Solid lipid nanodispersions containing mixed lipid core and a polar heterolipid: Characterization

Fructus Xanthii and Magnolia liliiflora Volatile Oils Liposomes-Loaded Thermosensitive in situ Gel for Allergic Rhinitis Management

Purpose

The aim of the present study was to fabricate a Fructus Xanthii and Magnolia liliiflora volatile oils liposomes-loaded thermosensitive in situ gel (gel/LIP/volatile oil) for effectively treating allergic rhinitis via intranasal administration.

Patients and Methods

Particle size, polymer dispersity index (PDI), entrapment effectiveness, and cumulative drug permeation of the developed liposomes were assessed. Then, a thermoreversible in situ gel was created using the liposomes loaded with volatile oils of Fructus Xanthii and Magnolia liliiflora. The effectiveness of this treatment for allergic rhinitis was confirmed by evaluating nasal symptoms, and hematological results, after injecting the formulation into the ovalbumin (OVA)-sensitized mice, we conducted hematoxylin-eosin staining (HE) and immunohistochemistry to evaluate the outcomes. The effects of the gel/LIP/volatile oil formulation for nasal delivery of volatile oil in the treatment of rhinitis were then assessed.

Results

The average particle size was 95.1 ± 3.6 nm, and the encapsulation efficiencies of Fructus Xanthii and Magnolia liliiflora volatile oils were 70.42 ± 5.41% and 67.10 ± 6.08%, respectively. Drug loadings of Fructus Xanthii and Magnolia liliiflora volatile oils were 9.10 ± 0.98% and 16.10 ± 1.03%, respectively. The binary formulation produced a gel rapidly in the nasal cavity with a strong mucosal adherence at a temperature of delivering volatile oil to the nasal mucosa steadily and continuously. After nasal administration, the gel/LIP/volatile oil sustained the volatile oil delivery into the mucosa. In comparison to the monolithic formulations, the gel/LIP/volatile oil binary formulation exhibited superior performance in terms of drug delivery capability and pharmacodynamic effects.

Conclusion

This binary preparation displayed the ability to deliver drugs to the nasal mucosa and exhibited positive pharmacodynamic effects in treating OVA-induced rhinitis in mice. As a result, it has the potential to serve as a delivery platform for Traditional Chinese medicine in the treatment of allergic rhinitis.

Nano-platform Strategies of Herbal Components for the Management of Rheumatoid Arthritis: A Review on the Battle for Next-Generation Formulations

INTRODUCTION

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease that initially affects small joints and then spreads to the bigger joints. It also affects other organs of the body such as lungs, eyes, kidneys, heart, and skin. In RA, there is destruction of cartilage and joints, and ligaments and tendons become brittle. Damage to the joints leads to abnormalities and bone degradation, which may be quite painful for the patient.

METHOD

The nano-carriers such as liposomes, phytosomes, nanoparticles, microcapsules, and niosomes are developed to deliver the encapsulated phytoconstituents to targeted sites for the better management of RA.

RESULTS

The phytoconstituents loaded nano-carriers have been used in order to increase bioavailability, stability and reduce the dose of an active compound. In one study, the curcumin-loaded phytosomes increase the bioavailability of curcumin and also provides relief from RA symptoms. The drug-loaded nano-carriers are the better option for the management of RA.

CONCLUSION

In conclusion, there are many anti-arthritic herbal and synthetic medicine available in the market that are currently used in the treatment of RA. However, chronic use of these medications may result in a variety of side effects. Because therapy for RA is frequently necessary for the rest of ones life. The use of natural products may be a better option for RA management. These phytoconstituents, however, have several disadvantages, including limited bioavailability, low stability, and the need for a greater dosage. These problems can be rectified by using nano-technology.

A promising RNA nanotechnology in clinical therapeutics: a future perspective narrative review

Nanotechnology is the use of materials that have unique nanoscale properties. In recent years, nanotechnologies have shown promising results for human health, especially in cancer treatment. The self-assembly characteristic of RNA is a powerful bottom-up approach to the design and creation of nanostructures through interdisciplinary biological, chemical and physical techniques. The use of RNA nanotechnology in therapeutics is about to be realized. This review discusses different kinds of nano-based drug delivery systems and their characteristic features.

Carnauba wax nanoemulsion applied as an edible coating on fresh tomato for postharvest quality evaluation

Edible coatings to extend the shelf life and preserve the quality of fruit and vegetables are highly demanded nowadays. Recently, plant-based edible coatings have gained importance in the context of sustainability, which in combination with suitable top-down process can render “greener” nanoemulsions with optimized properties. Herein we developed a carnauba wax nanoemulsion (CWN) by using a high-pressure processing to be applied as an edible coating for fruit and vegetables. The as-developed nanoemulsion properties were compared to conventional carnauba wax emulsion (CWM), where CWN showed particle size diameter of 44 nm and narrow distribution, while CWM displayed larger particles and wider size distribution (from 200 to 1700 nm). For assessment of the postharvest quality, cv. ‘Debora’ tomatoes, employed here as a model, were coated with CWN or CWM, at concentrations of 9 and 18%, and then compared to uncoated fruit during storage at 23 °C for 15 days. Evaluation of fruit quality, including sugar, acids, pH, water vapor loss, firmness, gloss, color, ethylene and respiratory activity, were assessed at every 3 days, while sensory test were carried out at the end of storage. Uncoated tomatoes presented the highest water loss values, meanwhile, firmness, ethylene, and respiratory activity were not largely modified by the coatings during storage. Tomatoes coated with the CWN exhibited the highest instrumental gloss and were preferred by consumers in sensory evaluations, indicating the potential of the as-developed carnauba wax green nanoemulsion for postharvest applications.

Nano- and micro-sized carnauba wax emulsions-based coatings incorporated with ginger essential oil and hydroxypropyl methylcellulose on papaya: Preservation of quality and delay of post-harvest fruit decay

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Nanoemulsion with 18% carnauba wax maintained papaya quality by retarding firmness loss, color changes, and reducing respiration rates, resulting in delayed ripening.

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Changes in flavor was not perceived by the panel in tasting samples.

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Coatings protection level was dependent on the storage conditions.

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GEO associated with carnauba nano-emulsions, showed a positive effect in reducing natural diseases.

Carnauba wax nano and micro-sized emulsions and hydroxypropyl methylcellulose coatings, alone or combined with ginger essential oils (GEO) were applied on papayas and evaluated under several storage conditions. In a first experiment, storage parameters were: 6 days at 22 °C, and 9 days at 13 °C followed by 5 days at 22 °C. In a second experiment, storage was: 5 days at 22 °C, and 10 days at 16 °C followed by 3 days at 22 °C. Coating effects were dependent on storage conditions. While fruits were in cold storage, there were few changes; however, at 22 °C, the differences between coatings became more evident. Nanoemulsions maintained papaya quality during storage by retarding firmness loss, color changes, and reducing respiration rates, resulting in delayed ripening. GEO exhibited some positive effect on fungal disease control. Nanoemulsion-based coatings improved shelf life by reducing weight loss, color development, and slowing ripening of papaya fruit.

Atorvastatin-loaded solid lipid nanoparticles as eye drops: proposed treatment option for age-related macular degeneration (AMD)

Statins, widely prescribed for cardiovascular diseases, are also being eyed for management of age-related macular degeneration (AMD). Poor bioavailability and blood-aqueous barrier may however limit significant ocular concentration of statins following oral administration. We for the first time propose and investigate local application of atorvastatin (ATS; representative statin) loaded into solid lipid nanoparticles (SLNs), as self-administrable eye drops. Insolubility, instability, and high molecular weight > 500 of ATS, and ensuring that SLNs reach posterior eye were the challenges to be met. ATS-SLNs, developed (2339/DEL/2014) using suitable components, quality-by-design (QBD) approach, and scalable hot high-pressure homogenization, were characterized and evaluated comprehensively for ocular suitability. ATS-SLNs were 8 and 12 times more bioavailable (AUC) in aqueous and vitreous humor, respectively, than free ATS. Three-tier (in vitro, ex vivo, and in vivo) ocular safety, higher corneal flux (2.5-fold), and improved stability (13.62 times) including photostability of ATS on incorporation in ATS-SLNs were established. Autoclavability and aqueous nature are the other highlights of ATS-SLNs. Presence of intact fluorescein-labeled SLNs (F-SLNs) in internal eye tissues post–in vivo application as eye drops provides direct evidence of successful delivery. Perinuclear fluorescence in ARPE-19 cells confirms the effective uptake of F-SLNs. Prolonged residence, up to 7 h, was attributed to the mucus-penetrating nature of ATS-SLNs.

Gamma sterilization and in vivo evaluation of cationic nanostructured lipid carriers as potential ocular delivery systems for antiglaucoma drugs

Solid lipid nanoparticles and nanostructured lipid carriers showed promising results for enhancement of ocular bioavailability of drugs with poor corneal permeability. One of these drugs is methazolamide, which is an orally administered carbonic anhydrase inhibitor for glaucoma treatment. However, sterilization by autoclaving may result in loss of the physical properties of lipid nanoparticles such as particle size and surface charge. Here, we evaluated gamma radiation as an alternative sterilization method. Methazolamide loaded nanostructured lipid carriers were optimized using 2³ factorial design. Optimized formulations contained 6% lipid (85% solid lipid (Cetostearyl alcohol and glyceryl behenate) and 15% oil either medium chain triglycerides or isopropyl myristate) stabilized by 2% polysorbate 80 and 0.15% stearylamine. Nanoparticles were cationic, smaller than 500 nm, and had an entrapment efficiency of about 30%. They released methazolamide within 8 hours and showed a 5-fold enhanced reduction in intraocular pressure compared to methazolamide solution. Gamma sterilization was superior to autoclaving in preserving entrapped methazolamide, size, and surface charge of lipid nanoparticles. These findings demonstrate that gamma radiation is a viable alternative to autoclaving for sterilizing lipid nanoparticles. Moreover, this proves that nanostructured lipid carriers enhance pharmacological response of topically administered methazolamide for treating glaucoma.

Natural Lipids as Structural Components of Solid Lipid Nanoparticles and Nanostructured Lipid Carriers for Topical Delivery

BACKGROUND

Solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC) are useful drug delivery systems for dermal application. Thanks to their biocompatible and biodegradable profile, these carriers offer many advantages such as enhanced bioavailability, low toxicity, viable drug targeting and controlled release. SLN and NLC are composed of well-tolerated lipids, including natural fats and oils that are successfully used in the pharmaceutical and cosmetic dermal formulation.

OBJECTIVE

This article presents an overview of the benefits of selecting natural fats and oils as structural components of SLN and NLC for topical application.

METHODS

This review is based on data published over the past 20 years about the development of stable and nontoxic lipid nanoparticles with natural lipids. We shed light on the role of natural fats in skin restoration, as well as on the contributed penetration and occlusive properties of SLN and NLC.

RESULTS

The deliberate selection of excipients (type and lipid ratio) influences the quality of the final dermal formulation. Natural lipids show good compatibility with different active molecules and are able to create stable lipid matrices that facilitate the biopharmaceutical properties of lipid nanoparticles. Patents involving natural fats and oils in SLN and NLC composition are listed, yet it is important to note that the approved marketed formulations are mainly cosmetic, not pharmaceutical, products.

CONCLUSION

Natural lipids can enhance topical drug delivery by adding their ability of improving skin penetration and hydration to the permeation and occlusion properties of SLN and NLC.

Self-Assembled chitosan/phospholipid nanoparticles: from fundamentals to preparation for advanced drug delivery

With the development of nanotechnology, self-assembled chitosan/phospholipid nanoparticles (SACPNs) show great promise in a broad range of applications, including therapy, diagnosis, in suit imaging and on-demand drug delivery. Here, a brief review of the SACPNs is presented, and its critical underlying formation mechanisms are interpreted with an emphasis on the intrinsic physicochemical properties. The state-of-art preparation methods of SACPNs are summarized, with particular descriptions about the classic solvent injection method. Then SACPNs microstructures are characterized, revealing the unique spherical core-shell structure and the drug release mechanisms. Afterwards, a comprehensive and in-depth depiction of their emerging applications, with special attention to drug delivery areas, are categorized and reviewed. Finally, conclusions and outlooks on further advancing the SACPNs toward a more powerful and versatile platform for investigations covering from fundamental understanding to developing multi-functional drug delivery systems are discussed.

Improved antimalarial activity of caprol-based nanostructured lipid carriers encapsulating artemether-lumefantrine for oral administration

BACKGROUND

Artemether and lumefantrine display low aqueous solubility leading to poor release profile; hence the need for the use of lipid-based systems to improve their oral bioavailability so as to improve their therapeutic efficacy.

AIM AND OBJECTIVE

The objective of this work was to utilize potentials of nanostructured lipid carriers (NLCs) for improvement of the oral bioavailability of artemether and lumefantrine combination and to evaluate its efficacy in the treatment of malaria. This study reports a method of formulation, characterization and evaluation of the therapeutic efficacies of caprol-based NLC delivery systems with artemether and lumefantrine.

METHOD

The artemether-lumefantrine co-loaded NLCs were prepared using the lipid matrix (5% w/w) (containing beeswax and Phospholipon® 90H and Caprol-PGE 860), artemether (0.1%w/w) and lumefantrine (0.6%w/w), sorbitol (4%w/w), Tween® 80(2%w/w as surfactant) and distilled water (q.s to 100%) by high shear homogenization and evaluated for physicochemical performance. The in vivo antimalarial activities of the NLC were tested in chloroquine-sensitive strains of Plasmodium berghei (NK-65) using Peter´s 4-day suppressive protocol in mice and compared with controls. Histopathological studies were also carried out on major organs implicated in malaria.

RESULTS

The NLC showed fairly polydispersed nano-sized formulation (z-average:188.6 nm; polydispersity index, PDI=0.462) with no major interaction occurring between the components while the in vivo study showed a gradual but sustained drug release from the NLC compared with that seen with chloroquine sulphate and Coartem®. Results of histopathological investigations also revealed more organ damage with the untreated groups than groups treated with the formulations.

CONCLUSION

This study has shown the potential of caprol-based NLCs for significant improvement in oral bioavailability and hence antimalarial activity of poorly soluble artemether and lumefantrine. Importantly, this would improve patient compliance due to decrease in dosing frequency as a sustained release formulation.

Preparation, characterization, and physical stability of cocoa butter and tristearin nanoparticles containing β-carotene

Solid lipid nanoparticles (SLN) have emerged as a potential delivery system for bioactive ingredients, as they are associated with improving the stability of incorporated bioactive components by preventing their diffusion to the particle surface. The aim of this study was to investigate the impact of carrier lipid composition and surfactant type on the physical stability and thermal behavior of SLN containing β-carotene. As carrier lipids we used cocoa butter and/or tristearin and as surfactants we used Quillaja saponin extract in a combination with high- or low-melting lecithin. All the ingredients were food-grade. The results showed that all the SLN were physically stable and had a particle diameter < 200 nm, except for SLN containing only tristearin as carrier lipid and Quillaja saponins and low-melting lecithin as emulsifier, which showed slightly increased particle sizes during storage due to polymorphic transition. In general, this study indicated that the introduction of heterogenous lipids can improve the physical stability of the SLN due to the more random crystal structures formed. Moreover, the polymorphic stability is dependent on the surfactants applied. These results are of interest for manufacturers in food, pharmaceutical, cosmetic and personal care industries using cocoa butter or any lipid blend to enrich their products with bioactive components.

Plant-Derived Butters as Lipid Nanocarriers: A Systematic and Prospective Review

BACKGROUND

Pharmaceutical nanotechnology represents an efficient alternative for the delivery of pharmacologically active plant-derived compounds, considering their protective capacity, oral bioavailability and drug vectorization capacity. In this context, butters obtained from plant seeds have emerged as promising products for the development of pharmacologically active nanostructures. They possess a complex lipid composition, allowing the formation of different emulsion systems with solid cores, since this mixture of different triglycerides is solid at room temperature and body temperature. Therefore, the systematic mapping around the technological development of nanostructures produced from plant-derived butters is potentially valuable for researchers interested in novel alternative formulations for pharmacological therapy, with potential industrial, economic, health and societal impacts.

METHODS

Systematic review was carried out by the search of scientific papers and patents deposited in official databases concerning the development of nanostructured pharmaceutical products using plantderived butters as starting material. The publications obtained were subjected to sorting and analysis by applying the following inclusion/exclusion criteria.

RESULTS

The Solid Lipid Nanoparticle (SLN) was the type of nanostructure produced in all the analyzed scientific papers, due to the physicochemical characteristics of the lipid constituents of plantderived butters. In this sense, 54% of the articles have reported the use of Cocoa Butter for the production of nanostructures; 28% for Shea Butter; 6% for Cupuacu Butter, 6% for Murumuru Butter and 6% for Bacuri Butter.

DISCUSSION

In the technological prospection, only two patents exhibited SLN as an invention based on cocoa butter and on shea butter, respectively. The production methods employed have included: phase inversion temperature, microemulsion, hot high pressure homogenization, high shear homogenization and ultrasonication.

CONCLUSION

In light of this prospective review, the encouragement of novel studies in lipids-based nanotechnology is evident, considering the small number of findings so far, in order to stimulate new research involving plant-derived butters from easily cultivated fruits in tropical regions, then stimulating the pharmaceutical development of new therapeutic alternatives using biocompatible and sustainable raw materials.

Enhanced storage stability of solid lipid nanoparticles by surface modification of comb-shaped amphiphilic inulin derivatives

Solid lipid nanoparticles (SLNs) have been widely used as a vehicle for drug delivery. However, highly ordered lipid lattices and poor storage stability limit their practical application. Highly ordered crystal lattices may result from the low drug payload. In addition, the lipid matrix of SLNs may undergo a polymorphic transition from high energy and disordered modifications to low energy and ordered modifications during storage. This leads to drug expulsion and precipitation. Meanwhile, SLNs are susceptible to particle aggregation and size growth during storage. To improve the performance of SLNs, two comb-shaped amphiphilic macromolecular materials (CAMs), dodecyl inulin (Inu12) and octadecyl inulin (Inu18), were synthesized and utilized as emulsifiers to modify and stabilize SLNs (Inu12/Inu18-SLNs). The results indicated that Inu12 and Inu18 could more effectively reduce the lipid crystallinity and crystal lattice order of fresh SLNs versus Poloxamer 188 and Tween-80. Moreover, after six months of storage at 4 °C or 25 °C, both blank and Cyclosporine A (CsA)-loaded Inu12/Inu18-SLNs had a slower crystal transition than Tween/P188-SLNs. The particle size increases of Inu12/Inu18-SLNs were much smaller than those of Tween/P188-SLNs. The drug encapsulation efficiencies of CsA-loaded Inu12/Inu18-SLNs during storage decreased more slowly than Tween-SLNs. Therefore, Inu12 and Inu18 could more effectively inhibit lipid crystal transition and prevent particle aggregation during storage. This, in turn, leads to better storage physical stability of SLNs. Thus, the Inu12 and Inu18 CAMs were superior to Tween-80 and Poloxamer 188 (common straight-chain surfactants).

Microencapsulation of Ammonium Bicarbonate by Phase Separation and Using Palm Stearin/Carnauba Wax as Wall Materials

Ammonium bicarbonate microcapsules (AMBCMC) were prepared by phase separation method using palm stearin/carnauba wax (CNW) as wall materials. The morphology of AMBCMC showed that the microcapsules were mainly spherical shapes. DSC analysis results suggested that the microcapsule shells began melting at the temperature 47.9 °C, while the shells were thoroughly destructed at the temperature above 78.1 °C. The particle sizes of AMBCMC were chiefly distributed in the range of 30 ~ 300 μm. Ammonium bicarbonate (AMBC) in microcapsules was highly stable under different relative humidity, and AMBCMC was hardly damaged even at 95% relative humidity. The thermal stability of AMBC increased, while AMBC encapsulated in microcapsules still could decompose and release gas at 70 °C as well as free AMBC. Furthermore, AMBC encapsulated in microcapsules showed strong survivability in the presence of citric acid. The results indicated that the stability and compatibility of AMBC were effectively increased after microencapsulation.

Nanostructured lipid carriers versus solid lipid nanoparticles for the potential treatment of pulmonary hypertension via nebulization

With the non-selective vasodilating action, short half-life and first-pass metabolism of sildenafil (SC), local application in the lung for pulmonary arterial hypertension is of high demand. Although several nanosystems have been lately investigated, nanostructured lipid carriers (NLCs) give promises of potential safety, biodegradability and controlled drug release. In the current study, NLCs comprising either precirol, stearic acid or beeswax as solid lipid in presence of oleic acid as liquid lipid and PVA or poloxamer as emulsifier were prepared. Optimized NLCs (200-268 nm in size) were appraised versus SLNs both in vitro and in vivo. Precirol/PVA-based SLNs and NLCs ensued high entrapment efficiencies (EE > 95%) and controlled release behaviour over 6 h even though NLCs showed higher release profile. Stability studies at 4 °C indicated potential colloidal and entrapment stability over 3 months. Interestingly, NLCs demonstrated efficient nebulization, low interaction with mucin and higher viability of A549 cells (3-fold increase in IC₅₀ relative to SLNs) providing good aptitudes for pulmonary application. In vivo administration of free SC in rats revealed localized intra-alveolar bleeding, presumably related to excessive vasodilatation. Meanwhile, the nanoencapsulated drug confirmed normal lung parenchyma with minimal incidence of bleeding. Inspiring results highlight the potential of sildenafil-laden nanostructured lipid carriers as pulmonary drug delivery system.

Improving intestinal absorption and oral bioavailability of curcumin via taurocholic acid-modified nanostructured lipid carriers

The expression of multiple receptors on intestinal epithelial cells enables an actively targeted carrier to significantly enhance the oral delivery of payloads. Conjugating the receptors' ligands on the surfaces of a particulate-delivery system allows site-specific targeting. Here, we used taurocholic acid (TCA) as a ligand for uptake of nanostructured lipid carriers (NLCs) mediated by a bile-acid transporter to improve oral bioavailability of curcumin (Cur). First, synthesis of TCA-polyethylene glycol 100-monostearate (S100-TCA) was carried out. Then, the physical and chemical properties of S100-TCA-modified Cur-loaded NLCs (Cur-TCA NLCs) with varying levels of S100-TCA modifications were investigated. Small particle size (<150 nm), high drug encapsulation (>90%), drug loading (about 3%), negative ζ-potential (-7 to -3 mV), and sustained release were obtained. In situ intestinal perfusion studies demonstrated improved absorption rate and permeability coefficient of Cur-TCA NLCs. Depending on the degree of modification, Cur-TCA NLCs displayed about a five- to 15-fold higher area under the curve in rats after oral administration than unmodified Cur NLCs, which established that the addition of S100-TCA to the NLCs boosted absorption of Cur. Further investigations of TCA NLCs might reveal a bright future for effective oral delivery of poorly bioavailable drugs.

An Overview of Therapeutic Applications

Over the last few years' great advances have been made on the development drug delivery systems for different purposes for targeting the diseased conditions. Novel drug delivery originates from polymers or associated with some devices is generally related with the emergence of novel characteristics. These changes are what eventually comprise the value of drug delivery system and Novel drug delivery system. Novel properties become existed without making new materials. Novel drug delivery system comparable to traditional system, following Targeted Drug Delivery System (TDDS) is also called targeting drug system. A new drug delivery system makes the drugs densely gather pathological-change structures, and has an improved healing effect and less toxic side effects. The drugs can improve the strength of pharmacological action and reduce the bad effect all over the body, for they release in the target organs.

Nebulized solid lipid nanoparticles for the potential treatment of pulmonary hypertension via targeted delivery of phosphodiesterase-5-inhibitor

Phosphodiesterase type 5 (PDE-5) inhibitors - among which sildenafil citrate (SC) - play a primary role in the treatment of pulmonary hypertension (PH). Yet, SC can be only administered orally or parenterally with lot of risks. Targeted delivery of SC to the lungs via inhalation/nebulization is mandatory. In this study, solid lipid nanoparticles (SLNs) loaded with SC were prepared and characterized in terms of colloidal, morphological and thermal properties. The amount of drug loaded and its release behavior were estimated as a function of formulation variables. The potential of lipid nanocarriers to retain their properties following nebulization and autoclaving was investigated. In addition, toxicity aspects of plain and loaded SLNs on A549 cells were studied with respect to concentration. Spherical SLNs in the size range (100-250nm) were obtained. Particles ensured high encapsulation efficiency (88-100%) and sustained release of the payload over 24h. Cell-based viability experiments revealed a concentration-dependant toxicity for both plain and loaded SLNs recording an IC₅₀ of 516 and 384μg/mL, respectively. Nebulization with jet nebulizer and sterilization via autoclaving affected neither the colloidal stability of SLNs nor the drug entrapment, proving their potential as pulmonary delivery system. Interaction of SLNs with mucin was a function of the emulsifier coating layer. Results yet seeking clinical evidence - might give promises of new therapy for PH of higher safety, better performance and higher patient compliance.

Fungal diseases: could nanostructured drug delivery systems be a novel paradigm for therapy?

Invasive mycoses are a major problem for immunocompromised individuals and patients in intensive care units. Morbidity and mortality rates of these infections are high because of late diagnosis and delayed treatment. Moreover, the number of available antifungal agents is low, and there are problems with toxicity and resistance. Alternatives for treating invasive fungal infections are necessary. Nanostructured systems could be excellent carriers for antifungal drugs, reducing toxicity and targeting their action. The use of nanostructured systems for antifungal therapy began in the 1990s, with the appearance of lipid formulations of amphotericin B. This review encompasses different antifungal drug delivery systems, such as liposomes, carriers based on solid lipids and nanostructure lipids, polymeric nanoparticles, dendrimers, and others. All these delivery systems have advantages and disadvantages. Main advantages are the improvement in the antifungal properties, such as bioavailability, reduction in toxicity, and target tissue, which facilitates innovative therapeutic techniques. Conversely, a major disadvantage is the high cost of production. In the near future, the use of nanosystems for drug delivery strategies can be used for delivering peptides, including mucoadhesive systems for the treatment of oral and vaginal candidiasis.

Solid lipid nanoparticles encapsulating a fluorescent marker (coumarin 6) and antimalarials – artemether and lumefantrine: evaluation of cellular uptake and antimalarial activity

Artemisinins, the mainstay in the treatment of malaria today, are used in combination with other antimalarials to forestall resistance, as artemisinin-combination therapies. In line with the World Health Organization’s recommendation in that respect, solid lipid nanoparticles (SLN) were formulated to encapsulate two antimalarial drugs — artemether and lumefantrine. The nanoparticles were evaluated for size and solid state properties. Caco-2 cells were used to investigate the ability of the SLN to deliver its payload at the absorptive interface of the gastrointestinal tract. Mice heart endothelial cells (MHEC) were also used as marker cells to assess cellular uptake of coumarin 6 from the SLN with imaging by confocal laser scanning microscopy (CSLM). In vivo antimalarial activity was done using a standard suppressive protocol. The results of this study revealed different crystal properties for artemether and lumefantrine, which affected their solubility in the lipid matrix and thus, loading in the lipid nanoparticles. The particles of the SLN were within the range of 150 nm–500 nm with varied polydispersity indices. Wide angle X-ray diffraction analysis indicated the presence of particles of solid nature. Cellular uptake studies indicated uptake of coumarin 6 from the coumarin 6-labeled SLN. In vivo antimalarial studies indicated high clearance of parasitemia with minimal effect on hematological parameters tested.

Lipid-polyethylene glycol based nano-ocular formulation of ketoconazole

Ophthalmic mycoses including corneal keratitis or endophthalmitis affects 6-million persons/year and can cause blindness. Its management requires antifungals to penetrate the ocular tissue. Oral use of Ketoconazole (KTZ), the first broad-spectrum antifungal to be marketed, is now restricted to life-threatening infections due to severe adverse effects and drug-interactions. Local use of KTZ loaded nanocarrier system can address its toxicity, poor solubility, photodegradation, permeation and bioavailability issues. Solid lipid nanoparticles (SLNs) comprising Compritol(®) 888 ATO and PEG 600 matrix, were presently prepared using hot high-pressure homogenization. Employing extensive characterization: TEM, NMR, DSC, XRD and FTIR, it is proposed that SLNs comprise of a polyethylene glycol (PEG) core into which KTZ is dissolved. PEG endows the lipid matrix with amorphousness and imperfections; rigidity; and, stability to aggregation, on storage and autoclaving. PEG is a simple, cost-effective and safe polymer with superior solubilizing and surfactant-supporting properties. Without its inclusion KTZ could not be loaded into SLNs. It ensured high incorporation efficiency (70%) of KTZ; small size (126 nm); and, better permeation into the eye. Pharmacokinetic studies indicated 2.5 and 1.6 fold higher bioavailability (AUC) in aqueous and vitreous humor, respectively. Biocompatibility and in vitro (both in corneal and retinal cell lines) and in vivo (in rabbits) ocular safety is the other highlight of developed formulation.

The effect of formulative parameters on the size and physical stability of SLN based on "green" components

Cocoa butter (CB) is a largely used excipient in pharmaceutical field. Aim of this work was to set formulative parameters for the preparation of SLN based on "green" lipid matrix for drug delivery as natural, both human and environmental safe systems. Double emulsion technique (w1/o/w2) was selected for SLN preparation. The effect on the dimensional properties of different surfactants (Tween 80 and PEG 40 monostearate) and co-surfactants (PEG400 monostearate, Emulium® Kappa2 and Plurol®Stearique) at different concentrations was evaluated. Stability tests were performed. SLN dispersions were exsiccated and the effect of the dried process on SLN size was evaluated. The influence of temperature on SLN dimensions was investigated at 37 °C. MTT test was performed on raw materials and formulations. The w1/o/w2 is suitable, rapid and economic technique for the preparation of CB SLN. Tween 80-Plurol Stearique combination gives the best results: particles size less than 400 nm and PI of about 0.4 are obtained when PS 2% is used. Both raw materials and formulations are safe. The importance to evaluate the effect of different surfactant and/or co-surfactant on the dimensional properties of SLN is evident by selecting substances with preferable safety profiles, and favorable environmental properties to develop stable "green" SLN.

Lipid effects on expulsion rate of amphotericin B from solid lipid nanoparticles

We aimed to investigate the effects that natural lipids, theobroma oil (TO) and beeswax (BW), might have on the physical properties of formulated nanoparticles and also the degree of expulsion of encapsulated amphotericin B (AmB) from the nanoparticles during storage. Lecithin and sodium cholate were used as emulsifiers whilst oleic acid (OA) was used to study the influence of the state of orderliness/disorderliness within the matrices of the nanoparticles on the degree of AmB expulsion during storage. BW was found to effect larger z-average diameter compared with TO. Lecithin was found to augment the stability of the nanoparticles imparted by BW and TO during storage. An encapsulation efficiency (%EE) of 59% was recorded when TO was the sole lipid as against 42% from BW. In combination however, the %EE dropped to 39%. When used as sole lipid, TO or BW formed nanoparticles with comparatively higher enthalpies, 21.1 and 23.3 J/g respectively, which subsequently caused significantly higher degree of AmB expulsion, 81 and 83% respectively, whilst only 11.8% was expelled from a binary TO/BW mixture. A tertiary TO/BW/OA mixture registered the lowest enthalpy at 8.07 J/g and expelled 12.6% of AmB but encapsulated only 22% of AmB. In conclusion, nanoparticles made from equal concentrations of TO and BW produced the most desirable properties and worthy of further investigations.

Part I: Development and optimization of solid-lipid nanoparticles using Box-Behnken statistical design for ocular delivery of gatifloxacin

This study aims to improve gatifloxacin bioavailability to the eye using solid-lipid nanoparticles (SLN). Cationic SLNs were prepared by o/w-microemulsion method using stearylamine. The generated formulations were optimized by three-factor, three-level Box-Behnken statistical design. The independent variables were the lipid(mix) concentration (X1), poloxamers-188 (X2), and sodium-taurocholate (X3), while the dependent variables were drug release (Y1), encapsulation efficiency (EE) (Y2), and particle size (Y3 ) with applied constraints of maximizing drug release and EE and minimizing particle size. Response surface plots were drawn, statistical validity of the polynomials was established, optimized formulations were selected by feasibility and grid search, and the optimization process was validated. Particle size, polydispersity index, and zeta-potentials were measured by photon correlation spectroscopy. Particle's morphology was evaluated by transmission electron microscopy. Differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WXRD) studies were performed to characterize state of drug and lipid modification. SLN size was (250-305 nm) and zeta-potential (29-36 mV) after 3-month storage. Entrapment efficiencies were 46.58 and 78.55%, and loading efficiencies were 29.60 and 20.70 for SLN-C and SLN-D, respectively. DSC and WXRD analyses showed low-crystalline SLN and amorphous drug dispersion in SLN. In vitro release data were fitted to release kinetics equations, where the release pattern was found to follow Korsmeyer-Peppas model.

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.

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.

In vitro properties of surface-modified solid lipid microspheres containing an antimalarial drug: halofantrine

OBJECTIVE

To formulate and evaluate in vitro, surface-modified solid lipid microspheres containing halofantrine using lipid matrix formed from goat fat and a phospholipid (P90H).

METHODS

The model drug, halofantrine in an increasing concentration of 1%, 2%, 3%, 4% and 5% w/w was incorporated into surface-modified solid lipid microspheres formulated by hot homogenization. Effect of drug concentration on the encapsulation efficiency was studied. The dispersion was evaluated using particle size, particle morphology, pH and encapsulation efficiency. The drug formulation with highest encapsulation efficiency was selected and used for the release studies and compared with the release from a commercial dosage form (Halfan® 250 mg tablet, Glaxo-Smithkline, Mayenne France) using simulated gastric fluid (SGF pH 1.2), simulated intestinal fluid (SIF pH 7.2) and phosphate buffer (pH 6.8) as biorelevant media. Results were analyzed statistically and the level of significance was taken to be P < 0.05).

RESULTS

Discrete and spherical solid lipid microspheres were produced. The particle size of the dispersion was low (32.48-33.87 μm) with minimal particle growth and high encapsulation efficiencies (86.8%-91.0%) after 3 months. The pH of the microspheres dispersion changed appreciably after 3 months. In vitro release result obtained revealed sustained and controlled drug release from the lipid microspheres compared with the tablet dosage form.

CONCLUSIONS

Formulation of halofantrine as solid lipid microspheres presents a better alternative to the conventional tablet formulation as the in vitro dissolution of the highly lipophilic halofantrine was highly improved.

Diclofenac-loaded Eudragit S100 nanosuspension for ophthalmic delivery

In this study, diclofenac-loaded Eudragit S100-based nanosuspension was prepared by nanoprecipitation method and characterised for particle size, morphology, in vitro release, and for its in vivo ocular anti-inflammatory activity. The diclofenac-loaded Eudragit S100 nanosuspension was found to have a particle size of 172 nm, polydispersibility index of 0.14 and zeta potential of -23.7 +/- 6.07 mV, indicating that the nanosuspension is fairly stable. The nanosuspended particles were found to be spherical in shape. The nanosuspension was found to provide a sustained in vitro release, following the Higuchi square-root release kinetics. The results indicated that the nanosuspension released the drug by combination of dissolution and diffusion. The in vivo evaluation of nanosuspension in PGE(2)-induced ocular inflammation in rabbit model revealed a significantly (p  <  0.05) higher inhibition of PGE(2)-induced polymorphonuclear leukocytes migration and lid-closure scores as compared with the aqueous solution of diclofenac.

Development and evaluation of colloidal modified nanolipid carrier: application to topical delivery of tacrolimus

Low solubility of tacrolimus in carrier matrix and subsequent poor in vivo bioavailability was overcome by constructing modified nanolipid carrier (MNLC) as a novel approach. The aim of this study was to develop MNLC with enhanced drug solubility in carrier lipid matrix using lipophilic solubilizers for topical delivery. Comprehensive characterization of tacrolimus-loaded MNLC (T-MNLC) was carried out for particle size, morphology, and rheology. Lipid modification resulted in the formation of less perfect crystals offering space to accommodate the dissolved drug leading to high entrapment efficiency of 96.66%. Compatibility and mixing behavior of carrier constituents was evaluated using DSC, FT-IR, and (1)H NMR. T-MNLC displayed sufficient stability that could be attributed to possibility to reduce total lipid concentration in carrier. T-MNLC-enriched gels showed significantly higher in vitro drug release, skin permeation, and in vivo bioavailability with dermatopharmacokinetic approach in guinea pigs compared to commercial ointment, Protopic® as reference. Penetration-enhancing effect was confirmed using gamma scintigraphy in vivo in rats. Radioactivity remained localized in skin at the application site avoiding unnecessary biodisposition to other organs with prospective minimization of toxic effects. Skin irritation studies showed T-MNLC to be significantly less irritating than reference. Research work could be concluded as successful development of novel T-MNLC using lipophilic solubilizers to increase the encapsulation efficiency of colloidal lipid carriers with advantage of improved performance in terms of stability and skin localization.

Physicochemical characterization of nanotemplate engineered solid lipid nanoparticles

As the physicochemical characteristics of solid lipid nanoparticles (SLNs) play a critical role in their success, it is important to understand how the materials and process used in their preparation affect these properties. In this study, two stearyl alcohol-based formulations were prepared using nanotemplate engineering technology and characterized. Both formulations were of a small particle size (<100 nm), ellipsoidal shape, and low polydispersity. (1)H NMR spectroscopy confirmed that the SLNs have the expected solid core structure and PEGylated surface. Analysis of the bulk materials indicated that a number of complex interactions are present among the SLN components, including a eutectic between stearyl alcohol and Brij 78. The decreased crystallinity resulting from these interactions may allow for enhanced drug loading. Physiological stability was identified and confirmed as a potential problem due to the low melting point of the eutectic. However, it is expected that with appropriate formulation modifications nanotemplate engineered SLNs will possess the properties necessary for a successful drug delivery system.

Solid lipid nanoparticles for ocular drug delivery

Ocular drug delivery remains challenging because of the complex nature and structure of the eye. Conventional systems, such as eye drops and ointments, are inefficient, whereas systemic administration requires high doses resulting in significant toxicity. There is a need to develop novel drug delivery carriers capable of increasing ocular bioavailability and decreasing both local and systemic cytotoxicity. Nanotechnology is expected to revolutionize ocular drug delivery. Many nano-structured systems have been employed for ocular drug delivery and yielded some promising results. Solid lipid nanoparticles (SLNs) have been looked at as a potential drug carrier system since the 1990s. SLNs do not show biotoxicity as they are prepared from physiological lipids. SLNs are especially useful in ocular drug delivery as they can enhance the corneal absorption of drugs and improve the ocular bioavailability of both hydrophilic and lipophilic drugs. SLNs have another advantage of allowing autoclave sterilization, a necessary step towards formulation of ocular preparations. This review outlines in detail the various production, characterization, sterilization, and stabilization techniques for SLNs. In-vitro and in-vivo methods to study the drug release profile of SLNs have been explained. Special attention has been given to the nature of lipids and surfactants commonly used for SLN production. A summary of previous studies involving the use of SLNs in ocular drug delivery is provided, along with a critical evaluation of SLNs as a potential ocular delivery system.

Chemical and structural investigation of lipid nanoparticles: drug-lipid interaction and molecular distribution

Lipid nanoparticles are a promising alternative to existing carriers in chemical or drug delivery systems. A key challenge is to determine how chemicals are incorporated and distributed inside nanoparticles, which assists in controlling chemical retention and release characteristics. This study reports the chemical and structural investigation of gamma-oryzanol loading inside a model lipid nanoparticle drug delivery system composed of cetyl palmitate as solid lipid and Miglyol 812 as liquid lipid. The lipid nanoparticles were prepared by high pressure homogenization at varying liquid lipid content, in comparison with the gamma-oryzanol free systems. The size of the lipid nanoparticles, as measured by the photon correlation spectroscopy, was found to decrease with increased liquid lipid content from 200 to 160 nm. High-resolution proton nuclear magnetic resonance ((1)H-NMR) measurements of the medium chain triglyceride of the liquid lipid has confirmed successful incorporation of the liquid lipid in the lipid nanoparticles. Differential scanning calorimetric and powder x-ray diffraction measurements provide complementary results to the (1)H-NMR, whereby the crystallinity of the lipid nanoparticles diminishes with an increase in the liquid lipid content. For the distribution of gamma-oryzanol inside the lipid nanoparticles, the (1)H-NMR revealed that the chemical shifts of the liquid lipid in gamma-oryzanol loaded systems were found at rather higher field than those in gamma-oryzanol free systems, suggesting incorporation of gamma-oryzanol in the liquid lipid. In addition, the phase-separated structure was observed by atomic force microscopy for lipid nanoparticles with 0% liquid lipid, but not for lipid nanoparticles with 5 and 10% liquid lipid. Raman spectroscopic and mapping measurements further revealed preferential incorporation of gamma-oryzanol in the liquid part rather than the solid part of in the lipid nanoparticles. Simple models representing the distribution of gamma-oryzanol and lipids (solid and liquid) inside the lipid nanoparticle systems are proposed.

Formulation and in vitro evaluation of a PEGylated microscopic lipospheres delivery system for ceftriaxone sodium

The aim of this study was to formulate and evaluate in vitro, ceftriaxone sodium lipospheres dispersions for oral administration. Ceftriaxone sodium lipospheres were prepared by melt-emulsification using 30%w/w Phospholipon 90H in Softisan 154 as the lipid matrix containing increasing quantities of PEG 4000 (10, 20, 30, and 40%w/w). Characterization based on particle size, particle morphology, encapsulation efficiency, loading capacity and pH were carried out on the lipospheres. Microbiological studies of the ceftriaxone sodium-loaded lipospheres were performed using Escherichia coli as the model organism. In vitro permeation of ceftriaxone sodium from the lipospheres through artificial membrane (0.22 microm pore size) was carried out using Franz cell and simulated intestinal fluid (SIF) without pancreatin as acceptor medium. Photomicrographs revealed spherical particles within a micrometer range with minimal growth after 1 month (Maximum size = 64.76 +/- 3.81 microm). Microbiological studies indicated that lipospheres formulated with 20%w/w of PEG 4000 containing 2%w/w or 3%w/w of ceftriaxone sodium gave significantly (p < 0.05) higher inhibition zone diameter than those with 30%w/w or 40%w/w of PEG 4000. The result also indicated that lipospheres with 10%w/w PEG 4000 resulted in significantly higher encapsulation efficiency (p < 0.05) while those with 30%w/w gave the least, while the loading capacity values ranged from 3.22 mg of ceftriaxone sodium/100 mg of lipid to 6.36 mg of ceftriaxone sodium/100 mg of lipid. Permeation coefficient values varied and ranged from 8.55 x 10(-7) cm/s to 2.08 x 10(-6) cm/s depending on the concentration of PEG 4000. The result of this study gave insight that the issue of ceftriaxone stability in oral formulation could be adequately addressed by tactical engineering of lipid drug delivery systems such as lipospheres.

Sustained release and permeation of timolol from surface-modified solid lipid nanoparticles through bioengineered human cornea

PURPOSE

The aim of the study was to formulate and evaluate surface-modified solid lipid nanoparticles sustained delivery system of timolol hydrogen maleate, a prototype ocular drug using a human cornea construct.

MATERIALS AND METHODS

Surface-modified solid lipid nanoparticles containing timolol with and without phospholipid were formulated by melt emulsification with high-pressure homogenization and characterized by particle size, wide-angle X-ray diffraction, encapsulation efficiency, and in vitro drug release. Drug transport studies through cornea bioengineered from human donor cornea cells were carried out using a modified Franz diffusion cell and drug concentration analyzed by high-performance liquid chromatography.

RESULTS

Results show that surface-modified solid lipid nanoparticles possessed very small particles (42.9 +/- 0.3 nm, 47.2 +/- 0.3 nm, 42.7 +/- 0.7 nm, and 37.7 +/- 0.3 nm, respectively for SM-SLN 1, SM-SLN 2, SM-SLN 3, and SM-SLN 4) with low polydispersity indices, increased encapsulation efficiency (> 44%), and sustained in vitro release compared with unmodified lipid nanoparticles whose particles were greater than 160 nm. Permeation of timolol hydrogen maleate from the surface-modified lipid nanoparticles across the cornea construct was sustained compared with timolol hydrogen maleate solution in distilled water.

CONCLUSIONS

Surface-modified solid lipid nanoparticles could provide an efficient way of improving ocular bioavailability of timolol hydrogen maleate.