Lipid nanoparticles for the topical delivery of retinoids and derivatives

Solid Lipid Nanoparticles vs. Nanostructured Lipid Carriers: A Comparative Review

Solid-lipid nanoparticles and nanostructured lipid carriers are delivery systems for the delivery of drugs and other bioactives used in diagnosis, therapy, and treatment procedures. These nanocarriers may enhance the solubility and permeability of drugs, increase their bioavailability, and extend the residence time in the body, combining low toxicity with a targeted delivery. Nanostructured lipid carriers are the second generation of lipid nanoparticles differing from solid lipid nanoparticles in their composition matrix. The use of a liquid lipid together with a solid lipid in nanostructured lipid carrier allows it to load a higher amount of drug, enhance drug release properties, and increase its stability. Therefore, a direct comparison between solid lipid nanoparticles and nanostructured lipid carriers is needed. This review aims to describe solid lipid nanoparticles and nanostructured lipid carriers as drug delivery systems, comparing both, while systematically elucidating their production methodologies, physicochemical characterization, and in vitro and in vivo performance. In addition, the toxicity concerns of these systems are focused on.

Release of Tretinoin Solubilized in Microemulsion from Carbopol and Xanthan Gel: In Vitro versus Ex Vivo Permeation Study

BACKGROUND

Tretinoin (TRE) is, for its anti-comedogenic and comedolytic activity, widely used in the topical treatment of acne vulgaris. The effect lies in the regulation of sebum production and collagen synthesis. The study is devoted to the formulation of dermal gels containing TRE using microemulsion as the drug solubilizer.

METHODS

The aim was to evaluate the effect of the reference microemulsion (ME) and lecithin-containing microemulsion (ME_L) on the release of TRE through the synthetic membrane (in vitro) and the pig's ear skin (ex vivo) through the Franz cell diffusion method. Subsequently, after an ex vivo study, the amount of the drug in the skin influenced by the applied formulation was determined. In addition, the impact of ME on the microscopic structure, texture, and rheological properties of gels was evaluated.

RESULTS

On the basis of the analysis of texture, rheological properties, and drug release studies, Carbopol formulations appear to be more appropriate and stable. Considering the synthetic membrane as a stratum corneum, the Carbopol gel penetrated about 2.5-higher amounts of TRE compared to the Xanthan gel. In turn, ex vivo studies suggest that ME_L slows the drug transfer to the dissolution medium, simulating absorption into the blood, which is a desirable effect in local treatment. The drug retention study proved the highest amounts of TRE in the skin to which microemulsion-Carbopol formulations were applied.

CONCLUSION

The results confirm the benefit of TRE solubilization in ME due to its bioavailability from the tested dermal formulations.

Laser-assisted nanoparticle delivery to promote skin absorption and penetration depth of retinoic acid with the aim for treating photoaging

Retinoic acid (RA) is an approved treatment for skin photoaging induced by ultraviolet (UVA). Topically applied RA is mainly located in the stratum corneum (SC) with limited diffusion into the deeper strata. A delivery system capable of facilitating dermal delivery and cellular internalization for RA is critical for a successful photoaging therapy. Two delivery approaches, namely nanoparticles and laser ablation, were combined to improve RA's absorption efficacy and safety. The nanoparticle absorption enhancement by the lasers was compared between full-ablative (Er:YAG) and fractional (CO₂) modalities. We fabricated poly-L-lactic acid (PLA) and PLA/poly(lactic-co-glycolic acid) (PLGA) nanoparticles by an emulsion-solvent evaporation technique. The mean size of PLA and PLA/PLGA nanocarriers was 237 and 222 nm, respectively. The RA encapsulation percentage in both nanosystems was > 96 %. PLA and PLA/PLGA nanocarriers promoted RA skin deposition by 5- and 3-fold compared to free control. The ablative lasers further enhanced the skin deposition of RA-loaded nanoparticles, with the full-ablative laser showing greater permeation enhancement than the fractional mode. The skin biodistribution assay evaluated by confocal and fluorescence microscopies demonstrated that the laser-assisted nanoparticle delivery achieved a significant dermis and follicular accumulation. The cell-based study indicated a facile uptake of the nanoparticles into the human dermal fibroblasts. The nanoparticulate RA increased type I collagen and elastin production in the UVA-treated fibroblasts. A reduction of matrix metalloproteinase (MMP)-1 was also highlighted in the photoaging cells. The calculation of therapeutic index (TI) by multiplying collagen/elastin elevation percentage and skin deposition predicted better anti-photoaging performance in Er:YAG laser-assisted nanoparticle delivery than CO₂ laser. Nanoencapsulation of RA decreased the cytotoxicity against skin fibroblasts. In vivo skin tolerance test on a nude mouse showed less skin damage after topical application of the nanoparticles than free RA. Our results hypothesized that the laser-mediated nanoparticle delivery provided an efficient and safe use for treating photoaging.

Features, applications, and sustainability of lipid nanoparticles in cosmeceuticals

Cosmeceuticals are a branch of cosmetic products that forms a bridge between cosmetic and drug products. It is a fast-growing branch of the cosmetic industry, especially after the introduction of novel formulation and manufacturing techniques such as lipid nanoparticles (LNPs). These LNPs-based cosmeceutical products offer several advantages such as enhanced bioavailability of cosmeceutical active ingredients (CAIs), improved aesthetic appeal, and stability of the final products. However, the use of these LNPs may raise some concerns about possible side effects of these LNPs and potential hazards to the customer’s health. Accordingly, an update that focuses on the use of this important branch of nanoparticles is necessary since most review papers are dealing with all types of nanocarriers in the same review with little focus on LNPs. Therefore, in the current review, a detailed analysis of the advantages and disadvantages of LNPs in this field was highlighted, to emphasize the LNPs-based cosmeceuticals on the market, as well as the potential risk posed by LNPs on exposure and recently introduced regulatory guidelines to address them. In addition, if these products can be a candidate as products that meet the sustainable development goals raised by the UN are discussed.

Synthetic Retinoids Beyond Cancer Therapy

While the uses of retinoids for cancer treatment continue to evolve, this review focuses on other therapeutic areas in which retinoids [retinol (vitamin A), all-trans retinoic acid (RA), and synthetic retinoic acid receptor (RAR)α-, β-, and γ-selective agonists] are being used and on promising new research that suggests additional uses for retinoids for the treatment of disorders of the kidneys, skeletal muscles, heart, pancreas, liver, nervous system, skin, and other organs. The most mature area, in terms of US Food and Drug Administration-approved, RAR-selective agonists, is for treatment of various skin diseases. Synthetic retinoid agonists have major advantages over endogenous RAR agonists such as RA. Because they act through a specific RAR, side effects may be minimized, and synthetic retinoids often have better pharmaceutical properties than does RA. Based on our increasing knowledge of the multiple roles of retinoids in development, epigenetic regulation, and tissue repair, other exciting therapeutic areas are emerging. Expected final online publication date for the Annual Review of Pharmacology and Toxicology, Volume 62 is January 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Nanostructured lipid carriers enhances the safety profile of tretinoin: in vitro and healthy human volunteers' studies

Aim: To enhance the tretinoin (TRE) safety profile through the encapsulation in nanostructured lipid carriers (NLC). Materials & methods: NLC-TRE was developed using a 2³ experimental factorial design, characterized (HPLC, dynamic light scattering, differential scanning calorimetry, x-ray diffraction analysis, transmission electron microscopy, cryo-transmission electron microscopy) and evaluated by in vitro studies and in healthy volunteers. Results: The NLC-TRE presented spherical structures, average particle size of 130 nm, zeta potential of 24 mV and encapsulation efficiency of 98%. The NLC-TRE protected TRE against oxidation (p < 0.0001) and promoted epidermal targeting (p < 0.0001) compared with the marketed product, both 0.05% TRE. The in vitro assay on reconstructed human epidermis and the measurement of transepidermal water loss in healthy volunteers demonstrated an enhanced safety profile in comparison to the marketed product (p < 0.0002). Conclusion: The NLC-TRE enhances the epidermal targeting and safety profile of TRE, representing a potential safer alternative for the topical treatment of skin disorders using TRE.

Development and Characterization of Stingless Bee Propolis Properties for the Development of Solid Lipid Nanoparticles for Loading Lipophilic Substances

Stingless bees are insects which are popularly bred by agriculturists in the eastern region of Thailand for the pollination of their orchards. The products from stingless bee breeding include bee honey and bee propolis. The objective of this experiment is to study the possibility of developing stingless bee propolis wax into solid lipid nanoparticles (SLN) by the comparison of five surfactants (Brij 721, Cremophor WO 7, Myrj 52, Poloxamer 188, and Tween 80). Each surfactant is used at three concentrations: 10%, 20%, and 30%. A master formula is selected according to the following: physical features, particle size, zeta potential, and entrapment. The results showed that Brij 721 and Myri 52 at 20% can be used in preparing SLN and have good preservation properties for vitamin E (size: 451.2 nm and 416.8 nm, zeta potential: - 24.0 and - 32.7; % EE: 92.32% and 92.00%, resp.). Therefore, they are further developed by adding the following drugs at low solubility: curcumin, ibuprofen, and astaxanthin. It is found that a formula using the surfactants Brij 721 and Myrj 52 at 20% have similar drug entrapment. The entrapment study involves curcumin 82%, ibuprofen 40%, and astaxanthin 67%. Moreover, the cytotoxicity test of blank solid lipid nanoparticle found no toxicty in fibroblast cell line (CRL-2522). Therefore, from this study, it is determined that stingless bee propolis wax has the potential to be developed to provide more efficient SLN in the future.

Design, Preparation, and Characterization of Effective Dermal and Transdermal Lipid Nanoparticles: A Review

Limited permeability through the stratum corneum (SC) is a major obstacle for numerous skin care products. One promising approach is to use lipid nanoparticles as they not only facilitate penetration across skin but also avoid the drawbacks of conventional skin formulations. This review focuses on solid lipid nanoparticles (SLNs), nanostructured lipid nanocarriers (NLCs), and nanoemulsions (NEs) developed for topical and transdermal delivery of active compounds. A special emphasis in this review is placed on composition, preparation, modifications, structure and characterization, mechanism of penetration, and recent application of these nanoparticles. The presented data demonstrate the potential of these nanoparticles for dermal and transdermal delivery.

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.

Molecular Dynamics Studies of Poly(Lactic Acid) Nanoparticles and Their Interactions with Vitamin E and TLR Agonists Pam1CSK4 and Pam3CSK4

Poly(lactic acid) (PLA) nanoparticles (NPs) are widely investigated due to their bioresorbable, biocompatible and low immunogen properties. Interestingly, many recent studies show that they can be efficiently used as drug delivery systems or as adjuvants to enhance vaccine efficacy. Our work focuses on the molecular mechanisms involved during the nanoprecipitation of PLA NPs from concentrated solutions of lactic acid polymeric chains, and their specific interactions with biologically relevant molecules. In this study, we evaluated the ability of a PLA-based nanoparticle drug carrier to vectorize either vitamin E or the Toll-like receptor (TLR) agonists Pam₁CSK₄ and Pam₃CSK₄, which are potent activators of the proinflammatory transcription factor NF-κB. We used dissipative particle dynamics (DPD) to simulate large systems mimicking the nanoprecipitation process for a complete NP. Our results evidenced that after the NP formation, Pam₁CSK₄ and Pam₃CSK₄ molecules end up located on the surface of the particle, interacting with the PLA chains via their fatty acid chains, whereas vitamin E molecules are buried deeper in the core of the particle. Our results allow for a better understanding of the molecular mechanisms responsible for the formation of the PLA NPs and their interactions with biological molecules located either on their surfaces or encapsulated within them. This work should allow for a rapid development of better biodegradable and safe vectorization systems with new drugs in the near future.

Lipid-nanopotentiated combinatorial delivery of tamoxifen and sulforaphane: ex vivo, in vivo and toxicity studies

Aim: This study aims to load tamoxifen (TAM) and sulforaphane (SFN) into nanostructured lipid carriers (NLCs) to enhance their oral delivery. Materials & methods: TAM-SFN-NLCs were prepared using Precirol® ATO5 and Transcutol® HP, characterized and evaluated in vitro and ex vivo to assess the drug release profile and intestinal permeability, respectively. In vivo pharmacokinetic and acute toxicity assessment was performed in Wistar rats. Results: Optimized TAM-SFN-NLCs exhibited a particle size of 121.9 ± 6.42 nm and zeta potential of -21.2 ± 2.91 mV. The NLCs enhanced intestinal permeability of TAM and SFN and augmented oral bioavailability of TAM and SFN 5.2-fold and 4.8-fold, respectively. SFN significantly reduced TAM-associated toxicity in vivo. Conclusion: This coencapsulation of a chemotherapeutic agent with a herbal bioactive in NLCs could pave a novel treatment approach against cancer.

Advances and challenges in retinoid delivery systems in regenerative and therapeutic medicine

Retinoids regulate a wide spectrum of cellular functions from the embryo throughout adulthood, including cell differentiation, metabolic regulation, and inflammation. These traits make retinoids very attractive molecules for medical purposes. In light of some of the physicochemical limitations of retinoids, the development of drug delivery systems offers several advantages for clinical translation of retinoid-based therapies, including improved solubilization, prolonged circulation, reduced toxicity, sustained release, and improved efficacy. In this Review, we discuss advances in preclinical and clinical tests regarding retinoid formulations, specifically the ones based in natural retinoids, evaluated in the context of regenerative medicine, brain, cancer, skin, and immune diseases. Advantages and limitations of retinoid formulations, as well as prospects to push the field forward, will be presented.

Synthesis of Gelatin-Based Dual-Targeted Nanoparticles of Betulinic Acid for Antitumor Therapy

Betulinic acid (BA) is a natural antitumor agent and has biological activity against multiple human tumor cell lines with low cytotoxicity to normal cells, while the high hydrophobicity and the short half-life of this compound limit its clinical application. Here, gelatin-based dual-targeted nanoparticles of BA are promising to solve this problem. Hydrophobic BA is loaded in cyclodextrin to increase its solubility and prolong the circulation time in vivo. The nanoscale drug delivery systems can further enhance the bioavailability and the antitumor effect of BA and are passively targeted to the tumor tissue sites by enhanced permeability and retention effect. The RGD sequence of gelatin specifically recognizes tumor cells and brings agents into tumor cells. The nanoparticles were characterized by transmission electron microscopy, Fourier transform infrared, nuclear magnetic resonance, etc. In addition, we observed antitumor activity of the nanoparticles using both cell-based assays and mouse xenograft tumors, which proved that betulinic acid/gelatin-γ-cyclodextrin nanoparticles had a better tumor inhibition effect than betulinic acid/γ-cyclodextrin inclusion compound.

Nanoemulgel for Improved Topical Delivery of Retinyl Palmitate: Formulation Design and Stability Evaluation

Retinyl palmitate is a vitamin A ester belonging to the family of endogenous natural retinoid and used to treat various skin disorders like acne, skin aging, wrinkles, and dark spots, as well as to protect against psoriasis. Despite the known therapeutic benefits of retinyl palmitate, the conventional topical delivery of retinyl palmitate commonly associated with adverse reactions such as skin irritation, redness, excessive peeling, and dryness. Therefore, the current study aims to encapsulate the retinyl palmitate in nanoemulsion then incorporate it into a hydrogel system to improve the topical delivery and stability. Low-energy emulsification method was used for the nano-encapsulation of retinyl palmitate. The phase behavior study was used for the investigation and the optimization of the formulation. The droplet size of the optimized nanoemulsion was in nano dimension (16.71 nm) with low polydispersity index (PdI) (0.015), negative zeta potential (-20.6 mV). It demonstrated the influence of vortexing on droplet size and PdI during nanoemulsion preparation. The retinyl palmitate loaded nanoemulgel delivery system exhibited significant improvement (p < 0.05) in skin permeability after topical application. Employment of the nano-encapsulation approach afterward dispersion into hydrogel system for the development of a topical delivery system of retinyl palmitate resulted in improvement in its UV and storage stability as well.

Nanoparticle Delivery Systems for DNA/RNA and their Potential Applications in Nanomedicine

The rapid development of nanotechnology has a great influence on the fields of biology, physiology, and medicine. Over recent years, nanoparticles have been widely presented as nanocarriers to help the delivery of gene, drugs, and other therapeutic agents with cellular targeting ability. Advances in the understanding of gene delivery and RNA interference (RNAi)-based therapy have brought increasing attention to understanding and tackling complex genetically related diseases, such as cancer, cardiovascular and pulmonary diseases, autoimmune diseases and infections. The combination of nanocarriers and DNA/RNA delivery may potentially improve their safety and therapeutic efficacy. However, there still exist many challenges before this approach can be practiced in the clinic. In this review, we provide a comprehensive summary on the types of nanoparticle systems used as nanocarriers, highlight the current use of nanocarriers in recombinant DNA and RNAi molecules delivery, and the current landscape of gene-based nanomedicine-ranging from diagnosis to therapeutics. Finally, we briefly discuss the biosafety concerns and limitations in the preclinical and clinical development of nanoparticle gene systems.

Formulation And Evaluation Of Nanostructured Lipid Carriers (NLCs) Of 20(S)-Protopanaxadiol (PPD) By Box-Behnken Design

Background

20(S)-Protopanaxadiol (PPD) has a higher anti-wrinkle effect than the other glycone forms of ginsenosides. However, as PPD has low solubility in water and a high molecular weight, it cannot easily penetrate the stratum corneum layer, which is the rate-limiting step of topical skin delivery. Thus, the objective was to enhance the topical skin deposition of PPD using an optimized nanostructured lipid carriers (NLC) formulation. NLC formulations were optimized using a Box-Behnken design.

Materials and methods

NLC formulations were optimized using a Box-Behnken design, where the amount of PDD (X₁), volume of the liquid lipid (X₂), and amount of surfactant (X₃) were set as the independent variables, while the particle size (Y₁), polydispersity index (PDI) (Y₂), and entrapment efficiency (EE) (Y₃) were dependent factors. An in vitro deposition study was performed using Strat-M^® and human cadaver skin, while in vivo skin irritation effect of the NLC formulation was evaluated in humans.

Results

An NLC was successfully prepared based on the optimized formulation determined using the Box-Behnken design. The particle size, PDI, and EE of the NLC showed less than 5% difference from the predicted values. The in vitro deposition of PPD after the application of the NLC formulation on a Strat-M^® artificial membrane and human cadaver skin was significantly higher than that of the controls. Moreover, NLC formulations with and without PDD were not skin irritants in a human study.

Conclusion

An NLC formulation for the topical delivery of PPD was successfully optimized using the Box-Behnken design, and could be further developed to enhance the topical skin deposition of PPD.

Improved Dermal Delivery of Cyclosporine A Loaded in Solid Lipid Nanoparticles

Cyclosporine A (CsA) is an immunosuppressant frequently used in the therapy of autoimmune disorders, including skin-related diseases. Aiming towards topical delivery, CsA was successfully incorporated into lipid nanoparticles of Lipocire DM and Pluronic F-127 using the hot homogenization method. Two different nanocarriers were optimized: solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs) where oleic acid was the liquid lipid. The developed nanoparticles showed mean sizes around 200 nm, a negative surface charge, and drug entrapment efficiencies around 85% and 70% for SLNs and NLCs, respectively. The spherical CsA-loaded lipid nanoparticles were stable for 9 weeks when stored at room temperature, and exhibited in vitro pH-dependent release under skin mimetic conditions, following the Peppas-Korsmeyer model. CsA, when loaded in SLNs, was safe to be used up to 140 μg mL-1 in fibroblasts and keratinocytes, while CsA-loaded NLCs and free drug exhibited IC50 values of 55 and 95 μg mL-1 (fibroblasts) and 28 and 30 μg mL-1 (keratinocytes), respectively. The developed SLNs were able to retain the drug in pork skin with a reduced permeation rate in relation to NLCs. These findings suggest that SLNs are a potential alternative to produce stable and safe CsA nanocarriers for topical administration.

Formulation approaches for improved retinoids delivery in the treatment of several pathologies

Retinoid acid (RA) and other retinoids are extensively used as therapeutic agents in the treatment of several types of cancer and skin disorders. However, the efficiency of these medical agents is compromised due to the unsatisfactory concentration of retinoids in the target cells/tissues. Furthermore, severe side-effects are related to retinoids administration. Incorporation of retinoids into carrier-based delivery systems using encapsulation technology has been proposed in order to overcome the limitations of using free retinoids in the treatment of several pathologies. The present work starts exploring the competences and the difficulties of using retinoids in health care. The metabolism and the main considerations about the mechanism of action of retinoids are also discussed. The final sections are focused on the most recent studies about RA controlled delivery systems to be used in the medical field.

Transdermal permeability of triamcinolone acetonide lipid nanoparticles

Background

Triamcinolone acetonide (TAA) is an effective and the most commonly used corticosteroid hormone for the treatment of hypertrophic scars (HSs). However, the clinically used dosage has poor tissue permeability and injection safety. By contrast, lipid nanoparticles (LNPs) have the advantage of high affinity for the skin.

Materials and methods

This article describes the preparation of TAA-LNPs using poly(lactic-co-glycolic acid) as a carrier material, which have good biocompatibility and biodegradability. Based on a systematic investigation of its physicochemical properties, a rabbit ear HSs model was established to evaluate the percutaneous permeability of TAA-LNPs in scar tissue in vitro as well as to assess its curative effect and skin irritation.

Results

The results showed that the TAA-LNPs formed uniform and round particles under fluoroscopy and had a complex structure in which a nanoparticle core was surrounded by multiple vesicles. The particles were 232.2±8.2 nm in size, and the complimentary potential was -42.16 mV. The encapsulation efficiency was 85.24%, which is greater than that of other common liposomes and nanoparticles. A test of in vitro scar tissue permeability showed that penetration into scar tissue was twofold and 40-fold higher for TAA-LNPs than for common liposome and commercial suspensions, respectively. The concentration of the absorbed drug effectively inhibited fibroblast proliferation, achieved a therapeutic effect in HSs, and did not stimulate intact or damaged skin.

Conclusion

The preparation of TAA into LNPs for transdermal administration can enhance transdermal permeation performance and the safety of this drug, which is beneficial for the treatment of HSs.

Development of Pranoprofen Loaded Nanostructured Lipid Carriers to Improve Its Release and Therapeutic Efficacy in Skin Inflammatory Disorders

Pranoprofen (PF)-loaded nanostructured lipid carriers (NLCs), prepared using a high-pressure homogenization method, have been optimized and characterized to improve the biopharmaceutical profile of the drug. The optimized PF-NLCs exhibited physicochemical characteristics and morphological properties that were suitable for dermal application. Stability assays revealed good physical stability, and the release behavior of PF from these NLCs showed a sustained release pattern. Cell viability results revealed no toxicity. Ex vivo human skin permeation studies in Franz diffusion cells were performed to determine the influence of different skin penetration enhancers (pyrrolidone, decanol, octanoic acid, nonane, menthone, squalene, linoleic acid, and cineol) on skin penetration and retention of PF, being the highest dermal retention in the presence of linoleic acid. The selected formulations of NLCs exhibited a high retained amount of PF in the skin and no systemic effects. In vivo mice anti-inflammatory efficacy studies showed a significant reduction in dermal oedema. NLCs containing linoleic acid presented better anti-inflammatory efficacy by decreasing the production of interleukins in keratinocytes and monocytes. The biomechanical properties of skin revealed an occlusive effect and no hydration power. No signs of skin irritancy in vivo were detected. According to these results, dermal PF-NLCs could be an effective system for the delivery and controlled release of PF, improving its dermal retention, with reduced dermal oedema as a possible effect of this drug.

Non-Provitamin A and Provitamin A Carotenoids as Immunomodulators: Recommended Dietary Allowance, Therapeutic Index, or Personalized Nutrition?

Vegetables and fruits contain non-provitamin A (lycopene, lutein, and zeaxanthin) and provitamin A (β-carotene, β-cryptoxanthin, and α-carotene) carotenoids. Within these compounds, β-carotene has been extensively studied for its health benefits, but its supplementation at doses higher than recommended intakes induces adverse effects. β-Carotene is converted to retinoic acid (RA), a well-known immunomodulatory molecule. Human interventions suggest that β-carotene and lycopene at pharmacological doses affect immune functions after a depletion period of low carotenoid diet. However, these effects appear unrelated to carotenoids and retinol levels in plasma. Local production of RA in the gut-associated lymphoid tissue, as well as the dependency of RA-induced effects on local inflammation, suggests that personalized nutrition/supplementation should be considered in the future. On the other hand, the differential effect of RA and lycopene on transforming growth factor-beta suggests that lycopene supplementation could improve immune functions without increasing risk for cancers. However, such preclinical evidence must be confirmed in human interventions before any recommendations can be made.

Selective delivery of adapalene to the human hair follicle under finite dose conditions using polymeric micelle nanocarriers

Drug delivery systems that target the pilosebaceous unit (PSU) selectively could improve the clinical management of diseases that originate in the hair follicle. The aims of this study were (i) to prepare polymeric micelles using d-α-tocopheryl polyethylene glycol succinate diblock copolymer that incorporated adapalene (ADA), a retinoid indicated for Acne vulgaris, and (ii) to investigate the feasibility of delivering ADA preferentially to the PSU under finite dose conditions - thereby better approximating actual conditions of use by patients. Incorporation of ADA into spherical micelles (d_n <20 nm) increased aqueous solubility by ∼50 000-fold (from <4 ng mL^-1 to 0.2 mg mL^-1). Optimized micelle solution and gel formulations (0.02% ADA) were stable after storage for 4 weeks at 4 °C. Finite dose experiments using full-thickness porcine and human skin revealed that ADA delivery efficiency from micelle solution and gel formulations was equivalent and was >2- and 10-fold higher than that from Differin® gel and Differin® cream (products containing ADA at 0.1% (w/w)). Follicular delivery studies in human skin, using a punch biopsy technique to extract the intact PSU, demonstrated that the micelle solution and gel formulations did indeed enable preferential delivery of ADA to the PSU (4.5- and 3.3-fold higher, respectively, than that to PSU-free skin biopsies). Confocal laser scanning microscopy provided visual corroboration that ADA was uniformly distributed in the hair follicles. In conclusion, the results confirmed that polymeric micelle nanocarriers enabled selective, targeted drug delivery to the PSU under finite dose conditions and so might improve therapy of follicular diseases and decrease off-site side-effects.

Topical co-delivery of methotrexate and etanercept using lipid nanoparticles: A targeted approach for psoriasis management

Methotrexate is indicated in psoriasis systemic therapy and its topical administration may be an option to overcome several side effects. A targeted delivery may be achieved through etanercept. Thus, a combination targeted therapy using methotrexate and etanercept could bring new perspectives for psoriasis patients. This work intended to develop and characterize co-delivery of methotrexate and etanercept using lipid nanoparticles, mediated by a carbopol hydrogel and to evaluate their potential for delivering the drug into the skin with reduced transdermal permeation. The nanoparticles were physico-chemically characterized. In vitro methotrexate release from solid lipid nanoparticles revealed a sustained release for 8h. The solid lipid nanoparticles were non-toxic towards human keratinocytes and fibroblasts. Permeation studies using pig ear as model revealed enhanced skin deposition of the applied methotrexate when incorporated within solid lipid nanoparticles in relation to free drug. Therapeutic amounts of methotrexate were delivered to psoriatic human skin after application of solid lipid nanoparticles, with reduced transdermal permeation.

Retinol-binding protein-4 expression marks the short-term mortality of critically ill patients with underlying liver disease: Lipid, but not glucose, matters

The implications of retinol-binding protein-4 (RBP4) expression in critically ill patients with underlying liver diseases remain unclear. A prospective cohort study involving 200 liver intensive care unit (ICU) patients was conducted, with 274 blood donors as controls. Patient outcomes were assessed using Cox and Kaplan-Meier analyses. Of the 200 ICU patients (mean age: 56.0 yrs), 79.5% were male, 72.5% were cirrhotic, 62% were septic, 29.5% were diabetic, and 29% expired in the ICU (median admission: 7.5 days). ICU patients had lower baseline RBP4 (25.6+/−18.4 vs. 43.8+/−35.0 mg/L, p < 0.001) and total cholesterol (TC) levels than controls. The surviving ICU patients had lower baseline international normalized ratios (INRs) of prothrombin time, model for end-stage liver disease (MELD) scores and sepsis rates, but higher estimated glomerular filtration rates (eGFRs) and RBP4 levels than non-surviving patients. eGFRs, INRs and TC levels were independently associated with RBP4 levels. Only surviving patients exhibited significantly increased RBP4 levels after ICU discharge. Baseline RBP4 levels and MELD scores predicted 21-day (≤10 mg/L) and 1-year (≥25) mortality, respectively. In critically ill patients with underlying liver disease, with a link to eGFRs, INRs and TC levels, the baseline RBP4 may serve as a marker for short-term mortality.

In vivo confocal Raman spectroscopy and molecular dynamics analysis of penetration of retinyl acetate into stratum corneum

OBJECTIVE

The purpose of this study is to elucidate the behavior of retinyl acetate in penetrating human skin without the presence of enhancers by using confocal Raman spectroscopy and molecular dynamics simulation.

METHODS

In this study, in vivo confocal Raman spectroscopy was combined with molecular dynamics simulation to investigate the transdermal permeation of the aqueous suspension of retinyl acetate.

RESULTS

Permeation was measured after 30min, and retinyl acetate was found up to 20μm deep inside the stratum corneum. The delivery of retinyl acetate inside a skin membrane model was studied by molecular dynamics. The membrane model that was used represented normal young skin containing a lipid bilayer with 25% ceramide, 36% fatty acid, 30% cholesterol, and 6% cholesterol sulfate.

CONCLUSION

Spectroscopy data indicate that retinyl acetate permeates into the stratum corneum. Molecular dynamics data showed that retinyl acetate permeates in the membrane model and that their final location is deep inside the lipid bilayer. We showed, for the first time, a correlation between Raman permeation data and computational data.

Potential use of nanocarriers with pentacyclic triterpenes in cancer treatments

Ursolic, oleanolic and betulinic acids are representative pentacyclic triterpenoids found in various plants and fruits. Despite having marked antitumor potentials, the very poor water solubility of these triterpenes hinders treatment development. Nanotechnology can enhance solubility, stability, bioavailability and phytochemical delivery, improving the therapeutic efficiency of triterpenes. This review focuses on the formulation, characterization and in vitro/in vivo evaluation of several delivery nanosystems used to enhance the physicochemical properties of ursolic, oleanolic and betulinic acids.

Nanostructured lipid carriers as robust systems for topical lidocaine-prilocaine release in dentistry

In dental practice, local anesthesia causes pain, fear, and stress, and is frequently the reason that patients abandon treatment. Topical anesthetics are applied in order to minimize the discomfort caused by needle insertion and injection, and to reduce the symptoms of superficial trauma at the oral mucosa, but there are still no efficient commercially available formulations. Factorial design is a multivariate data analysis procedure that can be used to optimize the manufacturing processes of lipid nanocarriers, providing valuable information and minimizing development time. This work describes the use of factorial design to optimize a process for the preparation of nanostructured lipid carriers (NLC) based on cetyl palmitate and capric/caprylic triglycerides as structural lipids and Pluronic 68 as the colloidal stabilizer, for delivery of the local anesthetics lidocaine and prilocaine (both at 2.5%). The factors selected were the excipient concentrations, and three different responses were followed: particle size, polydispersity index and zeta potential. The encapsulation efficiency of the most effective formulations (NLC 2, 4, and 6) was evaluated by the ultrafiltration/centrifugation method. The formulations that showed the highest levels of encapsulation were tested using in vitro release kinetics experiments with Franz diffusion cells. The NLC6 formulation exhibited the best sustained release profile, with 59% LDC and 66% PLC released after 20h. This formulation was then characterized using different techniques (IR-ATR, DSC, DRX, TEM, and NTA) to obtain information about its molecular organization and its physicochemical stability, followed during 14months of storage at 25°C. This thorough pre-formulation study represents an important advance towards the development of an efficient pre-anesthetic for use in dentistry.

The potential of protein-nanomaterial interaction for advanced drug delivery

Nanomaterials, like nanoparticles, micelles, nano-sheets, nanotubes and quantum dots, have great potentials in biomedical fields. However, their delivery is highly limited by the formation of protein corona upon interaction with endogenous proteins. This new identity, instead of nanomaterial itself, would be the real substance the organs and cells firstly encounter. Consequently, the behavior of nanomaterials in vivo is uncontrollable and some undesired effects may occur, like rapid clearance from blood stream; risk of capillary blockage; loss of targeting capacity; and potential toxicity. Therefore, protein-nanomaterial interaction is a great challenge for nanomaterial systems and should be inhibited. However, this interaction can also be used to functionalize nanomaterials by forming a selected protein corona. Unlike other decoration using exogenous molecules, nanomaterials functionalized by selected protein corona using endogenous proteins would have greater promise for clinical use. In this review, we aim to provide a comprehensive understanding of protein-nanomaterial interaction. Importantly, a discussion about how to use such interaction is launched and some possible applications of such interaction for advanced drug delivery are presented.

Development of a novel solid lipid nanoparticles-loaded dual-reverse thermosensitive nanomicelle for intramuscular administration with sustained release and reduced toxicity

The DRTN was prepared with flurbiprofen-loaded SLNs, poloxamers and water. The suspension transformed into a hydrogel at body temperature. The rheological characterization, release, pharmacokinetics and morphology were evaluated.