替莫唑胺壳聚糖缓释微球的制备及体外释药特性

目的:制备替莫唑胺壳聚糖缓释微球,并对其体外释药模式进行研究.方法:以替莫唑胺为模型药物,采用乳化交联法制备壳聚糖微球,两步优化法优化处方和制备工艺.通过测定微球的粒径及其分布、载药量、包封率和体外释放速度对微球进行质量评价.结果:优化工艺制得的微球平均粒径为(3.9±1.6)μm,载药量为(7.1±0.5)%(n=3),包封率为(25.0±0.8)%(n=3),体外释药特性研究具有良好的缓释特性,在0～8 h符合Higuchi方程,Q=11.717 26.951t1/2(r=0.980),8～24 h符合一级释放曲线,lnQ=4.37 0.007 5t(r=0.983).结论:通过优化处方和制备工艺,采用乳化交联法可制备出以壳聚糖为载体、替莫唑胺为模型药物的缓释微球,其体外释药具有明显的缓释作用.     

盐酸维拉帕米缓释微球的制备及其质量评价

目的:制备维拉帕米缓释微球,并对其进行质量评价.方法:采用低温喷雾干燥法制备盐酸维拉帕米缓释微球,评价内容包括:微球的粒径及其分布、微球含药量、载药量和包封率、收率以及不同pH值下的释放速率.结果:成功制备了盐酸维拉帕米缓释微球,平均收率为28.97%,所得微球55%以上的粒径在3.0~5.0μm,载药量为26.11%,包封率为76.40%.结论:微球的体外累积释放度完全符合Higuchi方程,初步证实该微球的释放属于骨架溶蚀性过程.     

替加氟白蛋白微球的制备

用乳化交联热固化法制备FT-207白蛋白微球,并测定微球的一些基本特征,包括微球大小、形态与表面状态.结果表明微球粒径主要分布在0.3～2.0μm范围内,药物包封量为11.8 6±0.93%;体外释放实验表明,在pH7.4磷酸盐缓冲溶液中,微球具有显著的缓释作用,其释放特征符合Higuchi方程.本研究制备的FT-207白蛋白微球,静脉注射后可望对肝、脾等组织有一定的靶向作用,为肝癌的化疗提供一种新的靶向制剂.     

替加氟白蛋白微球的制备

用乳化交联热固化法制备FT-207白蛋白微球,并测定微球的一些基本特征,包括微球大小、形态与表面状态.结果表明微球粒径主要分布在0.3～2.0μm范围内,药物包封量为11.8 6±0.93%;体外释放实验表明,在pH7.4磷酸盐缓冲溶液中,微球具有显著的缓释作用,其释放特征符合Higuchi方程.本研究制备的FT-207白蛋白微球,静脉注射后可望对肝、脾等组织有一定的靶向作用,为肝癌的化疗提供一种新的靶向制剂.     

依托泊苷鼻用壳聚糖微球的制备及体外释放度考察

目的研制依托泊苷鼻黏膜给药壳聚糖微球,对微球的制备方法及体外释放度进行考察.方法以壳聚糖为栽体,甲醛为交联剂,采用乳化交联固化法制备微球,对微球的粒径、形态及体外释药进行研究.结果微球的外观圆整,平均粒径为(46.9±0.7)μm,78.4 %的微球粒径在30～70μm范围内,体外释药符合Higuchi模型.结论依托泊苷壳聚糖微球制备工艺简单、稳定,包封率高,药物释放符合鼻腔给药要求.     

球晶造粒法制备硝苯地平缓释微球

目的考察硝苯地平缓释微球的制备工艺及其体外释放度。方法以邻苯二甲酸羟丙甲纤维素酯(HP55)为载体材料,采用球晶造粒技术制备硝苯地平缓释微球。考察硝苯地平微球的粒径、形态、载药量、包封率及体外释放度。结果所得微球外观圆整度好,粒径分布在70~150μm,载药量为18.91%,包封率为94.95%。结论该法可用于硝苯地平缓释微球的制备。     

双氯芬酸钠/海藻酸钠微球的制备与体外释药行为考察

目的以海藻酸钠为载体材料,双氯芬酸钠为模型药物,制备载药微球并考察其性质及体外释放行为。方法本文采用海藻酸钠为药物载体,采用喷雾干燥法制备双氯芬酸钠/海藻酸钠微球。考察于双氯芬酸钠/海藻酸钠投料比对载药微球理化性质的影响。采用扫描电镜对所得到的微球进行形貌观察。同时考察其体外药物释放行为。结果所得到的载药微球形态呈不规则的扁平状,粒径分布较为均匀。通过控制投料比,可以得到不同粒径(5.64～9.58μm),载药量(5.76～18.43%)和包封率(35.45～43.92%)的载药微球。体外药物释放行为结果显示微球在含有0.5%氯化钙的PBS(pH=7.4)溶液的药物释放时间可以持续96h,具有一定的缓释效果。结论通过喷雾干燥法制备的双氯芬酸钠/海藻酸钠载药微球具有较高载药量和一定的药物缓释效果。     

PLGA包埋硫酸庆大霉素缓释微球的制备及体外释放行为

以生物可降解乙交酯和丙交酯的无规共聚物(PLGA)为载体,将硫酸庆大霉素分散在PLGA的有机溶液中,采用复乳溶剂挥发法制备了药物缓释微球。研究搅拌速度、PLGA浓度、乳化剂浓度和硫酸庆大霉素溶液体积对微球粒径的影响,观察微球的表面形貌,测定微球粒径、粒径分布和包封率,评价载药微球的体外释放行为。结果表明,采用甲基纤维素为乳化剂制备的微球形态完整,中粒径为(130±30)μm,微球中硫酸庆大霉素的包封率均在36%以上,平均42%,最高达56%。硫酸庆大霉素/PLGA微球具有显著的药物缓释作用,体外释放30d的累积释药率达80%以上。     

布比卡因缓释微球的制备及体外释药特性评价

目的研究布比卡因缓释微球制备方法并对其体外释药特性进行评价。方法采用紫外分光光度法测定布比卡因微球载药量、包封率;采用HPLC法测定微球体外释放;通过正交设计优选微球制备工艺;以乳酸羟基乙酸共聚物为载体,使用乳化溶剂挥发法制备布比卡因微球;用扫描电镜观察所得微球的粒径和形态;通过体外释药实验考察布比卡因乳酸羟基乙酸共聚物微球的缓释作用。结果微球载药量、包封率和体外释放的测定方法符合方法学要求;按照优选处方制备所得的微球为圆整球体,表面多孔,呈蜂窝状,粒径50~100μm之间的微球占80%;体外释放符合Ritger-Peppas方程,t1/2=242.05 h。结论乳化溶剂挥发法适用于布比卡因乳酸羟基乙酸共聚物微球的制备,所制得的微球形态圆整,在体外具有明显缓释作用。     

芹菜素壳聚糖微球的制备及体外释药研究

目的以芹菜素为模型药物、脱乙酰壳聚糖为药物载体,制备芹菜素壳聚糖微球,并测定微球中芹菜素的体外释放度。方法采用复乳-乳化化学交联法制备微球,正交试验优化微球制备的工艺,高效液相色谱法检测芹菜素含量。结果最佳工艺制备4批微球,形态良好,微球圆整,平均载药量为8.54%,平均包封率为69.69%,平均粒径为84.33μm。微球在pH 6.8和pH 7.4的磷酸盐缓冲液中释放36 h。结论所选制备工艺稳定,适用于芹菜素壳聚糖微球的制备,体外药物释放结果显示,微球具有良好的缓释效果。     

Efficacy of gut lavage,hemodialysis, and hemoperfusion in the therapy of paraquat or diquat intoxication

Clinical and in vitro investigations were carried out to test the efficacy of gut lavage, hemodialysis, and hemoperfusion in the treatment of poisoning with paraquat or diquat. In a patient suffering from diquat intoxication 130 times more diquat was removed by gut lavage 30 h after ingestion than was removed by complete aspiration of the gastric contents.Determination of in vitro clearances for paraquat and diquat by hemodialysis showed that, at serum concentrations of 1–2 ppm, such as are frequently encountered in poisoning in man, toxicologically relevant quantities of herbicide cannot be removed from the body. At a concentration of 20 ppm, on the other hand, hemodialysis proved to be effective, the clearance being 70 ml/min at a blood flow rate of 100 ml/min. The efficacy of hemoperfusion with coated activated charcoal was on the whole better. Especially at concentrations around 1–2 ppm, the clearance values for hemoperfusion were some 5–7 times higher than those for hemodialysis.In a patient suffering from paraquat poisoning, both hemodialysis as well as hemoperfusion were carried out. The in vitro results could be confirmed: At serum concentrations of paraquat less than 1 ppm no clearance could be obtained by hemodialysis while by hemoperfusion with activated charcoal quite high clearance values were measured and the serum level dropped down to zero.

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Zusammenfassung Klinische Untersuchungen und Laboratoriumsversuche wurden durchgeführt, um die Wirksamkeit von Darmspülung, Hämodialyse und Hämoperfusion bei Paraquat- und Deiquat-Vergiftungen zu prüfen.Bei einem Patienten wurde 30 Std nach Deiquat-Aufnahme durch Darmspülung 130mal mehr Deiquat entfernt als durch vollständige Aspiration des Mageninhaltes. In vitro-Versuche ergaben, daß bei Blutserumkonzentrationen von 1–2 ppm, die bei Vergiftungen oft gemessen werden, durch Hämodialyse keine toxikologisch relevanten Paraquat- oder Deiquat-Mengen entfernt werden können. Dagegen erwies sich die Hämodialyse bei 20 ppm und einer Blutumlaufgeschwindigkeit von 100 ml/min mit einer Clearance von 70 ml/min als wirksam. Die Hämoperfusion mit beschicheter Aktivkohle war in diesen Versuchen aber eindeutig überlegen, denn insbesondere bei Konzentrationen um 1–2 ppm waren die Clearance-Werte 5–7mal höher als bei der Hämodialyse.Die in vitro-Ergebnisse wurden bei einem Patienten mit einer Paraquat-Vergiftung bestätigt: Bei Konzentrationen unter 1 ppm war die Hämodialyse wirkungslos, während durch Hämoperfusion relativ hohe Clearance-Werte erreicht wurden, so daß der Serumspiegel rasch unter die Nachweisgrenze abfiel.

     

In vitro studies on sterically stabilized liposomes (SL) as enzyme carriers in organophosphorus (OP) antagonism

This study describes a new approach for organophosphorous (OP) antidotal treatment by encapsulating an OP hydrolyzing enzyme, OPA anhydrolase (OPAA), within sterically stabilized liposomes. The recombinant OPAA enzyme was derived from Alteromonas strain JD6. It has broad substrate specificity to a wide range of OP compounds: DFP and the nerve agents, soman and sarin. Liposomes encapsulating OPAA (SL)* were made by mechanical dispersion method. Hydrolysis of DFP by (SL)* was measured by following an increase of fluoride ion concentration using a fluoride ion selective electrode. OPAA entrapped in the carrier liposomes rapidly hydrolyze DFP, with the rate of DFP hydrolysis directly proportional to the amount of (SL)* added to the solution. Liposomal carriers containing no enzyme did not hydrolyze DFP. The reaction was linear and the rate of hydrolysis was first order in the substrate. This enzyme carrier system serves as a biodegradable protective environment for the recombinant OP-metabolizing enzyme, OPAA, resulting in prolongation of enzymatic concentration in the body. These studies suggest that the protection of OP intoxication can be strikingly enhanced by adding OPAA encapsulated within (SL)* to pralidoxime and atropine.     

Aquatic Insects and Trace Metals: Bioavailability,Bioaccumulation, and Toxicity

Abstract

The uptake of metals from food and water sources by insects is thought to be additive. For a given metal, the proportions taken up from water and food will depend both on the bioavailable concentration of the metal associated with each source and the mechanism and rate by which the metal enters the insect. Attempts to correlate insect trace metal concentrations with the trophic level of insects should be made with a knowledge of the feeding relationships of the individual taxa concerned. Pathways for the uptake of essential metals, such as copper and zinc, exist at the cellular level, and other nonessential metals, such as cadmium, also appear to enter via these routes. Within cells, trace metals can be bound to proteins or stored in granules. The internal distribution of metals among body tissues is very heterogeneous, and distribution patterns tend to be both metal and taxon specific. Trace metals associated with insects can be both bound on the surface of their chitinous exoskeleton and incorporated into body tissues. The quantities of trace meals accumulated by an individual reflect the net balance between the rate of metal influx from both dissolved and particulate sources and the rate of metal efflux from the organism. The toxicity of metals has been demonstrated at all levels of biological organization: cell, tissue, individual, population, and community. Much of the literature pertaining to the toxic effects of metals on aquatic insects is based on laboratory observations and, as such, it is difficult to extrapolate the data to insects in nature. The few experimental studies in nature suggest that trace metal contaminants can affect both the distribution and the abundance of aquatic insects. Insects have a largely unexploited potential as biomonitors of metal contamination in nature. A better understanding of the physico-chemical and biological mechanisms mediating trace metal bioavailability and exchange will facilitate the development of general predictive models relating trace metal concentrations in insects to those in their environment. Such models will facilitate the use of insects as contaminant biomonitors.     

Alzheimer’s disease – current trends in basic and clinical research. Highlights from the 16th ECNP

Advances in the molecular biological knowledge of neuronal nicotinic acetylcholine receptors (nAChRs) have led to a growing interest by the pharmaceutical industry in the development of novel compounds that selectively modulate nAChR function. The ability of (-)-nicotine, an activator of nAChRs, to enhance attentional aspects of cognition in animals and humans, to exert neuroprotective and anxiolytic-like effects, and presumably to mediate the negative correlation between smoking and Alzheimer's (and Parkinson's) Disease, has focused interest on the potential therapeutic utility of modulators of nAChR function for treatment of some of the deficits associated with these progressive, neurodegenerative conditions. Numerous compounds are known which activate nAChRs and which might serve as lead compounds toward the development of such agents. The pharmacologic diversity of neuronal nAChR subtypes suggests the possibility of developing selective compounds which would have more favourable side-effect profiles than existing agents. This broader class of agents, collectively called cholinergic channel modulators (ChCMs), is anticipated to encompass compounds which would have more favourable side-effect profiles than existing agents, which generally exhibit low selectivity. This selectivity may be achieved by preferentially activating some subtypes of nAChRs (i.e., Cholinergic Channel Activators, ChCAs) or inhibiting the function of other subtypes (Cholinergic Channel Inhibitors, ChCIs). An overview of the biology of nAChRs and the rationale for the use of ChCMs for the treatment of dementia related to neurodegenerative diseases are presented, followed by a discussion of lead compounds and compounds under consideration for clinical evaluation.     

Steroidal sapogenin contents in some domestic plants

In order to find out the values of the steroid resources for the future use. the compositions and contents of steroidal sapogenins from 13 domestic plants have been investigated. As a result,Dioscorea nipponica, D. quinqueloba andSmilax china were found to have large amount of diosgenin. And pennogenin inTrillium kamtschaticum andParis verticillata, yuccagenin inAllium fistulosum, hecogenin inAgave americana and neochlorogenin inSolanum nigum were appeared to be major steroidal sapogenins.