Nanotechnology strategies to address challenges in topical and cellular delivery of siRNAs in skin disease therapy.

Gene therapy is one of the most advanced therapies in current medicine. In particular, interference RNA-based therapy by small interfering RNA (siRNA) has gained attention in recent years as it is a highly versatile, selective and specific therapy. In dermatological conditions, topical delivery of siRNA offers numerous therapeutic advantages, mainly by inhibiting the expression of target transcripts directly in the skin. However, crossing the stratum corneum and overcoming intracellular barriers is an inherent challenge. Substantial efforts by scientists have moved towards the use of multimodal and multifunctional nanoparticles to overcome these barriers and achieve greater bioavailability in their site of action, the cytoplasm. In this review the most innovative strategies based on nanoparticle and physical methods are presented, as well as the design principles and the main factors that contribute to the performance of these systems. This review also highlights the synergistic contributions of medicine, nanotechnology, and molecular biology to advancing translational research into siRNA-based therapeutics for skin diseases.

Solid Lipid-Polymer Hybrid Nanoplatform for Topical Delivery of siRNA: In Vitro Biological Activity and Permeation Studies.

Small interfering RNA (siRNA) molecules have limited transfection efficiency and stability, necessitating the use of delivery systems to be effective in gene knockdown therapies. In this regard, lipid-polymeric nanocarriers have emerged as a promising class of nanoparticles for siRNA delivery, particularly for topical applications. We proposed the use of solid lipid-polymer hybrid nanoparticles (SLPHNs) as topical delivery systems for siRNA. This approach was evaluated by assessing the ability of SLPHNs-siRNA complexes to internalize siRNA molecules and both to penetrate skin layers in vitro and induce gene knocking down in a skin cell line. The SLPHNs were formed by a specific composition of solid lipids, a surfactant polymer as a dispersive agent, and a cationic polymer as a complexing agent for siRNA. The optimized nanocarriers exhibited a spherical shape with a smooth surface. The average diameter of the nanoparticles was found to be 200 nm, and the zeta potential was measured to be +20 mV. Furthermore, these nanocarriers demonstrated excellent stability when stored at 4 °C over a period of 90 days. In vitro and in vivo permeation studies showed that SLPHNs increased the cutaneous penetration of fluorescent-labeled siRNA, which reached deeper skin layers. Efficacy studies were conducted on keratinocytes and fibroblasts, showing that SLPHNs maintained cell viability and high cellular uptake. Furthermore, SLPHNs complexed with siRNA against Firefly luciferase (siLuc) reduced luciferase expression, proving the efficacy of this nanocarrier in providing adequate intracellular release of siRNA for silencing specific genes. Based on these results, the developed carriers are promising siRNA delivery systems for skin disease therapy.

TNFα siRNA delivery by nanoparticles and photochemical internalization for psoriasis topical therapy.

Psoriasis is a chronic inflammatory skin disease that presents increased expression of tumor necrosis factor α (TNFα), a proinflammatory cytokine. The discovery of RNA interference (RNAi), mediated by short interfering RNA (siRNA), made it possible for the expression of some genes to be eliminated. However, for its application, it is necessary to use carriers that can protect siRNA and release it in the target cells. Herein, we developed a delivery system for siRNA based on hybrid polymer-lipid nanoparticles (PLNs) and combined this system with photochemical internalization (PCI), photoactivating the photosensitizer TPPS2a, to optimize the endosomal escape of TNFα siRNA in the cytoplasm, aiming to use the system as a topical formulation to treat psoriasis. The PLNs composed of 2.0% of Compritol® 888 ATO (lipid), 1.5% of poloxamer 188 and 0.1% of the cationic polymer poly(allylamine hydrochloride) showed an average nanoparticle size of 142 nm, a zeta potential of +25 mV, and the ability to efficiently coencapsulate TPPS2a and complexed siRNA. In addition, these materials did not present cellular toxicity and showed high cellular uptake. In vitro delivery studies using porcine skin model revealed that the PLNs delivered siRNA and TPPS2a into the skin. The efficacy was verified using an in vivo psoriasis animal (hairless mouse) model induced by imiquimod (IMQ) cream. The results revealed that PLN-TPPS2a-TNFα siRNA combined with PCI resulted in a decrease in the levels of TNFα, showing the efficiency of the treatment to silence this cytokine in psoriatic lesions, which was accompanied by a reduction in the redness and scaling of the mouse skin. The results showed the potential of the developed PLNs in combined silencing gene therapy and PCI for topical treatment of psoriasis.

Advances in lyotropic liquid crystal systems for skin drug delivery.

INTRODUCTION: Lyotropic liquid crystals (LLCs) are organized mesophases with intermediate properties between liquids and solids. The LLC and its liquid crystalline nanoparticles (LCNPs) have attracted great interest from the scientific community in recent years as potential drug delivery systems due to the high internal ordering and symmetry with a wide interfacial area. AREAS COVERED: This article aims to gather information and to provide a description of the highly organized structures of LLCs. Updates on production methods and new insights for LCNPs optimization and physico-chemical and morphological caracterization techniques were discussed. We also discussed why these systems proved to be a platform for the design of nanocarrier drug delivery, with an emphasis on topical and transdermal applications. EXPERT OPINION: Drug delivery platforms are of particular importance to improve the biopharmaceutical aspects of therapies topically. Although several systems can be used, LLC or LCNPs appear to be favored due to their similarity to the lipid structure of the skin. The highly ordered structure and the possibility of chemical modifications make it possible to obtain better clinical responses. The results of several studies support the innovations in this field and predict that these systems can innovate the market of technologies for the treatment of cutaneous diseases and cosmetology.

Liquid crystalline nanodispersion functionalized with cell-penetrating peptides improves skin penetration and anti-inflammatory effect of lipoic acid after in vivo skin exposure to UVB radiation.

In this study, the development and the performance of a new targeted liquid crystalline nanodispersion (LCN) by the attachment of cell-penetrating peptides (CPP) onto their surfaces to improve skin delivery of lipoic acid (LA) were evaluated. For that, the synthesis and characterization of this new platform as well as its spatiotemporal analysis from in vitro and in vivo topical application were explored and extensively discussed in this paper. The TAT or D4 peptides were chosen as CPP due to specific target strategies by the charge grouping on the skin surface or target the overexpressed epidermal growth factor receptor (EGFR) of cell membrane of keratinocytes, respectively. Thus, the nanoparticle characterization results when taken together suggested that designed LCNs maintained their hexagonal phase structure, nanoscale particle size, and low polydispersity index even after drug, lipopolymers, and peptide additions, which are proved to be favorable for topical skin delivery. There were no statistical differences among the LCNs investigated, except for superficial charge of LCN conjugated with TAT which may have altered the LCN zeta potential due to cationic charge of TAT amino acid sequence compared with D4. The cumulative amounts of LA retained into the skin were determined to be even higher coming from the targeted LCNs. Moreover, the exogenous antioxidant application of the LA from the LCNs can prevent ROS damage, which was demonstrated by this study with the less myeloperoxidase (MPO) activity and decrease in cytokine levels (TNF-alpha and IL-1ß) generated by the oxidative stress modulation. Together, the data presented highlights the potential of these targeted LCNs, and overall, opens new frontiers for preclinical trials.

Therapeutic applications and delivery systems for triptolide.

Triptolide (TPL) is a natural compound and active component of Tripterygium wilfordii Hook F., an Asian native woody vine widely used for over 200 years in Chinese medicine. Hot water, ethanol-ethyl acetate, and chloroform-methanol extracts are the first reported TPL preparations in the literature, and since then, several studies for application in inflammation processes and cancer are described due to the antitumor, anti-inflammatory, and immunosuppressive characteristics of the molecule. However, physicochemical properties such as poor solubility and bioavailability are the main concerns regarding the TPL safety and efficacy in clinical studies since trials have reported adverse side effects alongside the excellent TPL therapeutic effects. Here, we review the main TPL applications and issues related to the drug usage, and a comprehensive summary of diseases is provided. Special emphasis is given to drug delivery systems designed to overcome the TPL physicochemical characteristics such as poor drug solubility, and how to increase efficacy and obtain a safe drug profile. Graphical abstract.

Microemulsion co-delivering vitamin A and vitamin E as a new platform for topical treatment of acute skin inflammation.

In this study, we developed a water-in-oil microemulsion containing vitamin A (retinol) and vitamin E (α-tocopherol), which serves as a multifunctional nanosystem that co-delivers antioxidants and displayed additive effect against acute skin inflammation. Microemulsion (ME) was prepared by mixing a surfactant blend (Tween 80 and propylene glycol, 5:1) with isopropyl myristate and water (ratio of 50:40:10, respectively). Vitamin A (0.05% w/w concentration) and/or vitamin E (0.1% w/w concentration) were incorporated into the surfactant mixture of ME by stirring with a magnetic stirrer for 30 min. This multifunctional ME displayed physical stability, with low cytotoxicity in 3T3 cell line, as well as cellular internalization into the cytosol. In vivo treatments using ME delivering α-tocopherol reduced dermal expression of TNF-α by 1.3-fold (p < 0.01), when compared to unloaded ME treatment group. When retinol was added into the ME containing α-tocopherol, it further reduced TNF-α expression by 2-fold (p < 0.001), suggesting the additive effect of vitamin E and vitamin A in the treatment against skin inflammation. In conclusion, we successfully developed the use of water-in-oil ME to pack both vitamin E and vitamin A, and demonstrated for the first time its anti-inflammatory potential when applied topically to TPA-induced inflamed skin.

Nanostructured lipid carrier co-delivering tacrolimus and TNF-α siRNA as an innovate approach to psoriasis.

Since psoriasis is an immuno-mediated skin disease, long-term therapies are necessary for its treatment. In clinical investigations, tacrolimus (TAC), a macrolide immunosuppressive inhibitor of calcineurin, arises as an alternative for the treatment of psoriasis, acting in some cytokines involved in the pathogenesis of the disease. Here, we aim to study the psoriasis treatment with TAC and siRNA for one of most cytokines expressed in psoriasis, the TNF-α. A multifunctional nanostructure lipid carrier (NLC) was developed to co-delivery TAC and siRNA. Results showed that the particle size and zeta potential were around 230 nm and + 10 mV, respectively. The release study demonstrated a controlled release of TAC, and the permeation and retention profile in the skin tissue show to be promising for topical application. The cell viability and uptake in murine fibroblast presented low toxicity associated to uptake of NLC in 4 h, and finally, the in vivo animal model demonstrates the efficiency of the NLC multifunctional, exhibiting a reduction of the cytokine TNF-α expression about 7-fold and presenting a synergic effect between the TAC and TNF-α siRNA. The developed system was successfully to treat in vivo psoriatic animal model induced by imiquimod and the synergic combination was reported here for the first time. Graphical abstract.

Current Non-viral siRNA Delivery Systems as a Promising Treatment of Skin Diseases.

BACKGROUND: Gene therapy is a new approach to discover and treat many diseases. It has attracted considerable attention from researchers in the last decades. The gene therapy through RNA interference has been considered one of the most recent and revolutionary approaches used in individualized therapy. In the last years, we have witnessed the rapid development in the field of the gene silencing and knockdown by topical siRNA. Its application in gene therapy has become an attractive alternative for drug development. METHODS: This article will address topical delivery of siRNA as a promising treatment for skin disorders. An update on the advances in siRNA-based nanocarriers as a powerful therapeutic strategy for several skin diseases will be discussed giving emphasis on in vitro evaluations. RESULTS: Through the in-depth review of the literature on the use of siRNAs for skin diseases we realize how widespread this use is. We have also realized that nanoparticles as non-viral vectors are increasingly being explored. Skin diseases where the use of siRNA has been explored most are skin cancer (melanoma and nonmelanoma), psoriasis, vitiligo, dermatitis and leprosy. But we also report here other diseases where the use of siRNA has been growing as acne, alopecia areata, cutaneous leishmaniasis, mycoses, herpes, epidermolysis bullosa and oculocutaneous albinism. Also highlighted, the first clinical trial of siRNA for cutaneous diseases, aimed at Pathyounychia Congenita. CONCLUSION: The treatment of skin diseases based on topical delivery of siRNA, which act by inhibiting the expression of target transcripts, offers many potential therapeutic advantages for suppressing genes into the skin.

In Vitro TyRP-1 Knockdown Based on siRNA Carried by Liquid Crystalline Nanodispersions: an Alternative Approach for Topical Treatment of Vitiligo.

PURPOSE: Vitiligo is a skin disease characterized by depigmentation and the presence of white patches that are associated with the loss of melanocytes. The most common explanation for the cause of this condition is that it is an autoimmune condition. TyRP-1 is involved in melanin pigment synthesis but can also function as a melanocyte differentiation antigen. This protein plays a role in the autoimmune destruction of melanocytes, which results in the depigmentation, characteristic of this disease. In this study, we evaluated liquid crystalline nanodispersions as non-viral vectors to deliver siRNA-TyRP-1 as an alternative for topical treatment of vitiligo. METHODS: Liquid crystalline nanodispersions were obtained and characterized with respect to their physical-chemical parameters including size, PdI and zeta potential, as well as Small Angle X-ray Scattering and complexing to siRNA. The effects of the liquid crystalline nanodispersions on the cellular viability, cell uptake and levels of the knockdown target TyRP-1 were evaluated in melan-A cells after 24 h of treatment. RESULTS: The liquid crystalline nanodispersions demonstrated adequate physical-chemical parameters including nanometer size and a PdI below 0.38. These systems promoted a high rate of cell uptake and an impressive TyRP-1 target knockdown (> 80%) associated with suitable loading of TyRp-1 siRNA. CONCLUSIONS: We demonstrated that the liquid crystalline nanodispersions showed promising alternative for the topical treatment of vitiligo due to their physical parameters and ability in knockdown the target protein involved with autoimmune destruction of melanocytes.

Ketoprofen Microemulsion for Improved Skin Delivery and In Vivo Anti-inflammatory Effect.

We have designed a microemulsion (ME) containing Ketoprofen (KET) for anti-inflammatory effect evaluated using the rat paw edema model. The ME was prepared by adding propylene glycol (PG) loaded with 1% KET/water (3:1, w/w), to a mixture of sorbitan monooleate and polysorbate 80 (47.0%) at 3:1 (w/w) and canola oil (38.0%). The physicochemical characterization of KET-loaded ME involved particle size and zeta potential determination, entrapment efficiency, calorimetric analysis, and in vitro drug release. The in vivo anti-inflammatory study employed male Wistar rats. Measurement of the foot volume was performed using a caliper immediately before and 2, 4, and 6 h after injection of Aerosil. KET-loaded ME showed particle size around 20 nm, with zeta potential at -16 mV and entrapment efficiency at 70%. Moreover, KET was converted to the amorphous state when loaded in the formulation and it was shown that the drug was slowly released from the ME. Finally, the in vivo biological activity was similar to that of the commercial gel, but ME better controlled edema at 4 h. These results demonstrated that the ME formulation is an alternative strategy for improving KET skin permeation for anti-inflammatory effect. Furthermore, our findings are promising considering that the developed ME was loaded with only 1% KET, and the formulation was able to keep a similar release profile and in vivo effect compared to the commercial gel with 2.5% KET. Therefore, the KET-loaded developed herein ME is likely to have a decreased side effect compared with that of the commercial gel, but both presented the same efficacy.

Optimization of protoporphyrin IX skin delivery for topical photodynamic therapy: Nanodispersions of liquid-crystalline phase as nanocarriers.

Nanodispersions of liquid-crystalline phases (NLPs) composed of monoolein and oleic acid were chosen as nanocarriers to improve the topical retention of the photosensitizer protoporphyrin IX (PpIX) and thereby optimize photodynamic therapy (PDT) using this photosensitizer. The nanodispersions were characterized by polarized light microscopy, small-angle X-ray diffraction and dynamic light scattering. The stability and encapsulation efficiency (EE%) of the nanodispersions were also evaluated. In vitro and in vivo skin penetration studies were performed to determine the potential of the nanodispersions for cutaneous application. In addition, skin penetration and skin irritancy (in an animal model) after in vivo application were visualized by fluorescence light microscopy. The nanodispersion obtained was characterized as a monodisperse system (~150.0 nm) of hexagonal liquid-crystalline phase, which provided a high encapsulation efficiency of PpIX (~88%) that remained stable over 90 days of investigation. Skin penetration studies demonstrated that the nanodispersion enhanced PpIX skin uptake 11.8- and 3.3-fold (in vitro) and 23.6- and 20.8-fold (in vivo) compared to the PpIX skin uptake of control formulations, respectively. In addition, the hexagonal phase nanodispersion did not cause skin irritation after application for two consecutive days. Overall, the results show that the nanocarrier developed is suitable for use in topical PDT with PpIX.

Liquid crystalline systems containing Vitamin E TPGS for the controlled transdermal nicotine delivery

ABSTRACT Transdermal nicotine patches have been used in smoking cessation therapy, suggested for the treatment of skin disorders with eosinophilic infiltration and have been found to improve attention performance in patients with Alzheimer's disease and age-associated memory impairment. However, skin irritation with extended patch use is still a problem. The aim of this work was to develop a simple to prepare liquid crystalline system containing vitamin E TPGS that would be able to control nicotine delivery and reduce irritation and sensitization problems. The liquid crystalline phases were macroscopically characterized by visual analysis and examined microscopically under a polarized light microscope. Topical and transdermal delivery of nicotine were investigated in vitro using porcine ear skin mounted on a Franz diffusion cell. Nicotine skin permeation from the developed cubic phase followed zero-order kinetics (r = 0.993) and was significantly enhanced after 12 h when compared to the control formulation (nicotine solution) (p < 0.05) (138.86 ± 20.44 and 64.91 ± 4.06 μg/cm2, respectively). Cubic phase was also able to target viable skin layers in comparison to control solution (8.18 ± 1.89 and 2.63 ± 2.51 μg/cm2, respectively). Further studies to evaluate skin sensitization and irritation are now necessary.

RESUMO Adesivos transdérmicos de nicotina são utilizados para cessação de fumar, tratamento de problemas de pele com infiltração de eosinófilos e para melhorar a atenção em pacientes com doença de Alzheimer e enfraquecimento da memória associada à idade. No entanto, a irritação da pele com o uso prolongado dos adesivos ainda é um problema. O objetivo deste trabalho foi desenvolver sistema líquido cristalino (SLC) de preparo simples contendo vitamina E TPGS capaz de controlar a liberação de nicotina e reduzir os problemas de irritação cutânea. Os SLCs foram caracterizados por análise visual e microscopia de luz polarizada. As administrações tópica e transdérmica de nicotina foram investigadas in vitro utilizando pele de orelha de porco em célula de difusão de Franz. A permeação da nicotina veiculada pela fase cúbica desenvolvida seguiu cinética de ordem zero (r = 0,993) e foi significativamente maior do que o controle (solução de nicotina) após 12 h (p < 0,05) (138,86 ± 20,44 e 64,91 ± 4,06 µg/cm2, respectivamente). A fase cúbica também promoveu aumento da penetração de nicotina nas camadas viáveis da pele quando comparado ao controle (8,18 ± 1,89 e 2,63 ± 2,51 µg/cm2, respectivamente). Estudos futuros para avaliar a sensibilização e irritação da pele são necessários.

Advances in the bioanalytical study of drug delivery across the skin.

The study of a drug's dermal penetration profile provides important pharmaceutical data for the rational development of topical and transdermal delivery systems because the skin is a broadly used delivery route for local and systemic drugs and a potential route for gene therapy and vaccines. Monitoring drug penetration across the skin and quantifying its levels in different skin layers have been constant challenges due to the detection limitations of the available techniques, as well as the inherent interference in this tissue. This review explores and discusses several bionalytical methods that are indispensable tools to study drugs across the skin. In addressing the main topic, we structure the review highlighting the skin as an important route of drug administration and its structure, skin membrane models most used and its properties, in vitro and in vivo assays most used in the study of drug delivery to the skin, the techniques for processing the skin for subsequent analysis by bioanalytical methods that have a theoretical and practical approach showing its applicability, limitations and also including examples of its use. This review has a comprehensive approach in order to help researchers design their experiments and update the applicability and advances in this area of expertise.

An in situ gelling liquid crystalline system based on monoglycerides and polyethylenimine for local delivery of siRNAs.

The development of delivery systems able to complex and release siRNA into the cytosol is essential for therapeutic use of siRNA. Among the delivery systems, local delivery has advantages over systemic administration. In this study, we developed and characterized non-viral carriers to deliver siRNA locally, based on polyethylenimine (PEI) as gene carrier, and a self-assembling drug delivery system that forms a gel in situ. Liquid crystalline formulations composed of monoglycerides (MO), PEI, propylene glycol (PG) and 0.1M Tris buffer pH 6.5 were developed and characterized by polarized light microscopy, Small Angle X-ray Scattering (SAXS), for their ability to form inverted type liquid crystalline phases (LC2) in contact with excess water, water absorption capacity, ability to complex with siRNA and siRNA release. In addition, gel formation in vivo was determined by subcutaneous injection of the formulations in mice. In water excess, precursor fluid formulations rapidly transformed into a viscous liquid crystalline phase. The presence of PEI influences the liquid crystalline structure of the LC2 formed and was crucial for complexing siRNA. The siRNA was released from the crystalline phase complexed with PEI. The release rate was dependent on the rate of water uptake. The formulation containing MO/PEI/PG/Tris buffer at 7.85:0.65:76.5:15 (w/w/w/w) complexed with 10 µM of siRNA, characterized as a mixture of cubic phase (diamond-type) and inverted hexagonal phase (after contact with excess water), showed sustained release for 7 days in vitro. In mice, in situ gel formation occurred after subcutaneous injection of the formulations, and the gels were degraded in 30 days. Initially a mild inflammatory process occurred in the tissue surrounding the gel; but after 14 days the tissue appeared normal. Taken together, this work demonstrates the rational development of an in situ gelling formulation for local release of siRNA.

Self-assembling gelling formulation based on a crystalline-phase liquid as a non-viral vector for siRNA delivery.

Liquid crystalline systems (LCSs) form interesting drug delivery systems. These include in situ gelling delivery systems, which present several advantages for use as self-assembling systems for local drug delivery. The aim of this study was to develop and characterize in situ gelling delivery systems for local siRNA delivery. The influence of the components that form the systems was investigated, and the systems were characterized by polarized light microscopy, Small Angle X-ray Scattering (SAXS), swelling studies, assays of their ability to form a complex with genes and of the stability of the genes in the system, as well as assays of in situ gelling formation and local toxicity using an animal model. The system containing a mixture of monoglycerides (MO), oleylamine (OAM), propylene glycol (PG) and tris buffer (8.16:0.34:76.5:15, w/w/w/w) was considered the most appropriate for local siRNA delivery purposes. The molecular structure was characterized as hexagonal phase; the swelling studies followed a second order kinetic model and the water absorption was a fast process reaching equilibrium at 2 h. The system formed a complex with siRNA and remained in a stable form. The gel was formed in vivo after subcutaneous administration of a precursor fluid formulation in mice and was biodegradable in 30 days. The inflammatory process that took place was considered normal. Therefore, the developed liquid crystalline delivery system shows the appropriate characteristics for use as a local siRNA delivery method for gene therapy.

Caracterização do intumescimento de sistemas líquido-cristalinos de fase lamelar de monoleína e água contendo polihexametilenobiguanida / Characterization of swelling of lamellar phases of monoolein and water containing polyhexamethylenebiguanide

A monoleína é um lipídeo polar capaz de absorver água e formar sistemas líquido-cristalinos, os quais são utilizados como sistemas de liberação para administração de vários fármacos. Neste estudo foi avaliado o potencial de sistemas de fase lamelar constituídos por monoleína e água para veicular polihexametilenobiguanida (PHMB). A formação dos sistemas líquido-cristalinos foi caracterizada por microscopia de luz polarizada. Estudos de intumescimento foram realizados gravimetricamente em várias condições avaliando-se os efeitos de parâmetros como pH, força iônica e temperatura do meio de imersão. O processo de intumescimento foi caracterizado através da obtenção dos perfis de intumescimento e análise de sua cinética, além da determinação da capacidade máxima de intumescimento dos sistemas. Os sistemas de fase lamelar foram obtidos em presença de PHMB, os quais absorveram água rapidamente de acordo com cinética de segunda ordem e sofreram transição de fase, formando a fase cúbica. O intumescimento dos sistemas não foi influenciado pela presença do fármaco nos vários meios de imersão estudados, exceto pela imersão em meio ácido, no qual a presença do PHMB aumentou a captação de água. O intumescimento dos sistemas contendo PHMB não foi afetado pela força iônica do meio de imersão, porém foi diminuído com o aumento da temperatura. Desta maneira, sistemas líquido-cristalinos de monoleína e água foram obtidos e o processo de intumescimento foi caracterizado. Os sistemas apresentaram potencial para serem propostos como sistemas de liberação para administração de PHMB e estudos de liberação de fármacos serão realizados futuramente.

Monoolein is a polar lipid that absorbs water and forms liquid crystalline systems that are used as drug delivery systems for different medications. The aim of the present study was to investigate lamellar phases formed by monoolein and water as potential vehicles for the administration of polyhexamethylene biguanide (PHMB). Lamellar phase systems formed by monoolein and water containing PHMB were characterized by polarizing microscopy. Swelling studies were performed gravimetrically under different conditions for the evaluation of the effects of pH, ionic strength and temperature. Analyses of swelling profiles, swelling kinetics and maximum swelling capacity were performed. The lamellar phase systems of monoolein and water obtained in the presence of PHMB absorbed water very quickly following second-order swelling kinetics and formed a cubic phase. The swelling of the systems was not influenced by the presence of the drug in the immersion media studied, except under acidic conditions, in which the drug exhibited increased water uptake. The swelling of systems containing PHMB was not affected by the ionic strength of the immersion media, but was reduced with an increase in temperature. Liquid crystalline systems of monoolein and water were obtained and swelling behavior was investigated. The systems exhibited the potential for use as a drug delivery system for PHMB administration. However, further drug-release studies should be performed.

PLGA nanoparticles as delivery systems for protoporphyrin IX in topical PDT: cutaneous penetration of photosensitizer observed by fluorescence microscopy.

Poly(D,L lactic-co-glycolic acid) (PLGA) based nanoparticles (NPs) are proposed for topical delivery of Protoporphyrin IX (PpIX) in Photodynamic Therapy of skin cancers. PpIX loaded into PLGA NPs showed nanometric average diameter (-280 nm), spherical forms and pH - 5.7, conditions suitable for topical application. In vitro release of PpIX from NPs was sustained up to 24 hr with a burst release effect of about 37.0% at 2 hr. Penetration and distribution of PpIX in hairless mice skin was determined by fluorescence microscopy 8 or 24 hrs after application of PpIX-NPs in the animals. At 24 hours, areas located in deeper regions of the skin were found to have greater fluorescence intensity. The finding indicates a localized effect of PpIX-NPs in the epidermis plus dermis--a site of action for topical PDT--and suggests a potential use of PpIX-NPs in PDT associated to skin cancer treatments.

Delivery systems and local administration routes for therapeutic siRNA.

With the increasing number of studies proposing new and optimal delivery strategies for the efficacious silencing of gene-related diseases by the local administration of siRNAs, the present review aims to provide a broad overview of the most important and latest developments of non-viral siRNA delivery systems for local administration. Moreover, the main disease targets for the local delivery of siRNA to specific tissues or organs, including the skin, the lung, the eye, the nervous system, the digestive system and the vagina, were explored.

A Validated Reverse Phase HPLC Analytical Method for Quantitation of Glycoalkaloids in Solanum lycocarpum and Its Extracts.

Solanum lycocarpum (Solanaceae) is native to the Brazilian Cerrado. Fruits of this species contain the glycoalkaloids solasonine (SN) and solamargine (SM), which display antiparasitic and anticancer properties. A method has been developed for the extraction and HPLC-UV analysis of the SN and SM in different parts of S. lycocarpum, mainly comprising ripe and unripe fruits, leaf, and stem. This analytical method was validated and gave good detection response with linearity over a dynamic range of 0.77-1000.00 µg mL(-1) and recovery in the range of 80.92-91.71%, allowing a reliable quantitation of the target compounds. Unripe fruits displayed higher concentrations of glycoalkaloids (1.04% ± 0.01 of SN and 0.69% ± 0.00 of SM) than the ripe fruits (0.83% ± 0.02 of SN and 0.60% ± 0.01 of SM). Quantitation of glycoalkaloids in the alkaloidic extract gave 45.09% ± 1.14 of SN and 44.37% ± 0.60 of SM, respectively.