乳剂的缓释和控释作用研究进展

乳剂药物转运系统的某些独特性质，使其具有淋巴输送和靶向定位及缓释作用。影响乳剂稳定性和药物缓释作用遥因素较多，主要有药物性质，油相性质、相体积比、乳化剂、ＰＨ值、粘度、添加剂、制备工艺等。本文主要叙述了乳剂的缓释和控释作用，释药机制及其影响因素。     

定量评价去氢骆驼蓬碱注射用乳剂的组织靶向性

目的:定量评价静脉注射用乳剂作为药物载体给药后对主要脏器的靶向性并对给药系统靶向性的定量评价参数进行讨论和评价。方法:用3H标记的去氢骆驼蓬碱(harmine,HAR)分别制成静脉注射乳剂、水溶液和脂质体,经小鼠静脉注射后测定主要脏器组织中的总放射性强度,计算重量-平均总靶向性系数Te和靶向性系数Te,并对乳剂的靶向性意义作出定量评价。结果:静脉乳剂可显著提高放射性在肝、脾、淋巴器官的分布,降低放射性向脑组织的转运。结论:静脉注射乳剂是一很有意义的靶向给药系统,重量-平均总靶向性系数Te是较全面的靶向性评价参数。     

定量评价去氢骆驼蓬碱注射用乳剂的组织靶向性

目的：定量评价静脉注射用乳剂作为药物载体给药后对主要脏器的靶向性并对给药系统靶向性的定量评价参数进行讨论和评价。方法：用3H标记的去氢骆驼蓬碱(harmine,HAR)分别制成静脉注射乳剂、水溶液和脂质体,经小鼠静脉注射后测定主要脏器组织中的总放射性强度,计算重量-平均总靶向性系数Te^*和靶向性系数Te,并对乳剂的靶向性意义作出定量评价。结果：静脉乳剂可显著提高放射性在肝、脾、淋巴器官的分布,降低放射性向脑组织的转运。结论：静脉注射乳剂是一很有意义的靶向给药系统,重量-平均总靶向性系数Te^*是较全面的靶向性评价参数。     

脂质乳剂释药机制及其靶向性的研究进展

简要介绍了脂质乳剂释药机制、体内外试验方法及影响释药特性和靶向性的因素，如粒径、药物性质、表面修饰等研究进展。     

含药脂肪乳剂的靶向作用研究进展

作为药物载体的脂肪乳剂由于其自身毒性小,能减小药物的毒性和副作用,增加药物疗效,并具有良好的靶向作用,从而在临床上逐渐得到应用。综述了含药脂肪乳剂作为被动靶向制剂和主动靶向制剂两方面的应用进展。     

中西药被动靶向制剂的研究新进展

目的：综述被动靶向制剂在药学领域的新进展。方法：查阅近几年有关被动靶向制剂的国内外文献。结果：从脂质体、乳剂、微球、纳米粒、药质体在现代医药及传统医药学领域中的应用等方面进行了概括。结论：被动靶向给药系统已有了很大的发展，促进了现代中西药药剂学的研究。     

磷酸川芎嗪乳剂在大鼠体内的药动学及组织分布研究

目的： 通过研究磷酸川芎嗪乳剂在大鼠体内的药动学和组织分布，探究磷酸川芎嗪乳剂的生物利用度和脑靶向性。方法： 大鼠静脉注射50 mg·kg^-1磷酸川芎嗪制剂，给药后，在不同时间采血，最后切除大鼠心脏，肝脏，脾脏，肺，肾，和脑。所有样品均采用液相色谱-质谱/质谱联用法（HPLC/MS/MS）进行检测，用DAS 2.1.1软件使用非房室分析计算药动学参数。结果： 与参比制剂（磷酸川芎嗪注射液）相比，乳剂制剂血浆中的药动学参数无显著差异。在血浆中，乳剂的AUC_0-∞和C_max分别为（4 406.96±977.08）mg·L^-1·min和（52.131±13.61）mg·L^-1。组织分布研究发现磷酸川芎嗪乳剂较参比制剂在脑组织分布更多。结论： 磷酸川芎嗪乳剂在心、肝、脾、肺、肾中有靶向趋势，比参比制剂更易分布在组织中。磷酸川芎嗪乳剂制剂具有脑靶向性。     

纳米粒的靶向修饰研究进展

［摘要］纳米粒在转运基因，运载多肽和蛋白质药物，输送免疫调节药、抗肿瘤药、抗病毒药和抗原或疫苗等方面有广泛应用前景。综述了提高纳米粒靶向性的几种方法，包括被动靶向修饰、主动靶向修饰和物理化学靶向修饰等。通过对纳米粒表面进行修饰提高其靶向性是目前药学领域研究的一个新热点，随着研究的不断深入，纳米粒给药系统必将广泛应用于临床。     

中药靶向制剂的研究进展

对近年来靶向制剂研究文献进行检索,从脂质体,微球和微囊,纳米粒,乳剂,前体前药,单克隆抗体等方面介绍中药靶向制剂的研究进展,并介绍了中药靶向制剂研究中存在的问题。     

淋巴靶向给药系统研究与应用

本文对淋巴靶向给药系统的设计机制、给药途径、制剂类型及载体材料、制剂的应用及展望进行了论述。通过制备纳米粒、乳剂、脂质体等新型给药系统可以达到淋巴靶向给药的目的。将药物制成淋巴靶向给药系统是预防、诊断、治疗淋巴癌、淋巴转移癌及其他淋巴疾病的有力工具,具有广阔的研究和应用前景。     

Binding Characterization of Aptamer-Drug Layered Microformulations and In Vitro Release Assessment

Efficient delivery of adequate active ingredients to targeted malignant cells is critical, attributing to recurrent biophysical and biochemical challenges associated with conventional pharmaceutical delivery systems. These challenges include drug leakage, low targeting capability, high systemic cytotoxicity, and poor pharmacokinetics and pharmacodynamics. Targeted delivery system is a promising development to deliver sufficient amounts of drug molecules to target cells in a controlled release pattern mode. Aptameric ligands possess unique affinity targeting capabilities which can be exploited in the design of high pay-load drug formulations to navigate active molecules to the malignant sites. This study focuses on the development of a copolymeric and multifunctional drug-loaded aptamer-conjugated poly(lactide-co-glycolic acid)–polyethylenimine (PLGA-PEI) (DPAP) delivery system, via a layer-by-layer synthesis method, using a water-in-oil-in-water double emulsion approach. The binding characteristics, targeting capability, biophysical properties, encapsulation efficiency, and drug release profile of the DPAP system were investigated under varying conditions of ionic strength, polymer composition and molecular weight (MW), and degree of PEGylation of the synthetic core. Experimental results showed increased drug release rate with increasing buffer ionic strength. DPAP particulate system obtained the highest drug release of 50% at day 9 at 1 M NaCl ionic strength. DPAP formulation, using PLGA 65:35 and PEI MW of ∼800 Da, demonstrated an encapsulation efficiency of 78.93%, and a loading capacity of 0.1605 mg bovine serum albumin per mg PLGA. DPAP (PLGA 65:35, PEI MW∼25 kDa) formulation showed a high release rate with a biphasic release profile. Experimental data depicted a lower targeting power and reduced drug release rate for the PEGylated DPAP formulations. The outcomes from the present study lay the foundation to optimize the performance of DPAP system as an effective synthetic drug carrier for targeted delivery.     

Brain-Targeted Nasal Clonazepam Microspheres

Gelatin-chitosan mucoadhesive microspheres of clonazepam were prepared using the emulsion cross linking method. Mirospheres were evaluated using the in vitro and ex vivo drug release patterns. In vivo CNS drug distribution studies were carried out in rats by administering the clonazepam microspheres intra-nasally and clonazepam solution intravenously. From the drug levels in plasma and CSF, drug targeting index and drug targeting efficiency were calculated. Results obtained indicated that intranasally administered clonazepam microspheres resulted in higher brain levels with a drug targeting index of 2.12. Gelatin-chitosan cross linked mucoadhesive microspheres have the potential to be developed as a brain-targeted drug delivery system for clonazepam.     

Albumin microspheres as vehicles for the sustained and controlled release of doxorubicin

Biodegradable albumin microspheres have been prepared with the intention of targeting doxorubicin preferentially to tumour tissue. A high-yielding microsphere manufacturing process has been developed that involved the denaturation of an aqueous protein emulsion by chemical and/or thermal crosslinking methods. Microspheres can be closely sized to a diameter of 25.3 +/- 2.6 microns with the aid of micro-sieves. The in-vitro release of doxorubicin from albumin microspheres was measured using a continuous flow system. Doxorubicin release can be sustained for up to 10 days and the rate of release could be controlled by manipulating protein denaturation conditions between the temperatures 110-135 degrees C in the presence of 0-2% glutaraldehyde. Release of doxorubicin was significantly faster in human plasma compared with isotonic saline.     

Enhancement of cancer therapy efficacy by trastuzumab-conjugated and pH-sensitive nanocapsules with the simultaneous encapsulation of hydrophilic and hydrophobic compounds

Trastuzumab-conjugated pH-sensitive double emulsion nanocapsules (DENCs) stabilized by a single-component Poly (vinyl alcohol) (PVA) with magnetic nanoparticles can be fabricated through a two-step double emulsion process; these nanocapsules can be used to encapsulate hydrophilic doxorubicin (Dox) and hydrophobic paclitaxel (PTX) simultaneously. When PMA_SH was attached to the shell of the DENCs, enhanced dual drug release of PTX/Dox was detected, specifically in intracellular acidic pH environments. The targeting ability of these Trastuzumab-conjugated DENCs was demonstrated with confocal images, which revealed a significantly elevated cellular uptake in HER-2 overexpressing SkBr3 cells. More importantly, an intravenous injection of this co-delivery system followed by magnetic targeting (MT) chemotherapy suppressed cancer growth in vivo more efficiently than the delivery of either PTX or Dox alone. The integration of the functionalities makes this combination therapy system a powerfully new tool for in vitro/in vivo cancer therapy, especially for in HER-2 positive cancers.From the Clinical EditorTrastuzumab-conjugated pH-sensitive nanocapsules were used in this study for simultaneous targeted delivery of hydrophobic (PTX) and hydrophilic (Dox) anti-cancer agents to HER-2 positive cancer cells. Additional use of magnetic targeting demonstrated superior efficacy of this delivery system compared to PTX or Dox alone.     

The effect of oil components on the physicochemical properties and drug delivery of emulsions: tocol emulsion versus lipid emulsion

An emulsion system composed of vitamin E, coconut oil, soybean phosphatidylcholine, non-ionic surfactants, and polyethylene glycol (PEG) derivatives (referred to as the tocol emulsion) was characterized in terms of its physicochemical properties, drug release, in vivo efficacy, toxicity, and stability. Systems without vitamin E (referred to as the lipid emulsion) and without any oils (referred to as the aqueous micelle system) were prepared for comparison. A lipophilic antioxidant, resveratrol, was used as the model drug for emulsion loading. The incorporation of Brij 35 and PEG derivatives reduced the vesicle diameter to <100nm. The inclusion of resveratrol into the emulsions and aqueous micelles retarded the drug release. The in vitro release rate showed a decrease in the order of aqueous micelle system>tocol emulsion>lipid emulsion. Treatment of resveratrol dramatically reduced the intimal hyperplasia of the injured vascular wall in rats. There was no significant difference in this reduction when resveratrol was delivered by either emulsion or the aqueous micelle system. The percentages of erythrocyte hemolysis by the emulsions and aqueous micelle system were approximately 0 and approximately 10%, respectively. Vitamin E prevented the aggregation of emulsion vesicles. The mean vesicle size of the tocol emulsion remained unchanged during 30 days at 37 degrees C. The lipid emulsion and aqueous micelle system, respectively, showed 11- and 16-fold increases in vesicle size after 30 days of storage.     

Enhanced targeting efficiency of PLGA microspheres loaded with Lornoxicam for intra-articular administration

Owing to its rationale of targeting the drug to the site of action and minimizing systemic toxic effects of the drug, intra-articular drug delivery system has gained growing interests. In this study, emphasis was placed on intra-articular Lornoxicam -loaded PLGA microspheres (Lnxc-PLGA-MS) preparation and improving the targeting of lornoxicam (Lnxc) in knee joint. The microspheres were prepared by a process involving solid-in-oil-in-water(S/O/W) emulsion, and evaluated for physicochemical properties. Joint cavity′s drug leakage into systemic circulation in rabbits was examined to define the drug stagnation. Meanwhile, drug retention in synovial fluid in rats was investigated to further validate the drug targeting. The microspheres were spherical as evidenced by the SEM photographs with mean size of 7.47μm, and encapsulation efficiency was observed 82.22% along with drug loading 12.17%. DSC revealed that the drug in the microspheres existed in the phase of uncrystallization. The formulated microspheres could prolong the drug release up to 32 days in vitro. Comparing with animals injected with lornoxicam solution, the plasma drug concentration decreased in rabbits and retention time increased in rats’ synovial fluid with intra-articular injections of microspheres, revealing good targeting efficiency. In conclusion, PLGA microspheres could be used to deliver lornoxicam following intra-articular administration for enhancing targeting efficiency.     

Enhanced targeting efficiency of PLGA microspheres loaded with Lornoxicam for intra-articular administration

Owing to its rationale of targeting the drug to the site of action and minimizing systemic toxic effects of the drug, intra-articular drug delivery system has gained growing interests. In this study, emphasis was placed on intra-articular Lornoxicam-loaded PLGA microspheres (Lnxc-PLGA-MS) preparation and improving the targeting of lornoxicam (Lnxc) in knee joint. The microspheres were prepared by a process involving solid-in-oil-in-water(S/O/W) emulsion, and evaluated for physicochemical properties. Joint cavity's drug leakage into systemic circulation in rabbits was examined to define the drug stagnation. Meanwhile, drug retention in synovial fluid in rats was investigated to further validate the drug targeting. The microspheres were spherical as evidenced by the SEM photographs with mean size of 7.47 μm, and encapsulation efficiency was observed 82.22% along with drug loading 12.17%. DSC revealed that the drug in the microspheres existed in the phase of uncrystallization. The formulated microspheres could prolong the drug release up to 32 days in vitro. Comparing with animals injected with lornoxicam solution, the plasma drug concentration decreased in rabbits and retention time increased in rats' synovial fluid with intra-articular injections of microspheres, revealing good targeting efficiency. In conclusion, PLGA microspheres could be used to deliver lornoxicam following intra-articular administration for enhancing targeting efficiency.     

Concanavalin-A conjugated fine-multiple emulsion loaded with 6-mercaptopurine

Fine-multiple (water-in-oil-in-water) emulsions were prepared by two-step emulsification using sonication. They were coated with concanavalin-A (Con-A) by three methods. The one involving covalent coupling of Con-A to the multiple emulsion incorporated anchor was better compared with lipid derivatized Con-A anchoring or the glutaraldehyde-based cross-linking method, as shown by the faster rate of dextran-induced aggregation. The selected multiple emulsions were characterized by physical properties such as droplet size, encapsulation efficiency, and zeta potential. Stability parameters such as droplet size, creaming, leakage, and aggregation as a function of relative turbidity were monitored over a 1-month period, which revealed good stability of the formulations. The release profile of 6-mercaptopurine followed zero-order kinetics. Pharmacokinetic studies showed an increase in half-life and bioavailability from multiple emulsion formulations administered intravenously. There was prolonged retention of drug in various tissues of rats when treated with Con-A-coated multiple emulsion as compared with uncoated one. Our study demonstrates the suitability of fine-multiple emulsion for intravenous administration and the potential for prolonged retention of drugs and targeting in biological systems.     

Intravesical delivery of 5‐aminolevulinic acid from water‐in‐oil nano/submicron‐emulsion systems

The present work reports on the development of water‐in‐oil (w/o) emulsions for the intravesical administration of 5‐aminolevulinic acid (ALA). The physicochemical properties of droplet size, zeta potential, and viscosity of the emulsions are characterized and the ability of the emulsions to release ALA following in vitro application is tested. The delivery systems are administered intravesically for 1 and 3 h in rats to examine the drug accumulation in bladder tissue. The mean size and zeta potential of the emulsions are 50–200 nm and ?3 to ?14 mV, respectively. The loading of ALA into the emulsions resulted in a slower and sustained release. The release extent was found to be inversely related to the droplet size of the emulsions. The emulsions did not increase the drug permeation into tissues during short exposure duration (1 h). When the dwell time was extended to 3 h, the systems showed a 2.7‐fold increase in the ALA concentration in the bladder wall. Images of confocal laser scanning microscopy demonstrated a higher and deeper fluorescence signal, with emulsion administration, as compared to the aqueous control. Intravesical emulsion delivery provides a significant advantage for drugs targeting bladder tissues. © 2009 Wiley‐Liss, Inc. and the American Pharmacists Association J Pharm Sci 99: 2375–2385, 2010