Dermal and Transdermal Macromolecule Delivery Using Enhancer Molecules and Colloidal Carrier Systems - Part 2: Percutaneous Administration of Heparin.

INTRODUCTION: Heparin is a commonly used anti-coagulant administered either by intravenous or subcutaneous injection for a systemic effect or topically for the treatment of peripheral vascular disorders. OBJECTIVE: This study aimed to formulate heparin in non-ionic colloidal carrier systems (CCSs) having enhanced percutaneous absorption for systemic and topical administration. METHODS: Five CCSs were developed and characterized for their rheological properties, droplet size, and drug loading. The percutaneous absorption of heparin was evaluated in vitro using Franz diffusion cells with rats' skin and with the aid of a developed high-pressure chromatography method. Furthermore, the efficacy of two developed heparin CCSs was tested percutaneously in rats by measuring the response against the time in comparison to subcutaneous administration. RESULTS: The rheograms and droplet size measurements showed that the developed drug delivery systems have Newtonian properties with a droplet size between 109 and 460 nm. As much as 500 mg of heparin could be loaded in around 5 mL of CCS. Furthermore, using Franz diffusion cells, a diffusion rate of 19.216 ± 2.01 USP U/cm2.h could be achieved for heparin-loaded CCSs. Moreover, the estimated percutaneous in vivo relative bioavailability in comparison to subcutaneous administration could reflect that at least more than 50% of the drug passed through the skin. CONCLUSION: The developed novel non-toxic CCSs containing heparin can be good candidates for percutaneous administration as alternative delivery systems for subcutaneous and intravenous invasive administration.

Free amino acid contents of selected Ethiopian plant and fungi species: a search for alternative natural free amino acid sources for cosmeceutical applications.

Free amino acids (FAAs), the major constituents of the natural moisturizing factor (NMF), are very important for maintaining the moisture balance of human skin and their deficiency results in dry skin conditions. There is a great interest in the identification and use of nature-based sources of these molecules for such cosmeceutical applications. The objective of the present study was, therefore, to investigate the FAA contents of selected Ethiopian plant and fungi species; and select the best sources so as to use them for the stated purpose. About 59 different plant species and oyster mushroom were included in the study and the concentrations of 27 FAAs were analyzed. Each sample was collected, lyophilized, extracted using aqueous solvent, derivatized with Fluorenylmethoxycarbonyl chloride (Fmoc-Cl) prior to solid-phase extraction and quantified using Liquid Chromatography Electrospray Ionization Tandem Mass Spectrometric (LC-ESI-MS/MS) system. All the 27 FAAs were detected in most of the samples. The dominant FAAs that are part of the NMF were found at sufficiently high concentration in the mushroom and some of the plants. This indicates that FAAs that could be included in the preparations for the management of dry skin condition can be obtained from a single natural resource and the use of these resources for the specified purpose have both economic and therapeutic advantage in addition to fulfilling customer needs.

State of the Art in Stratum Corneum Research. Part II: Hypothetical Stratum Corneum Lipid Matrix Models.

This review is the second part of a series which presents the state of the art in stratum corneum (SC) lipid matrix (LM) research in depth. In this part, the various hypothetical models which were developed to describe the structure and function of the SC LM as the skin's barrier will be discussed. New as well as a cumulative assortment of older results which change the view on the different models are considered to conclude how well the different models are holding up today. As a final conclusion, a model, factoring in as much of the known data as possible, is concluded, unifying the varying different models into one which can be developed further, as new results are found in the future. So far, the model is described with a single crystalline or gel-like phase with a certain amount of nanocrystallites of concentrated ceramides (CERs) and free fatty acids and more fluid nanodomains caused by a fluidizing effect of the cholesterol. These domains are dynamically resolved and reformed and do not impair the barrier function. The chain conformation is not completely clear yet; however, an equilibrium of fully extended and hairpin-folded CERs with ratios depending on the properties of each individual CER species is proposed as most likely. An overlapping middle layer as described for the tri-layer model in part I of this series would be present for both conformations. The macroscopic broad-narrow-broad layering, observed in electron micrographs, is explained by an external templating by the lipid envelope, and an internal templating by short and long lipid chains each preferentially show a homophilic association, forming thicker and thinner bilayers, respectively. The degree of influence of the very long ω-hydroxy-CERs is discussed as well.

Investigation of ex vivo Skin Penetration of Coenzyme Q10 from Microemulsions and Hydrophilic Cream.

INTRODUCTION: Coenzyme Q10 (CoQ10) has been widely used in topical and cosmeceutical products due to its cutaneous antioxidant and energizer effects. CoQ10 is found in a higher concentration in the epidermis compared to dermis. The epidermal level of CoQ10 can be reduced due to several factors such as skin UV irradiation and photoaging. Various dermal nano-formulations have been investigated to overcome the skin barrier and enhance the poor penetration of CoQ10. The nanocarriers are designed to target and concentrate the CoQ10 in the viable epidermis. Most of these studies, however, failed to show the depth and extent of penetration of CoQ10 from the various carrier systems. OBJECTIVE: The distribution of CoQ10 across the various skin layers has to be shown using skin slices representing the different skin layers. METHODS: To realize this objective, a sensitive and selective HPLC method was developed and validated for the quantification of CoQ10 in the different skin slices. The method applicability to skin penetration (using excised human skin) as well as stability studies was investigated using CoQ10-loaded lecithin-based microemulsion (ME) and hydrophilic cream formulations. RESULTS: It could be shown that the highest concentration of CoQ10 in the viable epidermis, the target skin layer for CoQ10, was observed after application of the CoQ10 in the hydrophilic cream. This cream contains 10% of 2-ethylhexyl laurate which works obviously as a penetration enhancer for CoQ10. In contrast, the penetration of CoQ10 was lower from the ME. Just in the deeper dermis, a certain amount of CoQ10 could be detected. CONCLUSIONS: The HPLC method quantified the trace quantities of the CoQ10 distributed across the various skin layers and, hence, can be used to investigate the skin penetration of CoQ10 from various dermal standard and nano-formulations.

Dermal Peptide Delivery Using Enhancer Molecules and Colloidal Carrier Systems - Part IV: Search for an Alternative Model Membrane for Future ATR Permeation Studies Using PKEK as the Model Substance.

The main barrier of the human skin is the stratum corneum (SC). Its properties (also depending on the health and age of the individual) and its influence on improved penetration of active ingredients into the skin are the subject of many research projects. Since the availability of human skin, as the ideal model membrane, is limited, the aim of this study was to find a suitable alternative model membrane from the animal kingdom. The alternative model membrane should be used in subsequent permeation experiments with the Teflon diffusion cell instead of human SC. Previous studies have already investigated the permeation properties of pig, snake, and human skin, but not in a Teflon diffusion cell using ATR. Therefore, it first had to be proven that comparable results can be achieved with animal membranes even under these measurement conditions. This is the precondition for meaningful future permeation experiments with potential enhancers. For this purpose, permeation experiments on various model membranes (human isolated SC, sunburned SC, pig isolated SC, and shed snake skin) by means of FTIR-ATR in a Teflon diffusion cell containing the acceptor and the donor compartment as well as the model membrane were conducted and concentration-time courses of the model peptide PKEK determined. These concentration-time courses were used to calculate and compare the pharmacokinetic parameters (permeation coefficients, lag time, and flux). The starting point was a 10% PKEK solution in D2O. It turned out that snake skin is the appropriate alternative model membrane for this type of permeation test.

Quantitative Analysis of Free Amino Acids and Urea Derived from Isolated Corneocytes of Healthy Young, Healthy Aged, and Diseased Skin.

BACKGROUND/AIMS: Free amino acids (FAAs) and urea, present inside the corneocytes, can be important indicators of skin condition. However, due to the lack of a standard extraction protocol for FAAs from corneocytes, conflicting research results have been reported. Therefore, the purpose of this study was (1) to standardize the extraction protocol and (2) to investigate FAA profiles in healthy young and healthy old volunteers, as well as in psoriasis and atopic dermatitis patients. METHODS: Skin samples were collected from four groups (healthy young, healthy old, and psoriasis and atopic dermatitis patients) with 5 volunteers per group. Corneocytes were isolated and examined microscopically. FAAs and urea were extracted from the isolated corneocytes, and their amounts were quantified using LC-ESI/MS/MS (after derivatization with Fmoc-Cl) and colorimetric methods, respectively. RESULTS: The micrographs of the corneocytes showed no morphological features attributable to age or disease conditions. The highest and lowest concentrations of total FAAs and urea were observed in the healthy old group and the healthy young group, respectively. Unlike the other FAAs and urea, citrulline was found at a higher level in the healthy young group than in the disease groups. CONCLUSION: This study suggests that the levels of FAAs and urea in the skin are affected by age and skin conditions (healthy/diseased). However, further studies are needed to show the effects of different skin conditions on the levels of FAAs and urea.

Investigation of a CER[NP]- and [AP]-Based Stratum Corneum Modeling Membrane System: Using Specifically Deuterated CER Together with a Neutron Diffraction Approach.

Neutron diffraction was used as a tool to investigate the lamellar as well as molecular nanostructure of ceramide-[NP]/ceramide-[AP]/cholesterol/lignoceric acid model systems with a nativelike 2:1 ratio and a 1:2 ratio to study the influence of the ceramide-[AP]. By using mixtures together with cholesterol and free fatty acids as well as a humidity and temperature chamber while measuring, natural conditions were simulated as closely as possible. Despite its simplicity, the system simulated the native stratum corneum lipid matrix fairly closely, showing a similar lamellar thickness with a repeat distance of 5.45 ± 0.1 nm and a similar arrangement with overlapping long C24 chains. Furthermore, despite the very minor chemical difference between ceramide-[NP] and ceramide-[AP], which is only a single OH group, it was possible to demonstrate substantial differences between the structural influence of the two ceramides. Ceramide-[AP] could be concluded to be arranged in such a way that its C24 chain in both ratios is somehow shorter than that of ceramide-[NP], not overlapping as much with the opposite lamellar leaflet. Furthermore, in the unnatural 1:2 ratio, the higher ceramide-[AP] content causes an increased tilt of the ceramide acyl chains. This leads to even less overlapping within the lamellar midplane, whereas the repeat distance stays the same as for the ceramide-[NP]-rich system. In this nativelike 2:1 ratio, the chains are arranged mostly straight, and the long C24 chains show a broad overlapping region in the lamellar midplane.

Development and validation of LC/APCI-MS method for the quantification of oat ceramides in skin permeation studies.

Ceramides (CERs) are the backbone of the intercellular lipid lamellae of the stratum corneum (SC), the outer layer of the skin. Skin diseases such as atopic dermatitis, psoriasis, and aged skin are characterized by dysfunctional skin barrier and dryness which are associated with reduced levels of CERs. Replenishing the depleted epidermal CERs with exogenous CERs has been shown to have beneficial effects in improving the skin barrier and hydration. The exogenous CERs such as phyto-derived CERs (PhytoCERs) can be delivered deep into the SC using novel topical formulations. This, however, requires investigating the rate and extent of skin permeation of CERs. In this study, an LC/APCI-MS method to detect and quantify PhytoCERs in different layers of the skin has been developed and validated. The method was used to investigate the skin permeation of PhytoCERs using Franz diffusion cells after applying an amphiphilic cream containing PhytoCERs to the surface of ex vivo human skin. As plant-specific CERs are not commercially available, well-characterized CERs isolated from oat (Avena abyssinica) were used as reference standards for the development and validation of the method. The method was linear over the range of 30-1050 ng/mL and sensitive with limit of detection and quantification of 10 and 30 ng/mL, respectively. The method was also selective, accurate, and precise with minimal matrix effect (with mean matrix factor around 100%). Even if more than 85% of oat CERs in the cream remained in the cream after the incubation periods of 30, 100, and 300 min, it was possible to quantify the small quantities of oat CERs distributed across the SC, epidermis, and dermis of the skin indicating the method's sensitivity. Therefore, the method can be used to investigate the skin permeation of oat CERs from the various pharmaceutical and cosmeceutical products without any interference from the skin constituents such as the epidermal lipids. Graphical abstract ᅟ.

Age- and Diabetes-Related Changes in the Free Fatty Acid Composition of the Human Stratum Corneum.

Of particular importance for Stratum corneum (SC) lipids are the free fatty acids (FFAs). Age-related changes of the SC structure lead to diminished capacity for barrier compensation. The aims of this cross-sectional study were to identify even-numbered especially odd-numbered FFAs within the intercorneocytic lamellar lipid structures of the SC and to explore age- and diabetes-related changes in FFAs. Gas chromatography - flame ionisation detection was used to qualitatively and quantitatively assess FFAs extracted from the SC. 110 subjects aged over 60 years (elderly/healthy), 110 subjects aged 18-40 (young/healthy) and 38 subjects with diabetes mellitus aged 18-40 (young/diabetic) were investigated. Overall, odd-numbered FFAs comprised about 21, 23 and 24% of total FFAs in subgroups elderly/healthy, young/healthy and young/diabetic. The most abundant short-chain FFAs were C16: 0 and C18: 0 and long-chain FFAs were C24: 0 and C26: 0. Only levels of C15: 0 and C17: 0 decreased with age. In contrast, levels of C18: 2 and C19 were significantly decreased and levels of C15, C17, C18: 1 and C23 were significantly increased in young diabetic subjects. In general, compared with younger healthy subjects, FFA composition was only partly significantly altered in older healthy subjects but was significantly altered in younger diabetic subjects.

Malusides, novel glucosylceramides isolated from apple pomace (Malus domestica).

Three new glucosylceramides (GluCers) named malusides I-III (1-3) were isolated from apple (cultivars of Malus domestica) pomace (fruit material remaining after juice extraction). An unusual oxo/hydroxy group pattern within the sphingadienine (d18:2) type sphingoid base was observed. All compounds contained the same α-hydroxylated fatty acid (h16:0) and a ß-D-glucose moiety. Their structures were assigned on the basis of one- and two-dimensional (1D and 2D) nuclear magnetic resonance (NMR) spectroscopic analyses and mass spectrometry (MS) measurements.

Localization of methyl-branched ceramide [EOS] species within the long-periodicity phase in stratum corneum lipid model membranes: A neutron diffraction study.

The outermost layer of the mammalian skin, the stratum corneum (SC), is a very thin structure and realizes simultaneously the main barrier properties. The penetration barrier for xenobiotica is mostly represented by a complex lipid matrix. There is great interest in the subject of getting information about the arrangement of the lipids, which are mainly ceramides (CER), free fatty acids (FFA) and cholesterol (CHOL). SC lipid model membranes containing synthetically derived lipids in a non-physiological ratio were investigated. To compare the study to a former experiment, a methyl-branched ceramide [EOS] species in presence of the ultra-long chain CER[AP], CHOL and behenic acid (23/10/33/33, wt%) was applied. The membrane structure was studied using the very versatile technique of neutron diffraction. We were able to identify a long-periodicity phase (LPP) with a size of 114Å or 118Å with CER[EOS]-br in a ratio of >60wt% of the ceramides. Furthermore, we figured out two additional coexisting short-periodicity phases (SPP) with repeat distances of 48Å and 45Å, respectively. Partial deuterations of CER[EOS]-br and CER[AP] enabled the localization of the molecules within the multiphase system. CER[EOS]-d3 was present in the LPP, but absent in both SPP. CER[AP]-d3 was determined in both short phases but not localized within the LPP. Besides, we revealed influences of humidity and time with respect to the long-periodicity phase.

Influence of the penetration enhancer isopropyl myristate on stratum corneum lipid model membranes revealed by neutron diffraction and 2H NMR experiments.

The stratum corneum (SC) provides the main barrier properties in native skin. The barrier function is attributed to the intercellular lipids, forming continuous multilamellar membranes. In this study, SC lipid membranes in model ratios were enriched with deuterated lipids in order to investigate structural and dynamical properties by neutron diffraction and 2H solid-state NMR spectroscopy. Further, the effect of the penetration enhancer isopropyl myristate (IPM) on the structure of a well-known SC lipid model membrane containing synthetically derived methyl-branched ceramide [EOS], ceramide [AP], behenic acid and cholesterol (23/10/33/33wt%) was investigated. IPM supported the formation of a single short-periodicity phase (SPP), in which we determined the molecular organization of CER[AP] and CER[EOS]-br for the first time. Furthermore, the thermotropic phase behavior of the lipid system was analyzed by additional neutron diffraction studies as well as by 2H solid-state NMR spectroscopy, covering temperatures of 32°C (physiological skin temperature), 50°C, and 70°C with a subsequent cooldown back to skin temperature. Both techniques revealed a phase transition and a hysteresis effect. During the cooldown, Bragg peaks corresponding to a long-periodicity phase (LPP) appeared. Additionally, 2H NMR revealed that the IPM molecules are isotopic mobile at all temperatures.

Influence of a Novel Dimeric Ceramide Molecule on the Nanostructure and Thermotropic Phase Behavior of a Stratum Corneum Model Mixture.

The stratum corneum (SC) is the outermost layer of the skin and is composed of a multilayered assembly of mostly ceramids (Cer), free fatty acids, cholesterol (Chol), and cholesterol sulfate (Chol-S). Because of the tight packing of these lipids, the SC features unique barrier properties defending the skin from environmental influences. Under pathological conditions, where the skin barrier function is compromised, topical application of molecules that rigidify the SC may lead to a restored barrier function. To this end, molecules are required that incorporate into the SC and bring back the original rigidity of the skin barrier. Here, we investigated the influence of a novel dimeric ceramide (dim-Cer) molecule designed to feature a long, rigid hydrocarbon chain ideally suited to forming an orthorhombic lipid phase. The influence of this molecules on the thermotropic phase behavior of a SC mixture consisting of Cer[AP18] (55 wt %), cholesterol (Chol, 25 wt %), steric acid (SA, 15 wt %), and cholesterol sulfate (Chol-S, 5 wt %) was studied using a combination of neutron diffraction and 2H NMR spectroscopy. These methods provide detailed insights into the packing properties of the lipids in the SC model mixture. Dim-Cer remains in an all-trans state of the membrane-spanning lipid chain at all investigated temperatures, but the influence on the phase behavior of the other lipids in the mixture is marginal. Biophysical experiments are complemented by permeability measurements in model membranes and human skin. The latter, however, indicates that dim-Cer only partially provides the desired effect on membrane permeability, necessitating further optimization of its structure for medical applications.

Phase separation in ceramide[NP] containing lipid model membranes: neutron diffraction and solid-state NMR.

The stratum corneum is the outermost layer of the skin and protects the organism against external influences as well as water loss. It consists of corneocytes embedded in a mixture of ceramides, fatty acids, and cholesterol in a molar ratio of roughly 1 : 1 : 1. The unique structural and compositional arrangement of these stratum corneum lipids is responsible for the skin barrier properties. Many studies investigated the organization of these barrier lipids and, in particular, the exact conformation of ceramides. However, so far no consensus has been reached. In this study, we investigate a model system comprised of N-(non-hydroxy-tetracosanoyl)-phytosphingosine/cholesterol/tetracosanoic acid (CER[NP]-C24/CHOL/TA) at a 1 : 1 : 1 molar ratio using neutron diffraction and 2H solid-state NMR spectroscopy at temperatures from 25 °C to 80 °C. Deuterated variants of all three lipid components of the model system were used to enable their separate investigation in the NMR spectra and quantification of the amount of molecules in each phase. Neutron scattering experiments show the coexistence of two lipid phases at low temperatures with repeat spacings of 54.2 Å and 43.0 Å at a physiological skin temperature of 32 °C. They appear to be indistinguishable in the 2H NMR spectra as both phases are crystalline and ceramide molecules do not rotate around their long axis on a microsecond timescale. The evolution of these phases upon heating is followed and with increasing temperature fluid and even isotropically mobile molecules are observed. A model of the organization of the lamellar phases is proposed in which the thicker phase consists of CER[NP]-C24 in a hairpin conformation mixed with CHOL and TA, while the phase with a repeat spacing of 43.0 Å contains CER[NP]-C24 in a V-shape conformation.

Potential Applications of Phyto-Derived Ceramides in Improving Epidermal Barrier Function.

The outer most layer of the skin, the stratum corneum, consists of corneocytes which are coated by a cornified envelope and embedded in a lipid matrix of ordered lamellar structure. It is responsible for the skin barrier function. Ceramides (CERs) are the backbone of the intercellular lipid membranes. Skin diseases such as atopic dermatitis and psoriasis and aged skin are characterized by dysfunctional skin barrier and dryness which are associated with reduced levels of CERs. Previously, the effectiveness of supplementation of synthetic and animal-based CERs in replenishing the depleted natural skin CERs and restoring the skin barrier function have been investigated. Recently, however, the barrier function improving effect of plant-derived CERs has attracted much attention. Phyto-derived CERs (phytoCERs) are preferable due to their assumed higher safety as they are mostly isolated from dietary sources. The beneficial effects of phytoCER-based oral dietary supplements for skin hydration and skin barrier reinforcement have been indicated in several studies involving animal models as well as human subjects. Ingestible dietary supplements containing phytoCERs are also widely available on the market. Nonetheless, little effort has been made to investigate the potential cosmetic applications of topically administered phytoCERs. Therefore, summarizing the foregoing investigations and identifying the gap in the scientific data on plant-derived CERs intended for skin-health benefits are of paramount importance. In this review, an attempt is made to synthesize the information available in the literature regarding the effects of phytoCER-based oral dietary supplements on skin hydration and barrier function with the underlying mechanisms.

Synthesis of specific deuterated derivatives of the long chained stratum corneum lipids [EOS] and [EOP] and characterization using neutron scattering.

The synthesis of specific deuterated derivatives of the long chained ceramides [EOS] and [EOP] is described. The structural differences with respect to the natural compounds are founded in the substitution of the 2 double bonds containing linoleic acid by a palmitic acid branched with a methyl group in 10-position. The specific deuteration is introduced both in the branched and in the terminal methyl group, which was realized by common methods of successive deuteration of carboxylic groups in 3 steps. These modified fatty acids resp. the corresponding ceramides [EOS] and [EOP] were prepared for neutron scattering investigations. First results of these investigations were presented in this manuscript showing that the deuterated compounds could be detected in the stratum corneum lipid model membranes. The deuterated ceramides [EOS] and [EOP] are valuable tools to investigate the influence of these long chained ceramide species on the nanostructure of stratum corneum lipid model membranes.

Preparation of a New Oligolamellar Stratum Corneum Lipid Model.

In this study, we present a preparation method for a new stratum corneum (SC) model system, which is closer to natural SC than the commonly used multilayer models. The complex setup of the native SC lipid matrix was mimicked by a ternary lipid mixture of ceramide [AP], cholesterol, and stearic acid. A spin coating procedure was applied to realize oligo-layered samples. The influence of lipid concentration, rotation speed, polyethylenimine, methanol content, cholesterol fraction, and annealing on the molecular arrangement of the new SC model was investigated by X-ray reflectivity measurements. The new oligo-SC model is closer to native SC in the total number of lipid membranes found between corneocytes. The reduction in thickness provides the opportunity to study the effects of drugs and/or hydrophilic penetration enhancers on the structure of SC in full detail by X-ray or neutron reflectivity. In addition, the oligo-lamellar systems allows one to infer not only the lamellar spacing, but also the total thickness of the oligo-SC model and changes thereof can be monitored. This improvement is most helpful for the understanding of transdermal drug administration on the nanoscale. The results are compared to the commonly used multilamellar lipid model systems and advantages and disadvantages of both models are discussed.

Drug Release from ß-Cyclodextrin Complexes and Drug Transfer into Model Membranes Studied by Affinity Capillary Electrophoresis.

PURPOSE: Is to characterize the drug release from the ß-cyclodextrin (ß-CD) cavity and the drug transfer into model membranes by affinity capillary electrophoresis. Phospholipid liposomes with and without cholesterol were used to mimic the natural biological membrane. METHODS: The interaction of cationic and anionic drugs with ß-CD and the interaction of the drugs with liposomes were detected separately by measuring the drug mobility in ß-CD containing buffer and liposome containing buffer; respectively. Moreover, the kinetics of drug release from ß-CD and its transfer into liposomes with or without cholesterol was studied by investigation of changes in the migration behaviours of the drugs in samples, contained drug, ß-CD and liposome, at 1:1:1 molar ratio at different time intervals; zero time, 30 min, 1, 2, 4, 6, 8, 10 and 24 h. Lipophilic drugs such as propranolol and ibuprofen were chosen for this study, because they form complexes with ß-CD. RESULTS: The mobility of the both drug liposome mixtures changed with time to a final state. For samples of liposomal membranes with cholesterol the final state was faster reached than without cholesterol. CONCLUSIONS: The study confirmed that the drug release from the CD cavity and its transfer into the model membrane was more enhanced by the competitive displacement of the drug from the ß-CD cavity by cholesterol, the membrane component. The ACE method here developed can be used to optimize the drug release from CD complexes and the drug transfer into model membranes.

Ex vivo Cutaneous Bioavailability of Topical Mometasone Furoate in an O/W Preparation.

Mometasone furoate (MMF) is a modern glucocorticoid of the 4th generation, which has been proven not only for inhalation but also for cutaneous treatment. Due to its lipophilic character, it is mainly used in ointments and creams with an outer lipophilic phase (W/O type). However, this study investigated the cutaneous cytotoxicology of MMF and tried to characterize its pharmacokinetic effects on the skin using an O/W preparation. An HPLC method has been developed and validated for the detection of MMF in cutaneous tissue, and concentration-time curves of MMF were created after cutaneous application on unaffected as well as lesional skin. Cytotoxicological characterization was carried out using scratch assays on keratinocytes and cutaneous fibroblasts. Results showed that the condition of the skin had no significant impact on the cutaneous bioavailability of MMF, but the intrinsic effect of the O/W vehicle could be utilized in periods of acute inflammation. Cytotoxicological data gave no new indications regarding the safety of MMF.

Controlled Penetration of a Novel Dimeric Ceramide into and across the Stratum Corneum Using Microemulsions and Various Types of Semisolid Formulations.

Ceramides (CERs) are integral parts of the intercellular lipid lamellae of the stratum corneum (SC), which is responsible for the barrier function of the skin. Many skin diseases such as atopic dermatitis and psoriasis are associated with the depletion or disturbance of the level of CERs in the SC. Administration of an exogenous novel dimeric ceramide (dCER) deep into the SC may help to stabilize the SC barrier substantially and to treat some skin disease conditions. Consequently, with the help of the existing technology, it might be possible to formulate various pharmaceutical dosage forms that can facilitate penetration of dCER into the SC. Therefore, the penetration of dCER was studied using a high-performance liquid chromatography/atmospheric-pressure ionization/mass spectrometry method for the detection and quantification of exogenous dCER in the SC as well as other skin layers. Penetration studies were carried out in the Franz diffusion cell using excised human skin ex vivo. Penetration of dCER was studied with 3 model formulations: a colloidal formulation (microemulsion), a cream formulation with ethoxydiglycol as penetration enhancer and a nanoformulation. The highest concentrations of dCER in the different skin layers were found after application of the cream with penetration enhancer. Surprisingly, the lowest concentrations of dCER in the different skin layers were found after application of the microemulsion.