Maria Rosa Gasco

Sterilization and freeze-drying of drug-free and drug-loaded solid lipid nanoparticles

Solid lipid nanoparticles (SLN) have been prepared from three oil-in-water microemulsions, whose internal phase was constituted of different lipid matrices. The dispersion media were two aqueous solution of trehalose and Pluronic F68 at 2% besides distilled water. SLN were sterilized by autoclaving, were stable during sterilization and maintained a spherical shape and narrow size distribution as confirmed by TEM analysis. SLN dispersions in water did not present nanoparticles larger than 1 μm after storage at 4°C for 1 year; they were freeze-dried after sterilization to obtain dry products. Diazepam was used as model drug to incorporate into SLN, where it was shown by calorimetric analysis to be in amorphous form.

Intravenous Administration to Rabbits of Non-stealth and Stealth Doxorubicin-loaded Solid Lipid Nanoparticles at Increasing Concentrations of Stealth Agent: Pharmacokinetics and Distribution of Doxorubicin in Brain and Other Tissues

The pharmacokinetics and tissue distribution of doxorubicin incorporated in non-stealth solid lipid nanoparticles (SLN) and in stealth solid lipid nanoparticles (SSLN) (three formulations at increasing concentrations of stearic acid-PEG 2000 as stealth agent) after intravenous administration to conscious rabbits have been studied. The control was the commercial doxorubicin solution. The experiments lasted 6 h and blood samples were collected at fixed times after the injections. In all samples, the concentration of doxorubicin and doxorubicinol were determined. Doxorubicin AUC increased as a function of the amount of stealth agent present in the SLN. Doxorubicin was still present in the blood 6 h after the injection of SLN or SSLN, while no doxorubicin was detectable after the i.v. injection of doxorubicin solution. Tissue distribution of doxorubicin was determined 30 min, 2 and 6 h after the administration of the five formulations. Doxorubicin was present in the brain only after the SLN administration. The increase in the stealth agent affected the doxorubicin transported into the brain; 6 h after injection, doxorubicin was detectable in the brain only with the SSLN at the highest amount of stealth agent. In the other rabbit tissues (liver, lungs, spleeen, heart and kidneys) the amount of doxorubicin present was always lower after the injection of any of the four types of SLN than after the commercial solution. In particular, all SLN formulations significantly decreased heart and liver concentrations of doxorubicin.

Incorporation of cyclosporin A in solid lipid nanoparticles (SLN)

The cyclic undecapeptide cyclosporin A (CyA) a potent immunosuppressive drug used in many therapies, is extremely hydrophobic. Commercial products employ solubilising agents to improve gastrointestinal absorption. In the present study CyA solid lipid nanoparticles (SLN) are prepared from warm o/w microemulsion, dispersed in cold water. The matrix chiefly consists of stearic acid, phosphatidylcholine and taurocholate; up to 13% of CyA can be incorporated. The average diameter of CyA-loaded SLNs is below 300 nm and transmission electron microscopy (TEM) analysis shows them to be spherical. In vitro release of CyA from SLNs is low. CyA-loaded SLNs can be proposed for most administration routes, in particular for the duodenal route.

Cellular uptake and cytotoxicity of solid lipid nanospheres (SLN) incorporating doxorubicin or paclitaxel

Solid Lipid Nanospheres (SLN) are colloidal therapeutic systems proposed for several administration routes and obtained by dispersing warm microemulsions in cold water. SLN as carriers of doxorubicin and paclitaxel have been previously studied. In this study, the cellular uptake of SLN and the cytotoxicity of doxorubicin and paclitaxel incorporated into SLN were investigated on two cell-lines, human promyelocytic leukemia (HL60) and human breast carcinoma (MCF-7). Cellular uptake of SLN was determined by incorporating 6-coumarin as fluorescent marker. The cellular uptake of fluorescent SLN was clearly evidenced by fluorescence microscopy. The cytotoxicity of doxorubicin incorporated in SLN was higher compared to the conventional doxorubicin solution, even at the lower concentrations. Paclitaxel in SLN was about 100-fold more effective than free paclitaxel on MCF-7 cells, while on HL60 cells a lower sensitivity was achieved with paclitaxel in SLN. Unloaded SLN had no cytotoxic effect on HL60 and MCF-7 cells.

Preparation and characterization of solid lipid nanospheres containing paclitaxel

The study describes the development of stealth and non-stealth solid lipid nanospheres (SLNs) as colloidal carriers for paclitaxel, a drug with very low solubility. SLNs are constituted mainly of bioacceptable and biodegradable lipids, such as tripalmitin and phosphatidylcholine, and can incorporate amounts of paclitaxel up to 2.8%. Stealth and non-stealth loaded SLNs are in the nanometer size range and can be sterilized and freeze-dried. Thermal analysis (differential scanning calorimetry) showed that paclitaxel is not able to crystallize in the SLNs. Release of paclitaxel from SLNs is very low. Non-stealth and stealth SLNs are stable over time without precipitation of paclitaxel and can be proposed for its parenteral administration.

Solid Lipid Nanoparticles in Lymph and Plasma After Duodenal Administration to Rats

AbstractPurpose. To evaluate the uptake and transport of solid lipid nanoparticles (SLN), which have been proposed as alternative drug carriers, into the lymph and blood after duodenal administration in rats. Methods. Single doses of two different concentrations of aqueous dispersions of unlabelled and labelled SLN (average diameter 80 nm) were administered intraduodenally to rats. At different times, samples of lymph were withdrawn by cannulating the thoracic duct and blood was sampled from the jugular vein. Monitoring continued for 45 and 180 minutes, for unlabelled and labelled SLN respectively. The biological samples were analysed by photon correlation spectroscopy (PCS), transmission electron microscopy (TEM) and gamma-counting. Results. TEM analysis evidenced SLN in lymph and blood after duodenal administration to rats; the size of SLN in lymph did not change markedly compared to that before administration. The labelled SLN confirmed the presence of SLN in lymph and blood. Conclusions. The uptake and transport of SLN in the lymph, and to a lesser extent in the blood, were evidenced. The in vivo physical stability of SLN may have important implications in designing drug-carrying SLN.

Solid lipid nanoparticles as carriers of hydrocortisone and progesterone complexes with β-cyclodextrins

Inclusion complexes of hydrocortisone and progesterone were formed with β-cyclodextrin or 2-hydroxypropyl-β-cyclodextrin. The formation of the complexes was confirmed by differential scanning calorimetry (DSC). The inclusion complexes were incorporated in two types of solid lipid nanoparticles (SLN). In the presence of the complexes the sizes of SLN remained below 100 nm. DSC analysis showed that hydrocortisone and progesterone are dispersed in SLN in an amorphous state. Using the β-cyclodextrin complexes the incorporation of the more hydrophilic drug, hydrocortisone, was higher than that of progesterone. Release of hydrocortisone and progesterone from SLN was lower when they were incorporated as inclusion complexes than as free molecules.

Solid lipospheres of doxorubicin and idarubicin

Abstract Solid lipospheres, constituted mainly of stearic acid and egg lecithin, containing amounts of doxorubicin and idarubicin up to 7 and 8.4%, respectively, were prepared. The high incorporation of drug is due to an increase in their lipophilicity as a result of the formation of ion-pairs with monoalkyl phosphate esters.

Phagocytic uptake of fluorescent stealth and non-stealth solid lipid nanoparticles

Abstract Fluorescent non-stealth and stealth solid lipid nanoparticles (SLN) were prepared using rhodamine B base as fluorescent marker. The steric stabilization of the nanoparticles was obtained using two lipid derivatives of monomethylpoly(ethylene) glycol 2000 (PEG 2000) as stealth agents: dipalmitoylphosphatidylethanolamine-PEG 2000 and stearic acid-PEG 2000. Stealth and non-stealth SLN were in the nanometer size range. Phagocytosis was evaluated by incubating SLN with murine macrophages and determining the extent of phagocytic uptake spectrofluorimetrically; stealth SLN inhibited phagocytosis to a greater extent than did non-stealth SLN.

Thymopentin in solid lipid nanoparticles

Abstract The pentapeptide thymopentin was englobed in solid lipid nanoparticles prepared from warm microemulsions following two different methods: from O/W microemulsion by forming the more lipophilic ion-pair with hexadecylphosphate, and from W/O/W microemulsion by dissolving the pentapeptide in the aqueous internal phase. The incorporation of the hydrophilic drug was 5.2% and 1.7% respectively; in both cases, the in vitro release of thymopentin from the solid lipid nanoparticles followed a pseudo-zero-order kinetics.