Characterisation of surface-modified solid lipid nanoparticles (SLN): influence of lecithin and nonionic emulsifier

Cationic lipid nanosystems as carriers for nucleic acids

Solid lipid nanoparticles (SLNs) consisting of tristearin or tribehenin, and monoolein aqueous dispersions (MADs) consisting of glyceryl-monoolein have been studied as potential nanocarriers for nucleic acids. The cationic character of nanocarriers was obtained by adding cationic surfactants, such as diisobutylphenoxyethyl-dimethylbenzyl ammonium chloride (DEBDA) or PEG-15 Cocopolyamine (PCPA), to the lipid composition. The products were characterised in terms of size and morphology by Cryo-TEM and PCS. The charge properties were determined by measuring the zeta potential. Our experimental protocol enabled us to obtain homogeneous and stable cationic nanosystems within 3-6 months of production. Assessment of cytotoxicity on HepG2 cells by MTT assays indicated that MAD preparations were less toxic than SLN, and in general PCPA-containing formulations are less cytotoxic than DEBDA-containing ones. The formation of electrostatic complexes with salmon sperm or plasmid DNA, used as model nucleic acids, was evaluated by electrophoresis on agarose gel. The results confirmed that all the formulations studied are able to form the complex. Finally, we investigated the ability of SLN and MAD to deliver DNA into HepG2 cells, and to this purpose we exploited expression plasmids for green fluorescent protein or firefly luciferase. Although with reduced efficiency, the results showed that the produced nanocarriers are able to convey plasmids into cells. The data obtained encourage further study aimed at improving these new formulations and proposing them as novel in vitro transfection reagents with potential application to in vivo delivery of nucleic acids.

Solid Lipid Nanoparticles (SLN) and Nanostructured Lipid Carriers (NLC) for pulmonary application: a review of the state of the art

Drug delivery by inhalation is a noninvasive means of administration that has following advantages for local treatment for airway diseases: reaching the epithelium directly, circumventing first pass metabolism and avoiding systemic toxicity. Moreover, from the physiological point of view, the lung provides advantages for systemic delivery of drugs including its large surface area, a thin alveolar epithelium and extensive vasculature which allow rapid and effective drug absorption. Therefore, pulmonary application is considered frequently for both, the local and the systemic delivery of drugs. Lipid nanoparticles - Solid Lipid Nanoparticles and Nanostructured Lipid Carriers - are nanosized carrier systems in which solid particles consisting of a lipid matrix are stabilized by surfactants in an aqueous phase. Advantages of lipid nanoparticles for the pulmonary application are the possibility of a deep lung deposition as they can be incorporated into respirables carriers due to their small size, prolonged release and low toxicity. This paper will give an overview of the existing literature about lipid nanoparticles for pulmonary application. Moreover, it will provide the reader with some background information for pulmonary drug delivery, i.e., anatomy and physiology of the respiratory system, formulation requirements, application forms, clearance from the lung, pharmacological benefits and nanotoxicity.

Structural characterization of the phospholipid stabilizer layer at the solid-liquid interface of dispersed triglyceride nanocrystals with small-angle x-ray and neutron scattering

Dispersions of crystalline nanoparticles with at least one sufficiently large unit cell dimension can give rise to Bragg reflections in the small-angle scattering range. If the nanocrystals possess only a small number of unit cells along these particular crystallographic directions, the corresponding Bragg reflections will be broadened. In a previous study of phospholipid stabilized dispersions of β-tripalmitin platelets [Unruh, J. Appl. Crystallogr. 40, 1008 (2007)], the x-ray powder pattern simulation analysis (XPPSA) was developed. The XPPSA method facilitates the interpretation of the rather complicated small-angle x-ray scattering (SAXS) curves of such dispersions of nanocrystals. The XPPSA method yields the distribution function of the platelet thicknesses and facilitates a structural characterization of the phospholipid stabilizer layer at the solid-liquid interface between the nanocrystals and the dispersion medium from the shape of the broadened 001 Bragg reflection. In this contribution an improved and extended version of the XPPSA method is presented. The SAXS and small-angle neutron scattering patterns of dilute phospholipid stabilized tripalmitin dispersions can be reproduced on the basis of a consistent simulation model for the particles and their phospholipid stabilizer layer on an absolute scale. The results indicate a surprisingly flat arrangement of the phospholipid molecules in the stabilizer layer with a total thickness of only 12 Å. The stabilizer layer can be modeled by an inner shell for the fatty acid chains and an outer shell including the head groups and additional water. The experiments support a dense packing of the phospholipid molecules on the nanocrystal surfaces rather than isolated phospholipid domains.

Preparation and optimization of transferrin-modified-artemether lipid nanospheres based on the orthogonal design of emulsion formulation and physically electrostatic adsorption

Artemether has been used for a long time in the treatment of malaria as safe and non expensive drug. It possesses potent anticancer effects in cancer cell lines. Our aim was to develop transferrin-modified-artemether lipid nanospheres as targeted anticancer drug delivery system. In this study, artemether intravenous delivery system was prepared by emulsifying method as lipid nanospheres containing mixture of soya oil and crodamol as the core and soya lecithin and Tween 80 as coating layer. According to the physicochemical characterization, the process and formulation variables were optimized by orthogonal design and ANOVA analysis. Based on the electrostatic interaction, transferrin (TR) was physically adsorbed onto the coating layer; the effect of medium pH and the charge of the nanocarriers on the adsorption were investigated. The in vitro characterizations were carried out including, the zeta potential, AFM, TEM, FTIR, (1)H NMR and gel filtration. ART-LNSs with high entrapment efficiency, small size of about 50 nm and monodispersity were formulated. Optimized and stable TR-LNSs, a lipoprotein like structure and size, were produced. We showed a method by which TR can be bound to lipid nanospheres without the need for chemical modification as a base for the development of safe, effective and non expensive anticancer drug delivery system.

Protein-coated nanoparticles embedded in films as delivery platforms

Objectives

This work aimed to evaluate the performance of nanoparticle-loaded films based on matrices of polymethacrylates and hydroxypropylmethylcellulose (HPMC) intended for delivery of macromolecules.

Methods

Lysozyme (Lys)-loaded nanoparticles were manufactured by antisolvent co-precipitation. After size, loading efficiency and stability characterization, the selected batch of particles was further formulated into films. Films were characterized for mechanical properties, mucoadhesion, Lys release and activity after manufacture.

Key findings

We found that protein-coated nanoparticles could be obtained in USP phosphate buffer pH 6.8. Particles obtained at pH 6.8 had a z-average of 347.2 nm, a zeta-potential of 21.9 mV and 99.2% remaining activity after manufacture. This formulation was further studied for its application in films for buccal delivery. Films loaded with nanoparticles that contained Eudragit RLPO (ERL) exhibited excellent mechanical and mucoadhesive properties. Due to its higher water-swelling and solubility compared with ERL, the use of HPMC allowed us to tailor the release of Lys from films. The formulation composed of equal amounts of ERL and HPMC revealed a sustained release over 4 h, with Lys remaining fully active at the end of the study.

Conclusions

Mucoadhesive films containing protein-coated nanoparticles are promising carriers for the buccal delivery of proteins and peptides in a stable form.

Design and in vitro evaluation of finasteride-loaded liquid crystalline nanoparticles for topical delivery

In this study, liquid crystalline nanoparticles (LCN) have been proposed as new carrier for topical delivery of finasteride (FNS) in the treatment of androgenetic alopecia. To evaluate the potential of this nanocarrier, FNS-loaded LCN was prepared by ultrasonication method and characterized for size, shape, in vitro release, and skin permeation-retention properties. The particle size ranged from 153.8 to 170.2 nm with a cubical shape and exhibited controlled release profile with less than 20% of the drug released in the first 24 h. The release profile was significantly altered with addition of different additives. Formulation with lower monoolein exhibited higher skin permeation with a flux rate of 0.061±0.005 μg cm(-2) h(-1) in 24 h. The permeation however, significantly increased with glycerol, propylene glycol, and polyethylene glycol 400, while it declined for the addition of oleic acid. A similar trend was observed with skin retention study. In conclusion, FNS-loaded LCN could be advocated as a viable alternative for oral administration of the drug.

Curcumin and genistein coloaded nanostructured lipid carriers: in vitro digestion and antiprostate cancer activity

To increase the oral bioavailability of curcumin and genistein, we fabricated nanostructured lipid carriers (NLCs), and the impact of these carriers on bioaccessibility of curcumin and genistein was studied. Entrapment efficiency was more than 75% for curcumin and/or genistein-loaded NLCs. Solubility of curcumin and/or genistein in simulated intestinal medium (SIM) was >75% after encapsulating within NLCs which otherwise was <20%. Both curcumin and genistein have shown good stability (≥85%) in SIM and simulated gastric medium (SGM) up to 6 h. Coloading of curcumin and genistein had no adverse effect on solubility and stability of each molecule. Instead, coloading increased loading efficiency and the cell growth inhibition in prostate cancer cells. Collectively, these results have shown that coloaded lipid based carriers are promising vehicles for oral delivery of poorly bioaccessible molecules like curcumin and genistein.

Characterization and cytotoxicity of nanostructured lipid carriers formulated with olive oil, hydrogenated palm oil, and polysorbate 80

Nanostructured lipid carriers (NLC) composed of solid and liquid lipids, and surfactants are potentially good colloidal drug carriers. Before NLC can be used as drug carriers, the cytotoxicity of their components must be ascertained. The cytotoxicity of solid lipids (trilaurin, palmitin, docosanoid acid, and hydrogenated palm oil [HPO]) and surfactants (Polysorbate 20, 80, and 85) were determined on BALB/c 3T3 cells. The HPO and Polysorbate 80 were least cytotoxic and used with olive oil in the formulation of NLC. The particle size, polydispersity index, zeta potential, specific surface area, and crystallinity index of the NLC were 61.14 nm, 0.461, -25.4 mV, and 49.07 m(2) and 27.12% respectively, while the melting point was 4.3 °C lower than of HPO. Unlike in serum-free, NLC incubated in fetal bovine serum-supplemented medium did not show particle growth, suggesting that serum proteins in medium inhibit nanoparticles aggregation. The study also showed that NLC was less toxic to BALB/c 3T3 cells than Polysorbate 80. Thus, NLC with olive oil, HPO, and Polysorbate 80 as components are potentially good drug carriers with minimal cytotoxicity on normal cells.

Improved therapeutic performance of dithranol against psoriasis employing systematically optimized nanoemulsomes

Despite marked antipsoriatic activity of dithranol (anthralin), the drug is quite infrequently employed in therapeutic practice owing to its strong propensity to cause skin problems like irritation, erythema and peeling, and potential formulation problems like photolability and high lipophilicity. Accordingly, it was planned to systematically formulate optimized dithranol-loaded emulsomes with enhanced biocompatibility, efficacy and stability. Emulsomes were prepared by a thin film hydration technique and optimized for composition using formulation by design (FbD). The optimized dithranol-loaded emulsomes were found to substantially enhance the antipsoriatic activity on a mouse-tail model vis-à-vis marketed product. Also, the selected composition offered enhanced drug permeation and marked skin retention. The formulation was found to be quite non-irritant, stable and biocompatible in comparison to the marketed product. The present findings establish the usefulness of lipid-based colloidal carriers to increase the stability, and enhance the efficacy and patient compliance of an age-old irritant dithranol.

Brain delivery of camptothecin by means of solid lipid nanoparticles: formulation design, in vitro and in vivo studies

For the purpose of brain delivery upon intravenous injection, formulations of camptothecin-loaded solid lipid nanoparticles (SLN), prepared by hot high pressure homogenisation, were designed. Incorporation of camptothecin in the hydrophobic and acidic environment of SLN matrix was chosen to stabilise the lactone ring, which is essential for its antitumour activity, and for avoiding premature loss of drug on the way to target camptothecin to the brain. A multivariate approach was used to assess the influence of the qualitative and quantitative composition on the physicochemical properties of camptothecin-loaded SLN in comparison to plain SLN. Mean particle sizes of ≤200 nm, homogenous size distributions and high encapsulation efficiencies (>90%) were achieved for the most suitable formulations. In vitro release studies in plasma, showed a prolonged release profile of camptothecin from SLN, confirming the physical stability of the particles under physiological pH. A higher affinity of the SLN to the porcine brain capillary endothelial cells (BCEC) was shown in comparison to macrophages. MTT studies in BCEC revealed a moderate decrease in the cell viability of camptothecin, when incorporated in SLN compared to free camptothecin in solution. In vivo studies in rats showed that fluorescently labelled SLN were detected in the brain after i.v. administration. This study indicates that the camptothecin-loaded SLN are a promising drug brain delivery system worth to explore further for brain tumour therapy.

A comparative evaluation of coenzyme Q10-loaded liposomes and solid lipid nanoparticles as dermal antioxidant carriers

Background

The effective delivery of coenzyme Q10 (Q10) to the skin has several benefits in therapy for different skin pathologies. However, the delivery of Q10 to deeper layers of skin is challenging due to low aqueous solubility of Q10. Liposomes and solid lipid nanoparticles (SLN) have many advantages to accomplish the requirements in topical drug delivery. This study aims to evaluate the influence of these nanosystems on the effective delivery of Q10 into the skin.

Methods

Q10-loaded liposomes (LIPO-Q10) and SLNs (SLN-Q10) were prepared by thin film hydration and high shear homogenization methods, respectively. Particle size (PS), polydispersity index (PI), zeta potential (ZP), and drug entrapment efficiency were determined. Differential scanning calorimetry analysis and morphological transmission electron microscopy (TEM) examination were conducted. Biocompatibility/cytotoxicity studies of Q10-loaded nanosystems were performed by means of cell culture (human fibroblasts) under oxidative conditions. The protective effect of formulations against production of reactive oxygen species were comparatively evaluated by cytofluorometry studies.

Results

PS of uniform SLN-Q10 and LIPO-Q10 were determined as 152.4 ± 7.9 nm and 301.1 ± 8.2 nm, respectively. ZPs were −13.67 ± 1.32 mV and −36.6 ± 0.85 mV in the same order. The drug entrapment efficiency was 15% higher in SLN systems. TEM studies confirmed the colloidal size. SLN-Q10 and LIPO-Q10 showed biocompatibility towards fibroblasts up to 50 μM of Q10, which was determined as suitable for cell proliferation. The mean fluorescence intensity % depending on ROS production determined in cytofluorometric studies could be listed as Q10 ≥ SLN-Q10 > LIPO-Q10.

Conclusion

The LIPO-Q10 system was able to enhance cell proliferation. On the contrary, SLN-Q10 did not show protective effects against ROS accumulation. As a conclusion, liposomes seem to have advantages over SLN in terms of effective delivery of Q10 to skin for antioxidant purposes.

Influence of formulation factors on the preparation of zein nanoparticles

The main objective of the present study was to investigate the influence of various formulation parameters on the preparation of zein nanoparticles. 6,7-dihydroxycoumarin (DHC) was used as a model hydrophobic compound. The influence of pH of the aqueous phase, buffer type, ionic strength, surfactant, and zein concentration on particle size, polydispersity index, and zeta potential of DHC-loaded zein nanoparticles were studied. Smaller nanoparticles were formed when the pH was close to the isoelectric point of zein. DHC-loaded zein nanoparticles prepared using citrate buffer (pH 7.4) was better than phosphate buffer in preventing particle aggregation during lyophilization. The ionic strength did not have a significant influence on the particle size of DHC-loaded zein nanoparticles. A combination of Pluronic F68 and lecithin in 2:1 ratio stabilized the zein nanoparticles. An increase in zein concentration led to increase in particle size of DHC-loaded zein nanoparticles. The use of optimal conditions produced DHC-loaded nanoparticles of 256 ± 30 nm and an encapsulation efficiency of 78 ± 7%. Overall, the study demonstrated the optimal conditions to prepare zein nanoparticles for drug encapsulation.

Photoprotection for deltamethrin using chitosan-coated beeswax solid lipid nanoparticles

BACKGROUND

In the natural environment, photodegradation is one of the most common degradative processes of pesticides. In order to reduce the photodegradation of pesticides, and so increase their killing activity against target pests, chitosan-coated beeswax solid lipid nanoparticles (CH-BSLNs) were prepared by a combination of hot homogenization and sonication, with deltamethrin as an active ingredient.

RESULTS

Under optimal conditions, the highest encapsulation efficiency (95%) and a high payload of deltamethrin (approximately 12.5%) were achieved. In direct photolysis, in the case of CH-BSLNs after UV irradiation for 24 h, 37.3% of deltamethrin remained, as opposed to only 14.6% of the free-form deltamethrin. In addition, in indirect photolysis, in the case of CH-BSLNs after UV irradiation for 2 h in 2% acetone solution, approximately 74.5% of deltamethrin remained, as opposed to only 37.6% of the free-form deltamethrin.

CONCLUSION

CH-BSLNs showed good protection for deltamethrin against photodegradation. This novel nanocarrier may be useful in crop protection as an economical strategy to enhance the effect of pesticides in the field and protect the environment as well.

Design of cationic nanostructured heterolipid matrices for ocular delivery of methazolamide

Solid lipid nanoparticles (SLNs) formulated from one type of lipid (homolipid) suffer from low drug encapsulation and drug bursting due to crystallization of the lipid into the more ordered β modification, which leads to decreased drug entrapment and faster drug release. This study assessed the feasibility of using nanostructured lipid matrices (NLMs) for ocular delivery of methazolamide-(MZA) adopting heterolipids composed of novel mixtures of Compritol (®) and cetostearyl alcohol (CSA), and stabilized by Tween 80(®). The systems were prepared using the modified high shear homogenization followed by ultrasonication method, which avoids the use of organic solvents. A 3(2) full factorial design was constructed to study the influence of two independent variables, namely the ratio of CSA:Compritol and the concentration of Tween 80, each in three levels. The dependent variables were the entrapment efficiency percentages (EE%), mean particle size (PS), polydispersity index (PDI), and zeta potential (ZP). In vivo intraocular pressure (IOP) lowering activity for the selected formulae was compared to that of MZA solution. The results showed that increasing the ratio of CSA to Compritol increased the EE% and PS, while increasing the concentration of Tween 80, decreased PS with no significant effect on EE%. The ZP values of all formulae were positive, and greater than 30 mV. The best formula, composed of 4% CSA, 2% Compritol, 0.15% stearylamine, and 2% Tween 80, with EE% of 25.62%, PS of 207.1 nm, PDI of 0.243, and ZP of 41.50 mV, showed in vitro sustained release properties for 8 hours and lowered the intraocular pressure by 8.3 mmHg within 3 hours, with this drop in pressure lasting for 12 hours.

Nonionic surfactant and interfacial structure impact crystallinity and stability of β-carotene loaded lipid nanodispersions

The stability, crystallization, and melting behavior of canola stearin (CaSt) solid lipid nanoparticle dispersions (SLN) and canola oil-in-water emulsions (COE) with 10 wt % Poloxamer 188 (P188) or Tween 20 (T20) with and without 0.1 wt % β-carotene (BC) were investigated. Particles or droplets with diameters in the range of 115 nm were formed and stable for up to 90 days at 4 or 20 °C. Polymorphism was affected by surfactant type; that is, only β versus both β' and β were observed for the P188 and T20 SLN, respectively. According to Cryo-TEM, the emulsions and SLN were spherical versus platelet-like structures, respectively, with differences observed between SLN with P188 or T20. More surfactant was interfacially adsorbed in the SLN versus COE. Incorporation of BC at 0.1 wt % had no impact on SLN or COE size, polymorphism, or melting behavior. Less BC degradation was observed for the SLN versus COE and during storage at 4 versus 20 °C (p < 0.05).

Characterization and stability of nanostructured lipid carriers as drug delivery system

Recently more focus has been put to the development of innovative drug-delivery systems that includes polymer nanoparticles, emulsions and liposomes and solid lipid nanoparticles (SLNs). The SLNs have been proposed to be an alternative colloidal drug delivery system. The aim of this study was preparation and characterization of solid lipid nanoparticle (SLN) using varieties of emulsifier for encapsulation of the drug with poor water solubility. In these study four types of solid lipid nanoparticles were prepared based on different compositions of palm oil (S154) and lecithin (Lipoid 100) using the high pressure homogenization method. The SLN formulation had the following (palm oil+lecithin) compositions: SLN-01 (90 + 10%, respectively), SLN-02 (80 + 20%, respectively), SLN-03 (70 + 30%, respectively) and SLN-04 (60 + 40%, respectively). The SLNs were characterized and the optimum stability factors for one year storage determined. The parameters used to characterize the SLNs were particle size and polydispersity index (particle sizer), zeta potential (zetasizer), crystallinity (differential scanning calorimetry and wide angle X-ray diffraction), ultrastructure (transmission electron microscopy). Varying the palm oil and lecithin compositions resulted in SLNs of variable sizes and zeta potentials. The particle sizes of SLN-01, SLN-02, SLN-03 and SLN-04 were 298.40 +/- 11.80, 255.40 +/- 3.20, 145.00 +/- 3.39 and 273.00 +/- 86.50 nm, respectively, while the zeta potentials were -19.44 +/- 60.00, -19.50 +/- 1.80, -17.83 +/- 10.00 and -13.33 +/- 2.30 mV, respectively. Thermoanalysis and X-ray diffraction analysis showed that the SLNs had lower crystallinity than bulk lipid. The SLNs were generally round and uniform in shape under transmission electron microscopy. The SLN dimensional data suggested they had high quality physicochemical characteristics, which are conducive for the loading of poor water solubility drugs.

Current State-of-Art and New Trends on Lipid Nanoparticles (SLN and NLC) for Oral Drug Delivery

Lipids and lipid nanoparticles are extensively employed as oral-delivery systems for drugs and other active ingredients. These have been exploited for many features in the field of pharmaceutical technology. Lipids usually enhance drug absorption in the gastrointestinal tract (GIT), and when formulated as nanoparticles, these molecules improve mucosal adhesion due to small particle size and increasing their GIT residence time. In addition, lipid nanoparticles may also protect the loaded drugs from chemical and enzymatic degradation and gradually release drug molecules from the lipid matrix into blood, resulting in improved therapeutic profiles compared to free drug. Therefore, due to their physiological and biodegradable properties, lipid molecules may decrease adverse side effects and chronic toxicity of the drug-delivery systems when compared to other of polymeric nature. This paper highlights the importance of lipid nanoparticles to modify the release profile and the pharmacokinetic parameters of drugs when administrated through oral route.

Nanocarrier possibilities for functional targeting of bioactive peptides and proteins: state-of-the-art

This review attempts to provide an updated compilation of studies reported in the literature pertaining to production of nanocarriers encasing peptides and/or proteins, in a way that helps the reader direct a bibliographic search and develop an integrated perspective of the subject. Highlights are given to bioactive proteins and peptides, with a special focus on those from dairy sources (including physicochemical characteristics and properties, and biopharmaceutical application possibilities of e.g. lactoferrin and glycomacropeptide), as well as to nanocarrier functional targeting. Features associated with micro- and (multiple) nanoemulsions, micellar systems, liposomes and solid lipid nanoparticles, together with biopharmaceutical considerations, are presented in the text in a systematic fashion.

Lipid nanoparticles containing oryzalin for the treatment of leishmaniasis

Oryzalin is a dinitroaniline drug that has attracted recent interest for the treatment of leishmaniasis. Its use as an antiparasitic therapeutic agent is limited by the low water solubility associated with an in vivo rapid clearance, leading to the administration of larger and possibly toxic doses in in vivo studies, and the use of solvents that may lead to undesirable side effects. In the present work oryzalin-containing lipid nanoparticles were produced by a emulsion-solvent evaporation technique using a composition suitable for parenteral administration, i.e., tripalmitin (solid lipid) and a complex mixture of three emulsifying agents (soya lecithin, Tween® 20 and sodium deoxycholate). Physicochemical characterization included the determination of mean particle size, polydispersity index, zeta potential, encapsulation efficiency and DSC studies. Final formulations revealed values of <140 nm (PI<0.2) and zeta potential of ≈-35 mV, as well as encapsulation efficiency >75%. The effects of various processing parameters, such as lipid and surfactant and composition and concentration, as well as the stability during the harsh procedures of autoclaving (121°C/15 min) and freeze-drying were also evaluated. Formulations revealed to be stable throughout freeze-drying and moist-heath sterilization without significant variations on physicochemical properties and no significant oryzalin losses. The use of a complex surfactant mixture proved crucial for preserving formulation stability. Particularly, lecithin appears as a key component in the stabilization of tripalmitin-based oryzalin-containing lipid nanoparticles. Finally, cell viability studies demonstrated that the incorporation of oryzalin in nanoparticles decreases cytotoxicity, thus suggesting this strategy may improve tolerability and therapeutic index of dinitroanilines.

Statistical optimization of dithranol-loaded solid lipid nanoparticles using factorial design

This study describes a 3² full factorial experimental design to optimize the formulation of dithranol (DTH) loaded solid lipid nanoparticles (SLN) by the pre-emulsion ultrasonication method. The variables drug: lipid ratio and sonication time were studied at three levels and arranged in a 3² factorial design to study the influence on the response variables particle size and % entrapment efficiency (%EE). From the statistical analysis of data polynomial equations were generated. The particle size and %EE for the 9 batches (R1 to R9) showed a wide variation of 219-348 nm and 51.33- 71.80 %, respectively. The physical characteristics of DTH-loaded SLN were evaluated using a particle size analyzer, differential scanning calorimetry and X-ray diffraction. The results of the optimized formulation showed an average particle size of 219 nm and entrapment efficiency of 69.88 %. Ex-vivo drug penetration using rat skin showed about a 2-fold increase in localization of DTH in skin as compared to the marketed preparation of DTH.

The encapsulation effect of UV molecular absorbers into biocompatible lipid nanoparticles

The efficiency of a cosmetic product depends not only on the active ingredients, but also on the carrier system devoted to improve its bioavailability. This article aims to encapsulate two couples of UV molecular absorbers, with a blocking action on both UV-A and UV-B domains, into efficient lipid nanoparticles. The effect of encapsulation on the specific properties such as sun protection factor and photostability behaviour has been demonstrated. The lipid nanoparticles with size range 30-350 nm and a polydispersity index between 0.217 and 0.244 are obtained using a modified high shear homogenisation method. The nanoparticles had spherical shapes with a single crystallisation form of lipid matrices characteristic for the least ordered crystal structure (α-form). The in vitro determination of photoprotection has led to high SPF ratings, with values of about 20, which assure a good photoprotection and filtering about 95% of UV radiation. The photoprotection effect after irradiation stage was observed to be increased more than twice compared to initial samples as a result of isomerisation phenomena. All the results have shown that good photoprotection effect and improved photostability could be obtained using such sunscreen couples, thus demonstrating that UV absorbers-solid lipid nanoparticles are promising carriers for cosmetic formulations.

A potential new therapeutic system for glaucoma: solid lipid nanoparticles containing methazolamide

Methazolamide (MTA) is an antiglaucoma drug; however, there are many side effects of its systemic administration with insufficient ocular therapeutic concentrations. The aim of this study was to formulate MTA-loaded solid lipid nanoparticles (SLNs) and evaluate the potential of SLNs as a new therapeutic system for glaucoma. SLNs were prepared by a modified emulsion-solvent evaporation method and their physicochemical characteristics were evaluated. The pharmacodynamics was investigated by determining the percentage decrease in intraocular pressure. The ocular irritation was studied by Draize test. Despite a burst release of SLNs, the pharmacodynamic experiment indicated that MTA-SLNs had higher therapeutic efficacy, later occurrence of maximum action, and more prolonged effect than drug solution and commercial product. Formulation of MTA-SLNs would be a potential delivery carrier for ocular delivery, with the advantages of a more intensive treatment for glaucoma, lower in doses and better patient compliance compared to the conventional eye drops.

Formulation development and in vitro evaluation of didanosine-loaded nanostructured lipid carriers for the potential treatment of AIDS dementia complex

The purpose of this article was to investigate the feasibility of incorporating didanosine (DDI) into nanostructured lipid carriers (NLC) for potential treatment of AIDS dementia complex. Aqueous DDI-free and DDI-loaded NLC were manufactured using hot high-pressure homogenization. The lipid matrix contained a mixture of Precirol® ATO 5 and Transcutol® HP. Photon correlation spectroscopy revealed that the mean particle size for all formulations was below 250 nm with narrow polydispersity indices. In addition, the d99% values for all formulations determined using laser diffractometry were below 400 nm with the span values ranging from 0.84 to 1.0. The zeta potential values ranged from -18.4 to -11.4 mV and the encapsulation efficiency of NLC for DDI ranged from 33.02% to 78.34%. These parameters remained relatively constant for all formulations tested following storage for 2 months at 25°C indicating that all the formulations were relatively stable. Differential scanning calorimetry revealed a decrease in the degree of crystallinity of NLC in all formulations developed relative to the bulk lipid material. In addition, wide-angle X-ray scattering showed that NLC in all formulations tested existed in a single β-modification form and that DDI that had been incorporated into the NLC appeared to be molecularly dispersed in the lipid matrices. Images of the NLC formulations obtained using transmission electron microscopy revealed that all formulations contained a mixture of spherical and nonspherical particles irrespective of the amount of DDI that was added during the manufacture of the formulations.

Structured emulsion-based delivery systems: controlling the digestion and release of lipophilic food components

There is a need for edible delivery systems to encapsulate, protect and release bioactive and functional lipophilic constituents within the food and pharmaceutical industries. These delivery systems could be used for a number of purposes: controlling lipid bioavailability; targeting the delivery of bioactive components within the gastrointestinal tract; and designing food matrices that delay lipid digestion and induce satiety. Emulsion technology is particularly suited for the design and fabrication of delivery systems for lipids. In this article we provide an overview of a number of emulsion-based technologies that can be used as edible delivery systems by the food and other industries, including conventional emulsions, nanoemulsions, multilayer emulsions, solid lipid particles, and filled hydrogel particles. Each of these delivery systems can be produced from food-grade (GRAS) ingredients (e.g., lipids, proteins, polysaccharides, surfactants, and minerals) using relatively simple processing operations (e.g., mixing, homogenizing, and thermal processing). The structure, preparation, and utilization of each type of delivery system for controlling lipid digestion are discussed. This knowledge can be used to select the most appropriate emulsion-based delivery system for specific applications, such as encapsulation, controlled digestion, and targeted release.