Stability determination of solid lipid nanoparticles (SLN) in aqueous dispersion after addition of electrolyte

Preparation and In-Vitro Characterization of Solid Lipid Nanoparticles Containing Artemisinin and Curcumin

BACKGROUND

Malaria remains a formidable public health obstacle across Africa, Southeast Asia, and portions of South America, exacerbated by resistance to antimalarial medications, such as artemisinin-based combinations. The combination of curcumin and artemisinin shows promise due to its potential for dose reduction, reduced toxicity, synergistic effects, and suitability for drug delivery improvement.

OBJECTIVES

This research aims to enhance the solubility and dissolution rates of curcumin and artemisinin by employing Solid Lipid Nanoparticles (SLNs). Oral delivery of both drugs faces challenges due to their poor water solubility, inefficient absorption, and rapid metabolism and elimination.

METHODS

The study focuses on formulating and optimizing Solid Lipid Nanoparticles (SLNs) encapsulating artemisinin (ART) and curcumin (CUR). SLNs were developed using the hot homogenization method, incorporating ultrasonication. Drug-excipient compatibility was evaluated using Differential Scanning Calorimetry (DSC). Lipid and surfactant screening was performed to select suitable components. A 3² full factorial design was utilized to investigate the influence of lipid and surfactant concentrations on key parameters, such as entrapment efficiency (%EE) and cumulative drug release (%CDR). Additionally, evaluations of %EE, drug loading, particle size, zeta potential, and in-vitro drug release were conducted.

RESULTS

Successful development of artemisinin and curcumin SLNs was achieved using a full factorial design, demonstrating controlled drug release and high entrapment efficiency. The optimized nanoparticles exhibited a size of 114.7nm, uniformity (PDI: 0.261), and a zeta potential of -9.24 mV. Artemisinin and curcumin showed %EE values of 79.1% and 74.5%, respectively, with cumulative drug release of 85.1% and 80.9%, respectively. The full factorial design indicated that increased lipid concentration improved %EE, while higher surfactant concentration enhanced drug release and %EE. Stability studies of the optimized batch revealed no alterations in physical or chemical characteristics.

CONCLUSION

The study successfully developed Solid Lipid Nanoparticles (SLNs) for artemisinin and curcumin, achieving controlled drug release, high entrapment efficiency, and desired particle size and uniformity. This advancement holds promise for enhancing drug delivery of herbal formulations.

Prolonged Release Niosomes For Ocular Delivery of Loteprednol: Ocular Distribution Assessment on Dry Eye Disease Induced Rabbit Model

Loteprednol etabonate (LE) is a topical corticosteroid for the symptomatic management of ocular conditions, encompassing both allergic and infectious etiologies. Owing to the dynamic and static barriers of the eye, LE exhibits significantly low bioavailability, necessitating an increase in the frequency of drug administration. The objective of this study is to overcome the limitations by developing niosomal systems loaded with LE. Design of Experiments (DoE) approach was used for the development of optimal niosome formulation. The optimal formulation was characterized using DLS, FT-IR, and DSC analysis. In vitro and ex vivo release studies were performed to demonstrate drug release patterns. After that HET-CAM evaluation was conducted to determine safety profile. Then, in vivo studies were carried out to determine therapeutic activity of niosomes. Zeta potential (ZP), particle size, polydispersity index (PI), and encapsulation efficacy (EE) were -33.8 mV, 89.22 nm, 0.192, and 89.6%, respectively. Medicated niosomes had a broad distribution within rabbit eye tissues and was absorbed by the aqueous humor of the bovine eye for up to 6 h after treatment. Cumulative permeated drug in the bovine eye and rabbit eye were recorded 52.45% and 54.8%, respectively. No irritation or hemorrhagic situation was observed according to the results of HET-CAM study. Thus, novel LE-loaded niosomal formulations could be considered as a promising treatment option for the dry-eye-disease (DED) due to enhanced bioavailability and decreased side effects.

Anti-obesity effects of chlorogenic acid and caffeine- lipid nanoparticles through PPAR-γ/C/EBP-ɑ pathways

Obesity is considered one of the most crucial health problems of the century. Therefore, reducing obesity is critically important. Caffeine (CF) and chlorogenic acid (CLA), which are substantial components in green bean coffee which maximize thermogenesis in brown adipose tissue. In our study, we have prepared CF, CLA, and CF + CLA loaded-solid lipid nanoparticles (SLN) since the SLNs are cost-effective, tissue-localized, and highly stable. The central composite design model was preferred to select the optimized formulation. UHPLC was used for quantification related to the CF and CLA amounts. The high-pressure homogenization (HPH) method was used while SLN formulations were prepared in the presence of poloxamer® 407 (surfactant) and Compritol® 888 ATO (solid lipid). The nanoparticles were characterized, followed by the utilization of 3T3-F442A cell lines for the evaluation of the adipogenesis activity of the formulations. Then, rt-PCR and ELISA studies of adipogenic markers were conducted. After optimal formulations were selected with an average of 110.2 ± 0.1 nm, CF (1 mM) + CLA (0.5 mM)-loaded SLN formulation has been proven significantly effective by using PPAR-γ/C/EBP-a pathways. In a nutshell, our study has shown that CF + CLA loaded-SLN has been affected 45.8% times more than regular extracted coffee (p < 0.05) on the adipocyte cells.

Physicochemical and biopharmaceutical aspects influencing skin permeation and role of SLN and NLC for skin drug delivery

The skin is a complex and multifunctional organ, in which the static versus dynamic balance is responsible for its constant adaptation to variations in the external environment that is continuously exposed. One of the most important functions of the skin is its ability to act as a protective barrier, against the entry of foreign substances and against the excessive loss of endogenous material. Human skin imposes physical, chemical and biological limitations on all types of permeating agents that can cross the epithelial barrier. For a molecule to be passively permeated through the skin, it must have properties, such as dimensions, molecular weight, pKa and hydrophilic-lipophilic gradient, appropriate to the anatomy and physiology of the skin. These requirements have limited the number of commercially available products for dermal and transdermal administration of drugs. To understand the mechanisms involved in the drug permeation process through the skin, the approach should be multidisciplinary in order to overcome biological and pharmacotechnical barriers. The study of the mechanisms involved in the permeation process, and the ways to control it, can make this route of drug administration cease to be a constant promise and become a reality. In this work, we address the physicochemical and biopharmaceutical aspects encountered in the pathway of drugs through the skin, and the potential added value of using solid lipid nanoparticles (SLN) and nanostructured lipid vectors (NLC) to drug permeation/penetration through this route. The technology and architecture for obtaining lipid nanoparticles are described in detail, namely the composition, production methods and the ability to release pharmacologically active substances, as well as the application of these systems in the vectorization of various pharmacologically active substances for dermal and transdermal applications. The characteristics of these systems in terms of dermal application are addressed, such as biocompatibility, occlusion, hydration, emollience and the penetration of pharmacologically active substances. The advantages of using these systems over conventional formulations are described and explored from a pharmaceutical point of view.

Solid Lipid Nanoparticles as Carriers of Natural Phenolic Compounds

Phenolic compounds are one of the most widespread classes of compounds in nature, with several beneficial biological effects being associated with their anti-oxidant and anti-carcinogenic activities. Their application in the prevention or treatment of numerous chronic diseases have been studied, but a major drawback is still the low bioavailability of these compounds, as well as their instability towards pH, temperature, and light in some cases. Nanotechnology has emerged as an alternative to overcome these limitations, and the use of lipidic encapsulation systems is a promising technique to achieve an efficient drug delivery, protecting molecules from external factors and improving their bioavailability. In this review, solid lipid nanoparticles and nanostructured lipid carriers are highlighted as an important tool for the improvement of the bioavailability and stability of natural phenolic compounds, including their preparation methods and functionalization approaches and the discussion of several applications for putative use in cosmetic and pharmacologic products.

Formulating SLN and NLC as Innovative Drug Delivery Systems for Non-Invasive Routes of Drug Administration

Colloidal carriers diverge depending on their composition, ability to incorporate drugs and applicability, but the common feature is the small average particle size. Among the carriers with the potential nanostructured drug delivery application there are SLN and NLC. These nanostructured systems consist of complex lipids and highly purified mixtures of glycerides having varying particle size. Also, these systems have shown physical stability, protection capacity of unstable drugs, release control ability, excellent tolerability, possibility of vectorization, and no reported production problems related to large-scale. Several production procedures can be applied to achieve high association efficiency between the bioactive and the carrier, depending on the physicochemical properties of both, as well as on the production procedure applied. The whole set of unique advantages such as enhanced drug loading capacity, prevention of drug expulsion, leads to more flexibility for modulation of drug release and makes Lipid-based nanocarriers (LNCs) versatile delivery system for various routes of administration. The route of administration has a significant impact on the therapeutic outcome of a drug. Thus, the non-invasive routes, which were of minor importance as parts of drug delivery in the past, have assumed added importance drugs, proteins, peptides and biopharmaceuticals drug delivery and these include nasal, buccal, vaginal and transdermal routes. The objective of this paper is to present the state of the art concerning the application of the lipid nanocarriers designated for non-invasive routes of administration. In this manner, this review presents an innovative technological platform to develop nanostructured delivery systems with great versatility of application in non-invasive routes of administration and targeting drug release.

Amazonia Products in Novel Lipid Nanoparticles for Fucoxanthin Encapsulation

Lipid nanoparticles (LNs) are traditional systems able to effectively increase skin hydration. However, due to its reduced viscosity, LNs suspensions are less attractive for skin administration. To overcome this disadvantage, the LN were incorporated in the semi-solid formulation is easy manipulation. This study demonstrated that it is possible to obtain novel LN-loaded fucoxanthin (LN-FUCO) for topical administration containing a combination of bacuri butter and tucumã oil prepared by high shear homogenization for improved stability. The particle size was found to be 243.0 nm and the entrapment efficiency up to 98% of FUCO was incorporated and achieved the suitability of formula. The LN-FUCO hydrogel characteristics of slight acidity, drug content near 100%, and nanometric mean size assure to this formulation high compatibility to dermal application. Photostability assay by UVA, LN-FUCO, and LN-FUCO hydrogel improved photostability and conferred greater protection against FUCO degradation. The results obtained from in vitro skin permeation studies presented a significant difference between LN-FUCO hydrogel and FUCO (p < 0.05), with no detection of the drug in the receptor medium. Therefore, high shear homogenization is demonstrated to be a simple, available, and effective method to prepare high-quality LN-FUCO hydrogel for topical application.

Potential of Lipid Nanoparticles (SLNs and NLCs) in Enhancing Oral Bioavailability of Drugs with Poor Intestinal Permeability

Lipid-based drug delivery systems has become a popular choice for oral delivery of lipophilic drugs with dissolution rate limited oral absorption. Lipids are known to enhance oral bioavailability of poorly water-soluble drugs in multiple ways like facilitating dissolution as micellar solution, enhancing the lymphatic uptake and acting as inhibitors of efflux transporters. Lipid nanoparticles are matrix type lipid-based carrier systems which can effectively encapsulate both lipophilic and hydrophilic drugs. Lipid nanoparticles namely solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC) are versatile drug delivery system and can be used for multiple routes of delivery like parenteral, topical, ocular, transdermal, and oral. Lipid nanoparticles are particularly attractive vehicles for peroral delivery of drugs with oral bioavailability problems as they are composed of lipid excipients which are cheap, easily available, and non-toxic; manufacturing technique is simple and readily scalable for large-scale production; the formulations provide controlled release of active components and have no stability issue. A large number of drugs have been incorporated into lipid nanoparticles with the objective of overcoming their poor oral bioavailability. This review tries to assess the potential of lipid nanoparticles for enhancing the oral bioavailability of drugs with permeability limited oral absorption such as drugs belonging to class IV of Biopharmaceutic Classification System (BCS) and protein and peptide drugs and also discusses the mechanism behind the bioavailability enhancement and safety issues related to such delivery systems.

Solid lipid nanoparticles for ocular delivery of isoniazid: evaluation, proof of concept and in vivo safety & kinetics

AIM

Evaluation of solid lipid nanoparticles (SLNs) for ocular delivery of isoniazid (INH).

MATERIALS & METHODS

INH-SLNs were characterized for morphological, thermal, crystalline and nuclear magnetic resonance properties. In vitro release and ex vivo corneal permeability of INH-SLNs was also evaluated. Proof-of-concept uptake studies were performed in corneal and conjunctival cell lines and in vivo in rat eye using fluorescein-labeled SLNs. Antimycobacterial activity of INH-SLNs was confirmed. In vivo aqueous humor pharmacokinetics, toxicity and tolerance was performed in rabbit/rat eye.

RESULTS

INH-SLNs showed extended release (48 h), enhanced corneal permeability (1.6-times), five-times lower MIC, significant in vitro and in vivo uptake of fluorescein-labeled SLNs, 4.2-times ocular bioavailability (area under the curve) and in vivo acute and repeat dose safety.

CONCLUSION

INH-SLNs are an effective ocular delivery system.

Solid lipid nanoparticles for thermoresponsive targeting: evidence from spectrophotometry, electrochemical, and cytotoxicity studies

Thermoresponsive drug delivery systems are designed for the controlled and targeted release of therapeutic payload. These systems exploit hyperthermic temperatures (>39°C), which may be applied by some external means or due to an encountered symptom in inflammatory diseases such as cancer and arthritis. The objective of this paper was to provide some solid evidence in support of the hypothesis that solid lipid nanoparticles (SLNs) can be used for thermoresponsive targeting by undergoing solid–liquid phase transition at their melting point (MP). Thermoresponsive lipid mixtures were prepared by mixing solid and liquid natural fatty acids, and their MP was measured by differential scanning calorimetry (DSC). SLNs (MP 39°C) containing 5-fluorouracil (5-FU) were synthesized by hot melt encapsulation method, and were found to have spherical shape (transmission electron microscopy studies), desirable size (<200 nm), and enhanced physicochemical stability (Fourier transform infrared spectroscopy analysis). We observed a sustained release pattern (22%–34%) at 37°C (5 hours). On the other hand, >90% drug was released at 39°C after 5 hours, suggesting that the SLNs show thermoresponsive drug release, thus confirming our hypothesis. Drug release from SLNs at 39°C was similar to oleic acid and linoleic acid nanoemulsions used in this study, which further confirmed that thermoresponsive drug release is due to solid–liquid phase transition. Next, a differential pulse voltammetry-based electrochemical chemical detection method was developed for quick and real-time analysis of 5-FU release, which also confirmed thermoresponsive drug release behavior of SLNs. Blank SLNs were found to be biocompatible with human gingival fibroblast cells, although 5-FU-loaded SLNs showed some cytotoxicity after 24 hours. 5-FU-loaded SLNs showed thermoresponsive cytotoxicity to breast cancer cells (MDA-MB-231) as cytotoxicity was higher at 39°C (cell viability 72%–78%) compared to 37°C (cell viability >90%) within 1 hour. In conclusion, this study presents SLNs as a safe, simple, and effective platform for thermoresponsive targeting.

Skin targeting of resveratrol utilizing solid lipid nanoparticle-engrossed gel for chemically induced irritant contact dermatitis

Irritant contact dermatitis (ICD) is a chronic and relapsing skin disease with severe eczematous lesions. Despite its growing prevalence, therapeutic treatments remain limited. Long-term topical corticosteroid treatment can induce skin atrophy, hypopigmentation, and increase in transepidermal water loss. An innovative dermal treatment is essential to reduce the side effects of corticosteroids. Topical resveratrol (RES), although effective for ICD, is a challenging molecule due to low solubility and poor bioavailability. The objective of this work was to build RES-loaded solid lipid nanoparticles (RES-SLNs) with skin targeting. For this purpose, RES-SLNs were prepared using the probe ultrasonication method utilizing Precirol ATO 5 and Tween 20. The RES-SLNs were evaluated for particle size, entrapment efficiency (EE), and transmission electron microscopy (TEM) studies. Further, RES-SLNs were incorporated into Carbopol gel and investigated for ex vivo skin permeation, deposition study on human cadaver skin, and finally skin irritation study on New Zealand White rabbits. It was further assessed for possible beneficial effects on ICD using BALB/c mice. RES-SLN showed mean size below 100 nm and 68-89% EE. TEM studies confirmed spherical particles in the nanometer range. An ex vivo study of RES-SLN-loaded gel exhibited controlled drug release up to 24 h; similarly, in vitro drug deposition studies showed potential of skin targeting with no skin irritation. RES-SLN gel confirmed competent suppression of ear swelling and reduction in skin water content in the BALB/c mouse model of ICD when compared to marketed gel. Thus, the formulated RES-SLN gel would be a safe and effective alternative to conventional vehicles for treatment of ICD.

Topical phenytoin nanostructured lipid carriers: design and development

Phenytoin (PHT) is an antiepileptic drug that was reported to exhibit high wound healing activity. Nevertheless, its limited solubility, bioavailability, and inefficient distribution during topical administration limit its use. Therefore, this study aims to develop, characterize nanostructured lipid carriers (NLCs), and evaluate their potential in topical delivery of PHT to improve the drug entrapment efficiency and sustained release. The NLCs were prepared by hot homogenization followed by ultra sonication method using 2³ factorial design. NLC formulations were characterized regarding their particle size (PS), zeta potential (ZP), entrapment efficiency percent (%EE), surface morphology, physicochemical stability, and in vitro release studies. The optimized NLC (F7) was further incorporated in 1%w/v carbopol gel and then characterized for appearance, pH, viscosity, stability, and in vitro drug release. The prepared NLCs were spherical in shape and possessed an average PS of 121.4-258.2 nm, ZP of (-15.4)-(-32.2) mV, and 55.24-88.80 %EE. Solid-state characterization revealed that the drug is dispersed in an amorphous state with hydrogen bond interaction between the drug and the NLC components. NLC formulations were found to be stable at 25 °C for six months. The stored F7-hydrogel showed insignificant changes in viscosity and drug content (p>.05) up to six months at 25 °C that pave a way for industrial fabrication of efficient PHT products. In vitro release studies showed a sustained release from NLC up to 48 h at pH 7.4 following non-Fickian Higuchi kinetics model. These promising findings encourage the potential use of phenytoin loaded lipid nanoparticles for future topical application.

Preclinical safety of solid lipid nanoparticles and nanostructured lipid carriers: Current evidence from in vitro and in vivo evaluation

Solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC) were designed as exceptionally safe colloidal carriers for the delivery of poorly soluble drugs. SLN/NLC have the particularity of being composed of excipientsalready approved for use in medicines for human use, which offers a great advantage over any other nanoparticulate system developed from novel materials. Despite this fact, any use of excipients in new route of administration or in new dosage form requires evidence of safety. After 25 years of research on SLN and NLC, enough evidence on their preclinical safety has been published. In the present work, published data on in vitro and in vivo compatibility of SLN/NLC have been surveyed, in order to provide evidence of high biocompatibility distinguished by intended administration route. We also identified critical factors and possible weak points in SLN/NLC formulations, such as the effect of surfactants on the cell viability in vitro, which should be considered for further development.

Lipid-based nanosystems for CD44 targeting in cancer treatment: recent significant advances, ongoing challenges and unmet needs

Extensive experimental evidence demonstrates the important role of hyaluronic acid (HA)-CD44 interaction in cell proliferation and migration, inflammation and tumor growth. Taking advantage of this interaction, the design of HA-modified nanocarriers has been investigated for targeting CD44-overexpressing cells with the purpose of delivering drugs to cancer or inflammatory cells. The effect of such modification on targeting efficacy is influenced by several factors. In this review, we focus on the impact of HA-modification on the characteristics of lipid-based nanoparticles. We try to understand how these modifications influence particle physicochemical properties, interaction with CD44 receptors, intracellular trafficking pathways, toxicity, complement/macrophage activation and pharmacokinetics. Our aim is to provide insight in tailoring particle modification by HA in order to design more efficient CD44-targeting lipid nanocarriers.

Advances in lipid-based drug delivery: enhancing efficiency for hydrophobic drugs

INTRODUCTION

Many drug candidates with high therapeutic efficacy have low water solubility, which limits the administration and transport across physiological barriers, for example, the tumor tissue barrier. Therefore, strategies are needed to permeabilize the physiological barriers safely so that hydrophobic drugs may be delivered efficiently.

AREAS COVERED

This review focuses on prospects for therapeutic application of lipid-based drug delivery carriers that increase hydrophobic drugs to improve their solubility, bioavailability, drug release, targeting and absorption. Moreover, novel techniques to prepare for lipid-based drug delivery to extend pharmaceuticals with poor bioavailability such as surface modifications of lipid-based drug delivery are presented. Industrial developments of several drug candidates employing these strategies are discussed, as well as applications and clinical trials.

EXPERT OPINION

Overall, hydrophobic drugs can be encapsulated in the lipid-based drug delivery systems, represent a relatively safe and promising strategy to extend drug retention, lengthen the lifetime in the circulation, and allow active targeting to specific tissues and controllable drug release in the desirable sites. However, there are still noticeable gaps that need to be filled before the theoretical advantage of these formulations may truly be realized such as investigation on the use of lipid-based drug delivery for administration routes. This research may provide further interest within the area of lipid-based systems, both in industry and in the clinic.

Oral Delivery of Bovine Lactoferrin Using Pectin- and Chitosan-Modified Liposomes and Solid Lipid Particles: Improvement of Stability of Lactoferrin

A critical problem associated with delivery of bovine lactoferrin (bLf) by the oral route is low bioavailability, which is derived from the enzymatic degradation in the gastrointestinal tract and poor permeation across the intestinal epitheliums. Particulate carrier systems have been identified to protect bLf against proteolysis via encapsulation. This study aimed to evaluate the physico-chemical stability of bLf-loaded liposomes and solid lipid particles (SLPs) modified by pectin and chitosan when exposed to various stress conditions. Transmission electron microscopy results showed liposomes and SLPs had a classic shell-core structure with polymer layers surrounded on surface, but the structure appeared to be partially broken after digestion in simulated intestinal fluid (SIF). Although HPLC and sodium dodecyl sulphate-polyacrylamide gel electrophoresis methods qualitatively and quantitatively described either liposomes or SLPs could retain intact bLf against proteolysis in SIF to some extent, all liposome formulations showed rapid rate of lipolysis mediated by pancreatic enzymes. On the other hand, all SLP formulations showed higher heat resistance and greater electrolyte tolerance compared to liposome formulations. After 180 days storage time, liposome-loaded bLf was completely degraded, whereas almost 30% of intact bLf still remained in SLP formulations. Overall, SLPs are considered as primary choice for oral bLf delivery.

Drug Interaction Between Oral Cyclosporine Modified and Iron

Objective: To describe a recent case of suspected interaction between oral cyclosporine modified and iron. Case Summary: A 33-year-old man underwent urgent cardiac transplantation for refractory cardiogenic shock caused by acute myocarditis. The patient had persistently low levels of cyclosporine despite a dose increase of the drug after the change of administration route from intravenous to oral. Spacing the administration of cyclosporine modified from oral iron resolved the problem. This drug interaction was reported as “probable” as determined by a Drug Interaction Probability Scale score of 7. Using this scoring system, the patient experienced a probable drug interaction between cyclosporine and iron both administered orally, and we surmise that the mechanism is that iron physicochemically destabilizes the cyclosporine microemulsion when both are administered concurrently. Discussion: This may be because of the interaction between cyclosporine microemulsion and iron because this cation can destabilize the immunosuppressant dosage form. Conclusions: Taking into account that joint administration of oral iron and cyclosporine modified can generate a physicochemical interaction that involves a decrease in the absorption of cyclosporine modified, we believe that it is necessary to recommend spacing administrations of both drugs as well as monitoring levels of cyclosporine in order to ensure optimal levels of immunosuppression.

Solid lipid nanoparticle-based calix[n]arenes and calix-resorcinarenes as building blocks: synthesis, formulation and characterization

Solid lipid nanoparticles (SLNs) have attracted increasing attention during recent years. This paper presents an overview about the use of calix[n]arenes and calix-resorcinarenes in the formulation of SLNs. Because of their specific inclusion capability both in the intraparticle spaces and in the host cavities as well as their capacity for functionalization, these colloidal nanostructures represent excellent tools for the encapsulation of different active pharmaceutical ingredients (APIs) in the area of drug targeting, cosmetic additives, contrast agents, etc. Various synthetic routes to the supramolecular structures will be given. These various routes lead to the formulation of the corresponding SLNs. Characterization, properties, toxicological considerations as well as numerous corresponding experimental studies and analytical methods will be also exposed and discussed.

Astragaloside IV-loaded nanoparticle-enriched hydrogel induces wound healing and anti-scar activity through topical delivery

This study aims to investigate the novel preparation of solid lipid nanoparticle-enriched hydrogel (SLN-gel) for the topical delivery of astragaloside IV and to determine the effects of astragaloside IV-based SLN-gel on wound healing and anti-scar formation. Solid lipid nanoparticles (SLNs) were prepared through the solvent evaporation method. The particle size, polydispersity index (PDI), zeta potential (ZP), encapsulation efficiency (EE), drug release, and morphological properties of the SLNs were characterized. The optimized SLNs were incorporated in carbomer hydrogel to form an SLN-enriched gel (SLN-gel) carrier. The effects of astragaloside IV-enriched SLNs on wound healing were determined using the wound scratch test, and their uptake by skin cells was tested in vitro. With the rat full-skin excision model, the in vivo regulation of astragaloside IV-based SLN-gel in the wound stages of re-epithelization, angiogenesis, and extracellular matrix remodeling was investigated. The best formulation of astragaloside IV-based SLNs had high EE (93% ± 5%) and ZP (-23.6 mV ± 1.5 mV), with a PDI of 0.18 ± 0.03 and a drug loading percentage of 9%. Astragaloside IV-based SLNs and SLN-gel could release drug sustainably. Astragaloside IV-based SLNs enhanced the migration and proliferation of keratinocytes and increased drug uptake on fibroblasts in vitro (P<0.01) through the caveolae endocytosis pathway, which was inhibited by methyl-β-cyclodextrin. Astragaloside IV-based SLN-gel strengthened wound healing and inhibited scar formation in vivo by increasing wound closure rate (P<0.05) and by contributing to angiogenesis and collagen regular organization. SLN-enriched gel is a promising topical drug delivery system. Astragaloside IV-loaded SLN-enriched gel was proven as an excellent topical preparation with wound healing and anti-scar effects.

Recent advances in lipid nanoparticle formulations with solid matrix for oral drug delivery

Lipid nanoparticles based on solid matrix have emerged as potential drug carriers to improve gastrointestinal (GI) absorption and oral bioavailability of several drugs, especially lipophilic compounds. These formulations may also be used for sustained drug release. Solid lipid nanoparticle (SLN) and the newer generation lipid nanoparticle, nanostructured lipid carrier (NLC), have been studied for their capability as oral drug carriers. Biodegradable, biocompatible, and physiological lipids are generally used to prepare these nanoparticles. Hence, toxicity problems related with the polymeric nanoparticles can be minimized. Furthermore, stability of the formulations might increase than other liquid nano-carriers due to the solid matrix of these lipid nanoparticles. These nanoparticles can be produced by different formulation techniques. Scaling up of the production process from lab scale to industrial scale can be easily achieved. Reasonably high drug encapsulation efficiency of the nanoparticles was documented. Oral absorption and bioavailability of several drugs were improved after oral administration of the drug-loaded SLNs or NLCs. In this review, pros and cons, different formulation and characterization techniques, drug incorporation models, GI absorption and oral bioavailability enhancement mechanisms, stability and storage condition of the formulations, and recent advances in oral delivery of the lipid nanoparticles based on solid matrix will be discussed.

Paclitaxel-loaded glyceryl palmitostearate nanoparticles: in vitro release and cytotoxic activity

Solid lipid nanoparticles (SLNs) of paclitaxel using glyceryl palmitostearate (GPS) as matrix were prepared by modified hot homogenization method. The SLNs were characterized for mean particle size, percent entrapment efficiency, and zeta potential, which were found to be 207 nm, 96.26%, and -28.26 mV, respectively. Transmission electron microscopic studies revealed that the prepared SLNs were of spherical shape. Drug retarding efficiency of the lipid (GPS) was better in pH 7.4 compared with pH 3.5. The release profile showed tendency to follow Higuchi diffusion pattern in both the media. Chemosensitivity assay carried out using B16F10 cell lines showed that antiproliferative activity of paclitaxel was not hindered because of encapsulation.

Preparation and characterization of stearic acid-pullulan nanoparticles

For a new anticancer drug carrier, we synthesized 4 compositions of amphiphilic stearic acidconjugated pullulan (SAP) and characterized them with FT-IR spectroscopy. Crystalline changes were verified by x-ray diffraction patterns before and after synthesis of the SAP conjugate. SAP nanoparticles were prepared by a diafiltration method, and the fluorescence spectroscopy using pyrene showed particle self-assembly in water. SAP nanoparticles were spherical in TEM photos, and particle size ranged between 200 approximately 500 nm in photon correlation spectroscopy. Release of all-trans-retinoic acid from the SAP nanoparticles was maintained over 5 weeks. For further study in vivo, we tested the cytotoxicity of SAP nanoparticles using an MTT assay, and cytotoxicity was augmented as the molar mass of stearic acid increased in human liver carcinoma HepG2 cells. Therefore, SAP nanoparticles might be a promising longterm delivery carrier for hydrophobic therapeutic molecules with the appropriate composition.

Studies on paclitaxel-loaded glyceryl monostearate nanoparticles

Solid lipid nanoparticles (SLNs) of Paclitaxel were prepared by modified Hot homogenization method using Glyceryl monostearate (GMS). The SLNs were characterized for its physicochemical characteristics such as mean particle size, percentage entrapment efficiency and zeta potential, which were found to be 226 nm, 92.43% and -29.4 mV, respectively. The Transmission Electron Microscopy (TEM) studies showed that prepared SLNs were of spherical shape. The drug retarding efficiency of the lipid (GMS) was better in pH 7.4 compared to pH 3.5. The release profile showed a tendency to follow Higuchi diffusion pattern at pH 7.4 and Peppas-Korsenmeyer model at pH 3.5. Chemosensitivity assay carried out using B16F10 cell lines showed that anti-proliferative activity of Paclitaxel was not hindered due to encapsulation.

Lipid nanoparticles: effect on bioavailability and pharmacokinetic changes

The main aim of pharmaceutical technology research is the design of successful formulations for effective therapy, taking into account several issues including therapeutic requirements and patient compliance. In this regard, several achievements have been reported with colloidal carriers, in particular with lipid nanoparticles, due to their unique physicochemical properties. For several years these carriers have been showing potential success for several administration routes, namely oral, dermal, parenteral, and, more recently, for pulmonary and brain targeting. The present chapter provides a review of the use of solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC) to modify the release profile and the pharmacokinetic parameters of active pharmaceutical ingredients (APIs) incorporated in these lipid matrices, aiming to modify the API bioavailability, either upwards or downwards depending on the therapeutic requirement. Definitions of the morphological characteristics, surface properties, and polymorphic structures will also be given, emphasizing their influence on the incorporation parameters of the API, such as yield of production, loading capacity, and encapsulation efficiency.

Formulation and evaluation of lidocaine lipid nanosystems for dermal delivery

The objective of the present investigation was to formulate solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC) for improving the dermal delivery of a local anesthetic agent lidocaine (LID). SLN and NLC were characterized for particle size distribution, polydispersity index, entrapment efficiency, X-ray powder diffraction pattern (XRD), thermal behavior by differential scanning colorimeter (DSC) and surface morphology by transmission electron microscopy (TEM). LID-loaded SLN and NLC were formulated into hydrogels for topical application. The in vitro permeation profiles of LID SLN gel, LID NLC gel, and a marketed LID formulation (Xylocaine gel) were evaluated by using guinea pig skin. The in vivo efficacy of LID SLN gel, LID NLC gel, and a marketed LID formulation (Xylocaine gel) gel was evaluated on guinea pig using pinprick test. LID SLN showed a particle size of 78.1 nm with a polydispersity index of 0.556, whereas LID NLC showed a particle size of 72.8 nm with a polydispersity index of 0.463. The entrapment efficiency of LID in both SLN and NLC was 97% and 95.9%, respectively. The TEM studies revealed the almost spherical nature of LID SLN and NLC formulations. The XRD and DSC studies of LID SLN suggested amorphization of drug in the carrier system. The SLN formulation was stable with respect to particle size, polydispersity, and entrapment efficiency for 6 months at 40 degrees C/75% relative humidity (RH). Negligible leakage was observed for the NLC formulation when stored for 1 month at 40 degrees C/75% RH. In vitro permeation studies indicated that LID SLN gel and LID NLC gel significantly sustained the LID release compared to that of Xylocaine gel. The in vivo efficacy results supported the results of the in vitro permeation studies wherein the LID SLN gel and LID NLC gel resulted in fivefold and sixfold increase in duration of anesthesia, respectively, compared to that of Xylocaine gel.

Lipid nanoparticles for transdermal delivery of flurbiprofen: formulation, in vitro, ex vivo and in vivo studies

The aim of the study is to prepare aqueous dispersions of lipid nanoparticles – flurbiprofen solid lipid nanoparticles (FLUSLN) and flurbiprofen nanostructured lipid carriers (FLUNLC) by hot homogenization followed by sonication technique and then incorporated into the freshly prepared hydrogels for transdermal delivery. They are characterized for particle size, for all the formulations, more than 50% of the particles were below 300 nm after 90 days of storage at RT. DSC analyses were performed to characterize the state of drug and lipid modification. Shape and surface morphology were determined by TEM which revealed fairly spherical shape of the formulations. Further they were evaluated for in vitro drug release characteristics, rheological behaviour, pharmacokinetic and pharmacodynamic studies. The pharmacokinetics of flurbiprofen in rats following application of SLN gel (A1) and NLC gel (B1) for 24 h were evaluated. The C_max of the B1 formulation was 38.67 ± 2.77 μg/ml, which was significantly higher than the A1 formulation (C_max = 21.79 ± 2.96 μg/ml). The C_max and AUC of the B1 formulation were 1.8 and 2.5 times higher than the A1 gel formulation respectively. The bioavailability of flurbiprofen with reference to oral administration was found to increase by 4.4 times when gel formulations were applied. Anti-inflammatory effect in the Carrageenan-induced paw edema in rat was significantly higher for B1 and A1 formulation than the orally administered flurbiprofen. Both the SLN and NLC dispersions and gels enriched with SLN and NLC possessed a sustained drug release over period of 24 h but the sustained effect was more pronounced with the SLN and NLC gel

Triptolide Loaded Solid Lipid Nanoparticle Hydrogel for Topical Application

Triptolide (TP) has been shown to have anti-inflammatory, antifertility, antineoplastic, and immunosuppressive activity. However, its clinical usage is limited to some extent due to its poor water solubility and toxicity. In order to use innovative ways to administer TP and to overcome or alleviate its disadvantages, controlled-release delivery systems such as solid lipid nanoparticle(SLN(s)) have been developed. In the present paper we describe the preparation and some characterization of specialized delivery systems for TP. The transdermal delivery and anti-inflammatory activity were also evaluated. The results indicated that SLN could serve as an efficient promoter of TP penetrating into skin. Furthermore, different formulations were optimized in this study. The best formulation of SLN, consisted of tristearin glyceride, soybean lecithin, and PEG400MS, with a particle size of 123+/-0.9 nm, polydispersity index (PI) of 0.19, and zeta potential of -45 mV. When this SLN dispersion was incorporated into hydrogel, the nanoparticulate structure was maintained, and aggregation and gel phenomena of the particle could be avoided. The cumulative transdermal absorption rate in 12 h was 73.5%, whereas the conventional TP hydrogel was 45.3%. The anti-inflammatory effect is over two-fold higher than that of conventional TP hydrogel. Moreover, this SLN hydrogel consists of pharmaceutically acceptable ingredients, such as soybean lecithin and lipid, and the nanoparticle can improve safety and minimize the toxicity induced by TP.