In vivo controlled release and prolonged antitumor effects of 2-methoxyestradiol solid lipid nanoparticles incorporated into a thermosensitive hydrogel

A two-phase delivery system involving local injections of solid lipid nanoparticles (SLNs) -loaded hydrogel was developed using 2-methoxyestradiol as a model anticancer drug. This approach improves the effectiveness of conventional treatments for subcutaneous tumors and avoids that solid lipid nanoparticles are rapidly cleared from the circulation following systemic administration. The specific aim of the study presented in this article was to investigate the in vivo release, delivery and antitumor effects of 2-ME SLNs entrapped in a hydrogel. The results indicated that the hydrogel could deliver fluorescence-marked SLNs to tumor masses and cancer cells, exhibiting a controlled release of 2-ME SLNs over 46 days following a zero-order model. After treatment with the 2-ME SLN-loaded hydrogel, BALB/c mice that had been inoculated with syngeneic 4T1 breast cancer cells displayed significantly more tumor growth suppression for at least 21 days than those treated with a hydrogel containing the free drug, which was consistent with the in vitro cytotoxicity of 2-ME SLNs. This experiment demonstrated the efficacy of the hydrogel as a depot of 2-ME SLNs. Additionally, the mice treated with the hydrogel did not exhibit a loss of body weight or abnormal levels of white blood cells compared to the control group. These experiments demonstrated the potential value of 2-ME SLN hydrogel local injections as a safer and more effective method for the chemotherapy of subcutaneous tumors.     

Investigation of a new injectable thermosensitive hydrogel loading solid lipid nanoparticles

For improving the effectiveness of cancer chemotherapy and avoiding rapid clearance of solid lipid nonoparticles (SLN) from the systemic circulation following systemic administration, 2-methoxyestradiol (2-ME) as model drug, PLGA-PEG-PLGA as hydrogel material, an injectable SLN loaded hydrogel was developed. Integrity of SLN within and released from the hydrogel was confirmed by direct visualization by a scanning electron microscope (SEM), particle size measurement by laser light scattering, and free drug concentration in the release medium by ultracentrifugation. Moreover, in vitro release, thermo-sensitive properties and rheological behavior were investigated. The results indicated that SLN were stable in the hydrogel. In the release medium, most 2-ME existed in the SLN and intact 2-ME SLN could be released from the hydrogel for a prolonged period over 46 days. Their concentration showed a significant effect on the release rate, in contrast to particle size and pH value of the release medium. In addition, the SLN loaded hydrogel could still exhibit reversible thermo-sensitive properties and better syringeability. These results suggested that the SLN loaded hydrogel could transport SLN to the target site and control prolonged release of SLN, which may increase the efficacy of cancer chemotherapy.     

In vitro and in vivo evaluation of thermosensitive chitosan hydrogel for sustained release of insulin

Injectable In situ gel-forming chitosan/β-glycerol phosphate (CS/β-Gp) solution can be introduced into the body in a minimally invasive manner prior to solidifying within the target tissue. This hydrogel is a good candidate for achieving a prolonged drug delivery system for insulin considering its high molecular weight. In addition to the physicochemical characterization of this hydrogel, in vitro and in vivo applications were studied as a sustained insulin delivery system. In the in vitro release studies, 19–63% of total insulin was released from the CS/β-Gp hydrogel within 150?h at different β-Gp and insulin concentrations. The best formulation was selected for in vivo experimentation to control the plasma glucose of diabetic mice models. The hypoglycemic effect of this formulation following subcutaneous injection in diabetic mice lasted 5?d, significantly longer than that of free insulin solution which lasted several hours.     

Tumoricidal effects of etoposide incorporated into solid lipid nanoparticles after intraperitoneal administration in Dalton's lymphoma bearing mice

The tumoricidal effects of etoposide incorporated into lipid nanoparticles after single-dose administration were investigated in Dalton's lymphoma ascites bearing mice. Etoposide and its nanoparticle formulations were administered intraperitoneally, and the cell cycle perturbation, cytogenetic damage, cell death (apoptosis), tumor regression, and animal survival were investigated as parameters of response with time. The tumor burden of mice treated with etoposide and its nanoparticle formulations decreased significantly (P < .001) compared with the initial up to 4 to 6 days, followed by an increase at later time intervals. Of the 3 different formulations, the survival time of mice was higher when treated with etoposide-loaded tripalmitin (ETP) nanoparticles, followed by etoposide-loaded glycerol monostearate (EGMS) (27.3%) and etoposide-loaded glycerol distearate (EGDS) (27.3%) compared with free etoposide. Cell cycle analysis revealed the hypodiploid peak (sub G0/G1 cell population) as well as G2 arrest in mice treated with etoposide and its nanoparticle formulations. The frequency of dead cells treated with the nanoparticle formulations remained high even after 8 days of treatment compared with free etoposide. The mice treated with nanoparticle formulations exhibited hypodiploid peaks and reduced S phase even 8 days after treatment, whereas the free etoposide-treated mice showed decrease in apoptosis after 3 days of treatment. The apoptotic frequency in cells 17 days after treatment was in the order of ETP > EGMS > EGDS > etoposide. The experimental results indicated that among the 3 nanoparticle formulations studied, the ETP nanoparticles showed greater and prolonged apoptotic induction properties, resulting in the higher increase in survival time of tumor bearing mice.     

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.     

Skin moisturizing effect and skin penetration of ascorbyl palmitate entrapped in solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC) incorporated into hydrogel

This study was performed as a complimentary to our previous study regarding the chemical stability of ascorbyl palmitate (AP) in solid lipid nanoparticles (SLN), nanostructured lipid carriers (NLC) and for comparison, in nanoemulsion (NE) incorporated into a hydrogel produced by high pressure homogenization. AP is known as an effective antioxidant that protects tissue integrity similar to vitamin C. Recently, its moisturizing activity in conventional topical formulations was found to be high. The aim of the present study was to investigate the moisturizing potential of AP in SLN and NLC incorporated into hydrogel as colloidal carrier systems. It has been known that SLN and NLC have occlusive effects, but AP incorporation moisturized skin significantly better than placebo in short-term (p < 0.001) and long-term trials (p < 0.01) for both SLN and NLC. In the second part of the study, SLN and NLC were found to sustain the penetration of AP through excised human skin about 1/2 and 2/3 times compared to NE (p < 0.001 and p < 0.01), respectively, due to the solid state of Witepsol E85 in the lipid phase.     

A novel preparation of solid lipid nanoparticles with cyclosporin A for prolonged drug release

Solid lipid nanoparticles were prepared by a novel solvent diffusion method in an aqueous system. The lipophilic model drug cyclosporin A was incorporated into SLN to study encapsulation efficiency, zeta potential (charge) and drug delivery. Stearylamine and cyclosporin A were dissolved in ethanol and acetone and the resultant organic solution was dropped into water at 60 degrees C. The drug-loaded SLN suspension quickly formed with an azury color. After burst drug release with 18% of the drug over the first 12 hours, a distinctly prolonged release over a monitored period of 16 days was observed, with nearly 4% of the drug being released each day. These results demonstrate the suitability of SLN produced with the proposed method as a prolonged release formulation for lipophilic drugs.     

Cellular uptake and antitumour activity of paclitaxel incorporated into trilaurin-based solid lipid nanoparticles in ovarian cancer

Abstract

Trilaurin-based solid lipid nanoparticles (TL-SLNs) containing paclitaxel (PTX) were prepared by hot-melt high-pressure homogenisation and subsequent freezing and thawing. PTX-containing TL-SLNs showed 160.0?±?15.8?nm of mean particle size and ?43.9?mV of zeta potential. Scanning electron microscopy also revealed the spherical shape and submicron-size of the TL-SLNs. Differential scanning calorimetry measurement presented melting transition peak of TL in SLNs indicating the solidified state of the core lipid. The prepared TL-SLNs were physically stable without significant particle size changes at 4?°C for 2 months. The amounts of uptake into the human ovarian cancer cells, SKOV-3, were similar between PTX delivered in Cremophor EL-based formulation and TL-SLNs. In vitro and in vivo antitumour activity of PTX in TL-SLNs was comparable to the commercial Cremophor EL-based formulation in SKOV-3. These results suggest that PTX-loaded TL-SLNs have promising potential as an alternative parenteral formulation for PTX.     

Characterization of pH- and temperature-sensitive hydrogel nanoparticles for controlled drug release

Monodispersed poly (N-isopropylacrylamide) (PNIPA) nanoparticles and their derivative poly (N-isopropylacrylamide-co-acrylic acid) (PNIPA-co-AA) nanoparticles were successfully synthesized. Regulation of the size and the lower critical solution temperature (LCST) of the hydrogel nanoparticles was intensively studied. The results showed that the diameters and LCST of the particles can be arbitrarily manipulated according to different application designs. The relationship between the size of the particles and the amount of surfactant were quantitatively disclosed. It was found that the LCST of PNIPA-co-AA nanoparticles ranging from 35-45 degrees C correlated with the molar fraction of acrylic acid which was copolymerized with NIPA. The pH sensitivity of PNIPA-co-AA nanoparticles was displayed by the transmittance transition of their aqueous solution in various pH conditions. Furthermore, the anti-cancer drug 5-fluorouracil (5-Fu) was first loaded into both PNIPA and PNIPA-co-AA hydrogel nanoparticles with an entrapment efficiency larger than 4%. In vitro release of 5-Fu from PNIPA-co-AA nanoparticle hydrogels was shown to be pH- and temperature-dependent, which demonstrated that the PNIPA-co-AA nanoparticles have great potential in the design of controlled drug delivery systems.     

Corticosteroid solubility and lipid polarity control release from solid lipid nanoparticles

Solid lipid nanoparticles (SLN) show promise as a drug delivery system for skin administration. The solid state of the lipid particle enables efficient drug encapsulation and controlled drug release. The present study addresses the influence of lipid composition and drug substance lipid solubility on the in vitro release profile of corticosteroids from SLN for topical administration. Firstly, the effect of lipid composition on the lipid solubility and in vitro release of betamethasone-17-valerate (BMV) was determined by varying the lipid monoglyceride content and the chain length of the fatty acid moiety. Secondly, the effect of drug substance physicochemical properties was determined by studying five different corticosteroid derivatives with different lipophilicity. A high concentration of monoglyceride in SLN increased the amount of BMV released. The corticosteroid release rate depended on the drug substance lipophilicity and it was clear that the release profiles depended on drug partitioning to the aqueous phase as indicated by zero order kinetics. The results emphasize that the corticosteroid solubility in the lipid phase greatly influence drug distribution in the lipid particles and release properties. Thus knowledge of drug substance solubility and lipid polarity contributes to optimize SLN release properties.     

吴茱萸碱丁酰基衍生物固体脂质纳米粒的体外释放及在体胃肠吸收研究

目的制备吴茱萸碱丁酰基衍生物(evodiamine butyryl derivative,EBD)和吴茱萸碱丁酰衍生物固体脂质纳米粒(evodiamine butyryl derivative-loaded solid lipid nanoparticles,EBDLN),并研究它们的体外释放特征以及在体胃肠吸收的能力。方法采用一步合成法制备EBD,经薄膜分散法制备EBDLN。采用动态透析法考察EBD和EBDLN的体外释药特征,并用单向灌流法研究吴茱萸碱(evodiamine,EDM)、EBD和EBDLN的胃肠道吸收。结果在同种释放介质中,EBD和EBDLN的释药趋势完全一致,但EBDLN相对于EBD而言其释药速度更慢。EBDLN在各个肠道的K_a值和P_(app)值均明显大于EDM和EBD。且EBDLN在胃、十二指肠、空肠、回肠、结肠中的K_a值分别为EDM的110.14、56.70、51.23、45.70、127.23倍,EBDLN在十二指肠、空肠、回肠、结肠中的P_(app)值分别为EDM的9.74、4.48、3.82、11.30倍。结论EBDLN具有缓释效应,增加了EDM和EBD在胃肠道的吸收。     

In vitro and in vivo study of solid lipid nanoparticles loaded with superparamagnetic iron oxide

Solid Lipid Nanoparticles (SLN) are already under investigation as a pharmaceutical tool able to change the pharmacokinetic and biodistribution of carried molecules. SLN are able to target drugs to lymph after duodenal administration and to overcome the Blood Brain Barrier (BBB). In this study, superparamagnetic SLN have been prepared, have colloidal size, in vitro analysis showed relaxometric properties similar to Endorem. In vivo Magnetic Resonance Imaging (MRI) of the central nervous system (CNS) with both SLN and Endorem showed that superparamagnetic SLN have slower blood clearance than Endorem. MRI data are consistent with CNS uptake of SLN lasting up to the end of the experiment (135 min). These findings confirm the ability of SLN to overcome the BBB; SLN might be used as a CNS MRI contrast agent.     

Injectable delivery system of 2-methoxyestradiol for breast cancer therapy using biodegradable thermosensitive poly(organophosphazene) hydrogel

2-Methoxyestradiol (2-ME) has been reported to have antiangiogenic and antitumor activity. Its biomedical application is limited due to its poor water solubility resulting in its low bioavailability. Poly(organophosphazenes) containing l-isoleucine ethyl ester, ethyl-2-(O-glycyl)lactate, and α-amino-ω-methoxy-poly(ethylene glycol) 550 were synthesized having M_W of 35–38?kDa and polydispersity index of 2.38–2.73. Using a viscometer, the thermosensitivity useful for locally injectable drug delivery was verified. The aqueous polymer solution showed a sol state at a low temperature and transformed to a gel state at body temperature. The polymer solution (10 wt%) enhanced the solubility of 2-ME by about 10⁴ times compared to that of phosphate buffered saline. 2-ME was released from the hydrogel mainly by diffusion, hydrophobic interaction, and surface erosion of the matrix. This release profile could be confirmed through an in vitro release test as a function of polymers and the concentration of 2-ME in hydrogels. By monitoring tumor volume and CD31 immunohistochemical staining in mouse orthotopic breast tumor (MDA-MB-231) model, it was found that the hydrogel containing a relatively low concentration (15?mg/kg) of 2-ME showed the improved antitumor and antiangiogenic activity relative to the original formulation. This research suggests that the developed formulation of poly(organophosphazenes) may have injectable carrier potentials for 2-ME and other lipophilic drugs.     

Development of topotecan loaded lipid nanoparticles for chemical stabilization and prolonged release

Topotecan is an important cytotoxic drug that has gained broad acceptance in clinical use for the treatment of refractory ovarian and small-cell lung cancer. The lactone active form of topotecan can be hydrolyzed in vivo, decreasing the drug’s therapeutic efficacy. Lipid encapsulation may promote in vivo stabilization by removing topotecan from aqueous media. Earlier reports of topotecan lipid nanoencapsulation have focused on liposomal encapsulation; however, the higher stability and cost-effectiveness of solid lipid nanoparticles (SLN) highlight the potential of these nanoparticles as an advantageous carrier for topotecan. The initial motivation for this work was to develop, for the first time, solid lipid nanoparticles and nanostructured lipid carriers (NLC) with a high drug loading for topotecan. A microemulsion technique was employed to prepare SLNs and NLCs and produced homogeneous, small size, negatively charged lipid nanoparticles with high entrapment efficiency and satisfactory drug loading. However, low recovery of topotecan was observed when the microemulsion temperature was high and in order to obtain high quality nanoparticles, and precise control of the microemulsion temperature is critical. Nanoencapsulation sustained topotecan release and improved its chemical stability and cytotoxicity. Surprisingly, there were no significant differences between the NLCs and SLNs, and both are potential carriers for topotecan delivery.     

In vivo and cytotoxicity evaluation of repaglinide-loaded binary solid lipid nanoparticles after oral administration to rats

The purpose of this work was to develop prolonged release binary lipid matrix-based solid lipid nanoparticles (SLN) of repaglinide (RG) for oral intestinal delivery and to improve the bioavailability of RG. SLN were designed by using glycerol monostearate and tristearin as lipid core materials and Pluronic-F68 as stabilizer. SLN were characterised by their particle size, zeta potential, entrapment efficiency, solid-state studies, in vitro drug release, particle surface and storage stability at 30 °C/65% relative humidity for 3 months. Pharmacodynamic (PD) and pharmacokinetic (PK) studies were also performed in diabetes-induced rat. Moreover, an in vitro toxicity study was performed in rat macrophage cells to establish the safety of the prepared SLN. It was observed that binary lipid matrix-based SLN had better drug entrapment, desired release characteristics, spherical shape and maximum storage stability. Pharmacodynamic study indicated that RG delivered through binary SLN significantly reduces blood glucose, blood cholesterol and blood triglycerides level. The area under the curves after oral administration of optimised RG-SLN formulation and RG control were 113.36 ± 3.01 and 08.08 ± 1.98 h/(ng · mL), respectively. The relative bioavailability of RG was enhanced with optimised SLN formulation when compared with RG control. There was a direct correlation found between the plasma drug level (drug concentration) and the peak response (% blood glucose inhibition) in optimised RG-SLN batch. The in vitro toxicity study indicated that the SLN were well tolerated.     

Entrapment and release of saquinavir using novel cationic solid lipid nanoparticles

Cationic solid lipid nanoparticles (CSLNs) with entrapped saquinavir (SQV) were fabricated by microemulsion method. Here, CSLNs were stabilized by polysorbate 80, and the lipid phase contained cationic stearylamine (SA) and dioctadecyldimethyl ammonium bromide (DODAB) and nonionic Compritol 888 ATO (CA) and cacao butter (CB). Properties of the present pharmaceutical formulations including the entrapment efficiency, the release kinetics, and the distribution of SQV in CSLNs were analyzed. The results indicated that a mixture of SA and DODAB and a mixture of CA and CB were beneficial to the entrapment efficiency of SQV. However, an increase in the content of cationic lipids insignificantly affected the entrapment efficiency of SQV when the weight percentage of SA and DODAB was greater than 1% during emulsification. Also, the rate of SQV released from CSLNs with lipid cores of a mixture of CA and CB was slower than that of pure CB. The temporal variation in the released SQV suggested that the carriers could be sustained delivery systems with no apparent initial burst. Hence, the current CSLNs could carry SQV for the improved medication of individuals infected by human immunodeficiency viruses.     

盐酸雷洛昔芬固体脂质纳米粒的制备与体内药动学研究

目的 制备盐酸雷洛昔芬固体脂质纳米粒(raloxifene hydrochloride solid lipid nanoparticles, RLX-SLNs),并研究其在大鼠体内的药动学。方法 采用热熔乳化-高压均质法制备RLX-SLNs,通过测定包封率、粒径分布、Zeta电位、微观形态并用差示扫描量热法(differential scanning calorimetry, DSC)对其进行表征;考察了RLX-SLNs的体外释药特性和稀释稳定性;比较了RLX混悬剂与RLX-SLNs经大鼠口服给药后的体内药动学。结果 制备的RLX-SLNs外观呈乳白色溶液状,包封率为97.8%±1.6%,粒径为(194.5±8.5) nm,多聚分散指数(polydispersity index, PDI)为0.183±0.08,Zeta电位为(-34.3±1.5) mV;在透射电镜下观察到RLX-SLNs呈球状分布,无聚集;DSC测定结果显示RLX-SLNs中的药物吸热峰消失;RLX-SLNs在4种释放介质中均表现为双相释药特征;大鼠口服RLX-SLNs后,其药物达峰质量浓度和口服生物利用度均显著高于RLX混悬剂。结论 将盐酸雷洛昔芬制备成固体脂质纳米粒,制备工艺可控,生物利用度显著提高,为盐酸雷洛昔芬的二次开发奠定了实验基础。     

The antitumor effect of a thermosensitive polymeric hydrogel containing paclitaxel in a peritoneal carcinomatosis model

The prognosis of peritoneal carcinomatosis is regarded as poor because safe, effective therapeutic modalities are lacking. Intraperitoneal chemotherapy is one treatment option, involving the delivery of a high concentration of chemotherapeutic drugs into the abdominal cavity, but the severe side effects associated with such treatment are a major obstacle in clinical application. We evaluated the anti-cancer effects of intraperitoneal delivery of a thermosensitive polymeric hydrogel containing chemotherapeutics in an animal model of carcinomatosis. The progress of peritoneal carcinomatosis, introduced by injecting a luciferase-transfected human gastric cancer cell line (HSC44Luc) into the peritoneal cavity of nude mice, was quantitatively evaluated by in vivo bioluminescence imaging. Three days after intraperitoneal (IP) injection of HSC44Luc cells, treatment solutions were injected into the peritoneal cavity. Mice were categorized into four groups depending on treatment method; these were (1) a control PBS group (n = 5), (2) a hydrogel-only group (n = 5), (3) a paclitaxel solution (30 mg/kg) group (n = 3), and (4) a hydrogel-with-paclitaxel (15 mg/kg) group (n = 5). Quantitative photon counting was performed weekly in each animal. Mice were sacrificed on the 5th or 28th day after treatment, for pathologic evaluation. In vivo bioluminescence imaging showed that photon counts in the hydrogel-with-paclitaxel and paclitaxel solution groups were significantly lower than in the PBS group over the entire experimental period. Although neither group of responding mice showed any peritoneal nodules on the 28th day after treatment, only the paclitaxel solution group exhibited dilated edematous changes in the intestine; these side effects were absent in animals treated with hydrogel-with-paclitaxel group. In conclusion, a thermosensitive hydrogel containing paclitaxel may be a safe and effective treatment option for peritoneal carcinomatosis.     

In vitro and in vivo antitumor effects of bisphosphonates

Bisphosphonates are powerful inhibitors of osteoclast-mediated bone resorption. They are currently used in the palliative treatment of bone metastases. However, bisphosphonates do not only act on osteoclasts. There is now extensive in vitro preclinical evidence that bisphosphonates can act on tumor cells: they inhibit tumor cell adhesion to mineralized bone as well as tumor cell invasion and proliferation. Bisphosphonates induce also tumor cell apoptosis and stimulate gammadelta T cell cytotoxicity against tumor cells. In vivo, bisphosphonates inhibit bone metastasis formation and reduce skeletal tumor burden. This may reflect direct antitumor effects and indirect effects via inhibition of bone resorption. In addition, bisphosphonates inhibit experimental angiogenesis in vitro and in vivo. Understanding the molecular mechanisms through which bisphosphonates act on tumor and endothelial cells will be undoubtedly an important task in the future. It will allow the design of clinical trials to investigate whether the antitumor activity of bisphosphonates can be realized in the clinical setting.