Niosomes as carriers for tretinoin. I. Preparation and properties

Polymer conjugated retinoids for controlled transdermal delivery

All-trans retinoic acid (ATRA), a derivative of vitamin A, is a common component in cosmetics and commercial acne creams as well as being a first-line chemotherapeutic agent. Today, formulations for the topical application of ATRA rely on creams and emulsions to incorporate the highly hydrophobic ATRA drug. These strategies, when applied to the skin, deliver ATRA as a single bolus, which is immediately taken up into the skin and contributes to many of the known adverse side effects of ATRA treatment, including skin irritation and hair loss. Herein we present a new concept in topical delivery of retinoids by covalently bonding the drug through a hydrolytically degradable ester linkage to a common hydrophilic polymer, polyvinyl alcohol (PVA), creating an amphiphilic nanomaterial that is water-soluble. This PVA bound ATRA can then act as a pro-drug and accumulate within the skin to allow for the sustained controlled delivery of active ATRA. This approach was demonstrated to release active ATRA out to 10days in vitro while significantly enhancing dermal accumulation of the ATRA in explant pig skin. In vivo we demonstrate that the pro-drug formulation reduces application site inflammation compared to free ATRA and retains the drug at the application site at measurable quantities for up to six days.

Niosome-based hydrogel of resveratrol for topical applications: An effective therapy for pain related disorder(s)

The present work endeavors for development and evaluation of resveratrol loaded niosomal hydrogel system for its anti-inflammatory action. Niosomes were prepared by thin film hydration and ether injection methods employing Span 80 as a surfactant at three different levels. Best optimized formulation was selected on the basis of entrapment efficiency (% EE), mean particle size, sedimentation volume, and microscopy. The vesicular and spherical nature of the niosomes was confirmed by optical microscopy and transmission electron microscope (TEM). Further, resveratrol entrapped niosomal gel was prepared by gelling in Carbopol 934, and evaluated for pH, viscosity, and in vitro release, employing dialysis membrane method. The in vitro release data after fitting to various models revealed it to follow Korsmeyer-Pappas model. Ex vivo permeation studies witnessed high permeation and deposition of resveratrol in skin when compared to plain resveratrol. Dermatokinetic studies elaborated that niosomal gel enhanced the biological half-life and reduced T_max of the drug, in both the skin layers. Finally, in vivo anti-inflammatory activity of niosomal gel was evaluated by carrageenan induced paw edema model and compared with standard sodium diclofenac gel. The resveratrol entrapped niosomal gel sufficiently reduced the edema and revealed prolonged therapeutic action vis-a-vis the marketed anti-inflammatory gel formulation. Our findings suggest that a topical drug delivery system using niosomal hydrogel could lead to expansion in the anti-inflammatory use of resveratrol.

Non-Ionic Surfactant Vesicles (Niosomes) as New Drug Delivery Systems

Lipid vesicular systems composed of hydrated amphihiles with or without bilayer inducing agents such as cholesterol. On the basis of used amphiphilic molecule different nomenclature are used as liposomes, ufasomes and niosomes. Nonionic surfactants with mono-, di- or trialkyl chains form niosomes which are lipid vesicles with more chemical stability in comparison with phospholipids of liposomes. Both hydrophobic and hydrophilic chemicals can be encapsulated in niosomes as a new drug delivery system. This drug carrier system could have administered via injection, oral, pulmonary, vaginal, rectal, ophthalmic, nasal or transdermal routes with penetration enhancing potential. This chapter presents a detailed explain about niosome forming components, methods of preparation and routes of administration. Many examples for drug delivery potential of niosomes are also available in this review. Vaccine adjuvant and genetic substances vector capabilities are not given here.

Non-Ionic Surfactant Vesicles (Niosomes) as New Drug Delivery Systems

Lipid vesicular systems composed of hydrated amphihiles with or without bilayer inducing agents such as cholesterol. On the basis of used amphiphilic molecule different nomenclature are used as liposomes, ufasomes and niosomes. Nonionic surfactants with mono-, di- or trialkyl chains form niosomes which are lipid vesicles with more chemical stability in comparison with phospholipids of liposomes. Both hydrophobic and hydrophilic chemicals can be encapsulated in niosomes as a new drug delivery system. This drug carrier system could have administered via injection, oral, pulmonary, vaginal, rectal, ophthalmic, nasal or transdermal routes with penetration enhancing potential. This chapter presents a detailed explain about niosome forming components, methods of preparation and routes of administration. Many examples for drug delivery potential of niosomes are also available in this review. Vaccine adjuvant and genetic substances vector capabilities are not given here.

α-Tocopherol-loaded niosome prepared by heating method and its release behavior

α-Tocopherol-loaded niosome was developed using modified heating method. The influence of surfactants (Span60 and Tween60) in different mole ratios, presence or absence of cholesterol (Chol) and dicetyl phosphate (DCP) as well as different concentration of α-tocopherol (α-TOC) on mean size, polydispersity index, zeta potential and entrapment efficiency (EE) was evaluated. The results showed that α-TOC loaded niosomes exhibited a small mean size (73.85±0.6-186±0.58nm), narrow size distribution and high EE (61.13±0.52-98.92±0.92). By decreasing the HLB, the EE and stability of the niosomes increased. The DCP and Chol improved the physicochemical properties of niosomes. 3:1 mole ratio of Span 60:Tween 60, 4mg/ml of α-TOC and 25:12.5:2.5 mole ratio of surfactant:Chol:DCP was the optimum formulation in the encapsulation of α-TOC applying niosome system. The niosomes had sustained release profile in the simulated gastric and intestinal fluid.

Tolterodine Tartrate Proniosomal Gel Transdermal Delivery for Overactive Bladder

The goal of this study was to formulate and evaluate side effects of transdermal delivery of proniosomal gel compared to oral tolterodine tartrate (TT) for the treatment of overactive bladder (OAB). Proniosomal gels are surfactants, lipids and soy lecithin, prepared by coacervation phase separation. Formulations were analyzed for drug entrapment efficiency (EE), vesicle size, surface morphology, attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, in vitro skin permeation, and in vivo effects. The EE was 44.87%-91.68% and vesicle size was 253-845 nm for Span formulations and morphology showed a loose structure. The stability and skin irritancy test were also carried out for the optimized formulations. Span formulations with cholesterol-containing formulation S1 and glyceryl distearate as well as lecithin containing S3 formulation showed higher cumulative percent of permeation such as 42% and 35%, respectively. In the in vivo salivary secretion model, S1 proniosomal gel had faster recovery, less cholinergic side effect on the salivary gland compared with that of oral TT. Histologically, bladder of rats treated with the proniosomal gel formulation S1 showed morphological improvements greater than those treated with S3. This study demonstrates the potential of proniosomal vesicles for transdermal delivery of TT to treat OAB.

Pulmonary targeting potential of rosuvastatin loaded nanostructured lipid carrier: Optimization by factorial design

Rosuvastatin (RSVS), an anti-lipidemic agent suggested for the treatment of airway remodeling in chronic obstructive pulmonary disease (COPD). It shows a pleiotropic effect on airway smooth muscles and inhibits proliferative activities of physiological mitogens. The aim of the present study was to develop and investigate the targeting potential of rosuvastatin (RSVS) to lung as loaded in nanostructured lipid carrier dry powder for inhalation (RNLC-DPI). RNLC dispersion was converted into respirable particle by lyophilization using 5% mannitol as cryoprotectant-carrier. Targeting efficiency of RNLC-DPI was evaluated in vitro for aerosol performance using 8-stage cascade impactor as well in vivo in Wistar rats for pulmokinetics. In vitro aerosol performance demonstrated mass median aerodynamic diameter of <3 μm with fine particle fraction of >90% at 60 L/min. Improved aerosol performance was observed for RNLC-DPI prepared using l-leucin as anti-static agent. Modified in vivo performance with higher Cmax (1.14-fold), improvement in t1/2 (5-fold) and 35-fold improvement in AUC0-∞ indicated significant improvement in bioavailability of RNLC-DPI. Lipidic nature and smaller size of particles helped in bypassing macrophage clearance leading to higher targeting factor. Thus, study demonstrated potential of RNLC-DPI for lung targeting and further for COPD treatment.

A synergistic approach of adapalene-loaded nanostructured lipid carriers, and vitamin C co-administration for treating acne

The present study documents the fabrication and characterization of a topically applicable gel loaded with nanostructured lipid carriers (NLCs) of adapalene (ADA) and vitamin C (ascorbyl-6-palmitate [AP]). The NLCs were prepared by high pressure homogenization (HPH) method followed by incorporation into AP loaded gel. The fabricated system was characterized for size, poly dispersity index, entrapment efficiency (EE) and in vitro drug release properties, and was further investigated for skin compliance, skin transport characteristics (skin permeation and bio-distribution), rheological behavior, texture profile analysis and anti-acne therapeutic potential against testosterone-induced acne in male Wistar rats. The NLC-based formulation improved targeting of the skin epidermal layer and reducing systemic penetration. The co-administration of vitamin C led to an adjunct effect in acne therapy in physiological conditions. In brief, the present results suggest the potential of NLCs as a novel carrier for the dermal delivery of ADA and also the synergistic effect of vitamin C in topical therapeutics.

Nitric Oxide-Releasing Nanoparticles Prevent Propionibacterium acnes-Induced Inflammation by Both Clearing the Organism and Inhibiting Microbial Stimulation of the Innate Immune Response

Propionibacterium acnes induction of IL-1 cytokines through the NLRP3 (NLR, nucleotide oligomerization domain-like receptor) inflammasome was recently highlighted as a dominant etiological factor for acne vulgaris. Therefore, therapeutics targeting both the stimulus and the cascade would be ideal. Nitric oxide (NO), a potent biological messenger, has documented broad-spectrum antimicrobial and immunomodulatory properties. To harness these characteristics to target acne, we used an established nanotechnology capable of generating/releasing NO over time (NO-np). P. acnes was found to be highly sensitive to all concentrations of NO-np tested, although human keratinocyte, monocyte, and embryonic zebra fish assays revealed no cytotoxicity. NO-np significantly suppressed IL-1β, tumor necrosis factor-α (TNF-α), IL-8, and IL-6 from human monocytes, and IL-8 and IL-6 from human keratinocytes, respectively. Importantly, silencing of NLRP3 expression by small interfering RNA did not limit NO-np inhibition of IL-1 β secretion from monocytes, and neither TNF-α nor IL-6 secretion, nor inhibition by NO-np was found to be dependent on this pathway. The observed mechanism by which NO-np impacts IL-1β secretion was through inhibition of caspase-1 and IL-1β gene expression. Together, these data suggest that NO-np can effectively prevent P. acnes-induced inflammation by both clearing the organism and inhibiting microbial stimulation of the innate immune response.

Photostability and ex-vivo permeation studies on diclofenac in topical niosomal formulations

Photostability studies were performed on topical formulations containing diclofenac (DC). Niosomal gels were designed as photostabilization systems and ascorbic acid was also added to the new topical formulations because of its antioxidant property. Photodegradation tests were applied on commercial formulations containing DC and novel prepared gels, according to the ICH rules. The experiments were monitored by spectrophotometry and the data processed by multivariate curve resolution analysis to estimate the spectra and concentration profiles of evolved components. Characterization of niosomes was evaluated by size and distribution measurement, morphological analysis and encapsulation efficiency. Permeation experiments were performed across rabbit ear skin up to 24 h. Photodegradation rate of DC was found very fast in commercial formulation, with a residual content of 90% after only 4.38 min under a radiant exposure of 450 W/m(2). Photostability resulted increased significantly when the drug was entrapped in niosomal systems. The best results were obtained by reaching a 10% degradation after 50.00 min of light exposure after incorporation of DC in niosomes in presence of 5% ascorbic acid. Moreover, niosomal gel also influenced the permeation capability of DC by enhancing the transdermal delivery of the drug. The cumulative dose permeated of DC from niosomal gel was about three times that obtained with the commercial gel.

Liposomes as nanomedical devices

Since their discovery in the 1960s, liposomes have been studied in depth, and they continue to constitute a field of intense research. Liposomes are valued for their biological and technological advantages, and are considered to be the most successful drug-carrier system known to date. Notable progress has been made, and several biomedical applications of liposomes are either in clinical trials, are about to be put on the market, or have already been approved for public use. In this review, we briefly analyze how the efficacy of liposomes depends on the nature of their components and their size, surface charge, and lipidic organization. Moreover, we discuss the influence of the physicochemical properties of liposomes on their interaction with cells, half-life, ability to enter tissues, and final fate in vivo. Finally, we describe some strategies developed to overcome limitations of the “first-generation” liposomes, and liposome-based drugs on the market and in clinical trials.

Lipid nanoparticles for the topical delivery of retinoids and derivatives

Retinoids are lipophilic compounds that are highly used in cosmetics/therapeutics for skin disorders. Conventional formulations are limited by poor water solubility, high chemical/photochemical instability and the irritation of retinoids. Interestingly, lipid nanoparticles enable the administration of retinoids in aqueous media, providing drug stabilization and controlled release. Recently, it has been demonstrated that retinoids in solid lipid nanoparticles, nanostructured lipid carriers, nanoemulsions and nanocapsules can decrease degradation, improve targeting and enhance efficacy for the treatment of skin disorders. This article focuses on the formulation, fabrication, characterization and in vitro/in vivo evaluation of solid lipid nanoparticles, nanostructured lipid carriers, nanoemulsions and nanocapsules loaded with retinoids for skin administration. Furthermore, the incorporation of these lipid nanoparticles into secondary vehicles is discussed.

Potentiating antimicrobial efficacy of propolis through niosomal-based system for administration

Background

Propolis is a multicomponent active, complex resinous substance collected by honeybees (Apis mellifera) from a variety of plant sources. This study was designed to improve the antimicrobial efficacy of propolis by engineering a niosomal-based system for topical application.

Methods

Propolis was extracted in ethanol and screened for total polyphenol content. Propolis-loaded niosomes (PLNs) were prepared with varying concentrations of Span 60 and cholesterol. The PLNs were evaluated for physicochemical parameters, namely, vesicle size, entrapment efficiency, zeta potential, surface topography and shape, and stability, followed by screening for in vitro antimicrobial activity. The PLNs were formulated into propolis niosomal gel (PNG) using Carbopol P934 base and subjected to ex vivo skin deposition study.

Results

The ethanolic extract of propolis had high polyphenolic content (270 ± 9.2 mg GAE/g). The prepared PLNs showed vesicle size between 294 nm and 427 nm, and the percent entrapment in the range of 50.62–71.29% with a significant enhancement in antimicrobial activity against Staphylococcus aureus and Candida albicans. Enhanced antimicrobial activity of PLNs was attributed to the ability of niosomes to directly interact with the bacterial cell envelop thereby facilitating the diffusion of propolis constituents across the cell wall. The formulated PNG exhibited a twofold better skin deposition due to improved retention of niosomes in the skin.

Conclusion

The findings indicate that the engineering of a niosomal-based system for propolis enhanced its antimicrobial potential through topical application.

Development and in vitro/in vivo evaluation of controlled release provesicles of a nateglinide-maltodextrin complex

The aim of this study was to characterize the provesicle formulation of nateglinide (NTG) to facilitate the development of a novel controlled release system of NTG with improved efficacy and oral bioavailability compared to the currently marketed NTG formulation (Glinate™ 60). NTG provesicles were prepared by a slurry method using the non-ionic surfactant, Span 60 (SP), and cholesterol (CH) as vesicle forming agents and maltodextrin as a coated carrier. Multilamellar niosomes with narrow size distribution were shown to be successfully prepared by means of dynamic laser scattering (DLS) and field emission scanning electron microscopy (FESEM). The absence of drug-excipient interactions was confirmed by Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC) and X-ray diffraction (XRD) studies. In vitro release of NTG in different dissolution media was improved compared to pure drug. A goat intestinal permeation study revealed that the provesicular formulation (F4) with an SP:CH ratio of 5:5 gave higher cumulative amount of drug permeated at 48 h compared to Glinate™ 60 and control. A pharmacodynamic study in streptozotocin-induced diabetic rats confirmed that formulation F4 significantly (P<0.05) reduced blood glucose levels in comparison to Glinate 60. Overall the results show that controlled release NTG provesicles offer a useful and promising oral delivery system for the treatment of type II diabetes.

New perspectives on antiacne plant drugs: contribution to modern therapeutics

Acne is a common but serious skin disease, which affects approximately 80% adolescents and young adults in 11-30 age group. 42.5% of men and 50.9% of women continue to suffer from this disease into their twenties. Bacterial resistance is now at the alarming stage due to the irrational use of antibiotics. Hence, search for new lead molecule/bioactive and rational delivery of the existing drug (for better therapeutic effect) to the site of action is the need of the hour. Plants and plant-derived products have been an integral part of health care system since time immemorial. Therefore, plants that are currently used for the treatment of acne and those with a high potential are summarized in the present review. Most active plant extracts, namely, P. granatum, M. alba, A. anomala, and M. aquifolium exhibit minimum inhibitory concentration (MIC) in the range of 4-50 µg/mL against P. acnes, while aromatic oils of C. obovoides, C. natsudaidai, C. japonica, and C. nardus possess MICs 0.005-0.6 μL/mL and phytomolecules such as rhodomyrtone, pulsaquinone, hydropulsaquinone, honokiol, magnolol, xanthohumol lupulones, chebulagic acid and rhinacanthin-C show MIC in the range of 0.5-12.5 μg/mL. Novel drug delivery strategies of important plant leads in the treatment of acne have also been discussed.

Single step spray drying method to develop proliposomes for inhalation: a systematic study based on quality by design approach

Quality by Design (QbD) is a systematic approach to develop drug products which includes evaluation of formulation parameters to achieve defined final product quality. In the present study principles of QbD were extended to the preparation, in-vitro and in-vivo performance of rifapentine-loaded proliposomes for pulmonary inhalation where final product needs to comply with specific properties. The rifapentine-loaded proliposomes for the treatment of tuberculosis were prepared in single step by spray drying method and independent variables were optimized using factorial design approach. Contour plots and multiple regression analysis were used to study the effect of selected independent variables on dependent variables. The effect of presence of drug: hydrogenated soya phosphatidylcholine (HSPC) and type of charged lipid in the formulation at three levels were studied on mass median diameter (MMD), liposomal vesicle size, % encapsulation efficiency (% EE), mass median aerodynamic diameter (MMAD) and fine particle fraction (FPF) as critical quality attributes. Optimized formulation (R-LDPI-7) with drug: HSPC ratio of 1:2 and stearyl amine as charged lipid were found to give respirable proliposomes with MMAD of 1.56 ± 0.16 μm and FPF of 92.5 ± 1.5%. Sustained drug release with Higuchi diffusion kinetics was achieved from liposomally encapsulated rifapentine. Pulmonary pharmacokinetics of optimized batch R-LDPI-7 revealed longer retention of drug in lungs with 7 fold increase in both, the mean residence time and t1/2 as compared to R-DPI-0. The study results demonstrated the application of QbD principles and design of experiment (DOE) approach to develop drug encapsulated proliposomes for inhalation by spray drying in single step.

Formulation of tretinoin-loaded topical proniosomes for treatment of acne: in-vitro characterization, skin irritation test and comparative clinical study

Tretinoin (TRT) is a widely used retinoid for the topical treatment of acne, photo-aged skin, psoriasis and skin cancer which makes it a good candidate for topical formulation. Yet side effects, like redness, swelling, peeling, blistering and, erythema, in addition to its high lipophilicity make this challenging. Therefore, the aim of this study was the development of TRT-loaded proniosomes to improve the drug efficacy and to increase user acceptability and compliance by reducing its side effects. Nine formulae were prepared according to 3(2) factorial design and were evaluated for their morphology, vesicle size, entrapment efficiency (EE %), and% of drug released after 5 h. Hydrogel of the candidate formula, N8G (proniosomes prepared with 0.025% TRT, and Span60: cholesterol molar ratio of 3:1 and incorporated in 1% carbopol gel) was developed and evaluated for skin irritation test and clinical study in acne patients compared to marketed product. Candidate formula showed higher efficacy and very low irritation potential when compared to marketed product in human volunteers.

Niosomes from 80s to present: the state of the art

Efficient and safe drug delivery has always been a challenge in medicine. The use of nanotechnology, such as the development of nanocarriers for drug delivery, has received great attention owing to the potential that nanocarriers can theoretically act as "magic bullets" and selectively target affected organs and cells while sparing normal tissues. During the last decades the formulation of surfactant vesicles, as a tool to improve drug delivery, brought an ever increasing interest among the scientists working in the area of drug delivery systems. Niosomes are self assembled vesicular nanocarriers obtained by hydration of synthetic surfactants and appropriate amounts of cholesterol or other amphiphilic molecules. Just like liposomes, niosomes can be unilamellar or multilamellar, are suitable as carriers of both hydrophilic and lipophilic drugs and are able to deliver drugs to the target site. Furthermore, niosomal vesicles, that are usually non-toxic, require less production costs and are stable over a longer period of time in different conditions, so overcoming some drawbacks of liposomes. The niosome properties are specifically dictated by size, shape, and surface chemistry which are able to modify the drug's intrinsic pharmacokinetics and eventual drug targeting to the areas of pathology. This up-to-date review deals with composition, preparation, characterization/evaluation, advantages, disadvantages and application of niosomes.

Carrier-based drug delivery system for treatment of acne

Approximately 95% of the population suffers at some point in their lifetime from acne vulgaris. Acne is a multifactorial disease of the pilosebaceous unit. This inflammatory skin disorder is most common in adolescents but also affects neonates, prepubescent children, and adults. Topical conventional systems are associated with various side effects. Novel drug delivery systems have been used to reduce the side effect of drugs commonly used in the topical treatment of acne. Topical treatment of acne with active pharmaceutical ingredients (API) makes direct contact with the target site before entering the systemic circulation which reduces the systemic side effect of the parenteral or oral administration of drug. The objective of the present review is to discuss the conventional delivery systems available for acne, their drawbacks, and limitations. The advantages, disadvantages, and outcome of using various carrier-based delivery systems like liposomes, niosomes, solid lipid nanoparticles, and so forth, are explained. This paper emphasizes approaches to overcome the drawbacks and limitations associated with the conventional system and the advances and application that are poised to further enhance the efficacy of topical acne formulations, offering the possibility of simplified dosing regimen that may improve treatment outcomes using novel delivery system.

Ammonium glycyrrhizinate-loaded niosomes as a potential nanotherapeutic system for anti-inflammatory activity in murine models

BACKGROUND

Liquorice extracts demonstrate therapeutic efficacy in treating dermatitis, eczema, and psoriasis when compared with corticosteroids. In this work, nonionic surfactant vesicles (niosomes, NSVs) containing polysorbate 20 (Tween 20), cholesterol, and cholesteryl hemisuccinate at different molar concentrations were used to prepare monoammonium glycyrrhizinate (AG)-loaded NSVs. The anti-inflammatory properties of AG-loaded NSVs were investigated in murine models.

METHODS

The physicochemical properties of the NSVs were characterized using dynamic light scattering. The fluidity of the lipid bilayer was evaluated by measuring the fluorescence intensity of diphenylhexatriene. The drug entrapment efficiency of AG was assessed using high-performance liquid chromatography. The physicochemical stability of the NSVs was evaluated as a function of time using dynamic light scattering combined with Turbiscan Lab Expert analysis. Serum stability was determined by incubating the NSVs with 10% v/v fetal bovine serum. The cytotoxic effects of the NSVs were investigated in human dermal fibroblasts using the Trypan blue dye exclusion assay (for cell mortality) and an MTT assay (for cell viability). Release profiles for the AG-loaded NSVs were studied in vitro using cellulose membranes. NSVs showing the most desirable physicochemical properties were selected to test for in vivo anti-inflammatory activity in murine models. The anti-inflammatory activity of the NSVs was investigated by measuring edema and nociception in mice stimulated with chemical agents.

RESULTS

NSVs showed favorable physicochemical properties for in vitro and in vivo administration. In addition, they demonstrated long-term stability based on Turbiscan Lab Expert analysis. The membrane fluidity of the NSVs was not affected by self-assembling of the surfactants into colloidal structures. Fluorescence anisotropy was found to be independent of the molar ratios of cholesteryl hemisuccinate and/or cholesterol during preparation of the NSVs. The anti-inflammatory AG drug showed no effect on the stability of the NSVs. In vivo experiments demonstrated that AG-loaded NSVs decreased edema and nociceptive responses when compared with AG alone and empty NSVs. In vitro and in vivo results demonstrated that pH sensitive and neutral NSVs show no statistical significant difference.

CONCLUSION

NSVs were nontoxic and showed features favorable for potential administration in vivo. In addition, neutral NSVs showed signs of increased anti-inflammatory and antinociceptive responses when compared with AG.

Amphiphilic designer nano-carriers for controlled release: from drug delivery to diagnostics

Our review highlights lipid liquid crystal nanocarriers, essentially their design considerations and sugar-based materials for specific targeted delivery.

Recent advances in gel technologies for topical and transdermal drug delivery

Transdermal drug delivery systems are a constant source of interest because of the benefits that they afford in overcoming many drawbacks associated with other modes of drug delivery (i.e. oral, intravenous). Because of the impermeable nature of the skin, designing a suitable drug delivery vehicle that penetrates the skin barrier is challenging. Gels are semisolid formulations, which have an external solvent phase, may be hydrophobic or hydrophilic in nature, and are immobilized within the spaces of a three-dimensional network structure. Gels have a broad range of applications in food, cosmetics, biotechnology, pharmatechnology, etc. Typically, gels can be distinguished according to the nature of the liquid phase, for example, organogels (oleogels) contain an organic solvent, and hydrogels contain water. Recent studies have reported other types of gels for dermal drug application, such as proniosomal gels, emulgels, bigels and aerogels. This review aims to introduce the latest trends in transdermal drug delivery via traditional hydrogels and organogels and to provide insight into the latest gel types (proniosomal gels, emulgels, bigels and aerogels) as well as recent technologies for topical and transdermal drug delivery.

A retinyl palmitate-loaded solid lipid nanoparticle system: effect of surface modification with dicetyl phosphate on skin permeation in vitro and anti-wrinkle effect in vivo

Surface-modified solid lipid nanoparticles (SLNs) containing retinyl palmitate (Rpal) were prepared by the hot-melt method using Gelucire 50/13(®) and Precirol ATO5(®). Dicetyl phosphate (DCP) was added to negatively charge the surfaces of the SLNs and thereby enhance the skin distribution properties of Rpal. In vitro skin permeation and in vivo anti-aging studies were performed using SLNs dispersed in a hydrogel. The SLNs were under 100 nm in size with an even polydispersity index (PDI), and the high absolute zeta-potential value was sufficient to maintain the colloidal stability of the SLNs. DCP-modified negative SLNs (DCPmod-SLNs) enhanced the skin distribution of Rpal 4.8-fold and delivered Rpal to a greater depth than did neutral SLNs. The in vivo anti-wrinkle effect of the DCPmod-SLN formulation was Rpal dose-dependent. However, the anti-wrinkle effects of the DCPmod-SLN formulations were significantly different from that of the negative control and effectively prevented the reduction of elastin and superoxide dismutase by UV irradiation. In conclusion, the DCPmod-SLN system presented is a good candidate for topical Rpal delivery.

Formulation and evaluation of metformin hydrochloride-loaded niosomes as controlled release drug delivery system

Lactic acidosis is a serious, metabolic complication that may occur due to metformin hydrochloride (MH) accumulation during the treatment of diabetes mellitus. The aim of this study is to enhance the bioavailability of MH by oral route. Span 40 and cholesterol were used for the preparation of MH-loaded niosomes by the reverse phase evaporation technique. Dicetyl phosphate (DCP) and 1,2-dioleoyl-3-trimethylammonium-propane chloride salt (DOTAP) were used to obtain negatively and positively charged vesicles, respectively. The mean particle size ranged from 223.5 to 384.6 nm and the MH-loaded niosomes' surface was negatively charged in the absence of charge inducing agents (-16.6 ± 1.4 mV) and also with DCP (-26.9 ± 1.0 mV), while it was positively charged (+8.7 ± 1.2 mV) with DOTAP. High entrapment efficiency was observed in all the formulations. MH-loaded niosomes were found to effectively sustain the release of drug, particularly with positively charged niosomes. The bioavailability of MH-loaded niosomes was assessed by measuring the serum values of glucose and metformin in the different studied Wistar rats groups. The pharmacokinetic data of MH-loaded niosomal preparation showed a significant prolongation and increased intensity of hypoglycemic effect more than that observed for free MH solution. Area above the blood glucose levels-time curve (AAC), maximum hypoglycemic response and time of maximum response (T(max)) were significantly higher (p < 0.001) when MH was administered in niosomal form compared to free drug solution. It could be concluded that MH-loaded niosome is promising extended-release preparation with better hypoglycemic efficiency.

Development of a novel niosomal system for oral delivery of Ginkgo biloba extract

Background

The aim of this study was to develop an optimal niosomal system to deliver Ginkgo biloba extract (GbE) with improved oral bioavailability and to replace the conventional GbE tablets.

Methods

In this study, the film dispersion-homogenization method was used to prepare GbE niosomes. The resulting GbE niosome suspension was freeze-dried or spray-dried to improve the stability of the niosomes. GbE-loaded niosomes were formulated and characterized in terms of their morphology, particle size, zeta potential, entrapment efficiency, and angle of repose, and differential scanning calorimetry analysis was performed. In vitro release and in vivo distribution studies were also carried out.

Results

The particle size of the optimal delivery system prepared with Tween 80, Span 80, and cholesterol was about 141 nm. There was a significant difference (P < 0.05) in drug entrapment efficiency between the spray-drying method (about 77.5%) and the freeze-drying method (about 50.1%). The stability study revealed no significant change in drug entrapment efficiency for the GbE niosomes at 4°C and 25°C after 3 months. The in vitro release study suggested that GbE niosomes can prolong the release of flavonoid glycosides in phosphate-buffered solution (pH 6.8) for up to 48 hours. The in vivo distribution study showed that the flavonoid glycoside content in the heart, lung, kidney, brain, and blood of rats treated with the GbE niosome carrier system was greater than in the rats treated with the oral GbE tablet (P < 0.01). No flavonoid glycosides were detected in the brain tissue of rats given the oral GbE tablets, but they were detected in the brain tissue of rats given the GbE niosomes.

Conclusion

Niosomes are a promising oral system for delivery of GbE to the brain.

Metformin loaded non-ionic surfactant vesicles: optimization of formulation, effect of process variables and characterization

Background

Metformin an oral hypoglycemic has been widely used as a fist line of treatment of Type II Diabetes but in a very high dose 2–3 times a day and moreover suffers from a number of side effects like lactic acidosis, gastric discomfort, chest pain, allergic reactions being some of them. The present work was conducted with the aim of sustaining the release of metformin so as to decrease its side effects and also reduce its dosing frequency using a novel delivery system niosomes (non-ionic surfactant vesicles). Non-ionic surfactant vesicles of different surfactants were prepared using thin film hydration technique and were investigated for morphology, entrapment, in-vitro release, TEM (transmission electron microscopy) and physical stability. Optimized formulation was further studied for the effect of Surfactant concentration, DCP (Dicetyl phosphate), Surfactant: cholesterol ratio and volume of hydration. The release studies data was subjected to release kinetics models.

Results

The prepared vesicles were uniform and spherical in size. Optimized formulation MN3 entrapped the drug with 84.50±0.184 efficiency in the vesicles of the size 487.60±2.646 and showed the most sustained release of 73.89±0.126. Also it was resulted that 100 molar concentration of cholesterol and surfactant, Presence of DCP, equimolar ratio of span 60: cholesterol and 15 ml of volume of hydration were found to be optimum for miosome preparation.

Conclusions

The present work concluded metformin loaded niosomes to be effective in sustaining the drug release leading to decreased side effects and increased patient compliance.

Niosomes: novel sustained release nonionic stable vesicular systems--an overview

Vesicular systems are novel means of delivering drug in controlled manner to enhance bioavailability and get therapeutic effect over a longer period of time. Niosomes are such hydrated vesicular systems containing nonionic surfactants along with cholesterol or other lipids delivering drug to targeted site which are non toxic, requiring less production cost, stable over a longer period of time in different conditions, so overcomes drawbacks of liposome. Present review describes history, all factors affecting niosome formulation, manufacturing conditions, characterization, stability, administration routes and also their comparison with liposome. This review also gives relevant information regarding various applications of niosomes in gene delivery, vaccine delivery, anticancer drug delivery, etc.

Nanostructured lipid carriers (NLC) for parenteral delivery of an anticancer drug

The purpose of this research was to formulate nanostructured lipid carriers (NLC) for the parenteral delivery of an anticancer drug, all-trans retinoic acid (ATRA). The ATRA was incorporated into NLC by the de novo emulsification method. The effect of the formulation factor, i.e., type and oil ratio, initial ATRA concentration on physicochemical properties was determined. The anticancer efficacy of ATRA-loaded NLC on HL-60 and HepG2 cells was also studied. NLC was formulated using a blend of solid lipids (cetyl palmitate) and liquid lipids (soybean oil (S), medium-chain triglyceride (M), S/oleic acid (O; 3:1) and M/O (3:1)) at a weight ratio of 1:1. ATRA-loaded NLC had an average size of less than 200 nm (141.80 to 172.95 nm) with a narrow PDI and negative zeta potential that was within an acceptable range for intravenous injection. The results indicated that oleic acid enhanced the ATRA-loading capacity of NLC. In vitro ATRA release was only approximately 4.06% to 4.34% for 48 h, and no significant difference in ATRA release rate from all NLC formulations in accordance with the composition of the oil phase. Moreover, no burst release of the drug was observed, indicating that NLC could prolong the release of ATRA. The initial drug concentration affected the photodegradation rate but did not affect the release rate. All ATRA-loaded NLC formulations exhibited the photoprotective property. The cytotoxicity results showed that all ATRA-loaded NLC had higher cytotoxicity than the free drug and HL-60 cells were more sensitive to ATRA than HepG2 cells.

Preparation and evaluation of niosomes containing autoclaved Leishmania major: a preliminary study

In this study, different positively charged niosomal formulations containing sorbitan esters, cholesterol and cetyl trimethyl ammonium bromide were prepared by film hydration method for the entrapment of autoclaved Leishmania major (ALM). Size distribution pattern and stability of niosomes were investigated by laser light scattering method and ALM encapsulation per cent was measured by the bicinchoninic acid method. Finally, the selected formulation was used for the induction of the immune response against cutaneous leishmaniasis in BALB/c mice. Size distribution curves of all the formulations followed a log-normal pattern and the mean volume diameter was in the range 7.57-15.80 µm. The mean volume diameters were significantly increased by adding Tween to Span formulations (p < 0.05). The percentage of ALM entrapped in all formulations varied between 14.88% and 36.65%. In contrast to ALM, in vivo studies showed that the niosomes containing ALM have a moderate effect in the prevention of cutaneous leishmaniasis in BALB/c mice.

Physicochemical properties and skin permeation of Span 60/Tween 60 niosomes of ellagic acid

Ellagic acid (EA) is a potent antioxidant phytochemical substance which has limitation to use due to its poor biopharmaceutical properties, low solubility and low permeability. The aim of the present study was to develop niosomal formulations obtained from the mixture of Span 60 and Tween 60 that could encapsulate EA for dermal delivery. The EA-loaded niosomes were prepared with 1:0, 2:1, 1:1, 0:1 Span 60 and Tween 60, using polyethylene glycol 400 (PEG 400), propylene glycol (PG) or methanol (MeOH) as a solubilizer. The influence of formulations on vesicle size, entrapment efficiency and stability of EA-loaded niosomes was investigated. It was found that all ratios of surfactants could produce EA-loaded niosomes when using 15% (v/v) PG, 15% (v/v) PEG 400 or 20% (v/v) MeOH. The niosomes were spherical multilamellar vesicles showing the localization of EA in the vesicles. The vesicle sizes of the niosomes after extrusion were 124-752 nm with PI less than 0.4. The percentages of entrapment efficiency (% E.E.) of all EA-loaded niosomes varied between 1.35% and 26.75% while PEG 400 niosomes gave the highest % E.E. The most stable and highest entrapped formulation was 2:1 Span 60 and Tween 60 niosomes. Additionally, the in vitro skin permeation revealed that penetration of EA from the niosomes depended on vesicle size, the amount of EA entrapped and the added solubilizers which could act as a permeation enhancer. From skin distribution study, the EA-loaded niosomes showed more efficiency in the delivery of EA through human epidermis and dermis than EA solution. The results indicated that the Span 60 and Tween 60 niosomes may be a potential carrier for dermal delivery of EA.