Amorphous cyclosporin A nanoparticles for enhanced dermal bioavailability

The epidermal lipid-microbiome loop and immunity: Important players in atopic dermatitis

BACKGROUND

The promotion of epidermal barrier dysfunction is attributed to abnormalities in the lipid-microbiome positive feedback loop which significantly influences the imbalance of the epithelial immune microenvironment (EIME) in atopic dermatitis (AD). This imbalance encompasses impaired lamellar membrane integrity, heightened exposure to epidermal pathogens, and the regulation of innate and adaptive immunity. The lipid-microbiome loop is substantially influenced by intense adaptive immunity which is triggered by abnormal loop activity and affects the loop's integrity through the induction of atypical lipid composition and responses to dysregulated epidermal microbes. Immune responses participate in lipid abnormalities within the EIME by downregulating barrier gene expression and are further cascade-amplified by microbial dysregulation which is instigated by barrier impairment.

AIM OF REVIEW

This review examines the relationship between abnormal lipid composition, microbiome disturbances, and immune responses in AD while progressively substantiating the crosstalk mechanism among these factors. Based on this analysis, the "lipid-microbiome" positive feedback loop, regulated by immune responses, is proposed.

KEY SCIENTIFIC CONCEPTS OF REVIEW

The review delves into the impact of adaptive immune responses that regulate the EIME, driving AD, and investigates potential mechanisms by which lipid supplementation and probiotics may alleviate AD through the up-regulation of the epidermal barrier and modulation of immune signaling. This exploration offers support for targeting the EIME to attenuate AD.

Nanosuspension-Based Drug Delivery Systems for Topical Applications

Nanosuspensions have garnered recent attention as a promising strategy for mitigating the bioavailability challenges of hydrophobic drugs, particularly those characterized by poor solubility in both aqueous and organic environments. Addressing solubility issues associated with poorly water-soluble drugs has largely resolved the need to enhance drug absorption and bioavailability. As mucosal formulations and topical administration progress in the future, nanosuspension drug delivery, straightforward formulation techniques, and versatile applications will continue to be subjects of interest. Nanosuspensions have undergone extensive scrutiny in preparation for topical applications, encompassing ocular, pulmonary, and dermal usage. Among the numerous methods aimed at improving cutaneous application, nanocrystals represent a relatively recent yet profoundly intriguing approach. Despite the increasing availability of various nanosuspension products, primarily designed for oral administration, only a limited number of studies have explored skin permeability and drug accumulation in the context of nanosuspensions. Nevertheless, the scant published research unequivocally underscores the potential of this approach for enhancing cutaneous bioavailability, particularly for active ingredients with low to medium solubility. Nanocrystals exhibit increased skin adhesiveness in addition to heightened saturation solubility and dissolution rate, thereby augmenting cutaneous distribution. The article provides a comprehensive overview of nanosuspensions for topical application. The methodology employed is robust, with a well-defined experimental design; however, the limited sample size raises concerns about the generalizability of the findings. While the results demonstrate promising outcomes in terms of enhanced drug delivery, the discussion falls short of addressing certain limitations. Additionally, the references largely focus on recent studies, but a more diverse inclusion of historical perspectives could offer a more holistic view of the subject.

Formulation Strategies of Nanosuspensions for Various Administration Routes

Nanosuspensions (NSs), which are nanosized colloidal particle systems, have recently become one of the most interesting substances in nanopharmaceuticals. NSs have high commercial potential because they provide the enhanced solubility and dissolution of low-water-soluble drugs by means of their small particle sizes and large surface areas. In addition, they can alter the pharmacokinetics of the drug and, thus, improve its efficacy and safety. These advantages can be used to enhance the bioavailability of poorly soluble drugs in oral, dermal, parenteral, pulmonary, ocular, or nasal routes for systemic or local effects. Although NSs often consist mainly of pure drugs in aqueous media, they can also contain stabilizers, organic solvents, surfactants, co-surfactants, cryoprotectants, osmogents, and other components. The selection of stabilizer types, such as surfactants or/and polymers, and their ratio are the most critical factors in NS formulations. NSs can be prepared both with top-down methods (wet milling, dry milling, high-pressure homogenization, and co-grinding) and with bottom-up methods (anti-solvent precipitation, liquid emulsion, and sono-precipitation) by research laboratories and pharmaceutical professionals. Nowadays, techniques combining these two technologies are also frequently encountered. NSs can be presented to patients in liquid dosage forms, or post-production processes (freeze drying, spray drying, or spray freezing) can also be applied to transform the liquid state into the solid state for the preparation of different dosage forms such as powders, pellets, tablets, capsules, films, or gels. Thus, in the development of NS formulations, the components/amounts, preparation methods, process parameters/levels, administration routes, and dosage forms must be defined. Moreover, those factors that are the most effective for the intended use should be determined and optimized. This review discusses the effect of the formulation and process parameters on the properties of NSs and highlights the recent advances, novel strategies, and practical considerations relevant to the application of NSs to various administration routes.

Enhanced intradermal delivery of Dragon's blood in biocompatible nanosuspensions hydrogel patch for skin photoprotective effect

Dragon's Blood is a member of the Chinese medicinal herb, having anti-oxygen and anti-inflammatory activity for the photoprotective effect. However, the poor water solubility of raw Dragon's Blood powder has limited its intradermal delivery process. In this study, we evaluated nanosuspensions to enhance intradermal delivery of Dragon's Blood exerting a photoprotective effect. The prepared nanosuspension was added to a composite hydrogel patch matrix for better skin application. In the present research, we used biocompatible materials hyaluronic acid and amino acid surfactants as nanosuspension stabilizers and agar/gelatin/sodium polyacrylate as hydrogel patch matrix. The prepared Dragon's Blood nanosuspension had a particle size of 447.0 ± 48.6 nm. The micro-structures morphology and viscoelasticity characteristics by SEM and rheological testing confirmed a sufficient crosslinked hydrogel network. The skin retention amount of Dragon's Blood nanosuspension was 1.48 times of raw Dragon's Blood powder water suspension, and the skin penetration amount of Dragon's Blood nanosuspension was only about 1/3 of Dragon's Blood DMSO solution. In the UVB-irradiated HaCaT cell phototoxicity model, Dragon's Blood nanosuspension also significantly increased cell viability by about 1 time of the model group and decreased the production of reactive oxygen species about 1/2 times of model group. In vivo safety and efficiency evaluation experiment illustrated that DB-NS hydrogel patch processes have favorable safety and photoprotective effect with no skin irritancy and phototoxicity. Furthermore, DB-NS and DB-NS hydrogel patches could protect skin from UVA and UVB irritating skin reactions. Overall, our study of the combined use of biocompatible and biodegradable materials as excipients of nanosuspension and hydrogel patch could be used as an effective additive of Intradermal delivery and skin photoprotection.

Exploring the translocation behaviours in vivo of herpetrione amorphous nanoparticles via oral delivery

Nanotechnology has been a primary strategy to enhance oral bioavailability of poorly water soluble drugs. However, the limited information in vivo fate of impedes the development of nanoparticles via the oral delivery, especially the amorphous nanoparticles with high energy states are rarely reported. This study is to track the translocation of oral herpetrione amorphous nanoparticles (HPE-ANPs). We prepare amorphous particles (ANPs) of various sizes (200 nm and 450 nm), which are embedded with an aggregation-caused quenching (ACQ) dyes for tracking the intact nanoparticles. Nanoparticles remain in the gastrointestinal tract (GIT) for 8 h following oral administration, suggesting that most ANPs was mainly degraded or absorbed in the small intestine. Ex vivo imaging shows that the fluorescent signals are observed in the GIT and liver but not in other organs, which attributed to low absorption of integral nanoparticles. Besides, HPE-ANPs may be directly interact with GIT epithelia, and ileum provides better absorption than the jejunum. Cellular studies prove that integral HPE-ANPs can be taken up by enterocyte, while it penetrates cell monolayers only small amounts. In conclusion, we speculate that the drug in the form of integral nanoparticles and small molecules may be co-absorbed to improve bioavailability in vivo.

Nanotechnology-based alternatives for the topical delivery of immunosuppressive agents in psoriasis

Psoriasis is a recurring, immune-mediated dermatological disorder. Many therapeutic agents are available for the treatment of psoriasis, including immunosuppressants and biologic treatments with immunosuppressant action. The employment of nanotechnology allows drug tailoring to achieve dermal targeting, improve efficacy and minimize undesirable effects. Here we discuss the use of the topical route in combination with nano-based drug delivery systems containing immunosuppressants for the management of psoriasis. This review is based on articles selected from 2011 to 2022, using the keywords "Psoriasis" AND "Immunosuppressants" AND "Nano*" in the main databases. Fifty-seven articles were retrieved, although only forty-two matched the inclusion criteria. Nanocarriers such as liposomes, ethosomes, niosomes, solid lipid nanoparticle, nanostructured lipid carriers and microspheres containing immunosuppressive drugs (methotrexate, cyclosporine, tacrolimus, and etanercept) were identified. The main findings of these studies are related to the improved in vitro/ex vivo permeation/penetration and therapeutic efficacy of nanoparticles in vitro and in vivo, compared to the drug in solution. Based on the studies discussed in this review, encapsulation in several types of nanocarriers decreases toxicity, dose, and dose frequency. Furthermore, it enables specific targeting of the active drug, pointing to the possibility of improving topical therapy for psoriasis. In conclusion, nanoformulations represent a novel and promising tool for psoriasis treatment.

Development of a Self-Assembled Hydrogels Based on Carboxymethyl Chitosan and Oxidized Hyaluronic Acid Containing Tanshinone Extract Nanocrystals for Enhanced Dissolution and Acne Treatment

This study aimed to construct a pH-responsive nanocrystalline hydrogel drug delivery system for topical delivery of insoluble drugs based on the self-assembly behavior of carboxymethyl chitosan (CMC) and oxidized hyaluronic acid (OHA). The tanshinone nanocrystal (TNCs) extract was prepared by dielectric milling method, the type and ratio of stabilizer of the drug were investigated to optimize the prescription, and the effector surface method was used to optimize the preparation process. OHA was prepared by the sodium periodate oxidation method, and the concentration of CMC and OHA was optimized using gel formation time as an indicator. OHA was dissolved in TNCs and self-assembled with CMC solution to form tanshinone extract nanocrystal hydrogels (CMC-OHA/TNCs), of which the physicochemical properties and in vitro antibacterial activity were evaluated. Results showed that the optimized prescription and process could produce tanshinone extract nanocrystals with a particle size of (223.67 ± 4.03) nm and a polydispersity index (PDI) of 0.2173 ± 0.0008. According to SEM and XRD results, TNCs were completely wrapped in the hydrogel as nanoparticles, and the crystallinity of TNCs was reduced and the diffraction peaks in CMC-OHA/TNCs almost disappeared. In vitro, transdermal test results showed that CMC-OHA/TNCs could release the drug continuously at the acne lesions. The cell-counting kit-8 (CCK-8) assay confirmed that the CMC-OHA/TNCs had no obvious cytotoxicity. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of CMC-OHA/TNCs against Propionibacterium acnes and Staphylococcus aureus were significantly lower and the diameter of the inhibition circle was obviously higher than that of TNCs and tanshinone extract crude suspension. This study demonstrated that CMC-OHA/TNCs was a promising delivery system for topical delivery of insoluble drugs, which could improve the solubility of tanshinone extract and enhance its in vitro bacterial inhibitory activity.

An Alternative Device for the Topical Treatment of Oral Cancer: Development and Ex-Vivo Evaluation of Imiquimod-Loaded Polysaccharides Formulations

The topical use of imiquimod (IMQ), a non-specific immune response modifier, showed to be a promising therapeutic option for the early-stage treatment of some type of oral cancer, even when performed with a formulation (Aldara®) developed and approved for skin application. The aim of this work was the development of buccal formulations for the topical administration of IMQ with improved mucosal retention and reduced trans-mucosal permeation when compared to the reference formulation. Three different hydrogels based on carboxymethyl chitosan (CMChit), sodium alginate (A), and xanthan gum (X) in different combinations were prepared, and the loading of imiquimod was successfully performed by using a micellar formulation based on d-α-tocopheril polyethylene glycol 100 succinate (TPGS). Except for CMChit formulation, in all the other cases, the performance in vitro on the mucosa resulted comparable to the commercial formulation, despite the drug loading being 50-fold lower. Converting the gels in films did not modify the IMQ accumulated with respect to the correspondent gel formulation but produced as a positive effect a significant reduction in the amount permeated. Compared to the commercial formulation, this reduction was significant (p < 0.01) in the case of X film, resulting in an improvement of the retained/permeated ratio from 1 to 5.44. Mucoadhesion evaluation showed similar behavior when comparing the developed gels and the commercial formulation, and an excellent bioadhesion was observed for the films.

Biological and Intracellular Fates of Drug Nanocrystals through Different Delivery Routes: Recent Development Enabled by Bioimaging and PK Modeling

Nanocrystals have contributed to exciting improvements in the delivery of poorly water-soluble drugs. The biological and intracellular fates of nanocrystals are currently under debate. Due to the remarkable commercial success in enhancing oral bioavailability, nanocrystals have originally been regarded as a simple formulation approach to enhance dissolution. However, the latest findings from novel bioimaging tools lead to an expanded view. Intact nanocrystals may offer long-term durability in the body and offer drug delivery capabilities like those of other nano-carriers. This review renews the understanding of the biological fates of nanocrystals administered via oral, intravenous, and parenteral (e.g., dermal, ocular, and pulmonary) routes. The intracellular pathways and dissolution kinetics of nanocrystals are explored. Additionally, the future trends for in vitro and in vivo quantification of nanocrystals, as well as factors impacting the biological and intracellular fates of nanocrystals are discussed. In conclusion, nanocrystals present a promising and underexplored therapeutic opportunity with immense potential.

The Study of Cyclosporin A Nanocrystals Uptake and Transport across an Intestinal Epithelial Cell Model

Cyclosporin A nanocrystals (CsA-NCs) interaction with Caco-2 cells were investigated in this study, including cellular uptake and transport across Caco-2 cell monolayers. CsA-NCs of 165 nm, 240 nm and 450 nm were formulated. The dissolution of CsA-NCs was investigated by paddle method. The effect of size, concentration and incubation time on cellular uptake and dissolution kinetics of CsA-NCs in cells were studied. Uptake mechanisms were also evaluated using endocytotic inhibitors and low temperature (4 °C). The cell monolayers were incubated with each diameter CsA-NCs to evaluate the effect of size on the permeation characteristics of CsA across the intestinal mucosa. The results of dissolution study showed that 165 nm CsA-NC had the highest dissolution rate followed by 240 CsA-NC and finally 450 nm CsA-NC. The saturation of cell uptake of CsA-NCs was observed with the increase of incubation concentration and time. 240 nm and 450 nm CsA-NCs had the lowest and highest uptake efficiency at different time and drug concentration, respectively. The uptake of all three-sized CsA-NCs declined significantly in some different degree after the pre-treatment with different endocytosis inhibitors. 165 nm CsA-NC showed a highest transport capacity across monolayers at the same concentration and time. The results suggest that the size of CsA-NCs can not only affect the efficiency of cellular uptake, but also the type of endocytosis. Decreasing particle size of CsA-NCs can improve transport capacity of CsA through cell monolayer.

The Effect of Particle Size on the Absorption of Cyclosporin A Nanosuspensions

Background

Cyclosporin A (CsA) is a hydrophobic drug widely used as an immunosuppressant and anti-rejection drug in solid organ transplantation. On the market, there are two oral CsA formulations available containing polyoxyethylene castor oil, which can cause serious allergic reactions and nephrotoxicity. In order to eliminate polyoxyethylene castor oil, CsA was formulated into a nanosuspension. This study aimed to design an oral cyclosporin A nanosuspensions (CsA-NSs) and investigate the effect of particle size on absorption of CsA-NSs.

Methods

CsA-NSs were prepared using a wet bead milling method. Particle size, morphology and crystallinity state of CsA-NSs were characterized. The in vitro dissolution, the intestinal absorption properties and pharmacokinetic study of CsA-NSs were investigated.

Results

CsA-NSs with sizes of 280 nm, 522 nm and 2967 nm were prepared. The shape of CsA-NSs with smaller size was similar to that of spheres. The crystallinity of CsA in nanocrystals was reduced. The dissolution rate of CsA-NSs (280 nm) was greater than that of CsA-NSs (522 nm) and CsA-NSs (2967 nm). CsA-NSs (280 nm) showed higher absorption rate constants (K_α) and effective permeability coefficients (P_eff) of different intestinal segments compared with that of CsA-NSs (522 nm) and CsA-NSs (2967 nm). AUC_0-48h of 280 nm CsA-NSs was about 1.12-fold of that of 522 nm CsA-NSs, and about 1.51-fold of that of 2967 nm CsA-NSs. In particular, the particle size of CsA-NSs was nanoscale, and their bioavailability was bioequivalent with marked self-microemulsion (Sandimmun Neoral^®).

Conclusion

It is feasible to prepare CsA-NSs. The dissolution rate, gastrointestinal transport properties and the oral absorption of CsA-NSs were promoted by reducing size. Considering the cost, efficiency and energy consumption, there should be an optimal particle size range in industrial production.

Transition from Amorphous Cyclosporin A Nanoparticles to Size-Reduced Stable Nanocrystals in a Poloxamer 407 Solution

Amorphous drug nanoparticles usually exhibit low storage stability. A comprehensive understanding of the molecular states and physicochemical properties of the product is indispensable for designing stable formulations. In the present study, an amorphous cyclosporin A (CyA) nanosuspension with a mean particle size of approximately 370 nm was prepared by wet bead milling with poloxamer 407 (P407). Interestingly, the prepared amorphous CyA nanoparticles were transformed into uniform CyA nanocrystals with a reduced mean particle size of approximately 200 nm during storage at 25 °C. The CyA nanocrystals were stably maintained for at least 1 month. The particle morphologies and molecular structures of the CyA nanosuspensions before and after storage were thoroughly characterized by cryogenic transmission electron microscopy and magic-angle spinning nuclear magnetic resonance spectroscopy, respectively. They revealed that the freshly prepared amorphous CyA nanoparticles (∼370 nm) were secondary particles composed of aggregated primary particles with an estimated size of 50 nm. A portion of P407 was found to be entrapped at the gaps between the primary particles due to aggregation, while most of P407 was dissolved in the solution either adsorbing at the solid/liquid interface or forming polymeric micelles. The entrapped P407 is considered to play an important role in the destabilization of the amorphous CyA nanoparticles. The resultant CyA nanocrystals (∼200 nm) were uniform single crystals of Form 2 hydrate and showed corner-truncated bipyramidal features. Owing to the narrow particle size distribution of the CyA nanocrystals, the rate of Ostwald ripening was slow, giving long-term stability to the CyA nanocrystals. This study provides new insights into the destabilization mechanism of amorphous drug nanoparticles.

A Nanocrystals-Based Topical Drug Delivery System with Improved Dermal Penetration and Enhanced Treatment of Skin Diseases

Topical drug delivery methods are important in the treatment of skin diseases. Drug nanocrystals, which are nanometersized particles of active pharmaceutical ingredients, offer efficient topical delivery with high stability, high drug loading capacity, steady dissolution, and sustained drug release profiles. The use of nanocrystals for the topical delivery of skin disease therapies is currently being evaluated; this review focuses on how nanocrystals facilitate active pharmaceutical ingredient transport across skin barriers, exploring the underlying transportation mechanisms of the nanocrystals and active pharmaceutical ingredient molecules to the dermal and epidermal skin cells. In topical delivery, previous skin treatments, choice of excipients and vehicles, and penetration enhancement strategies critically influence the topical delivery of drug nanocrystals. Various research and applications of drug nanocrystals in skin disease therapy are highlighted in this review, and intellectual property protection for drug nanocrystal formulations, clinical trial data, and products with commercial potential are also discussed.

A comprehensive review on possibilities of treating psoriasis using dermal cyclosporine

Psoriasis is an autoimmune, chronic proliferative, inflammatory skin disease with high comorbidity. Psoriasis is not a curable disease; it can only be managed. Cyclosporine A (CyA) is one of the FDA-approved immunosuppressant drug used in severe Psoriasis. Till date only oral route is used for its administration. Administration of CyA by this route causes serious side effects such as hypertension and renal toxicity. Due to these side effects, a number of researches have been done and taking place in the current times for the dermal delivery of CyA for the management of psoriasis. Dermal delivery of CyA is not an easy task because of its physiochemical properties like high molecular weight, lipophilicity and resistance offered by stratum corneum (SC). Because of the above problems in the dermal delivery a number of new approaches such as nanolipid carriers, microemulsion, liposomes, niosomes etc. are explored. To those deep findings for psoriasis management with dermal delivery of CyA have not been discussed. This comprehensive review includes all the studies, advancements and their critical findings which took place in the recent times for the dermal delivery of CyA and along with the suitable modification needed for the efficient dermal delivery of CyA are also suggested.

Enhanced Dermal Delivery of Flurbiprofen Nanosuspension Based Gel: Development and Ex Vivo Permeation, Pharmacokinetic Evaluations

PURPOSE

The objective of this study was to optimize the Flurbiprofen (FB) nanosuspension (NS) based gel and to investigate the in vitro release, ex vivo permeation, the plasma concentration-time profile and pharmacokinetic parameters.

METHODS

FB-NSs were developed using the wet milling process with the Design of Experiment (DoE) approach. The optimum FB-NS was characterized on the basis of SEM, DSC, XRPD, solubility and permeation studies. The dermal gel was prepared by incorporating FB-NS into HPMC gel. Then the in-vitro release, ex vivo permeation studies were performed, and pharmacokinetic studies were evaluated on rats.

RESULTS

The particle size, polydispersity index and zeta potential values of optimum NS were determined as 237.7 ± 6.8 nm, 0.133 ± 0.030 and - 30.4 ± 0.7 mV, respectively. By means of the surfactant content and nanosized particles of the nanosuspension, the solubility of FB was increased about 7-fold. The percentage permeated amount of FB from FB-NS gel (8.40%) was also found to be higher than the physical mixture (5.25%) and coarse suspension (reference) (2.08%) gels. The pharmacokinetic studies showed that the C_max of FB-NS gel was 2.5 times higher than the reference gel, while AUC_0-24 was 2.96 times higher.

CONCLUSION

FB-NSs were successfully prepared with a wet milling method and optimized with the DoE approach. The optimized FB nanosuspension gel provided better permeation and pharmacokinetic performance compared to FB coarse suspension gel.

Rediscovering Tocophersolan: A Renaissance for Nano-Based Drug Delivery and Nanotheranostic Applications

A unique and pleiotropic polymer, d-alpha-tocopheryl polyethylene glycol succinate (Tocophersolan), is a polymeric, synthetic version of vitamin E. Tocophersolan has attracted enormous attention as a versatile excipient in different biomedical applications including drug delivery systems and nutraceuticals. The multiple inherent properties of Tocophersolan allow it to play flexible roles in drug delivery system design, including excipients with outstanding biocompatibility, solubilizer with the ability to promote drug dissolution, drug permeation enhancer, P-glycoprotein inhibitor, and anticancer compound. For these reasons, Tocophersolan has been widely used for improving the bioavailability of numerous pharmaceutical active ingredients. Tocophersolan has been approved by stringent regulatory authorities (such as the US FDA, EMA, and PMDA) as a safe pharmaceutical excipient. In this review, the current advances in nano-based delivery systems consisting of Tocophersolan, with possibilities for futuristic applications in drug delivery, gene therapy, and nanotheranostics, were systematically curated.

Emerging Nanomedicines for the Treatment of Atopic Dermatitis

Globally, the prevalence of Atopic dermatitis (AD) is significantly increasing and affecting around 20% of population including children. Complex interactions amongst abnormality in epidermal barrier function, environment, infectious agents and immunological defects are considered as key factors in the pathogenesis of AD. Although the role of oxidative stress has been studied in some skin diseases, investigation of the same in AD is intermittent. Calcineurin inhibitors and/or topical corticosteroids are currently available; however, it causes atrophy of the skin, burning sensation, and systemic side effects which leads to poor patient compliance. These limitations provoke the strong need to develop an innovative approach in managing AD. Nanomaterials for effective drug delivery to skin conditions such as AD have attracted a lot of attention owing to its ability to encapsulate, protect, and release the cargo at the diseased skin site. However, there are lots of unmet challenges especially in terms of development of non-toxic formulations and clinical translation of established nanomedicines in the form of accessible products. Numerous formulations have emerged as carrier for poorly soluble and permeable drugs, viz., lipidic, polymeric, metal, silica, liposomes, hydrocarbon gels and this field is evolving. This review is intended to provide an insight incidences associated with pathophysiology of AD and challenges with existing treatments of AD. Focus is kept on reviewing current development and emerging nanomedicines for effective treatment of AD. The review also inculcates merits of several nanomedicines in overcoming challenges of existing products and its future implications.

Combining Antimicrobial Peptides with Nanotechnology: An Emerging Field in Theranostics

The emergence of multidrug-resistant pathogens and their rapid adaptation against new antibiotics is a major challenge for scientists and medical professionals. Different approaches have been taken to combat this problem, which includes rationally designed potent antimicrobial peptides (AMPs) and several nanoparticles and quantum dots. AMPs are considered as a new generation of super antibiotics that hold enormous potential to fight against bacterial resistance by the rapidly killing planktonic as well as their biofilm form while keeping low toxicity profile against eukaryotic cells. Various nanoparticles and quantum dots have proved their effectiveness against a vast array of infections and diseases. Conjugation and functionalization of nanoparticles with potentially active antimicrobial peptides have added advantages that widen their applications in the field of drug discovery as well as delivery system including imaging and diagnostics. This article reviews the current progress and implementation of different nanoparticles and quantum dots conjugated antimicrobial peptides in terms of bio-stability, drug delivery, and therapeutic applications.

Nanocarriers for treatment of dermatological diseases: Principle, perspective and practices

Skin diseases are the fourth leading non-fatal skin conditions that act as a burden and affect the world economy globally. This condition affects the quality of a patient's life and has a pronounced impact on both their physical and mental state. Treatment of these skin conditions with conventional approaches shows a lack of efficacy, long treatment duration, recurrence of conditions, systemic side effects, etc., due to improper drug delivery. However, these pitfalls can be overcome with the applications of nanomedicine-based approaches that provide efficient site-specific drug delivery at the target site. These nanomedicine-based strategies are evolved as potential treatment opportunities in the form of nanocarriers such as polymeric and lipidic nanocarriers, nanoemulsions along with emerging others viz. carbon nanotubes for dermatological treatment. The current review focuses on challenges faced by the existing conventional treatments along with the topical therapeutic perspective of nanocarriers in treating various skin diseases. A total of 213 articles have been reviewed and the application of different nanocarriers in treating various skin diseases has been explained in detail through case studies of previously published research works. The toxicity related aspects of nanocarriers are also discussed.

Preparation and in vitro / in vivo evaluation of flurbiprofen nanosuspension-based gel for dermal application

Flurbiprofen (FB) is an analgesic and anti-inflammatory drug, but its low water solubility (BCS Class II) limits its dermal bioavailability. The aim of this study is to develop a FB nanosuspension (NS) based gel and to evaluate its analgesic and anti-inflammatory activities in rats. FB-NS was produced by the wet milling method with Plantacare 2000^Ⓡ, as stabilizer. The FB-NS was then incorporated in different carrier gels such as hydroxypropyl methyl cellulose (HPMC), polycarbophil, oleogel, and chitosan. To select the optimum gel type, visual examinations, pH and rheological property measurements, texture profile analysis, in vitro release and ex vivo permeation studies were performed. Following these tests, the analgesic and anti-inflammatory activities of the optimum NS based gel were evaluated using the tail flick and carrageenan-induced paw edema methods consecutively. The NS was successfully prepared with the wet milling method, and the PS, PDI and ZP values were found to be 237.7 ± 6.8 nm, 0.133±0.030, and -30.4 ± 0.7 mV; respectively. Among the NS-based gels, HPMC gel showed more suitable rheological and mechanical properties, also the percentage of permeated FB and the flux value observed for HPMC gel were higher for HPMC than for the other gels. Thus, HPMC gel was selected as a carrier gel for in vivo pharmacodynamics studies. The anti-inflammatory activity of FB-NS HPMC gel was higher than that of the physical mixture gel and that of the coarse suspension gel. Results of our analgesic activity studies showed that, in the 180th min of FB nanosuspension treatment, the latency time was significantly prolonged compared to that of the control group (p<0.05). As a conclusion, while nanosuspensions increased the in vivo pharmacodynamics effect of FB by means of nanosized particles and a large surface area, the HPMC gel as a carrier prolonged the contact time of NSs with skin and eased the dermal application.

Non-invasive drug delivery technology: development and current status of transdermal drug delivery devices, techniques and biomedical applications

Pay-load deliveries across the skin barrier to the systemic circulation have been one of the most challenging delivery options. Necessitated requirements of the skin and facilitated skin layer cross-over delivery attempts have resulted in development of different non-invasive, non-oral methods, devices and systems which have been standardized, concurrently used and are in continuous upgrade and improvements. Iontophoresis, electroporation, sonophoresis, magnetophoresis, dermal patches, nanocarriers, needled and needle-less shots, and injectors are among some of the methods of transdermal delivery. The current review covers the current state of the art, merits and shortcomings of the systems, devices and transdermal delivery patches, including drugs' and other payloads' passage facilitation techniques, permeation and absorption feasibility studies, as well as physicochemical properties affecting the delivery through different transdermal modes along with examples of drugs, vaccines, genes and other payloads.

Treatment of Psoriasis: A Comprehensive Review of Entire Therapies

Background:

Psoriasis is an autoimmune disease that ingeminates itself with the repeated proliferation of keratinocytes. It globally strikes a 2-5 % population on an average. Management of psoriasis remains a daunting task with various challenges influencing treatment, such as patient conformity and adherence to therapy, delicate patient profiles, psychological aspects, and skin as a barrier to topical delivery. The first part reviewed pathophysiology, triggering factors, and clinical classification. The second part reviewed all the therapies, such as topical, oral, biological, parenteral therapy, phototherapy, and the phyto-pharmaceuticals.

Methods:

The research data related to the existing and upcoming therapies for psoriasis treatment, several nanocarriers, existing marketed formulations, and detailed description of phytopharmaceuticals with their mechanism.

Results:

Topical therapy is the mainstay treatment option with limited adverse effects. Biological therapy has reformed conventional psoriasis treatment by being more efficacious and has increased patient acceptance due to decreased adverse events. Nanoformulations present an edge over conventional therapy due to improved anti-psoriatic effect and decreased side effects. Phyto-pharmaceuticals act as a complementary and alternative therapy for diminishing psoriasis symptoms.

Conclusion:

A rationalized cost-effective patient compliant therapy is required for effective management and complete cure of psoriasis.

Freeze-Dried Softisan® 649-Based Lipid Nanoparticles for Enhanced Skin Delivery of Cyclosporine A

Inflammatory skin diseases, including psoriasis and atopic dermatitis, affect around one quarter to one third of the world population. Systemic cyclosporine A, an immunosuppressant agent, is included in the current therapeutic armamentarium of these diseases. Despite being highly effective, it is associated with several side effects, and its topical administration is limited by its high molecular weight and poor water solubility. To overcome these limitations, cyclosporine A was incorporated into solid lipid nanoparticles obtained from Softisan^® 649, a commonly used cosmetic ingredient, aiming to develop a vehicle for application to the skin. The nanoparticles presented sizes of around 200 nm, low polydispersity, negative surface charge, and stability when stored for 8 weeks at room temperature or 4 °C. An effective incorporation of 88% of cyclosporine A within the nanoparticles was observed, without affecting its morphology. After the freeze-drying process, the Softisan^® 649-based nanoparticles formed an oleogel. Skin permeation studies using pig ear as a model revealed low permeation of the applied cyclosporine A in the freeze-dried form of the nanoparticles in relation to free drug and the freshly prepared nanoparticles. About 1.0 mg of cyclosporine A was delivered to the skin with reduced transdermal permeation. These results confirm local delivery of cyclosporine A, indicating its promising topical administration.

Nanocrystals of Fusidic Acid for Dual Enhancement of Dermal Delivery and Antibacterial Activity: In Vitro, Ex Vivo and In Vivo Evaluation

With the alarming rise in incidence of antibiotic-resistant bacteria and the scarcity of newly developed antibiotics, it is imperative that we design more effective formulations for already marketed antimicrobial agents. Fusidic acid (FA), one of the most widely used antibiotics in the topical treatment of several skin and eye infections, suffers from poor water-solubility, sub-optimal therapeutic efficacy, and a significant rise in FA-resistant Staphylococcus aureus (FRSA). In this work, the physico-chemical characteristics of FA were modified by nanocrystallization and lyophilization to improve its therapeutic efficacy through the dermal route. FA-nanocrystals (NC) were prepared using a modified nanoprecipitation technique and the influence of several formulation/process variables on the prepared FA-NC characteristics were optimized using full factorial statistical design. The optimized FA-NC formulation was evaluated before and after lyophilization by several in-vitro, ex-vivo, and microbiological tests. Furthermore, the lyophilized FA-NC formulation was incorporated into a cream product and its topical antibacterial efficacy was assessed in vivo using a rat excision wound infection model. Surface morphology of optimized FA-NC showed spherical particles with a mean particle size of 115 nm, span value of 1.6 and zeta potential of −11.6 mV. Differential scanning calorimetry and powder X-ray diffractometry confirmed the crystallinity of FA following nanocrystallization and lyophilization. In-vitro results showed a 10-fold increase in the saturation solubility of FA-NC while ex-vivo skin permeation studies showed a 2-fold increase in FA dermal deposition from FA-NC compared to coarse FA. Microbiological studies revealed a 4-fofd decrease in the MIC against S. aureus and S. epidermidis from FA-NC cream compared to commercial Fucidin cream. In-vivo results showed that FA-NC cream improved FA distribution and enhanced bacterial exposure in the infected wound, resulting in increased therapeutic efficacy when compared to coarse FA marketed as Fucidin cream.

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.

Hybrid drug nanocrystals

Nanocrystals show promise to deliver poorly water-soluble drugs to yield systemic exposure. However, our knowledge regarding the in vivo fate of nanocrystals is in its infancy, as nanocrystallization is simply viewed as an approach to enhance the dissolution of drug crystals. The dying crystal phenomenon inspired the development of hybrid nanocrystals by physically embedding fluorophores into the crystal lattice. This approach achieved concurrent therapy and bioimaging and is well-established to study pharmacokinetics and nanocrystal dissolution in vivo. Nanocrystals also offer the advantage of long-term durability in the body for interacting with biological tissues and cells. This review introduces the hybrid nanocrystal technique, including the theoretical concepts, preparation, and applications. We also discuss the latest development in self-discriminative hybrid nanocrystals utilizing environment-responsive probes. This review will stimulate further development and application of nanocrystal-based drug delivery systems for theranostic strategies.

Molecular strategy for blocking isopeptide bond formation in nascent pilin proteins

Bacteria anchor to their host cells through their adhesive pili, which must resist the large mechanical stresses induced by the host as it attempts to dislodge the pathogens. The pili of gram-positive bacteria are constructed as a single polypeptide made of hundreds of pilin repeats, which contain intramolecular isopeptide bonds strategically located in the structure to prevent their unfolding under force, protecting the pilus from degradation by extant proteases and oxygen radicals. Here, we demonstrate the design of a short peptide that blocks the formation of the isopeptide bond present in the pilin Spy0128 from the human pathogen Streptococcus pyogenes, resulting in mechanically labile pilin domains. We use a combination of protein engineering and atomic-force microscopy force spectroscopy to demonstrate that the peptide blocks the formation of the native isopeptide bond and compromises the mechanics of the domain. While an intact Spy0128 is inextensible at any force, peptide-modified Spy0128 pilins readily unfold at very low forces, marking the abrogation of the intramolecular isopeptide bond as well as the absence of a stable pilin fold. We propose that isopeptide-blocking peptides could be further developed as a type of highly specific antiadhesive antibiotics to treat gram-positive pathogens.

Antimicrobial Peptides and Nanotechnology, Recent Advances and Challenges

Antimicrobial peptides are sequences of amino acids, which present activity against microorganisms. These peptides were discovered over 70 years ago, and are abundant in nature from soil bacteria, insects, amphibians to mammals and plants. They vary in amino acids number, the distance between amino acids within individual peptide structure, net charge, solubility and other physical chemical properties as well as differ in mechanism of action. These peptides may provide an alternative treatment to conventional antibiotics, which encounter resistance such as the peptide nisin applied in treating methicillin resistant Staphylococcus aureus (MRSA) or may behave synergistically with known antibiotics against parasites for instance, nisin Z when used in synergy with ampicillin reported better activity against Pseudomonas fluorescens than when the antibiotic was alone. AMPs are known to be active against viruses, bacteria, fungi and protozoans. Nanotechnology is an arena which explores the synthesis, characterization and application of an array of delivery systems at a one billionth of meter scale. Such systems are implemented to deliver drugs, proteins, vaccines, and peptides. The role of nanotechnology in delivering AMPs is still at its early development stage. There are challenges of incorporating AMPs into drug delivery system. This review intends to explore in depth, the role of nanotechnology in delivering AMPs as well as presenting the current advances and accompanying challenges of the technology.

Development of microemulsions of suitable viscosity for cyclosporine skin delivery

Psoriasis is a widespread chronic disease affecting 2-4% of the population in Western countries. Its mild-to-moderate form, representing approximately 80% of the total cases, is treated by topical application, with corticosteroid being the standard treatment. However, in case of psoriasis, no single treatment works for every patient and optimizing topical therapy is a key aspect. A possible alternative is represented by cyclosporine, an immunosuppressant cyclic peptide administered orally in the treatment of the severe form. Its topical application could avoid the problems related to systemic immunosuppression, but the unfavourable physico-chemical properties (MW: 1202 Da; LogP ≈ 3) hinder its permeation across the stratum corneum. The aim of the paper was the preparation, characterization and ex-vivo evaluation of cyclosporine loaded microemulsions using oleic acid as oil phase, either Tween^®80 or a soluble derivative of vitamin E (TPGS) as surfactants and either Transcutol^®, propylene glycol or 1,3 propanediol as co-surfactants. The issue of formulation viscosity was also addressed 1) by evaluating the thickening of Tween^®80-based microemulsions by direct addition of different rheological modifiers, 2) by building pseudo-ternary phase diagrams using TPGS, to identify the water/oil/surfactants proportions resulting in viscous self-gelifying systems. Nine formulations (five Tween^®80-based and four TPGS-based) were selected, characterized in terms of droplets size (low viscosity systems) or rheological properties (high viscosity systems), loaded with 6 mg/g cyclosporine and applied ex-vivo on porcine skin for 22 h. A relevant skin accumulation was obtained either with a low-viscosity Tween^®80-based microemulsion (9.78 ± 3.86 µg/cm²), or with a high viscosity TPGS-based microemulsion (18.3 ± 5.69 µg/cm²), with an increase of about 3 and 6 times respectively for comparison with a control cyclosporine solution in propylene glycol. The role of water content, surfactant, co-surfactant and viscosity was also addressed and discussed. The kinetic of skin uptake from the best performing formulation was finally evaluated, highlighting a relatively quick skin uptake and the achievement, after 2 h of contact, of potentially therapeutic cyclosporine skin concentrations.

Nanocrystals for improved dermal drug delivery

Nanocrystals are composed of 100% active and possess an increased aqueous solubility and dissolution velocity when compared to larger sized materials. Nanocrystals can be used to improve the bioavailability of poorly soluble actives not only for oral, but also for topical application. In this study nanocrystals of different sizes were produced and the influence of size on dermal penetration was investigated. The influence of different excipients and vehicles on the penetration efficacy upon dermal application was also investigated. Results confirm that dermal penetration of poorly soluble actives increases with decreasing size of the nanocrystals. Unexpectedly, it was observed that many classical penetration enhancers failed to promote the penetration of actives from nanocrystals. Also hydrogels were found to be non-suitable vehicles for the formulation of nanocrystals. As most suitable vehicles for nanocrystals oleogels and creams were identified.

Nanocrystal: a novel approach to overcome skin barriers for improved topical drug delivery

INTRODUCTION

Skin is an important route of drug delivery for the treatment of various dermatological conditions. The advent of nanotechnology is paving the roadmaps for topical drug delivery by providing sustained release as well as maintaining a localized effect, outweighing the toxicity concern.

AREAS COVERED

This review highlighted the morphology of skin, its barrier nature as well as drug penetration pathways after topical application of formulations. The existing methods to improve topical drug delivery, by infringing or permeating the skin barriers, are discussed. This context concretes the foundation to accentuate the need for the development of nanocrystal-based topical formulation. The mechanism of drug release, immediate as well as sustained release, after topical administration of drug nanocrystals is also elaborated. The special emphasis is given on the breakthrough achieved, in topical drug delivery using drug nanocrystals, so far in the plethora of literature, patents, and products, under clinical trial as well as in the market.

EXPERT OPINION

The current research on nanocrystals for topical drug delivery is highlighting the breakthroughs achieved so far. The output of these research envisages that topical nanocrystals based formulations can be a novel strategy for the drugs which are facing solubility, bioavailability and toxicity concerns.

Enhanced transdermal delivery of meloxicam by nanocrystals: Preparation, in vitro and in vivo evaluation

Meloxicam (MLX) is efficient in relieving pain and inflammatory symptoms, which, however, is limited by the poor solubility and gastrointestinal side effects. The objective of this study is to develop a nanocrystal formulation to enhance transdermal delivery of MLX. MLX nanocrystals were successfully prepared by the nanoprecipitation technique based on acid-base neutralization. With poloxamer 407 and Tween 80 (80/20, w/w) as mixed stabilizers, MLX nanocrystals with particle size of 175 nm were obtained. The crystalline structure of MLX nanocrystals was confirmed by both differential scanning calorimetry and X-ray powder diffractometry. However, the nanoprecipitation process reduced the crystallinity of MLX. Nanocrystals increased both in vitro and in vivo transdermal permeation of MLX compared with the solution and suspension counterparts. Due to the enhanced apparent solubility and dissolution as well as the facilitated hair follicular penetration, nanocrystals present a high and prolonged plasma MLX concentration. And 2.58- and 4.4-fold increase in AUC_0→24h was achieved by nanocrystals comparing with solution and suspension, respectively. In conclusion, nanocrystal is advantageous for transdermal delivery of MLX.

Epithelia transmembrane transport of orally administered ultrafine drug particles evidenced by environment sensitive fluorophores in cellular and animal studies

Little is known about the in vivo fate of drug particles taken orally, in particular, the drug release kinetics and interaction with the gastrointestinal (GI) membrane. Lacking is analytical means that can reliably identify the integrity of drug particles under the complexity of biological environment. Herein, we explored fluorescent probes whose signals become quenched upon being released from drug carriers. Taking advantage of so-called the aggregation caused quenching (ACQ), particles may be identified by the integrated fluorophores, which are "turned off" when the particles become destructed and dyes are released. In the current study, ultrafine amorphous particles (UAPs) of cyclosporin A (CsA) were prepared with synthesized ACQ dyes physically entrapped. The fluorescence intensity of suspension of these UAPs was found correlated well with the dissolution of the particles. When given to rats orally, it was found that some of the administered UAPs could survive the animal's GI tracts for as long as 18h. Whole-body fluorescence imaging detected fluorescent signals in the liver and lungs. Particularly noticed in sections of jejunum and ileum, the detection suggested the possibility of direct absorption of UAPs through epithelial membranes. Moreover, 250nm particles were absorbed faster via transepithelia than larger ones (550nm), while the latter were preferably taken up by M cells in the follicle-associated epithelium (FAE) region of Peyer's patches. In vitro permeation studies with Caco-2 cells confirmed the transmembrane transport of the dye-integrated UAPs. Our study supports the idea of using ACQ fluorophores for imaging and characterizing the fate of intact particles in a biological environment.

Promoting bioengineered tooth innervation using nanostructured and hybrid scaffolds

The innervation of teeth mediated by axons originating from the trigeminal ganglia is essential for their function and protection. Immunosuppressive therapy using Cyclosporine A (CsA) was found to accelerate the innervation of transplanted tissues and particularly that of bioengineered teeth. To avoid the CsA side effects, we report in this study the preparation of CsA loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles, their embedding on polycaprolactone (PCL)-based scaffolds and their possible use as templates for the innervation of bioengineered teeth. This PCL scaffold, approved by the FDA and capable of mimicking the extracellular matrix, was obtained by electrospinning and decorated with CsA-loaded PLGA nanoparticles to allow a local sustained action of this immunosuppressive drug. Dental re-associations were co-implanted with a trigeminal ganglion on functionalized scaffolds containing PLGA and PLGA/cyclosporine in adult ICR mice during 2weeks. Histological analyses showed that the designed scaffolds did not alter the teeth development after in vivo implantation. The study of the innervation of the dental re-associations by indirect immunofluorescence and transmission electron microscopy (TEM), showed that 88.4% of the regenerated teeth were innervated when using the CsA-loaded PLGA scaffold. The development of active implants thus allows their potential use in the context of dental engineering.

STATEMENT OF SIGNIFICANCE

Tooth innervation is essential for their function and protection and this can be promoted in vivo using polymeric scaffolds functionalized with immunosuppressive drug-loaded nanoparticles. Immunosuppressive therapy using biodegradable nanoparticles loaded with Cyclosporine A was found to accelerate the innervation of bioengineered teeth after two weeks of implantation.

The in vivo fate of nanocrystals

There has been significant research interest in, and development of, nanocrystals in recent years for the delivery of poorly water-soluble drugs via various routes. However, there is a common misinterpretation of nanocrystallization as an approach to modulate, and more specifically to enhance, the dissolution of drug crystals. Nevertheless, it is possible for nanocrystals to interact with biological tissues because nanocrystals can survive for a longer duration in vivo compared with solution counterparts. Therefore, understanding the in vivo fate of nanocrystals and determining its contribution to efficacy is of tremendous significance for optimizing the performance of nanocrystals. Here, we critically review the general hypotheses related to the in vivo fate of nanocrystals.

Sustained subconjunctival delivery of cyclosporine A using thermogelling polymers for glaucoma filtration surgery

We successfully developed a subconjunctival delivery system of CsA using an injectable thermogel to inhibit post-surgical scar formation after glaucoma filtration surgery.

Nanoparticle-Enabled Transdermal Drug Delivery Systems for Enhanced Dose Control and Tissue Targeting

Transdermal drug delivery systems have been around for decades, and current technologies (e.g., patches, ointments, and creams) enhance the skin permeation of low molecular weight, lipophilic drugs that are efficacious at low doses. The objective of current transdermal drug delivery research is to discover ways to enhance skin penetration of larger, hydrophilic drugs and macromolecules for disease treatment and vaccination. Nanocarriers made of lipids, metals, or polymers have been successfully used to increase penetration of drugs or vaccines, control drug release, and target drugs to specific areas of skin in vivo. While more research is needed to identify the safety of nanocarriers, this technology has the potential to expand the use of transdermal routes of administration to a wide array of therapeutics. Here, we review the current state of nanoparticle skin delivery systems with special emphasis on targeting skin diseases.