Dual influence of colloidal silica on skin deposition of vitamins C and E simultaneously incorporated in topical microemulsions

Cannabidiol-Loaded Lipid-Stabilized Nanoparticles Alleviate Psoriasis Severity in Mice: A New Approach for Improved Topical Drug Delivery

Cannabidiol (CBD) is a promising natural agent for treating psoriasis. CBD activity is attributed to inhibition of NF-kB, IL-1β, IL-6, and IL-17A. The present study evaluated the anti-psoriatic effect of cannabidiol in lipid-stabilized nanoparticles (LSNs) using an imiquimod (IMQ)-induced psoriasis model in mice. CBD-loaded LSNs were stabilized with three types of lipids, Cetyl alcohol (CA), Lauric acid (LA), and stearic-lauric acids (SALA), and were examined in-vitro using rat skin and in-vivo using the IMQ-model. LSNs loaded with coumarin-6 showed a localized penetration depth of about 100 µm into rat skin. The LSNs were assessed by the IMQ model accompanied by visual (psoriasis area severity index; PASI), histological, and pro-psoriatic IL-17A evaluations. Groups treated with CBD-loaded LSNs were compared to groups treated with CBD-containing emulsion, unloaded LSNs, and clobetasol propionate, and to an untreated group. CBD-loaded LSNs significantly reduced PASI scoring compared to the CBD emulsion, the unloaded LSNs, and the untreated group (negative controls). In addition, SALA- and CA-containing nanoparticles significantly inhibited IL-17A release, showing a differential response: SALA > CA > LA. The data confirms the effectiveness of CBD in psoriasis therapy and underscores LSNs as a promising platform for delivering CBD to the skin.

Nanocellulose-Based Film-Forming Hydrogels for Improved Outcomes in Atopic Skin

Atopic dermatitis (AD) is a chronic inflammatory skin disease characterized by impaired skin barrier function. Amongst the various dermal formulations that are being used and/or investigated for AD treatment, one of the advanced approaches is the use of hydrogels as film-forming systems that are applied directly to the skin and have the added value of providing a physical barrier, which is lacking in atopic skin. Novel film-forming hydrogels based on two different nanocrystalline celluloses (NCCs) in combination with one of two natural polymers (alginate or pectin) were developed for incorporation of betamethasone dipropionate (BDP). Initially, the low water solubility of BDP was resolved by prior dissolution in a self-microemulsifying drug delivery system (SMEDDS). The mixture of Kolliphor^® EL/Capryol^® 90 in a ratio of 8/2 was chosen on the merit of its high BDP-saturated solubility and no BDP precipitation upon water dilution, enabling BDP to remain dissolved after incorporation into hydrogels. The solvent evaporation method was used to prepare the films, and their high water retention capacity was confirmed in vitro on artificial membranes and pig ear skin. The presented results thus confirm NCC-based film-forming hydrogels as a very promising drug delivery system for AD treatment.

Chemical Permeation Enhancers for Topically-Applied Vitamin C and Its Derivatives: A Systematic Review

This paper reports the permeation-enhancing properties and safety of different chemical permeation enhancers (CPEs) on the topical delivery of vitamin C (VC) and its derivatives. A literature search using search keywords or phrases was done in PubMed®, ScienceDirect, and MEDLINE databases. The calculated Log P (cLog P) values were referenced from PubChem and the dermal LD50 values were referenced from safety data sheets. Thirteen studies described the permeation-enhancing activity of 18 identified CPEs in the topical delivery of VC. Correlation analysis between ER and cLog P values for porcine (r = 0.114) and rabbit (r = 0.471) showed weak and moderate positive correlation, while mouse (r = −0.135), and reconstructed human epidermis (r = −0.438) had a negative correlation. The majority (n = 17) of the CPEs belonged to Category 5 of the Globally Harmonized System of Classification or low toxicity hazard. CPEs alone or in combination enhanced permeation (ER = 0.198–106.57) of VC in topical formulations. The combination of isopropyl myristate, sorbitan monolaurate, and polyoxyethylene 80 as CPEs for VC resulted in the highest permeation enhancement ratio.

Permeation, stability and acute dermal irritation of miroestrol and deoxymiroestrol from Pueraria candollei var. mirifica crude extract loaded transdermal gels

In this study, permeation behaviors and chemical stability of miroestrol and deoxymiroestrol from Pueraria candollei var. mirifica (PM), Thai traditional medicine, crude extract containing transdermal gels were firstly evaluated. Three different PM extract containing gels were formulated, including hydroalcoholic and microemulsion gels using carbomer, and silicone gel using silicone elastomer. In vitro permeation through porcine ear skin demonstrated that the flux and 24 h cumulative permeation of miroestrol and deoxymiroestrol were in the order of hydroalcoholic > silicone > microemulsion gels. Hydroalcoholic gel provided the highest partition coefficient from gel onto skin, and thus the skin permeability coefficient. After 24 h permeation, no miroestrol and deoxymiroestrol remained deposited in the skin. Accelerated study using heating-cooling revealed insignificant difference between the remaining percentages of miroestrol and deoxymiroestrol in aqueous and non-aqueous based gels. Long-term stability study showed that miroestrol contents remained constant for 90 d and 30 d under 5 ± 3 °C and 30 ± 2 °C, 75 ± 5%RH, respectively; whereas the percentage of deoxymiroestrol decreased significantly after 30 d storage, irrespective of storage conditions. Acute dermal irritation test on New Zealand White rabbits showed that PM hydroalcoholic gels were non-irritant, with no signs of erythema or oedema.[Figure: see text].

Novel microemulsion-based gels for topical delivery of indomethacin: Formulation, physicochemical properties and in vitro drug release studies

HYPOTHESIS

Microemulsion-based semisolid systems may be considered as an interesting alternative to the traditional dosage forms applied in topical drug delivery. Mechanical properties of topical products are important both in terms of application and dosage form effectiveness. In this study we designed and evaluated novel microemulsion-based gels with indomethacin and analyzed the factors affecting their mechanical characteristics and drug release.

EXPERIMENTS

The impact of the microemulsion composition on the extent of isotropic region was investigated with the use of pseudoternary phase diagrams. Selected microemulsions were analyzed in terms of electrical conductivity and surface tension in order to determine the microemulsion type. Microemulsions were transformed into polymer-based gels and subjected to rheological and textural studies. Finally, the indomethacin release from the analyzed gels was studied and compared to commercially available product.

FINDINGS

The extent of isotropic domain in pseudoternary phase diagrams seems to be dependent on the polarity of the oil phase. The surface tension and conductivity monitored as a function of water content in microemulsion systems revealed possible structural transformations from w/o through bicontinuous systems into o/w. The mechanical properties of semisolid microemulsion-based systems depended on the composition of surface active agents and the drug presence. The drug release profiles observed in the case of the investigated gels differed from those recorded for the commercially available product which was most probably caused by the different structure of both systems.

Development of medicated foams that combine incompatible hydrophilic and lipophilic drugs for psoriasis treatment

The focus was on the development of medicated foam for incorporation of two incompatible active agents for psoriasis treatment; i.e., lipophilic cholecalciferol, and hydrophilic salicylic acid. Emphasis was given to formulation of a propellant-free foam, with sufficient foaming properties, physical and chemical stability, and low irritancy potential to maintain relevance for later translation into clinical practice. Various excipients and concentrations were examined to achieve suitable foam stability parameters, viscoelasticity, and bubble-size, which relate to foamability and spreadability. The major positive impact on these properties was through a combination of surfactants, and by inclusion of a viscosity-modifying polymer. Incorporation of the incompatible drugs was then examined, noting the instability of cholecalciferol in an acidic environment, with the design aim to separate the drug distributions among the different foam phases. Cholecalciferol was stabilized in the emulsion-based foam, with at least a 30-fold lower degradation rate constant compared to its aqueous solution. The composition of the emulsion-based foam itself protected cholecalciferol from degradation, as well as the addition of the radical-scavenging antioxidant tocopheryl acetate to the oil phase. With the patient in mind, the irritancy potential was also examined, which was below the set limit that defines a non-irritant dermal product.

The influence of microemulsion structure on their skin irritation and phototoxicity potential

The purpose of this study was to examine skin irritation and phototoxicity potentials of several microemulsions (ME), all comprising approximately the same percentage of surfactant mixture, but varying oil/water content and consequently inner structure being either droplet-like (o/w ME, o/w ME carbomer, w/o ME and w/o ME white wax) or lamellar (gel-like ME). Two different in vitro methods were used: MTT assay (performed either on reconstructed human epidermis (RHE) or NCTC 2544 cells) and pig ear test. Neither assay revealed the difference among ME with droplet-like structure. Then again, pig ear test and MTT assay performed on RHE indicated that gel-like ME is more irritant compared to other tested ME, whereas no difference among formulations were observed by MTT assay on NCTC 2544 cells. The reasonable explanation is destruction and consequently uniform structure of ME upon dilution that is inevitable for testing on cell cultures. The results of phototoxicity test again indicated the increased potential of gel-like ME to cause adverse effects on skin. It can be concluded that for ME consisting of the same amount of identical surfactants but having different structure the latter represent a crucial factor that determines their dermal toxicity.

Main approaches for delivering antioxidant vitamins through the skin to prevent skin ageing

INTRODUCTION

One of the major contributions to skin photoageing and diseases is oxidative stress, caused by UV radiation inducing reactive oxygen and nitrogen species. Successful prophylaxis and therapy would necessitate control of the oxidant/antioxidant balance at the affected site, which can be achieved through the external supply of endogenous antioxidants.

AREAS COVERED

This review discusses possible strategies for dermal delivery of the antioxidant vitamins E and C, as oral supplementation has proved insufficient. These antioxidants have low skin bioavailability, owing to their poor solubility, inefficient skin permeability, or instability during storage. These drawbacks can be overcome by various approaches, such as chemical modification of the vitamins and the use of new colloidal drug delivery systems. New knowledge is included about the importance of: enhancing the endogenous skin antioxidant defense through external supply; the balance between various skin antioxidants; factors that can improve the skin bioavailability of antioxidants; and new delivery systems, such as microemulsions, used to deliver vitamins C and E into the skin simultaneously.

EXPERT OPINION

A promising strategy for enhancing skin protection from oxidative stress is to support the endogenous antioxidant system, with antioxidants containing products that are normally present in the skin.