vein. Dialysate samples were analyzed using HPLC. The in vitro and in vivo recovery rate of the microdialysis probe was 30.42+/-0.74% (n=3) and 40.27+/-2.74% (n=3), respectively. The pharmacokinetic parameters for ketoprofen after intravenous administration of KPI-loaded LM and ketoprofen solution exhibited no statistically significant differences. The results of this pharmacokinetic study indicate that the microdialysis technique can be widely applicable to investigations of in vivo free-drug of microcarrier systems.     

Blood microdialysis in pharmacokinetic and drug metabolism studies

Microdialysis is a sampling technique allowing measurement of endogenous and exogenous substances in the extracellular fluid surrounding the probe. In vivo microdialysis sampling offers several advantages over conventional methods of studying the pharmacokinetics and metabolism of xenobiotics, both in experimental animals and humans. In the first part of this review article various practical aspects related to blood microdialysis will be discussed, such as: probe design, surgical implantation techniques, methods to determine the in vivo relative recovery of the analyte of interest by the probe, special analytical considerations related to small volume microdialysate samples, and pharmacokinetic calculations based on microdialysis data. In the second part of this review a few selected applications of in vivo microdialysis sampling to investigate pharmacokinetic processes are briefly discussed: determination of in vivo plasma protein binding in small laboratory animals, distribution of drugs across the blood-brain barrier, the use of microdialysis sampling to study biliary excretion and enterohepatic cycling, blood microdialysis sampling in man and in the mouse, and in vivo drug metabolism studies.