Cytotoxicity of submicron emulsions and solid lipid nanoparticles for dermal application

The cytotoxicity and physical properties of various submicron O/W emulsions and solid lipid nanoparticles for dermal applications were investigated. Droplet size and zetapotential of submicron emulsions depended on the composition of the cosurfactant blend used. The viability of J774 macrophages, mouse 3T3 fibroblasts and HaCaT keratinocytes was significantly reduced in the presence of stearylamine. Nanoparticles consisting of stearic acid or different kinds of adeps solidus could be manufactured when formulated with lecithin, sodium taurocholate, polysorbate 80 and stearylamine. Survival of macrophages was highly affected by stearic acid and stearylamine. In general a viability of more than 90% was observed when semi-synthetic glycerides or hard fat was employed to formulate nanoparticles.     

Isotretinoin-loaded solid lipid nanoparticles with skin targeting for topical delivery

The purpose of this study was to construct isotretinoin-loaded SLN (IT-SLN) formulation with skin targeting for topical delivery of isotretinoin. PRECIROL ATO 5 was selected as the lipid of SLN. Tween 80 and soybean lecithin were used as the surfactants to stabilize SLN. The hot homogenization method was performed to prepare the drug-loaded SLN. The various formulations were characterized by photon correlation spectroscopy and all the SLN formulations had low average size between 30 and 50 nm. Transmission electron microscopy studies showed that the IT-SLN formulation had a spherical shape. All the formulations had high entrapment efficiency ranging from 80% to 100%. The penetration of isotretinoin from the IT-SLN formulations through skins and into skins were evaluated in vitro using Franz diffusion cells fitted with rat skins. The in vitro permeation data showed that all the IT-SLN formulations can avoid the systemic uptake of isotretinoin in skins, however the control tincture had a permeation rate of 0.76+/-0.30 microg cm(-2)h(-1) through skins. The IT-SLN consisting of 3.0% PRECIROL ATO 5, 4.0% soybean lecithin and 4.5% Tween 80 could significantly increased the accumulative uptake of isotretinoin in skin and showed a significantly enhanced skin targeting effect. The studied IT-SLN showed a good stability. These results indicate that the studied IT-SLN formulation with skin targeting may be a promising carrier for topical delivery of isotretinoin.     

Lopinavir loaded solid lipid nanoparticles (SLN) for intestinal lymphatic targeting

The poor orally available lopinavir was successfully encapsulated in glyceryl behenate based solid lipid nanoparticles (Lo-SLN) for its ultimate use to target intestinal lymphatic vessels in combined chemotherapy—the so-called Highly Active Anti-Retroviral Therapy (HAART). SLN with mean particle size of 230 nm (polydispersity index, PDI < 0.27) and surface electrical charge of approx. ?27 mV, were produced by hot homogenization process followed by ultrasonication. Particles were characterized using differential scanning calorimetry (DSC), wide angle X-ray scattering (WAXS) and atomic force microscopy (AFM) to confirm their solid character and the homogeneous distribution of drug within the lipid matrix. In vitro release studies at pH 6.8 phosphate buffer (PBS) and at pH 1.2 HCl 0.1 N showed a slow release in both media. From the intestinal lymphatic transport study it became evident that SLN increased the cumulative percentage dose of lopinavir secreted into the lymph, which was 4.91-fold higher when compared with a conventional drug solution in methyl cellulose 0.5% (w/v) as suspending agent (Lo-MC). The percentage bioavailability was significantly enhanced. The AUC for the Lo-SLN was 2.13-fold higher than that obtained for the Lo-MC of similar concentration. The accelerated stability studies showed that there was no significant change in the mean particle size and PDI after storage at 25 ± 2 °C/60 ± 5% RH. The shelf life of optimized formulation was assessed based on the remained drug content in the stabilized formulation and was shown to be 21.46 months.     

Adsorption kinetics of plasma proteins on solid lipid nanoparticles for drug targeting

The interactions of intravenously injected carriers with plasma proteins are the determining factor for the in vivo fate of the particles. In this study the adsorption kinetics on solid lipid nanoparticles (SLN) were investigated and compared to the adsorption kinetics on previously analyzed polymeric model particles and O/W-emulsions. The adsorbed proteins were determined using two-dimensional polyacrylamide gel electrophoresis (2-DE). Employing diluted human plasma, a transient adsorption of fibrinogen was observed on the surface of SLN stabilized with the surfactant Tego Care 450, which in plasma of higher concentrations was displaced by apolipoproteins. This was in agreement with the "Vroman-effect" previously determined on solid surfaces. It says that in the early stages of adsorption, more plentiful proteins with low affinity are displaced by less plentiful with higher affinity to the surface. Over a period of time (0.5 min to 4 h) more interesting for the organ distribution of long circulating carriers, no relevant changes in the composition of the adsorption patterns of SLN, surface-modified with poloxamine 908 and poloxamer 407, respectively, were detected. This is in contrast to the chemically similar surface-modified polymeric particles but well in agreement with the surface-modified O/W-emulsions. As there is no competitive displacement of apolipoproteins on these modified SLN, the stable adsorption patterns may be better exploited for drug targeting than particles with an adsorption pattern being very dependent on contact time with plasma.     

氟尿苷二丁酸酯固体脂质纳米粒的制备和肝靶向性研究

采用薄膜-超声分散法制备氟尿苷二丁酸酯(FUDRB)固体脂质纳米粒(FUDRB-SLN)和半乳糖苷(G₂)修饰的FUDRB-SLN(FUDRB-G₂SLN)。透射电镜研究其形态及粒径分布；凝胶色谱法测定载药量、包封率。结果表明，FUDRB-SLN和FUDRB-G₂SLN的粒径分别为(137.5±11.1)nm和(95.0±10.7)nm，载药量分别为9.64%和8.56%，包封率分别为99.81%和96.23%。为比较其肝靶向作用，小鼠尾静脉给药后，HPLC法测定氟尿苷(FUDR)在血清及肝、 肾、 肺匀浆中的浓度，计算出FUDR-sol、 FUDRB-SLN和FUDRB-G₂SLN的肝靶向效率分别为2.56、 5.90和8.28。FUDRB-G₂SLN组480 min时在肝脏中仍可检测到FUDR。这些结果说明FUDRB-SLN和FUDRB-G₂SLN在小鼠体内具有良好的肝靶向性，G₂修饰的SLN是一种良好的药物载体，可使药物选择性地导向肝细胞，且具有缓释作用。     

Injectable actarit-loaded solid lipid nanoparticles as passive targeting therapeutic agents for rheumatoid arthritis

This work systematically studied the intravenous injection formulation of solid lipid nanoparticles (SLNs) loaded with actarit, a poor water soluble anti-rheumatic drug. The goal of this study was to design passive targeting nanoparticles which could improve therapeutic efficacy and reduce side-effects such as nephrotoxicity and gastrointestinal disorders commonly associated with oral formulations of actarit. Based on the optimized results of single-factor and orthogonal design, actarit-loaded SLNs were prepared by a modified solvent diffusion-evaporation method. The formulated SLNs were found to be relatively uniform in size (241+/-23 nm) with a negative zeta potential (-17.14+/-1.6 mV). The average drug entrapment efficiency and loading were (50.87+/-0.25)% and (8.48+/-0.14)%, respectively. The actarit-loaded SLNs exhibited a longer mean retention time in vivo (t(1/2(beta)), 9.373 h; MRT, 13.53 h) compared with the actarit 50% propylene glycol solution (t(1/2(ke)), 0.917 h; MRT, 1.323 h) after intravenous injection to New Zealand rabbits. The area under curve of plasma concentration-time (AUC) of actarit-loaded SLNs was 1.88 times greater than that of the actarit in 50% propylene glycol solution. The overall targeting efficiency (TE(C)) of the actarit-loaded SLNs was enhanced from 6.31% to 16.29% in spleen while the renal distribution of actarit was significantly reduced as compared to that of the actarit solution after intravenous administration to mice. These results indicated that injectable actarit-loaded solid lipid nanoparticles were promising passive targeting therapeutic agents for rheumatoid arthritis.     

Vitamin A loaded solid lipid nanoparticles for topical use: occlusive properties and drug targeting to the upper skin.

To evaluate the potential use of solid lipid nanoparticles (SLN) in dermatology and cosmetics, glyceryl behenate SLN loaded with vitamin A (retinol and retinyl palmitate) and incorporated in a hydrogel and o/w-cream were tested with respect to their influence on drug penetration into porcine skin. Conventional formulations served for comparison. Excised full thickness skin was mounted in Franz diffusion cells and the formulations were applied for 6 and 24 h, respectively. Vitamin A concentrations in the skin tissue suggested a certain drug localizing effect. High retinol concentrations were found in the upper skin layers following SLN preparations, whereas the deeper regions showed only very low vitamin A levels. Because of a polymorphic transition of the lipid carrier with subsequent drug expulsion following the application to the skin, the drug localizing action appears to be limited for 6-24 h. Best results were obtained with retinol SLN incorporated in the oil-in-water (o/w) cream retarding drug expulsion. The penetration of the occlusion sensitive drug retinyl palmitate was even more influenced by SLN incorporation. Transepidermal water loss (TEWL) and the influence of drug free SLN on retinyl palmitate uptake exclude pronounced occlusive effects. Therefore enhanced retinyl palmitate uptake should derive from specific SLN effects and is not due to non-specific occlusive properties.     

Lactoferrin bioconjugated solid lipid nanoparticles: a new drug delivery system for potential brain targeting

Background: Delivery of drugs to brain is a subtle task in the therapy of many severe neurological disorders. Solid lipid nanoparticles (SLN) easily diffuse the blood–brain barrier (BBB) due to their lipophilic nature. Furthermore, ligand conjugation on SLN surface enhances the targeting efficiency. Lactoferin (Lf) conjugated SLN system is first time attempted for effective brain targeting in this study.

Purpose: Preparation of Lf-modified docetaxel (DTX)-loaded SLN for proficient delivery of DTX to brain.

Methods: DTX-loaded SLN were prepared using emulsification and solvent evaporation method and conjugation of Lf on SLN surface (C-SLN) was attained through carbodiimide chemistry. These lipidic nanoparticles were evaluated by DLS, AFM, FTIR, XRD techniques and in vitro release studies. Colloidal stability study was performed in biologically simulated environment (normal saline and serum). These lipidic nanoparticles were further evaluated for its targeting mechanism for uptake in brain tumour cells and brain via receptor saturation studies and distribution studies in brain, respectively.

Results: Particle size of lipidic nanoparticles was found to be optimum. Surface morphology (zeta potential, AFM) and surface chemistry (FTIR) confirmed conjugation of Lf on SLN surface. Cytotoxicity studies revealed augmented apoptotic activity of C-SLN than SLN and DTX. Enhanced cytotoxicity was demonstrated by receptor saturation and uptake studies. Brain concentration of DTX was elevated significantly with C-SLN than marketed formulation.

Conclusions: It is evident from the cytotoxicity, uptake that SLN has potential to deliver drug to brain than marketed formulation but conjugating Lf on SLN surface (C-SLN) further increased the targeting potential for brain tumour. Moreover, brain distribution studies corroborated the use of C-SLN as a viable vehicle to target drug to brain. Hence, C-SLN was demonstrated to be a promising DTX delivery system to brain as it possessed remarkable biocompatibility, stability and efficacy than other reported delivery systems.     

Development and characterization of 5-FU bearing ferritin appended solid lipid nanoparticles for tumour targeting

Ferritin coupled solid lipid nanoparticles were investigated for tumour targeting. Solid lipid nanoparticles were prepared using HSPC, cholesterol, DSPE and triolien. The SLNs without ferritin which has similar lipid composition were used for comparison. SLNs preparations were characterized for shape, size and percentage entrapment. The average size of SLNs was found to be in the range 110-152 nm and maximum drug entrapment was found to be 34.6-39.1%. In vitro drug release from the formulations is obeying fickian release kinetics. Cellular uptake and IC(50) values of the formulation were determined in vitro in MDA-MB-468 breast cancer cells. In vitro cell binding of Fr-SLN exhibits 7.7-folds higher binding to MDA-MB-468 breast cancer cells in comparison to plain SLNs. Ex-vivo cytotoxicity assay on targeted nanoparticles gave IC(50) of 1.28 microM and non-targeted nanoparticles gave IC(50) of 3.56 microM. In therapeutic experiments, 5-FU, SLNs and Fr-SLNs were administered at the dose of 10 mg 5-FU/kg body weight to MDA-MB-468 tumour bearing Balb/c mice. Administration of Fr-SLNs formulation results in effective reduction in tumour growth as compared with free 5-FU and plain SLNs. The result demonstrates that this delivery system possessed an enhanced anti-tumour activity. The results warrant further evaluation of this delivery system.     

Development and characterization of 5-FU bearing ferritin appended solid lipid nanoparticles for tumour targeting

Ferritin coupled solid lipid nanoparticles were investigated for tumour targeting. Solid lipid nanoparticles were prepared using HSPC, cholesterol, DSPE and triolien. The SLNs without ferritin which has similar lipid composition were used for comparison. SLNs preparations were characterized for shape, size and percentage entrapment. The average size of SLNs was found to be in the range 110–152 nm and maximum drug entrapment was found to be 34.6–39.1%. In vitro drug release from the formulations is obeying fickian release kinetics. Cellular uptake and IC₅₀ values of the formulation were determined in vitro in MDA-MB-468 breast cancer cells. In vitro cell binding of Fr-SLN exhibits 7.7-folds higher binding to MDA-MB-468 breast cancer cells in comparison to plain SLNs. Ex-vivo cytotoxicity assay on targeted nanoparticles gave IC₅₀ of 1.28 µM and non-targeted nanoparticles gave IC₅₀ of 3.56 µM. In therapeutic experiments, 5-FU, SLNs and Fr-SLNs were administered at the dose of 10 mg 5-FU/kg body weight to MDA-MB-468 tumour bearing Balb/c mice. Administration of Fr-SLNs formulation results in effective reduction in tumour growth as compared with free 5-FU and plain SLNs. The result demonstrates that this delivery system possessed an enhanced anti-tumour activity. The results warrant further evaluation of this delivery system.     

微乳化技术制备固体脂质纳米粒微乳化技术制备固体脂质纳米粒

目的采用微乳化技术制备固体脂质纳米粒（SLN）。方法以硬脂酸为油相，卵磷脂为乳化剂，乙醇为助乳化剂，蒸馏水为水相，按不同比例混合制备微乳。通过改变卵磷脂与乙醇的配比（K_m），绘制出不同K_m值下的三元相图。从中选择适宜的微乳，将其分散于冷水中制备SLN。考察了工艺因素和处方因素对SLN制备和SLN质量的影响。在单因素考察的基础上，采用正交设计优化工艺，并对优化所得的工艺进行重现性考察。结果水相温度（T_w）、微乳的温度（T_i）、微乳注入速度（r_d）均直接影响SLN的制备，其中水相温度是影响SLN质量的重要因素；微乳各组分的配比、微乳与水相的比例也对SLN的质量有一定影响。结论微乳化技术制备固体脂质纳米粒是可行的。     

固体脂质纳米粒的研究新进展

固体脂质纳米粒是近年来很受重视的一种新型药物传递载体,具有靶向、控释、提高药物稳定性、毒性小、可大批量生产等优点,是一种极有发展前景的新型给药系统.现综述了近年来国内外固体脂质纳米粒的制备技术、作为药物载体的应用、存在问题以及发展前景.     

Formulation of acyclovir-loaded solid lipid nanoparticles: 2. Brain targeting and pharmacokinetic study

Acyclovir (ACV) is widely used in the treatment of herpes encephalitis. The present study was conducted to prepare chitosan-tween 80 coated solid lipid nanoparticles (SLNs) as a delivery system for brain targeting of ACV in rabbits. The SLNs were prepared and coated in one step by microemulsion method using a coating solution containing chitosan (0.1% w/v) and tween 80 (2% w/v) for loading sustained release ACV. In vitro characterization was performed for coated ACV-SLNs. Concerning in vivo experiments; a single intravenous bolus dose of coated ACV-SLNs was given versus free ACV solution to rabbits (62?mg/kg). Plasma pharmacokinetic parameters were calculated from the ACV concentration-time profiles in plasma using the two compartmental analysis. The values of AUC_0?∞ and MRT of coated ACV-SLNs were higher than free drug by about twofold, 233.36?±?41.56?μg.h/mL and 1.81?±?0.36?h, respectively. The noncompartmental analysis was conducted to estimate the brain pharmacokinetic parameters. The AUC_0?∞ brain/AUC_0?∞ plasma ratio for coated ACV-SLNs and free ACV was 0.22 and 0.12, respectively. These results indicated the effectiveness of using coated ACV-SLNs for brain targeting.     

Stavudine entrapped lipid nanoparticles for targeting lymphatic HIV reservoirs

The main objective of present research study was to evaluate the potential of lipid nanoparticles for active delivery of an antiretroviral drug to lymphatic tissues. Stavudine entrapped drug loaded solid lipid nanoparticles (SLNs) were prepared and characterized for a variety of physicochemical parameters such as appearance, particle size, polydispersity index and zeta potential. The targeting potential of the prepared nanoparticles was investigated by carrying out ex vivo cellular uptake studies in macrophages which depicted several times enhanced uptake as compared to pure drug solution. Further, the lymphatic drug levels and organ distribution studies demonstrated efficiency of the developed nanoparticles for prolonged residence in spleenic tissues. Thus it was concluded that stavudine entrapped lipid carriers can be exploited for effective and targeted delivery to cellular and anatomical HIV reservoirs and may ultimately increase the therapeutic safety and reduce side effects.     

Stability of lipid excipients in solid lipid nanoparticles

The paper is devoted to the investigation of chemical stability of lipids used as excipients in the production of Solid Lipid Nanoparticles (SLN). Different lipids and amounts of surfactants were considered. Most of the formulations were produced using identical binary surfactant mixtures and concentrations to analyze the effect of the chemical nature of the lipids on their stability in SLN. In some formulations, surfactants were exchanged or their concentration was increased to assess the contribution of surfactants on stability of lipids particles. Solid Lipid Nanoparticles were characterized by photon correlation spectroscopy, laser diffractometry, zeta potential determination and differential scanning calorimetry. Potential effects of lipid crystallinity and modifications were assessed. A gas chromatography (GC) analysis in combination with a method for lipid extraction from aqueous SLN dispersions was used to investigate the chemical stability of the lipid excipients forming the particle matrix. All formulations were produced by the hot homogenization technique. The production process of SLN itself did not affect the chemical stability of lipid excipient forming the particle matrix. The formulations where lipids consisted of trigylicerides showed a negligible decomposition of the structure during incubation at 25 degrees C. Dynasan 118 showed the highest chemical stability (loss<4%) within two years.     

糠酸莫米松固体脂质纳米粒的制备

目的：研究糠酸莫米松固体脂质纳米粒的处方和制备工艺，并对其质量进行评价。方法：用乳化-溶剂挥发法制备糠酸莫米松固体脂质纳米粒，以包封率为指标采用正交设计法优选处方，用透射电镜和激光粒径测定仪测定纳米粒的形态和粒径，用低速离心法测定药物的包封率。结果：制得的糠酸莫米松固体脂质纳米粒形态规整，几呈球形，体积均粒径为73．8nm，包封率为（92．8&#177;0．89）。结论：本研究所得的处方和工艺可制备性能优良的糠酸莫米松固体脂质纳米粒。     

溶剂扩散法制备丙酸倍氯米松固体脂质纳米粒溶剂扩散法制备丙酸倍氯米松固体脂质纳米粒

目的 建立一种高效的固体脂质纳米粒制备与分离方法。方法 用水性溶剂扩散法,制备得到甘油单硬脂酸酯固体脂质纳米粒。通过调节纳米粒表面Zeta电位,提高纳米粒的回收率。结果 用水性溶剂扩散法可以简便、快速制备得到含药固体脂质纳米粒,低转速离心(4 000 r·min^-1)即可达到纳米粒与分散体系之间的分离,回收率明显高于未调节纳米粒表面Zeta电位条件下的高速离心分离方法。用本法制备得到的纳米粒在最初3 h有药物的突释现象,随后4 d药物的释放明显缓慢,每天释放约药物总量的6%。结论 水性溶剂扩散法适用于固体脂质纳米粒的制备,得到的固体脂质纳米粒可实现药物的控制释放。     

溶剂扩散法制备丙酸倍氯米松固体脂质纳米粒

目的　建立一种高效的固体脂质纳米粒制备与分离方法。方法　用水性溶剂扩散法 ,制备得到甘油单硬脂酸酯固体脂质纳米粒。通过调节纳米粒表面Zeta电位 ,提高纳米粒的回收率。结果　用水性溶剂扩散法可以简便、快速制备得到含药固体脂质纳米粒 ,低转速离心 (40 0 0r·min- 1 )即可达到纳米粒与分散体系之间的分离 ,回收率明显高于未调节纳米粒表面Zeta电位条件下的高速离心分离方法。用本法制备得到的纳米粒在最初 3h有药物的突释现象 ,随后 4d药物的释放明显缓慢 ,每天释放约药物总量的 6%。结论　水性溶剂扩散法适用于固体脂质纳米粒的制备 ,得到的固体脂质纳米粒可实现药物的控制释放     

HPLC法测定多西他赛固体脂质纳米粒的药物含量

目的建立多西他赛固体脂质纳米粒的含量测定方法。方法采用Hypersil ODS C18柱(4.6 mm×200mm,5μm),流动相为乙腈-水(60∶40,V/V),检测波长:228 nm,流速:1 mL.min-1。结果多西他赛在0.50～50.00μg.mL-1的浓度范围内,峰面积对浓度有良好的线性关系(R2=0.999 9,n=7),方法的日内与日间精密度RSD均<2%,回收率分别为98.81%、99.22%、101.5%。结论该方法具有简便、快速、准确的特点,可用于多西他赛固体脂质纳米粒的含量测定。     

RP-HPLC法测定多西他赛固体脂质纳米粒中多西他赛的含量

目的建立RP-HPLC法测定多西他赛固体脂质纳米粒中多西他赛的含量。方法色谱柱:Century SIL BDS C18(4.6 mm×200 mm,5μm),检测波长:228 nm,流动相:乙腈-水(体积比为60∶40),流速:1.0 mL.min-1,柱温:室温。结果多西他赛与其他组分分离良好,线性1.05~21.0 mg.L-1(r=0.999 9),日内、日间精密度为1.12%、1.03%,平均回收率为99.3%,RSD=0.95%。结论可作为该制剂的质量控制方法。