Physicochemical characterization of curcuminoid-loaded solid lipid nanoparticles

Curcuminoid-loaded solid lipid nanoparticles (SLN) were produced by melt-homogenization. The used lipid matrices were medium chain triglycerides, trimyristin and tristearin. The resulting nanoparticles had an anisometric shape and a platelet-like structure. Curcuminoid-loaded trimyristin particles did not solidify when stored at room temperature. The supercooled state of trimyristin was studied by DSC and ¹H NMR experiments. A partial recrystallization of the lipid matrix was detected but no change of the mobility of the lipid was noted. Nanoparticles based on tristearin had an α- and β-modification which was subsequently converted into the stable β-phase. Curcuminoids did neither influence the melting behavior nor the crystalline or geometric structure of the particles. The interactions between the curcuminoids and the lipid matrix were investigated by Raman and fluorescence spectroscopy. The shape of the curcuminoid bands in the Raman spectra suggested that the drug was in an amorphous state. The fluorescence spectra showed an effect of the lipid matrix on fluorescence properties of the curcuminoids. It was further demonstrated that the drug was not secluded by the solid lipid matrix, but it was influenced by the surrounding aqueous environment. Fluorescence anisotropy measurements revealed a decreased mobility of the curcuminoids within the nanodispersions. From the results of Raman and fluorescence measurements it was concluded that the drug was mainly located on the surface of the crystalline particles.     

Ocular delivery of cyclosporine A based on glyceryl monooleate/poloxamer 407 liquid crystalline nanoparticles: preparation,characterization, in vitro corneal penetration and ocular irritation

The purpose of this study was to develop an ophthalmic drug delivery system for cyclosporine A (CsA) based on glyceryl monooleate (GMO)/poloxamer 407 liquid crystalline nanoparticles with reduced ocular irritancy and improved corneal penetration. CsA-loaded liquid crystalline nanoparticles were prepared via fragmentation of a bulk GMO/poloxamer 407 cubic phase gel by high-pressure homogenization and characterized. Corneal permeation and retention was evaluated using modified Franz diffusing cells. Intra-corneal transportation was investigated with fluorescein isothiocyanate (FITC)-labeled liquid crystalline nanoparticles. Ocular irritation was then evaluated using the Draize method. The mean particle size of liquid crystalline nanoparticles was 193.5?nm and the entrapment efficiency was 95.11?±?0.67%. A bicontinuous cubic phase of cubic P-type was determined using cryo-transmission electron microscopy (cryo-TEM) observation and small angle X-ray diffraction (SAXD) analysis. A 1.52-fold increase in J_s and a 2.2-fold increase in corneal retention was achieved by liquid crystalline nanoparticles compared with oil solution. In vitro corneal permeation investigated with FITC-labeled liquid crystalline nanoparticles revealed that CsA penetrated across the cornea under the transportation of liquid crystalline nanoparticles. Liquid crystalline nanoparticles exhibited excellent ocular tolerance in the ocular irritation test. This low-irritant vehicle based on liquid crystalline nanoparticles might be a promising system for effective ocular CsA delivery.     

Cubic liquid crystalline nanoparticles containing a polysaccharide from Ulva fasciata with potent antihyperlipidaemic activity

The present study involves the preparation of cubic liquid crystalline nanoparticles (cubsomes) for liver targeting to assess the potential of a formulated bioactive polysaccharide isolated from the hot aqueous extract of Ulva fasciata as an alternative natural agent with anti-hyperlipidaemic activity. Cubosomal nanoparticles were prepared by disrupting the cubic gel phase of the polysaccharide and water in the presence of a surfactant. Different lipid matrices and stabilizers were tested. All the formulations were in the nanosize range and showed sufficient negative charge to inhibit the aggregation of the cubosomes. Drug entrapment efficiencies (EEs%) were determined and in vitro release studies were performed. Transmission electron microscopy (TEM) and differential scanning calorimetry were used to analyze the loaded cubosomal nanoparticles containing glyceryl monostearate (GMO 2.25?g), poloxamer 407 (0.25?g) and 50?mg of the polysaccharide. A preclinical study comparing the cubic liquid crystalline nanoparticles containing polysaccharide to fluvastatin as a reference drug in hyperlipidaemic rats was conducted. The rats treated with the polysaccharide- loaded cubosomes showed significant decreases in total cholesterol (TC), triglycerides (TG) and total lipid (TL) compared to the untreated HL rats. In addition, oxidative stress and antioxidant biomarkers were measured in the HL rats. Compared to the untreated HL rats, the cubosome treated rats showed a significant reduction in malondialdehyde (MDA), whereas insignificant changes were detected in nitric oxide (NO), glutathione (GSH) levels and total antioxidant capacity (TAC). Further, vascular and intercellular adhesion molecules (VCAM, ICAM), and myeloperoxidase were demonstrated. A histopathological examination was conducted to study the alterations in histopathological lesions and to document the biochemical results. In conclusion, this study demonstrates the superiority of using a natural lipid regulator such as polysaccharide loaded cubosomes instead of fluvastatin.     

The effect of poloxamer 188 on nanoparticle morphology,size, cancer cell uptake,and cytotoxicity

The aim of this work was to investigate the effect of triblock copolymer poloxamer 188 on nanoparticle morphology, size, cancer cell uptake, and cytotoxicity. Docetaxel-loaded nanoparticles were prepared by oil-in-water emulsion/solvent evaporation technique using biodegradable poly(lactic-co-glycolic acid) (PLGA) with or without addition of poloxamer 188, respectively. The resulting nanoparticles were found to be spherical with a rough and porous surface. The nanoparticles had an average size of around 200 nm with a narrow size distribution. The in vitro drug-release profile of both nanoparticle formulations showed a biphasic release pattern. An increased level of uptake of PLGA/poloxamer 188 nanoparticles in the docetaxel-resistant MCF-7 TAX30 human breast cancer cell line could be found in comparison with that of PLGA nanoparticles. In addition, the docetaxel-loaded PLGA/poloxamer 188 nanoparticles achieved a significantly higher level of cytotoxicity than that of docetaxel-loaded PLGA nanoparticles and Taxotere (P < .05). In conclusion, the results showed advantages of docetaxel-loaded PLGA nanoparticles incorporated with poloxamer 188 compared with the nanoparticles without incorporation of poloxamer 188 in terms of sustainable release and efficacy in breast cancer chemotherapy.From the Clinical EditorThe effects of poloxamer 188, a triblock copolymer were studied on nanoparticle morphology, size, cancer cell uptake and cytotoxicity. An increased level of uptake of PLGA/poloxamer 188 nanoparticles in resistant human breast cancer cell line was demonstrated, resulting in a significantly higher level of cytotoxicity.     

Melittin liposomes surface modified with poloxamer 188: in vitro characterization and in vivo evaluation

Melittin liposomes surface modified with poloxamer 188 were developed, and the effect of poloxamer 188 was investigated with regard to anti-cancer effect and vascular stimulation. Melittin liposomes surface modified with poloxamer 188 at different concentrations (0%, 2%, and 5%) were prepared using the adsorption method, followed by in vitro characterization, including entrapment efficiency, zeta potential, particle size, and morphology. Subsequently, the influence of repeated freeze-thawing on the liposomes was investigated, and the effect of poloxamer 188 on the repeated freeze-thawing process was explored. Vascular stimulation effects of MLT, and MLT liposome that surface coated with or without poloxamer were all studied. Pharmacokinetics of the different MLT preparations were determined and the anticancer activity of the MLT formulations was investigated. The particle size of the liposomes gradually increased with increasing poloxamer 188 content, while the entrapment efficiency did not change significantly. After the first freeze-thaw cycle, size and PDI were both markedly reduced, entrapment efficiency rose, and there was no significant change of zeta potential. The vascular irritation caused by MLT could be reduced to an extent by encapsulation in liposome, but not completely eliminated, while liposomes coated with poloxamer 188 can effectively abolish the phenomenon. Melittin liposomes with surface modified by poloxamer exhibit enhanced bioavailability, effective anticancer activity, and reduced side effects compared with melittin solution. Poloxamer plays an important role in melittin liposomes.     

Preparation of nanoemulsions and solid lipid nanoparticles by premix membrane emulsification

In an attempt to overcome problems of conventional high-energy preparation processes for colloidal drug carrier systems, premix membrane emulsification was investigated for the first time as an alternative low-energy input process for the preparation of pharmaceutical nanoemulsions and solid lipid nanoparticles. The effect of process parameters on dispersions based on nonpolar lipids (medium-chain triglycerides, soybean oil, and trimyristin) and different emulsifiers (sodium dodecyl sulfate, poloxamer 188, polyglyceryl-10-laurate, and sucrose laurate) was studied in a small-volume device and a larger scale-up approach. For emulsions and suspensions, mean particle sizes in a range from about 100 to 200 nm were observed for monomodal to monodisperse particle size distributions after 21 cycles of extrusion through polycarbonate membrane filters. As the mass ratio of matrix lipid to emulsifier (4:3, w/w concentrations) usually applied for the preparation of stable colloidal lipid particles was quite high, the amount of emulsifier in the dispersions was minimized. It was observed that the minimal concentration of emulsifier increased with decreasing membrane pore size. The possibility to prepare colloidal drug carrier systems with a high concentration of matrix lipid (up to 20%) by an optimized membrane extrusion process offers new opportunities for the processing of sensitive substances.     

Investigations on 5-fluorouracil solid lipid nanoparticles (SLN) prepared by hot homogenization

The purpose of this study was to investigate the effect of different formulation factors on the properties of solid lipid nanoparticles (SLN) prepared by a hot homogenization method. Using the particle size, physical stability constant (K(e)) and zeta-potential as standards, the stability of SLNs was investigated as a function of phospholipid and poloxamer contents. It was demonstrated that the content of phospholipid had a significant influence on the zeta-potential, which increased considerably with increasing phospholipid content. However, the particle size increased remarkably when the phospholipid content was as high as 1.5% due to the increased viscosity. Poloxamer 188 exhibited no remarkable influence on particle size when the concentration was as low as 1.0%. The influence of the phospholipid and poloxamer content on the embedding ratios of drug substances was further studied using 5-fluorouracil (5-Fu) as a model drug. It was shown that the embedding ratio increased considerably with phospholipid content and independent of poloxamer content, implying that 5-Fu was incorporated into the phospholipid bilayer membrane.     

依托泊苷固体脂质纳米粒的研制

目的:制备依托泊苷固体脂质纳米粒(ET-SLN)并考察其药剂学性质。方法:采用乳化-超声分散法制备ET-SLN,以单硬脂酸甘油酯(A)、大豆磷脂(B)、泊洛沙姆188(C)、依托泊苷(D)的处方用量为考察因素,包封率为指标设计正交试验,筛选最优处方。考察纳米粒的粒径、表面电位、包封率、体外释放情况等。结果:A、B、C、D分别为0.020、0.010、0.015、0.015mg;所制纳米粒平均粒径(83±0.5)nm,表面电位(-23±0.3)mV,包封率81.2%,可持续48h缓释。结论:所制ET-SLN符合药剂学性质要求。     

Steric stabilization of nanoparticles: Size and surface properties

Nanoparticles of poly-(isobutylcyanoacrylate) (PIBCA), poly-lactic acid (PLA), poly-lactic-co-glycolic copolymer (PLAGA) and poly-ϵ-caprolactone were prepared according to conventional methods. In the preparation of PIBCA nanoparticles different steric stabilizers were used. Formulations included poloxamer 188, polyvinilic alcohol (PVA) or polyethyleneglycol 2000 (PEG 2000), with or without dextran, in order to characterize the influence of different steric stabilizers. All the formulations were tested for their electrophoretic mobility, zeta potential and particle size using DELSA. Particle size measurements were also performed using a PCS technique, employing two sets of apparatus, in an attempt to evaluate the influence of measuring principle and detection angle in the final results. Results indicate that PIBCA nanoparticles can be sterically stabilized by dextran, poloxamer and PVA, but PEG 2000 could need the presence of another steric stabilizer. The good correlation for the same detection angle between PCS and DELSA demonstrates the importance of DELSA in the characterization of size and surface properties associated with colloidal drug carriers like nanoparticles, as demonstrated by PLA, PLAGA and PCL nanoparticles (monodisperse particles). The differences between the two techniques could be explained by different detection angles and strongly suggests an integrated approach using PCS and DELSA when considering polydisperse particle populations.     

Incorporation of the Model Drug Ubidecarenone into Solid Lipid Nanoparticles

Purpose. The impact of drug incorporation on melt-homogenized tripalmitin nanoparticles is investigated with ubidecarenone as a model drug. The dispersions are studied with respect to their drug loading capacity, localization and physical state of the drug as well as to potential changes of the nanoparticle properties due to interactions between drug and triglyceride matrix. Methods. The investigations were carried out using photon correlation spectroscopy, differential scanning calorimetry, synchrotron radiation X-ray diffraction, ultracentrifugation, and cryo- and freeze-fracture transmission electron microscopy. Results. Ubidecarenone can be incorporated into the dispersions in concentrations higher than 50% of the dispersed phase. The drug is associated with the nanoparticles such that small drug amounts are bound tightly to the carrier matrix while excess drug adheres as a liquid phase to the crystalline particles. Drug incorporation lowers the crystallization and melting temperature of the particle matrix and accelerates the transition of the triglyceride into the stable -polymorph after crystallization. Conclusions. Drug incorporation may significantly alter important physicochemical parameters of solid lipid nanoparticles. Slow release of ubidecarenone may only be possible for the fraction of drug which is tightly bound to the matrix while the liquid fraction should be rapidly released.     

Effect of poloxamer 188 on lymphatic uptake of carvedilol-loaded solid lipid nanoparticles for bioavailability enhancement

The present work aimed to investigate the effect of different concentrations of poloxamer 188, a surfactant, on lymphatic uptake of carvedilol-loaded solid lipid nanoparticles (SLNs) for oral bioavailability enhancement. Microemulsion technique was employed to prepare the SLN formulations having varying concentrations of poloxamer 188, which were subsequently subjected to various in vitro and in vivo evaluations to study their release pattern. On increasing the percentage concentration of poloxamer 188, the bioavailability decreased from 4.91- to 2.84-fold after intraduodenal administration in the male Wister rat. It could be attributed to the increase in particle size as well as reduction in hydrophobicity of SLNs. As indicated by pharmacokinetic data, the AUC_(0–t) of all three (SLN) formulations (6.27?±?0.24 μgh/mL with FZ-1, 4.13?± 0.11 μgh/mL with FZ-2, and 3.63?±?0.10 μgh/mL with FZ-3) were significantly higher (p?<?0.05) than that of carvedilol suspension (1.27?±?0.23 μgh/mL). These findings augur well with the possibility of enhancement of the oral bioavailability of drug, via the lymphatic system bypassing hepatic first pass metabolism.     

Biodegradation of solid lipid nanoparticles as a function of lipase incubation time

The in vitro degradation of solid lipid nanoparticles (SLN) was studied in solutions of pancreatic lipase/colipase. Degradation was followed by turbidity measurements of SLN suspensions and by the determination of the formed free fatty acids (FFA). The degradation velocity was found to depend on the nature of the lipid matrix, being highest for Dynasan 114, medium for cetylpalmitate and relatively slow for lipids with longer fatty acid chains (Compritol ATO 888). The surfactant used for SLN stabilization had a dominating effect on degradation velocity. Use of the sterically stabilizing poloxamer 188 could prevent the in vitro degradation of well-degradable Dynasan 114 particles. This was attributed to the lack of anchoring of the lipase to the particle surface-prerequisite for enzymatic degradation. The dominating effect of the surfactant can be exploited to design SLN with optimum degradation velocity and matrix-controlled drug release-independent on the nature of the lipid matrix.     

卡莫氟固体脂质纳米粒的制备及工艺研究

目的:制备卡莫氟固体脂质纳米粒并考察其药剂性质。方法:采用高压均质法制备卡莫氟固体脂质纳米粒混悬液,以单因素考察和正交设计法筛选处方和工艺,并考察其形态、粒径、载药量及包封率。结果:优选出的较佳处方大豆卵磷脂、泊洛沙姆188、吐温-80和硬脂酸用量分别为8.0、12.0、1.0、7.5mg·mL-1;所制得的固体脂质纳米粒为圆整的实体粒子,表面光滑,平均粒径为78.7nm,载药量为23.47%,包封率为82.33%。结论:高压均质法可用于卡莫氟类脂溶性药物固体脂质纳米粒的制备。     

Development of Solid Self-Emulsifying Drug Delivery System (SEDDS) I: Use of Poloxamer 188 as Both Solidifying and Emulsifying Agent for Lipids

Purpose

To develop solid self-emulsifying drug delivery systems (SEDDS) for lipids using poloxamer 188 as both solidifying and emulsifying agents.

Methods

Mixtures of various lipids with poloxamer 188 and PEG 8000 were prepared at ~75°C. The molten mixtures, with and without dissolved drugs (fenofibrate and probucol), were then cooled to room temperature. When solids formed, they were characterized by powder XRD, DSC, microscopy using cross-polarization and confocal fluorescence techniques, dispersion test in water and particle size analysis of dispersions.

Results

When mixed with poloxamer 188 or PEG 8000, lipids consisting of monoesters of fatty acids with glycerol or propylene glycol formed solid systems, but not di- and tri-esters, which showed phase separation. Added to water, the solid systems containing poloxamer 188 started to disperse in water forming oil globules of 200–600?nm. No emulsification of lipids was observed from solids containing PEG 8000, indicating that the surfactant property of poloxamer 188 was responsible for emulsification. Powder XRD, DSC and microscopic examination revealed that poloxamer 188 and PEG 8000 maintained their crystallinity in solid systems, while the lipids were interspersed in between crystalline regions. The drug remained solubilized in the lipid phase.

Conclusions

A novel solid SEDDS is developed where the drug can be solubilized in liquid lipids and then the lipidic solution can be converted to solid mass by dispersing into the microstructure of poloxamer 188.     

Studies on binary lipid matrix based solid lipid nanoparticles of repaglinide: in vitro and in vivo evaluation

The purpose of present study is to examine effect of binary lipid matrix (combination of lipids) on the entrapment and storage stability of repaglinide (RG) loaded solid lipid nanoparticles (SLN). Solid lipid nanoparticles were prepared by modified solvent injection method for oral delivery to improve the bioavailability of RG, an antidiabetic drug. The stearic acid and tristearin were used to form lipid core materials, and Pluronic-F68 was used as a stabilizer. Nanoparticles were characterized by evaluating their particle size, zeta potential, entrapment efficiency, drug loading, solid-state studies (differential scanning calorimetry, X-ray diffraction), in vitro drug release, particle surface (transmission electron microscopy analysis with electron diffraction pattern), stability study in gastrointestinal fluids (GIFs) and storage stability at 30 °C/65% RH for 3 months. The characterization of SLN suggested that binary lipid matrix based nanoparticles had better drug entrapment and loading, desired release characteristics, stable in GIFs and significantly higher storage stability compared with single lipid formulations. Pharmacodynamic (blood glucose, blood cholesterol, blood triglyceride levels) and pharmacokinetic (AUC, T(max), peak plasma concentrations, K, t(1/2), mean residence time and relative bioavailabilities) studies were performed for the selected formulations. These studies indicate that the formulation based on binary lipid matrix significantly improves the oral bioavailability of RG.     

长春西汀固体分散体的制备及体外溶出特性

目的:制备长春西汀固体分散体,提高其溶出速度和程度。方法:以泊洛沙姆188(F68)为载体,用溶剂-熔融法制备固体分散体;差热分析、X-射线粉末衍射分析以鉴别药物在载体中的存在状态;并考察载体的用量、溶出介质和转速对药物体外溶出特性的影响。结果:长春西汀的固体分散体中药物部分以分子状态分散,部分以微晶分散。固体分散体VIN-F68(1∶6,w/w)的溶出参数t50t、d与相应物理混合物、原料药粉末和市售片剂间差异存在显著性(P<0.01),溶出介质和转速的选择对药物的溶出有一定影响。结论:长春西汀的固体分散体能显著提高药物的溶出速度和程度。     

In vitro toxicity of silica nanoparticles in human lung cancer cells

The cytotoxicity of 15-nm and 46-nm silica nanoparticles was investigated by using crystalline silica (Min-U-Sil 5) as a positive control in cultured human bronchoalveolar carcinoma-derived cells. Exposure to 15-nm or 46-nm SiO(2) nanoparticles for 48 h at dosage levels between 10 and 100 microg/ml decreased cell viability in a dose-dependent manner. Both SiO(2) nanoparticles were more cytotoxic than Min-U-Sil 5; however, the cytotoxicities of 15-nm and 46-nm silica nanoparticles were not significantly different. The 15-nm SiO(2) nanoparticles were used to determine time-dependent cytotoxicity and oxidative stress responses. Cell viability decreased significantly as a function of both nanoparticle dosage (10-100 microg/ml) and exposure time (24 h, 48 h, and 72 h). Indicators of oxidative stress and cytotoxicity, including total reactive oxygen species (ROS), glutathione, malondialdehyde, and lactate dehydrogenase, were quantitatively assessed. Exposure to SiO(2) nanoparticles increased ROS levels and reduced glutathione levels. The increased production of malondialdehyde and lactate dehydrogenase release from the cells indicated lipid peroxidation and membrane damage. In summary, exposure to SiO(2) nanoparticles results in a dose-dependent cytotoxicity in cultural human bronchoalveolar carcinoma-derived cells that is closely correlated to increased oxidative stress.     

Comparison of scanning electron microscopy, dynamic light scattering and analytical ultracentrifugation for the sizing of poly(butyl cyanoacrylate) nanoparticles.

Nanoparticles represent promising carriers for controlled drug delivery. This work focuses on the size and molecular mass characterization of polyalkylcyanoacrylate nanoparticles formed by anionic emulsion polymerization of butylcyanoacrylate in the presence of poloxamer 188 as a stabilizer. Three different methods were used to determine the size and size distribution of the particle populations: scanning electron microscopy (SEM), dynamic light scattering (DLS), and analytical ultracentrifugation (ANUC). SEM on freeze-dried and Au-shadowed samples showed a relatively narrow distribution of virtually spherical particles with a mean diameter of 167 nm. DLS yielded a monomodal distribution with hydrodynamic diameters around 199 nm (in the absence of additional stabilizer) or 184 nm (in the presence of 1% poloxamer 188). The size distribution determined by ANUC using sedimentation velocity analysis was somewhat more complex, the size of the most abundant particles being around 184 nm. Molar particle mass distributions centered around 2.3x10(9) g/mol. The advantages and disadvantages of the three sizing techniques are discussed.     

Preparation and characteristics of oridonin-loaded nanostructured lipid carriers as a controlled-release delivery system

In order to improve drug entrapment efficiency and loading capacity, nanostructured lipid carriers consisting of solid lipid and liquid lipid as a new type of colloidal drug delivery system were prepared. The dispersions of oridonin-loaded solid lipid nanoparticles and nanostructured lipid carriers were successfully prepared by the emulsion-evaporation and low temperature-solidification technique using monostearin as the solid lipid, caprylic/capric triglycerides as the liquid lipid and oridonin as the model drug. Their physicochemical properties of oridonin-loaded nanostructured lipid carriers and release behaviours were investigated and compared with those of solid lipid nanoparticles. As a result, the mean particle size was ～200 nm with narrow polydispersity index lower than 0.4 for all developed formulations. Zeta potential values were in the range ?35 mV ～ ?50 mV, providing good physical stability of all formulations. The differential scanning calorimetry and X-ray diffraction analysis results demonstrated lipid nanoparticles exhibited crystal order disturbance and thus left more space to accommodate drug molecules. The improved drug entrapment efficiency and loading capacity were observed for nanostructured lipid carriers and they enhanced with increasing the caprylic/capric triglycerides content. In vitro drug release experiments exhibited biphasic drug release patterns with burst release initially and prolonged release afterwards. These results indicated that nanostructured lipid carriers could potentially be exploited as a delivery system with improved drug entrapment efficiency and controlled drug release.     

Rotary spray congealing of a suspension: effect of disk speed and dispersed particle properties

Microspheres were produced by rotary spray congealing molten suspensions composed of poloxamer 188 and a single solid excipient. Six different excipients, spanning a range of particle size, density and morphology were used. The size distribution, true density and shape of the resulting congealed particles were assessed. Disk rotation speed had the most significant effect on microsphere size, with higher speeds yielding smaller congealed particles. At low disk speeds, congealed particle size decreases with increasing dispersed solid density. Over the range investigated, neither suspended solid size nor morphology had a significant effect on the congealed microsphere size. Measurements of the density of the microspheres suggest that the solids were homogeneously spread across the different congealed particle sizes. This suggests that rotary atomization of poloxamer 188 suspensions is an effective method for producing spherical particles for encapsulation for a wide variety of drug particle sizes, shapes and densities--with disk speed being used to control the mean size.