Encapsulation of ethylhexyl methoxycinnamate,a light-sensitive UV filter,in lipid nanoparticles

The aim of this study was to encapsulate ethylhexyl methoxycinnamate (EMC), a commonly used UVB filter, in a solid lipid matrix in order to obtain microparticles and then nanoparticles to reduce its photo-instability under UV light exposure. Glyceryl behenate, rice bran wax and ozokerite were investigated for encapsulating EMC. The suspensions of nanoparticles contained 70% encapsulated EMC (relative to the lipid mass). The absorbance level at 310?nm of suspensions containing nanoparticles was more than twice that of those containing microparticles. So, decreasing the size of particles improved the efficiency of light protection, regardless of the lipid material used. Moreover, free EMC presented a 30% loss of its efficiency after 2?h of irradiation, whereas the three NLC formulations showed a loss of absorbency between 10% and 21%. The in vitro cutaneous penetration test did not show a higher potential penetration for EMC contained in nanosuspensions compared to free EMC.     

左旋多巴固体脂质纳米粒的制备及包封率测定

目的:用微乳法制备左旋多巴固体脂质纳米粒(LDP-SLN),并建立包封率的测定方法。方法:通过绘制三元相图,采用微乳法制备LDP-SLN,用TEM和激光粒度仪进行了颗粒形貌和粒径分布的研究,用葡聚糖凝胶层析法分离测定包封率。对其粒径、形态、包封率等理化性质进行研究,并考察其稳定性。结果:实验制得LDP-SLN为稳定的略泛蓝色乳光的纳米混悬液,在透射电镜下显示为较为均匀的球体,激光粒度测定平均粒径为108nm,多分散系数1.153;4℃放置2个月,粒径、包封率无显著变化。包封率测定的线性范围为2～100mg·mL-1,线性良好(r=0.9999),精密度符合要求,LDP-SLN上柱洗脱后分离度和回收率均符合要求。结论:该研究中制备了物理性质较为稳定的LDP-SLN,建立了合适的包封率测定方法,并考查初步稳定性较好。     

丹参酮Ⅱ_A固体脂质纳米粒的体外释药和大鼠肠吸收特性的研究

目的　考察丹参酮ⅡA固体脂质纳米粒 (TA SLN)的体外释药性质,研究肠道最佳吸收部位和吸收机制。方法　用透析法测定TA SLN体外释药速率,大鼠在体肠吸收实验考察肠道吸收行为。结果　药物的体外释放符合Weibull方程,具有缓释特性。在十二指肠,TA SLN与丹参酮ⅡA溶液的吸收率差异无显著性(P>0 05),在空肠、回肠和结肠段,TA SLN与丹参酮ⅡA溶液的吸收率差异均有显著性 (P<0 05)。丹参酮ⅡA溶液在各肠段的吸收率差异无显著性 (P>0 05),但TA SLN在结肠段的吸收率高于其它肠段,差异具有显著性(P<0 05)。在纳米粒浓度较高时,吸收趋向饱和;加入空白纳米粒,未增加纳米粒小肠吸收率;降低Na+浓度以及加入吸收促进剂(脱氧胆酸钠、吐温 80和十二烷基硫酸钠)和能量抑制剂(2, 4 二硝基苯酚)均使纳米粒小肠吸收率增加。结论　TA SLN在体外释放介质中可缓慢持续释药;结肠是TA SLN的最佳吸收部位。     

非洛地平-硬脂酸固体脂质纳米粒的制备及其体外透皮吸收研究

目的:以固体脂质纳米粒为栽体,通过透皮给药达到提高非洛地平透皮吸收及缓释长效的目的.方法:采用溶剂挥发-超声法制备非洛地平固体脂质纳米粒水分散体,以大鼠皮肤为渗透屏障对非洛地平固体脂质纳米粒的经皮渗透进行研究.结果:非洛地平-硬脂酸固体脂质纳米粒为类球形实体粒子,平均粒径范围在50～150 nm,包封率大于85%,栽药量大于7%,药物体外释放符合一级动力学过程.体外经皮渗透速率显著高于空白对照组.结论:非洛地平固体脂质纳米粒处方设计合理,制备工艺可靠,以纳米粒作为透皮给药载体具有广阔的发展前景.     

人参皂苷Rd固体脂质纳米粒的体外释放和大鼠的在体吸收

目的研究人参皂苷Rd固体脂质纳米粒(Rd-SLN)的体外释药特性、在大鼠肠道的吸收和体内药物动力学行为。方法采用透析法测定Rd-SLN体外释药速率;通过大鼠在体分段肠回流实验,研究Rd-SLN的肠道吸收行为;建立血浆样品中人参皂苷Rd的HPLC分析方法,在大鼠灌胃给药后测定不同时间的血药浓度,观察Rd-SLN在体内的吸收和药动学特征。结果Rd-SLN具有缓释特征。在十二指肠和空肠段,Rd-SLN与人参皂苷Rd对照溶液的吸收率差异没有显著性;在回肠和结肠段,Rd-SLN与对照溶液的吸收率差异有显著性。Rd-SLN在回肠段的吸收率高于其它肠段。与对照组相比,Rd-SLN组的血药浓度水平维持时间更长,其Cmax、MRT、AUMC和AUC均明显增加。结论Rd-SLN具有一定的缓释作用,其在回肠的吸收优于其他肠段,并且能明显提高人参皂苷Rd的生物利用度。     

Candesartan cilexetil loaded solid lipid nanoparticles for oral delivery: characterization,pharmacokinetic and pharmacodynamic evaluation

Abstract

Candesartan cilexetil (CC) is used in the treatment of hypertension and heart failure. It has poor aqueous solubility and low oral bioavailability. In this work, CC loaded solid lipid nanoparticles (CC-SLNs) were developed to improve the oral bioavailability. Components of the SLNs include either of trimyristin/tripalmitin/tristearin, and surfactants (Poloxamer 188 and egg lecithin E80). The CC loaded nanoparticles were prepared by hot homogenization followed by ultrasonication method. The physicochemical properties, morphology of CC-SLNs were characterized, the pharmacokinetic and pharmacodynamic behaviour of CC-SLNs were evaluated in rats. Stable CC-SLNs having a mean particle size of 180–220?nm with entrapment efficiency varying in between 91–96% were developed. The physical stability of optimized formulation was studied at refrigerated and room temperature for 3 months. Further, freeze drying was tried for improving the physical stability. DSC and XRD analyses indicated that the drug incorporated into SLN was in amorphous form but not in crystalline state. The SLN-morphology was found to be nearly spherical by electron microscopic studies. Pharmacokinetic results indicated that the oral bioavailability of CC was improved over 2.75-fold after incorporation into SLNs. Pharmacodynamic study of SLNs in hypertensive rats showed a decrease in systolic blood pressure for 48?h, while suspension showed a decrease in systolic blood pressure for only 2?h. Taken together, these effects are due to enhanced bioavailability coupled with sustained action of CC in SLN formulation. Thus, the results conclusively demonstrated the role of CC-SLNs for a significant enhancement in oral bioavailability along with improved pharmacodynamic effect.     

Elucidation of intestinal absorption mechanism of carvedilol-loaded solid lipid nanoparticles using Caco-2 cell line as an in-vitro model

Abstract

Enhanced oral bioavailability of poorly aqueous soluble drugs encapsulated in solid lipid nanoparticles (SLNs) via lymphatic delivery has been documented. Since no in-vitro lymphoid tissue is currently available, human excised Caco-2 cell monolayer could be alternative tissue for development of an in-vitro model to be used as a screening tool before animal studies are undertaken. Therefore, optimized carvedilol-loaded SLNs (FOPT-SLNs) were prepared, characterized, and evaluated using Caco-2 cell line as an in-vitro model. Physical mixture of components of FOPT-SLNs (FOPT-PM) and carvedilol solution were used as control groups. From the studies of effect of SLNs concentration and cells incubation time, suitable carvedilol concentration and incubation time were selected for the model in which cells were subjected to five pretreatments for 24?h or 1?h of cell incubation and then followed with treatment of FOPT-SLNs, FOPT-PM or 100?µg/mL solution of carvedilol, for additional 24?h of cell incubation. The results obtained in this model suggest that main absorption mechanism of FOPT-SLNs could be endocytosis and, more specifically, clathrin-mediated endocytosis. When Transwell® permeable supports were used for the cells, carrier-mediated mechanism for FOPT-SLNs and passive absorption mechanism (transcellular and paracellular) for FOPT-PM and drug solution were concluded.     

山柰酚固体脂质纳米粒的制备及体外抗非小细胞肺癌作用研究

目的: 制备山柰酚(kaemperol,KA)固体脂质纳米粒(KA-SLN),并评价其体外抗肿瘤效果。方法: 首先建立KA的含量测定方法,并进行方法学考察,采用乳化超声分散法制备KA-SLN,测定其包封率、载药量、粒径及电位并拟合其体外释药方程,采用CCK-8法及溶血性试验评价空白载体及KA-SLN的体外安全性,采用CCK-8法评价A549细胞生存率变化,倒置光学显微镜下观察细胞形态学变化,采用Transwell法评价A549细胞迁移能力的变化,Hoechst染色法观察肿瘤细胞凋亡情况,平板克隆试验考察肿瘤细胞集落形成能力的变化。结果: 所得制剂平均粒径(242±21)nm,包封率为(72.34±4.15)%,载药量为(3.29±0.21)%,空白载体无毒性,空白载体及KA-SLN体外无溶血性,释药规律符合Ritger-peppas方程,相对于KA,KA-SLN展示出更好地抑制肿瘤细胞增殖、迁移、集落形成作用及促肿瘤细胞凋亡效果。结论: 通过将KA制成KA-SLN可以提高药物缓控释效果及体外抗肿瘤作用,且安全性较好,可进一步用于体内抗肿瘤研究。     

In vitro and ex vivo toxicological testing of sildenafil-loaded solid lipid nanoparticles

Abstract

The aim of this study was to investigate the potential cytotoxicity of solid lipid nanoparticles (SLN) loaded with sildenafil. The SLNs were tested as a new drug delivery system (DDS) for the inhalable treatment of pulmonary hypertension in human lungs. Solubility of sildenafil in SLN lipid matrix (30:70 phospholipid:triglyceride) was determined to 1% sildenafil base and 0.1% sildenafil citrate, respectively. Sildenafil-loaded SLN with particle size of approximately 180?nm and monomodal particle size distribution were successfully manufactured using a novel microchannel homogenization method and were stable up to three months. Sildenafil-loaded SLN were then used in in vitro and ex vivo models representing lung and heart tissue. For in vitro models, human alveolar epithelial cell line (A459) and mouse heart endothelium cell line (MHEC5-T) were used. For ex vivo models, rat precision cut lung slices (PCLS) and rat heart slices (PCHS) were used. All the models were treated with plain SLN and sildenafil-loaded SLN in a concentration range of 0–5000?µg/ml of lipid matrix. The toxicity was evaluated in vitro and ex vivo by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Median lethal dose 50% (LD₅₀) values for A549 cells and PCLS were found to be in the range of 1200–1900?µg/ml while for MHEC5-T cells and precision cut heart slices values were found between 1500 and 2800?µg/ml. PCHS showed slightly higher LD₅₀ values in comparison to PCLS. Considering the toxicological aspects, sildenafil-loaded SLN could have potential in the treatment of pulmonary hypertension via inhalation route.     

New probabilistic risk assessment of ethylhexyl methoxycinnamate: Comparing the genotoxic effects of trans‐ and cis‐EHMC

Ethylhexyl methoxycinnamate (EHMC) is a widely used UV filter present in a large number of personal care products (PCPs). Under normal conditions, EHMC occurs in a mixture of two isomers: trans‐EHMC and cis‐EHMC in a ratio of 99:1. When exposed to sunlight, the trans isomer is transformed to the less stable cis isomer and the efficiency of the UV filter is reduced. To date, the toxicological effects of the cis‐EHMC isomer remain largely unknown. We developed a completely new method for preparing cis‐EHMC. An EHMC technical mixture was irradiated using a UV lamp and 98% pure cis‐EHMC was isolated from the irradiated solution using column chromatography. The genotoxic effects of the isolated cis‐EHMC isomer and the nonirradiated trans‐EHMC were subsequently measured using two bioassays (SOS chromotest and UmuC test). In the case of trans‐EHMC, significant genotoxicity was observed using both bioassays at the highest concentrations (0.5 ‐ 4 mg mL^?1). In the case of cis‐EHMC, significant genotoxicity was only detected using the UmuC test at concentrations of 0.25 ‐ 1 mg mL^?1. Based on these results, the NOEC was calculated for both cis‐ and trans‐EHMC, 0.038 and 0.064 mg mL^?1, respectively. Risk assessment of dermal, oral and inhalation exposure to PCPs containing EHMC was carried out for a female population using probabilistic simulation and by using Quantitative in vitro to in vivo extrapolation (QIVIVE). The risk of cis‐EHMC was found to be ～1.7 times greater than trans‐EHMC. In the case of cis‐EHMC, a hazard index of 1 was exceeded in the 92nd percentile. Based on the observed differences between the isomers, EHMC application in PCPs requires detailed reassessment. Further exploration of the toxicological effects and properties of cis‐EHMC is needed in order to correctly predict risks posed to humans and the environment. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 569–580, 2017.     

雷公藤提取物固体脂质纳米粒水分散体的制备及体外透皮吸收

制备雷公藤乙酸乙酯提取物固体脂质纳米粒水分散体,并初步研究了体外透皮行为.     

Curcumin-loaded solid lipid nanoparticles with Brij78 and TPGS improved in vivo oral bioavailability and in situ intestinal absorption of curcumin

Abstract

Purpose: The present study was to formulate curcumin solid lipid nanoparticles (Cur-SLNs) with P-gp modulator excipients, TPGS and Brij78, to enhance the solubility and bioavailability of curcumin.

Methods: The formulation was optimized by Plackett–Burman screening design and Box–Behnken experiment design. Then physiochemical properties, entrapment efficiency and in vitro release of Cur-SLNs were characterized. In vivo pharmacokinetics study and in situ single-pass intestinal perfusion were performed to investigate the effects of Cur-SLNs on the bioavailability and intestinal absorption of curcumin.

Results: The optimized formulations showed an average size of 135.3?±?1.5?nm with a zeta potential value of ?24.7?±?2.1?mV and 91.09%?±?1.23% drug entrapment efficiency, meanwhile displayed a sustained release profile. In vivo pharmacokinetic study showed AUC_0→t for Cur-SLNs was 12.27-folds greater than curcumin suspension and the relative bioavailability of Cur-SLNs was 942.53%. Meanwhile, T_max and t_1/2 of curcumin for Cur-SLNs were both delayed comparing to the suspensions (p?<?0.01). The in situ intestinal absorption study revealed that the effective permeability (P_eff) value of curcumin for SLNs was significantly improved (p?<?0.01) comparing to curcumin solution.

Conclusion: Cur-SLNs with TPGS and Brij78 could improve the oral bioavailability and intestinal absorption of curcumin effectively.     

Skin permeation of buprenorphine and its ester prodrugs from lipid nanoparticles: lipid emulsion,nanostructured lipid carriers and solid lipid nanoparticles

The aim of this study was to develop and characterize lipid nanoparticle systems for the transdermal delivery of buprenorphine and its prodrugs. A panel of three buprenorphine prodrugs with ester chains of various lengths was synthesized and characterized by solubility, capacity factor (log K′), partitioning between lipids and water and the ability to penetrate nude mouse skin. Colloidal systems made of squalene (lipid emulsion, LE), squalene + Precirol (nanostructured lipid carriers, NLC) and Precirol (solid lipid nanoparticles, SLN) as the lipid core material were prepared. Differential scanning calorimetry showed that the SLN had a more-ordered crystalline lattice in the inner matrix compared to the NLC. The particle size ranged from 220–300 nm, with NLC showing the smallest size. All prodrugs were highly lipophilic and chemically stable, but enzymatically unstable in skin homogenate and plasma. The in vitro permeation results exhibited a lower skin delivery of drug/prodrug with an increase in the alkyl chain length. SLN produced the highest drug/prodrug permeation, followed by the NLC and LE. A small inter-subject variation was also observed with SLN carriers. SLN with soybean phosphatidylcholine (SLN-PC) as the lipophilic emulsifier showed a higher drug/prodrug delivery across the skin compared to SLN with Myverol, a palmitinic acid monoglyceride. The in vitro permeation of the prodrugs occurred in a sustained manner for SLN-PC. The skin permeation of buprenorphine could be adjusted within a wide range by combining a prodrug strategy and lipid nanoparticles.     

Box-Behnken效应面法优化姜黄素正负离子固体脂质纳米粒的处方

目的 采用Box-Behnken效应面法筛选姜黄素正负离子固体脂质纳米粒的最优处方.方法 采用乳化蒸发-低温固化法制备姜黄素的固体脂质纳米粒,以固体脂质的质量、卵磷脂的质量和混合表面活性剂为考察对象,以包封率和脂质载药量为考察指标,利用3因素3水平Box-Behnken效应面设计法筛选姜黄素固体脂质纳米粒的最优处方.结果 按最优处方制备固体脂质纳米粒的包封率为94.20％ ±2.55％、脂质载药量为3.49％±0.11％,平均粒径为194.9 ±12.0 nm,Zeta电位为-28.15 ±2.72 mV.结论 采用Box-Behnken效应面法优化姜黄素正负固体脂质纳米粒的处方是有效、可行的.     

Evaluation of hypericin-loaded solid lipid nanoparticles: Physicochemical properties,photostability and phototoxicity

Hypericin (HYP), a natural photosensitizer, has powerful photo-oxidizing ability, tumor-seeking characteristics, and minimal dark toxicity; nevertheless, it has proven high lipid solubility compared to its sparingly water soluble nature. Therefore, its formulation into solid lipid nanoparticles (SLNs) has attracted increasing attention as a potential drug-delivery carrier. Two HYP-loaded SLNs formulations were prepared utilizing microemulsion-based technique. Thereafter, the physicochemical properties of the formulations were investigated and evaluated. HYP-loaded SLNs showed spherical shape with mean particle size ranging from 200–300?nm for both formulations (FA and FB). The encapsulation efficiencies reached above 80% and FA showed significant higher encapsulation than FB (P?<?0.05), also, the thermal analysis using differential scanning calorimetry (DSC) indicated good compatibility between hypericin and lipids forming the cores in both formulations. Spectroscopic measurements of the photostability study showed that hypericin encapsulation into SLNs improved its photostability, compared to free HYP in 0.1% ethanolic solution. However, photocytotoxicity studies on HepG2 cells revealed an evident inhibition of the photodynamic efficacy of HYP-loaded SLNs, compared to free HYP. In conclusion, although the elevated entrapment efficiency of HYP into SLNs increased its photostability, it decreased its phototoxicity which might be due to the quenching deactivation of HYP molecules resulting from SLN compactness and thickness structure.