尼莫地平聚乳酸缓释微球的制备及其药剂学性质

目的制备尼莫地平聚乳酸缓释微球,并对其药剂学性质进行研究.方法采用溶剂蒸发萃取法制备微球,正交实验设计考察影响制备工艺的因素,用扫描电镜观察微球表面形态,红外光谱分析验证舍药微球的形成,对制备的尼莫地平微球的粒径、栽药量、包封率等性质及体外释放特性进行了研究.结果尼莫地平聚乳酸微球的最佳制备工艺稳定,微球形态圆整,粒径分布适宜,药物确已被包裹于微球中.优化工艺制得的微球平均粒径为(61.7±0.46)μm,载药量为(53.2±0.8)%,包封率为(86.2±0.6)%,体外释放符合Higuchi方程,Q=17.708t1/2-0.975 8(r=0.995 4),t1/2=8.29 d.结论本实验获得了较理想的尼莫地平聚乳酸微球,其体外释药特性符合长效制剂特征.     

甲睾酮聚乳酸缓释微球的制备

目的：制备甲睾酮聚乳酸缓释微球。方法：用乳化溶剂挥发法制备甲睾酮聚乳酸缓释微球。先设计单因素试验筛选制备微球的处方中的聚乳酸分子量、聚乳酸浓度、投药比（甲睾酮：聚乳酸）;再采用正交试验优化制备微球的温度、转速、聚乳酸浓度、投药比。考察微球表面形态、粒径、载药量、包封率、168h体外累积释药率,并对微球的体外释药模型进行零级、一级、Higuchi、双相动力学方程拟合。结果：优选结果为聚乳酸分子量11万、温度30℃、转速500r·min-1、聚乳酸浓度0.1g·mL-1、投药比1：5。采用最佳工艺条件制备的微球形态圆整,平均粒径为（2.5±0.2）μm,载药量为6.18%～6.62%,包封率为89.9%～91.3%,168h体外累积释药率为（41.8±0.1）%,微球的体外释药符合双相动力学方程（r=0.9945）。结论：甲睾酮聚乳酸缓释微球制备工艺稳定,具有良好的缓释能力。     

干扰素-α微球的制备及其体外释药性能研究

目的:通过正交设计试验优化干扰素-a聚乳酸-羟乙酸共聚物微球的制备工艺,并考察其体外释药性能.方法:采用复乳-溶剂挥发法制备干扰素微球,通过L9(3)4正交试验设计优选微球最佳制备工艺条件,并对制备工艺的重现性、微球的性质及体外释药性能进行了考察.结果:干扰素微球的最佳制备工艺稳定、重现性好,微球的形态圆整,粒度分布均匀,平均粒径为10.71μm,干扰素被证明包裹在微球中,载药量为8.06%,包封率为36.97%.干扰素微球在61 h的累积释药量约为86%,t1/2为10.8 h.结论:本研究获得了较满意的干扰素微球制备工艺,其体外释药性能符合长效制剂特征.     

阿立哌唑缓释微球的制备及体外释放特性的研究

目的 制备阿立哌唑聚乳酸-羟基乙酸共聚物(PLGA)缓释微球并考察其体外释放特性.方法 采用乳化-溶剂挥发法制备阿立哌唑缓释微球,通过正交试验优选最佳处方与制备工艺,并考察其载药量、包封率、粒径、形态和体外释放度.结果 所得微球的载药量为20.28％ ±0.38％,包封率为81.12％±0.02％,平均粒径为19.38 μm,形态圆整,30 d的体外累积释放度达88.73％.结论 所得阿立哌唑缓释微球形态圆整,载药量与包封率较高,具较好的缓释效果.     

盐酸四环素缓释微球的制备

目的制备盐酸四环素聚乳酸-聚羟基乙酸共聚物(PLGA)微球并优化其工艺。方法采用复乳-溶剂蒸发法制备盐酸四环素PLGA微球,以微球包封率为检测指标,通过单因素试验和正交试验优选最佳制备工艺。结果在优化条件下制备的微球形态规则,粒径为16.72±0.33μm,载药量为0.52%±0.01%,包封率为78.56%±1.05%,微球的体外释药规律符合Higuichi方程(r=0.9986)。结论该制备工艺合理,为制备盐酸四环素PLGA微球提供了理论基础。     

载羟基喜树碱聚乳酸微球的制备与体外释药研究

目的:研究载羟基喜树碱的聚乳酸微球的制备方法并考察其体外释药性质。方法:以PLA为成膜材料,采用改良乳化-溶剂挥发法,制备载羟基喜树碱的聚乳酸微球并优化制备工艺;对载药微球进行表征;超声介导下进行载药微球的体外释药试验。结果:微球粒径在1～7μm,大小均一;羟基喜树碱浓度在10mg.mL-1下,载药微球包封率为62.2%,载药量为1.69%;药物体外释药符合Higuchi方程。结论:采用乳化-溶剂挥发法,以PLA为成膜材料可制得具有较高包封率的羟基喜树碱微球,有望实现降低羟基喜树碱给药量、减少不良反应,提高靶向性的目标。     

GM-l PLGA微球的制备及其体外释药性质研究

目的制备GM l PLGA微球，考察其一般性质和体外释药特性。方法应用W/O/W乳化溶剂干燥法制备GM l PLGA微球，测定微球粒径、载药量、包封率和体外释药曲线。结果微球形态规则，粒径约为（18±8） μm，载药量约为4.9%，包封率约为61%，微球体外释药规律符合Higuichi方程：Q=0.153t1/2+0.037 05(r=0.995)。结论GM l PLGA微球的制备工艺良好，体外释药呈明显的缓释作用。     

胸腺肽明胶微球的制备和体外释药的特性

目的:为提高胸腺肽的生物利用度,增强疗效,制备胸腺肽的明胶微球.方法:用乳化交联法制备胸腺肽明胶微球,正交设计法筛选其最佳制备工艺,Lowry法测定药物的含量,计算微球的载药量、包封率及体外释药量.结果:微球粒径范围为1.0～30.2 μm,平均粒径为14.64 μm,平均载药量为20.20%(w/w),平均包封率为80.82%,其体外释药符合Higuchi方程,稳定性考察实验结果表明其稳定性较好.结论:本法制备的胸腺肽明胶微球粒径分布集中,粒径大小符合设计要求,体外释药有明显的缓释作用,具有良好应用前景.     

阿霉素聚乳酸微球的制备及体外释药特性研究

目的:对阿霉素聚乳酸微球的制备工艺、含量测定及体外释药特性进行初步研究.方法:以人工合成可生物降解聚合物聚乳酸为载体,采用乳化-溶剂挥发法制备阿霉素聚乳酸微球,用UV-260紫外分光光度计测定其药物含量和体外释药量.结果:所制备的阿霉素聚乳酸微球外形圆整,算术平均球径为55.2 μm,载药量为30.21 μg*mg-1,12 h体外累积释药量36%.结论:聚乳酸微球具有很好的控释能力,使用前景广阔.     

碱性成纤维细胞生长因子缓释微球的制备及其性质研究

目的 通过碱性成纤维细胞生长因子(bFGF)缓释微球的制备研究,为bFGF的缓释制剂提供科学依据。方法 以聚乳酸-聚乙二醇共聚物为包裹材料,采用复乳包囊法制备bFGF-聚乳酸-聚乙二醇共聚物缓释微球,并对微球的形态学、粒径分布、载药量、包封率和体外释药等进行研究。结果 所制备的微球表面光滑圆整,球体均匀度好;微球平均粒径为1.543±0.070 μm,平均径距为1.273±0.08;载药量和包封率分别为0.0267％和65.32％;微球的体外释药过程较为稳定,两周释药率为59.98％。结论 bFGF缓释微球比bFGF有明显的缓释作用。     

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.

     

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.     

2-(Acetoxyphenyl)-(Z)-styryl sulfides as cyclooxygenase inhibitors

2-(Acetoxyphenyl)-(Z)-styryl sulfides are described as selective cyclooxygenase-2 (COX-2) inhibitors, useful for treating inflammation and COX-2-mediated disorders including neoplasia. 2-(Acetoxyphenyl)-(Z)-styryl sulfide is claimed to be the most potent COX inhibitor in the series with a COX-2 selectivity ratio of 33. This compound is also claimed to be superior to celecoxib (Celebrex^®, Pfizer) in inhibiting cell growth of colorectal carcinoma cells. In this evaluation, the COX inhibitory activity of this compound is compared to that previously disclosed for diarylheterocycles and 2-(acetoxyphenyl)alkyl sulfides. The validity of the DLD-1 cell line in the growth inhibition studies is questioned based on recent literature reports indicating the lack of COX-2 expression in this cell line.     

Sleep-disordered breathing with chronic opioid use

Chronic opioid use for pain relief or as substitution therapy for illicit drug abuse is prevalent in our societies. In the US, retail distribution of methadone and oxycodone has increased by 824 and 660%, respectively, between 1997 and 2003. μ-Opioids depress respiration and deaths related to illicit and non illicit chronic opioid use are not uncommon. Since 2001 there has been an emerging literature that suggests that chronic opioid use is related to central sleep apnoea of both periodic and non-periodic breathing types, and occurs in ～ 30% of these subjects. The clinical significance of these sleep-related abnormalities are unknown. This review addresses the present knowledge of control of ventilation mechanisms during wakefulness and sleep, the effects of opioids on ventilatory control mechanisms, the sleep-disordered breathing found with chronic opioid use and a discussion regarding the future research directions in this area.     

Drug targets for cognitive enhancement in neuropsychiatric disorders

The investigation of novel drug targets for treating cognitive impairments associated with neurological and psychiatric disorders remains a primary focus of study in central nervous system (CNS) research. Many promising new therapies are progressing through preclinical and clinical development, and offer the potential of improved treatment options for neurodegenerative diseases such as Alzheimer's disease (AD) as well as other disorders that have not been particularly well treated to date like the cognitive impairments associated with schizophrenia (CIAS). Among targets under investigation, cholinergic receptors have received much attention with several nicotinic agonists (α7 and α4β2) actively in clinical trials for the treatment of AD, CIAS and attention deficit hyperactivity disorder (ADHD). Both glutamatergic and serotonergic (5-HT) agonists and antagonists have profound effects on neurotransmission and improve cognitive function in preclinical experiments with animals; some of these compounds are now in proof-of-concept studies in humans. Several histamine H3 receptor antagonists are in clinical development not only for cognitive enhancement, but also for the treatment of narcolepsy and cognitive deficits due to sleep deprivation because of their expression in brain sleep centers. Compounds that dampen inhibitory tone (e.g., GABA_A α5 inverse agonists) or elevate excitatory tone (e.g., glycine transporter inhibitors) offer novel approaches for treating diseases such as schizophrenia, AD and Down syndrome. In addition to cell surface receptors, intracellular drug targets such as the phosphodiesterases (PDEs) are known to impact signaling pathways that affect long-term memory formation and working memory. Overall, there is a genuine need to treat cognitive deficits associated with many neuropsychiatric conditions as well as an increasingly aging population.