Progress in Topical and Transdermal Drug Delivery Research-Focus on Nanoformulations.

Skin is the largest organ and a multifunctional interface between the body and its environment. It acts as a barrier against cold, heat, injuries, infections, chemicals, radiations or other exogeneous factors, and it is also known as the mirror of the soul. The skin is involved in body temperature regulation by the storage of fat and water. It is an interesting tissue in regard to the local and transdermal application of active ingredients for prevention or treatment of pathological conditions. Topical and transdermal delivery is an emerging route of drug and cosmetic administration. It is beneficial for avoiding side effects and rapid metabolism. Many pharmaceutical, technological and cosmetic innovations have been described and patented recently in the field. In this review, the main features of skin morphology and physiology are presented and are being followed by the description of classical and novel nanoparticulate dermal and transdermal drug formulations. The biophysical aspects of the penetration of drugs and cosmetics into or across the dermal barrier and their investigation in diffusion chambers, skin-on-a-chip devices, high-throughput measuring systems or with advanced analytical techniques are also shown. The current knowledge about mathematical modeling of skin penetration and the future perspectives are briefly discussed in the end, all also involving nanoparticulated systems.

Freeze-dried nanocrystal dispersion of novel deuterated pyrazoloquinolinone ligand (DK-I-56-1): Process parameters and lyoprotectant selection through the stability study.

Recently, nanocrystal dispersions have been considered as a promising formulation strategy to improve the bioavailability of the deuterated pyrazoloquinolinone ligand DK-I-56-1 (7­methoxy-2-(4­methoxy-d3-phenyl)-2,5-dihydro-3H-pyrazolo[4,3-c]quinolin-3-one). In the current study, the freeze-drying process (formulation and process parameters) was investigated to improve the storage stability of the previously developed formulation. Different combinations of lyoprotectant (sucrose or trehalose) and bulking agent (mannitol) were varied while formulations were freeze-dried under two conditions (primary drying at -10 or -45 °C). The obtained lyophilizates were characterized in terms of particle size, solid state properties and morphology, while the interactions within the samples were analyzed by Fourier transform infrared spectroscopy. In the preliminary study, three formulations were selected based on the high redispersibility index values (around 95%). The temperature of primary drying had no significant effect on particle size, but stability during storage was impaired for samples dried at -10 °C. Samples dried at lower temperature were more homogeneous and remained stable for three months. It was found that the optimal ratio of sucrose or trehalose to mannitol was 3:2 at a total concentration of 10% to achieve the best stability (particle size < 1.0 µm, polydispersity index < 0.250). The amorphous state of lyoprotectants probably provided a high degree of interaction with nanocrystals, while the crystalline mannitol provided an elegant cake structure. Sucrose was superior to trehalose in maintaining particle size during freeze-drying, while trehalose was more effective in keeping particle size within limits during storage. In conclusion, results demonstrated that the appropriate combination of sucrose/trehalose and mannitol together with the appropriate selection of lyophilization process parameters could yield nanocrystals with satisfactory stability.

Nanoparticle-Based Adjuvants and Delivery Systems for Modern Vaccines.

Ever since the development of the first vaccine, vaccination has had the great impact on global health, leading to the decrease in the burden of numerous infectious diseases. However, there is a constant need to improve existing vaccines and develop new vaccination strategies and vaccine platforms that induce a broader immune response compared to traditional vaccines. Modern vaccines tend to rely on certain nanotechnology platforms but are still expected to be readily available and easy for large-scale manufacturing and to induce a durable immune response. In this review, we present an overview of the most promising nanoadjuvants and nanoparticulate delivery systems and discuss their benefits from tehchnological and immunological standpoints as well as their objective drawbacks and possible side effects. The presented nano alums, silica and clay nanoparticles, nanoemulsions, adenoviral-vectored systems, adeno-associated viral vectors, vesicular stomatitis viral vectors, lentiviral vectors, virus-like particles (including bacteriophage-based ones) and virosomes indicate that vaccine developers can now choose different adjuvants and/or delivery systems as per the requirement, specific to combatting different infectious diseases.

Parenteral Lipid-Based Nanoparticles for CNS Disorders: Integrating Various Facets of Preclinical Evaluation towards More Effective Clinical Translation.

Contemporary trends in combinatorial chemistry and the design of pharmaceuticals targeting brain disorders have favored the development of drug candidates with increased lipophilicity and poorer water solubility, with the expected improvement in delivery across the blood-brain barrier (BBB). The growing availability of innovative excipients/ligands allowing improved brain targeting and controlled drug release makes the lipid nanocarriers a reasonable choice to overcome the factors impeding drug delivery through the BBB. However, a wide variety of methods, study designs and experimental conditions utilized in the literature hinder their systematic comparison, and thus slows the advances in brain-targeting by lipid-based nanoparticles. This review provides an overview of the methods most commonly utilized during the preclinical testing of liposomes, nanoemulsions, solid lipid nanoparticles and nanostructured lipid carriers intended for the treatment of various CNS disorders via the parenteral route. In order to fully elucidate the structure, stability, safety profiles, biodistribution, metabolism, pharmacokinetics and immunological effects of such lipid-based nanoparticles, a transdisciplinary approach to preclinical characterization is mandatory, covering a comprehensive set of physical, chemical, in vitro and in vivo biological testing.

Efficient Development of Green Emulsifier/Emollient-Based Emulsion Vehicles: From RSM Optimal Experimental Design to Abridged In Vivo Assessment.

Since natural-origin, sustainable ingredients are preferred by modern consumers, novel emulsifiers and emollients keep entering the market. This study hypothesizes that a combination of in silico, instrumental tools and simplified sensory studies could be used to efficiently characterize emulsions in a shorter timeframe. A total of 22 rather simple o/w emulsions were prepared by a time/energy-saving emulsification process. A natural mixed emulsifier (Lauryl Glucoside/Myristyl Glucoside/Polyglyceryl-6 Laurate) and two emollients (both with INCI name C15-19 Alkane) were used. The performed D-optimal experimental design within the response surface method (RSM) significantly narrowed down the number of samples about to enter the stage of texture, friction and sensory studies to the samples comprising 30% of a respective Emogreen emollient and 2% or 3% of the emulsifier. The sample comprising 2% emulsifier/30% Emogreen® L15 showed significantly higher firmness (42.12 mN) when compared to the one with 2% emulsifier/30% Emogreen® L19 (33.62 mN), which was somewhat unexpected considering the emollients' inherent viscosity values (4.5 mPa·s for L15 and 9 mPa·s for L19). The sample with 2% emulsifier/30% Emogreen® L19 managed to maintain the lowest friction, while the one with 3% emulsifier/30% Emogreen® L19 released its full lubricating potential in the second part of the measurement (30-60 s). The obtained results revealed the strengths and weaknesses of each formulation, narrowing down their possible applications in the early development stage.

High amount of lecithin facilitates oral delivery of a poorly soluble pyrazoloquinolinone ligand formulated in lipid nanoparticles: Physicochemical, structural and pharmacokinetic performances.

Preclinical development of deuterated pyrazoloquinolinone ligands, promising drug candidates for various neuropsychiatric disorders, was hindered by unusually low solubility in water and oils. DK-I-60-3 (7-methoxy-d3-2-(4-methoxy-d3-phenyl)-2,5-dihydro-3Hpyrazolo[4,3-c]quinolin-3-one) is one of such pyrazoloquinolinones, and we recently reported about increased oral bioavailability of its nanocrystal formulation (NC). Lipid nanoparticles (LNP) with a high concentration of lecithin, which enhances loading capacity of the lipid matrix, may give rise to further improvement. After preformulation studies by differential scanning calorimetry and polarized light microscopy, LNP were prepared by the hot high pressure homogenization, and characterized in terms of particle size, morphology, and encapsulation efficacy. The layered structure visible on atomic force micrographs was confirmed by nuclear magnetic resonance. Obtained formulations were desirably stable, with small particle size (<100 nm), and high encapsulation efficacy (>99 %). Lecithin was partially fluid and most probably located in the outer shell of the particle, together with DK-I-60-3. While the hydrophobic part of polysorbate 80 was completely immobilized, its hydrophilic part was free in the aqueous phase. In oral neuropharmacokinetic study in rats, an around 1.5-fold increase of area under the curve with LNP compared to NC was noticed both in brain and plasma. In bioavailability study, F value of LNP (34.7 ± 12.4 %) was 1.4-fold higher than of NC (24.5 ± 7.8 %); however, this difference did not reach statistical significance. Therefore, employment of LNP platform in preclinical formulation of DK-I-60-3 imparted an incremental improvement of its physicochemical as well as pharmacokinetic behavior.

Encapsulation of cannabidiol in oil-in-water nanoemulsions and nanoemulsion-filled hydrogels: A structure and biological assessment study.

HYPOTHESIS: Lipophilic cannabidiol can be solubilized in oil-in water nanoemulsions, which can then be impregnated into chitosan hydrogels forming another colloidal system that will facilitate cannabidiol's release. The delivery from both systems was compared, alongside structural and biological studies, to clarify the effect of the two carriers' structure on the release and toxicity of the systems. EXPERIMENTS: Oil-in-water nanoemulsions (NEs) and the respective nanoemulsion-filled chitosan hydrogels (NE/HGs) were formulated as carriers of cannabidiol (CBD). Size, polydispersity and stability of the NEs were evaluated and then membrane dynamics, shape and structure of both systems were investigated with EPR spin probing, SAXS and microscopy. Biocompatibility of the colloidal delivery systems was evaluated through cytotoxicity tests over normal human skin fibroblasts. An ex vivo permeation protocol using porcine ear skin was implemented to assess the release of CBD and its penetration through the skin. FINDINGS: Incorporation of the NEs in chitosan hydrogels does not significantly affect their structural properties as evidenced through SAXS, EPR and confocal microscopy. These findings indicate the successful development of a novel nanocarrier that preserves the NE structure with the CBD remaining encapsulated in the oil core while providing new rheological properties advantageous over NEs. Moreover, NE/HGs proved to be more efficient as a carrier for the release of CBD. Cell viability assessment revealed high biocompatibility of the proposed colloids.

Red Raspberry Seed Oil Low Energy Nanoemulsions: Influence of Surfactants, Antioxidants, and Temperature on Oxidative Stability.

The aim of this study was to assess and improve the oxidative stability of red raspberry seed oil−RO, a potential topical ingredient derived from food industry by-products, on its own and when incorporated in low energy nanoemulsion (NE). The RO's oxidative stability was assessed at 5, 25, and 40 °C during one month of storage and expressed in: peroxide value, p-anisidine, and thiobarbituric reactive substances­TBARS value, while for NEs, lipid hydroperoxides and TBARS values were monitored. Both synthetic (butylated hydroxytoluene­BHT and ethylenediaminetetraacetic acid­EDTA), and natural (oregano essential oil­ORE and oak fruit extract­OAK) antioxidants were used. Pure RO and RO with BHT or ORE were stable at 5 °C and 25 °C, but at 40 °C BHT showed only moderate protection, while ORE was prooxidant. NEs prepared with new biodegradable polyglycerol esters-based surfactants, with droplet sizes of < 50 nm and narrow size distribution, showed improved physicochemical stability at room temperature, and especially at 40 °C, compared to NEs with polysorbate 80, which required the addition of antioxidants to preserve their stability. Natural antioxidants ORE and OAK were compatible with all NEs; therefore, their use is proposed as an effective alternative to synthetic antioxidants.

Behavioural interaction of pyrazoloquinolinone positive allosteric modulators at α6GABAA receptors and diazepam in rats: Anti-diazepam-induced ataxia action as a structure-dependent feature.

Several pyrazoloquinolinone (PQ) ligands were recently discovered as functionally selective positive modulators at the PQ site of α6-containing GABAA receptors. PQs are also neutral modulators at the benzodiazepine site. We assessed the influence of PQ compounds from three structural groups (PZ-II-029 and related deuterated analogues DK-I-56-1, RV-I-029, DK-I-60-3 and DK-I-86-1; LAU 463 and related analogues DK-I-58-1 and DK-II-58-1; and DK-I-87-1), alone and in combination with diazepam, on the behaviour of male Sprague-Dawley rats. An excellent behavioural safety profile of all tested PQs was demonstrated in the spontaneous locomotor activity, rotarod, loss of righting reflex and pentylenetetrazol tests. In interaction studies, only PZ-II-029 and its analogues prevented the ataxic effects of the benzodiazepine, as assessed in the rotarod test and during monitoring of rat locomotor activity after awakening from the loss of righting reflex. Published electrophysiological profiles of PQ ligands imply that positive modulation elicited at α6-GABAA receptors that contain the γ2 and δ subunit, rather than their neutral modulatory action at the benzodiazepine site, may prevent the ataxic action of diazepam. Thus, PZ-II-029 and its deuterated analogues are not prone to untoward interactions with benzodiazepines and may indeed completely abolish their ataxic action, seen at therapeutic, and especially toxic concentrations.

ex vivo-in vivo comparison of drug penetration analysis by confocal Raman microspectroscopy and tape stripping.

When it comes to skin penetration analysis of a topically applied formulation, the number of suitable methods is limited, and they often lack in spatial resolution. In vivo studies are pivotal, especially in the approval of a new product, but high costs and ethical difficulties are limiting factors. For that reason, good ex vivo models for testing skin penetration are crucial. In this study, caffeine was used as a hydrophilic model drug, applied as a 2% (w/w) hydrogel, to compare different techniques for skin penetration analysis. Confocal Raman microspectroscopy (CRM) and tape stripping with subsequent HPLC analysis were used to quantify caffeine. Experiments were performed ex vivo and in vivo. Furthermore, the effect of 5% (w/w) 1,2-pentanediol on caffeine skin penetration was tested, to compare those methods regarding their effectiveness in detecting differences between both formulations.

Topically applied lipid-containing emulsions based on PEGylated emulsifiers: Formulation, characterization, and evaluation of their impact on skin properties ex vivo and in vivo.

PEGylated emulsifiers have been largely used in topical formulations for skin research. They have been a continuous study focus in our group as well. According to our previous studies, severe interruptions of the skin barrier were observed with certain types of emulsifiers. To restore the skin barrier function and counteract the effects of emulsifiers, we considered topically delivering lipids into the lipid matrix of the SC. Herein, PEG-20 cetyl ether (C20) -based oil-in-water (O/W) emulsions were developed owing to the stronger interactions of C20 with skin. The lipids containing ceramides (Cers), palmitic acids (PA), and cholesterol with different ratios and combinations were merged into the base emulsion. PEG-40 stearyl ether (S40)-based emulsion was used as a reference as S40 showed negligible impact on SC lipids. The evaluations were conducted ex vivo with confocal Raman spectroscopy (CRS) regarding the SC lipid, SC thickness, and skin penetration properties. In parallel, the in vivo irritation studies were also implemented including the transepidermal-water-loss (TEWL), skin hydration, and erythema index. The results indicated less SC lipid extraction of topically delivered lipids on ex vivo porcine skin with the addition and ratio of incorporated Cers influencing the extent of formulations counteracting the skin interruption by C20. The ex vivo penetration study showed a similar trend in drug penetration depths. In regards to the in vivo studies, TEWL was demonstrated to be suitable for differentiating the impact on skin barrier properties. The in vivo observations were generally correlated with the ex vivo results. The exact findings in this research can lead us to a better selection of applied lipid components and compositions. Future research will elucidate which type of Cer was predominantly extracted by C20, advancing future formulation development.

The Impact of the Oil Phase Selection on Physicochemical Properties, Long-Term Stability, In Vitro Performance and Injectability of Curcumin-Loaded PEGylated Nanoemulsions.

A nanotechnology-based approach to drug delivery presents one of the biggest trends in biomedical science that can provide increased active concentration, bioavailability, and safety compared to conventional drug-delivery systems. Nanoemulsions stand out amongst other nanocarriers for being biodegradable, biocompatible, and relatively easy to manufacture. For improved drug-delivery properties, longer circulation for the nanoemulsion droplets should be provided, to allow the active to reach the target site. One of the strategies used for this purpose is PEGylation. The aim of this research was assessing the impact of the oil phase selection, soybean or fish oil mixtures with medium chain triglycerides, on the physicochemical characteristics and injectability of curcumin-loaded PEGylated nanoemulsions. Electron paramagnetic resonance spectroscopy demonstrated the structural impact of the oil phase on the stabilizing layer of nanoemulsions, with a more pronounced stabilizing effect of curcumin observed in the fish oil nanoemulsion compared to the soybean oil one. The design of the experiment study, employed to simultaneously assess the impact of the oil phase, different PEGylated phospholipids and their concentrations, as well as the presence of curcumin, showed that not only the investigated factors alone, but also their interactions, had a significant influence on the critical quality attributes of the PEGylated nanoemulsions. Detailed physicochemical characterization of the NEs found all formulations were appropriate for parenteral administration and remained stable during two years of storage, with the preserved antioxidant activity demonstrated by DPPH and FRAP assays. In vitro release studies showed a more pronounced release of curcumin from the fish oil NEs compared to that from the soybean oil ones. The innovative in vitro injectability assessment, designed to mimic intravenous application, proved that all formulations tested in selected experimental setting could be employed in prospective in vivo studies. Overall, the current study shows the importance of oil phase selection when formulating PEGylated nanoemulsions.

Coupling AFM, DSC and FT-IR towards Elucidation of Film-Forming Systems Transformation to Dermal Films: A Betamethasone Dipropionate Case Study.

Polymeric film-forming systems have emerged as an esthetically acceptable option for targeted, less frequent and controlled dermal drug delivery. However, their dynamic nature (rapid evaporation of solvents leading to the formation of thin films) presents a true characterization challenge. In this study, we tested a tiered characterization approach, leading to more efficient definition of the quality target product profiles of film-forming systems. After assessing a number of physico-chemico-mechanical properties, thermal, spectroscopic and microscopic techniques were introduced. Final confirmation of betamethasone dipropionate-loaded FFS biopharmaceutical properties was sought via an in vitro skin permeation study. A number of applied characterization methods showed complementarity. The sample based on a combination of hydrophobic Eudragit® RS PO and hydroxypropyl cellulose showed higher viscosity (47.17 ± 3.06 mPa·s) and film thickness, resulting in sustained skin permeation (permeation rate of 0.348 ± 0.157 ng/cm2 h), and even the pH of the sample with Eudragit® NE 30D, along with higher surface roughness and thermal analysis, implied its immediate delivery through the epidermal membrane. Therefore, this study revealed the utility of several methods able to refine the number of needed tests within the final product profile.

Chemical vs. Physical Methods to Improve Dermal Drug Delivery: A Case Study with Nanoemulsions and Iontophoresis.

So far, various approaches have been proposed to improve dermal drug delivery. The use of chemical penetration enhancers has a long history of application, while methods based on the electrical current (such as iontophoresis) stand out as promising "active" techniques. Aiming to evaluate the contribution of different approaches to dermal delivery, in this work curcumin-loaded nanoemulsions with and without monoterpenes (eucalyptol or pinene) as chemical penetration enhancers, and a custom-made adhesive dermal delivery system based on iontophoresis were designed and assessed. In an in vivo study applying skin bioengineering techniques, their safety profile was proven. Three examined iontophoresis protocols, with total skin exposure time of 15 min (continuous flow for 15 min (15-0); 3 min of continuous flow and 2 min pause (3-2; 5 cycles) and 5 min of continuous flow and 1 min pause (5-1; 3 cycles) were equally efficient in terms of the total amount of curcumin that penetrated through the superficial skin layers (in vivo tape stripping) (Q3-2 = 7.04 ± 3.21 µg/cm2; Q5-1 = 6.66 ± 2.11 µg/cm2; Q15-0 = 6.96 ± 3.21 µg/cm2), significantly more efficient compared to the referent nanoemulsion and monoterpene-containing nanoemulsions. Further improvement of an efficient mobile adhesive system for iontophoresis would be a practical contribution in the field of dermal drug application.

Simultaneous Physico-Mechanical and In Vivo Assessment towards Factual Skin Performance Profile of Topical Polymeric Film-Forming Systems.

Topical film-forming systems (FFS) change drastically after solvent displacement, therefore indicating their skin metamorphosis/transformation as a property of special regulatory and research interest. This paper deals with the lack of suitable characterization techniques, suggesting a set of methods able to provide a comprehensive notion of FFS skin performance. After screening the physico-chemical, mechanical and sensory properties of FFS and resulting films, an elaborate three-phase in vivo study was performed, covering skin irritation, friction and substantivity. Upon removal of 24-hour occlusion, no significant change in erythema index was observed, while the film-former type (cellulose ether, acrylate and/or vinyl polymer) affected transepidermal water loss (TEWL); hydrophobic methacrylate copolymer-based samples decreased TEWL by 40-50%, suggesting a semi-occlusive effect. Although both the tribological parameters related to the friction coefficient and the friction curve's plateau provided valuable data, their analysis indicated the importance of the moment the plateau is reached as the onset of the secondary formulation, while the tertiary state is still best described by the completion of the film's drying time. The final part of the in vivo study proved the high in-use substantivity of all samples but confirmed the optimal 4:1 ratio of hydrophobic cationic and hydrophilic polymers, as indicated during early physico-mechanical screening.

Overcoming the Low Oral Bioavailability of Deuterated Pyrazoloquinolinone Ligand DK-I-60-3 by Nanonization: A Knowledge-Based Approach.

Poor water solubility of new chemical entities is considered as one of the main obstacles in drug development, as it usually leads to low bioavailability after administration. To overcome these problems, the selection of the appropriate formulation technology needs to be based on the physicochemical properties of the drug and introduced in the early stages of drug research. One example of the new potential drug substance with poor solubility is DK-I-60-3, deuterated pyrazoloquinolinone, designed for the treatment of various neuropsychiatric disorders. In this research, based on preformulation studies, nanocrystal technology was chosen to improve the oral bioavailability of DK-I-60-3. Nanocrystal dispersions stabilized by sodium lauryl sulfate and polyvinylpyrrolidone were prepared by modified wet media milling technique, with the selection of appropriate process and formulation parameters. The nanoparticles characterization included particle size and zeta potential measurements, differential scanning calorimetry, X-ray powder diffraction, dissolution and solubility study, and in vivo pharmacokinetic experiments. Developed formulations had small uniform particle sizes and were stable for three months. Nanonization caused decreased crystallite size and induced crystal defects formation, as well as a DK-I-60-3 solubility increase. Furthermore, after oral administration of the developed formulations in rats, two to three-fold bioavailability enhancement was observed in plasma and investigated organs, including the brain.

Curcumin Loaded PEGylated Nanoemulsions Designed for Maintained Antioxidant Effects and Improved Bioavailability: A Pilot Study on Rats.

The current study describes the experimental design guided development of PEGylated nanoemulsions as parenteral delivery systems for curcumin, a powerful antioxidant, as well as the evaluation of their physicochemical characteristics and antioxidant activity during the two years of storage. Experimental design setup helped development of nanoemulsion templates with critical quality attributes in line with parenteral application route. Curcumin-loaded nanoemulsions showed mean droplet size about 105 nm, polydispersity index <0.15, zeta potential of -40 mV, and acceptable osmolality of about 550 mOsm/kg. After two years of storage at room temperature, all formulations remained stable. Moreover, antioxidant activity remained intact, as demonstrated by DPPH (IC50 values 0.078-0.075 mg/mL after two years) and FRAPS assays. In vitro release testing proved that PEGylated phospholipids slowed down the curcumin release from nanoemulsions. The nanoemulsion carrier has been proven safe by the MTT test conducted with MRC-5 cell line, and effective on LS cell line. Results from the pharmacokinetic pilot study implied the PEGylated nanoemulsions improved plasma residence of curcumin 20 min after intravenous administration, compared to the non-PEGylated nanoemulsion (two-fold higher) or curcumin solution (three-fold higher). Overall, conclusion suggests that developed PEGylated nanoemulsions present an acceptable delivery system for parenteral administration of curcumin, being effective in preserving its stability and antioxidant capacity at the level highly comparable to the initial findings.

'All-natural' anti-wrinkle emulsion serum with Acmella oleracea extract: A design of experiments (DoE) formulation approach, rheology and in vivo skin performance/efficacy evaluation.

OBJECTIVE: The growing consumers' preferences and concerns regarding healthy ageing, youthful skin appearance, environmental protection and sustainability have triggered an ever-increasing trend towards natural, eco-friendly and ethically sourced anti-ageing products. Accordingly, this paper describes design and evaluation of novel, safe, effective and high-quality emulsion serums, completely based on ingredients of natural origin, intended for improving facial fine lines and wrinkles. METHODS: Model formulations, stabilized by an innovative glycolipid mixed emulsifier (lauryl glucoside/myristyl glucoside/polyglyceryl-6 laurate) and containing Acmella oleracea extract as a model anti-ageing active, were prepared by cold process and fully assessed regarding their rheological behaviour (continuous rotational and oscillatory tests) and physical stability (dynamic-mechanical thermoanalysis - DMTA test). To study and optimize the simultaneous influence of varied formulation factors (emollients and emulsifier concentrations) on critical rheological attributes of the developed serums, a central composite design within 'design of experiments' approach was employed. The general skin performance - preliminary safety and anti-wrinkle efficacy of selected model serum, was evaluated in human volunteers, by employing several objective, non-invasive bioengineering techniques. RESULTS: Rheological characterization revealed favourable shear-thinning flow behaviour with yield point, and dominating elastic character (storage modulus G' > loss modulus G") in both amplitude and frequency sweeps, which together with relatively small structural change obtained in DMTA test indicated overall satisfying rheological and stability properties of formulated serums. From the established design space, and taking into account formulation cost and carbon footprint, promising model serum (desired/optimal apparent viscosity, yield point and loss factor, rather small and constant structural change), containing 15% of emollients and 1% of emulsifier, was chosen for in vivo evaluations. Screening of skin irritation effects revealed the absence of potential irritancy of investigated serum, suggesting overall satisfying skin tolerability/preliminary safety. Silicone skin replica image analysis demonstrated noticeable reduction/improvement in all measured skin wrinkle parameters after only 2 weeks of test serum application in periorbital and perioral areas, indicating its rapid and beneficial effects on the facial expression lines and wrinkles. CONCLUSION: Altogether, the results corroborate the promising potential of the developed Acmella oleracea extract-loaded emulsion serum as safe, effective and non-invasive natural anti-wrinkle product.

OBJECTIF: Les préférences et les préoccupations croissantes des consommateurs concernant le vieillissement sain, l'apparence jeune de la peau, la protection de l'environnement et la durabilité ont déclenché une tendance toujours croissante vers des produits anti-âge naturels, respectueux de l'environnement et éthiques. En conséquence, ce document décrit le plan et l'évaluation de nouveaux sérums d'émulsion sûrs, efficaces et de haute qualité, entièrement basés sur des ingrédients d'origine naturelle, destinés à améliorer les ridules et rides du visage. MÉTHODES: Des formulations modèles stabilisées par un émulsifiant mixte glycolipide innovant (lauryl glucoside/myristyl glucoside/polyglycéryl-6 laurate) et contenant de l'extrait d'Acmella oleracea comme anti-vieillissement actif de modèle, ont été préparées par un procédé à froid et ont été pleinement évaluées en ce qui concerne leur comportement rhéologique (tests de rotation continue et examens oscillatoires) et stabilité physique (analyse thermomécanique dynamique - DMTA). Pour étudier et optimiser l'influence simultanée de facteurs de formulation variés (concentrations d'émollients et d'émulsifiants) sur les attributs rhéologiques critiques des sérums développés, une conception composite centrale dans le cadre d'une approche « conception d'expériences ¼ a été employée. Les performances cutanées générales - sécurité préliminaire et efficacité antirides du sérum du modèle sélectionné ont été évaluées chez des sujets humains volontaires, en utilisant plusieurs techniques de bio-ingénierie objectives et non invasives. RÉSULTATS: La caractérisation rhéologique a révélé un comportement favorable du débit de cisaillement avec une limite de rendement et une domination du caractère élastique (modulus de stockage G' > module de perte G) dans les balayages d'amplitude et de fréquence, qui, avec un changement structurel relativement faible obtenu dans l'analyse DMTA, a indiqué des propriétés rhéologiques et de stabilité satisfaisante globales des sérums. A partir de l'espace de conception établi, et en tenant compte du coût de composition et de l'empreinte carbone, un sérum modèle prometteur (viscosité apparente souhaitée/optimale, seuil de rendement et facteur de perte, changement structurel assez faible et constant), contenant 15 % d'émollients et 1 % d'émulsifiant, a été choisi pour les évaluations in vivo. Le dépistage des effets d'irritation cutanée a révélé l'absence d'irritation potentielle du sérum expérimental, suggérant une tolérance cutanée/une sécurité préliminaire globalement satisfaisante. L'analyse de l'image de la réplique cutanée en silicone a démontré une réduction/amélioration notable de tous les paramètres de rides cutanées mesurés après seulement deux semaines d'application du sérum test dans les zones périorbitaires et péribuccales, indiquant ses effets rapides et bénéfiques sur les lignes d'expression et les rides du visage. CONCLUSION: Au total, les résultats corroborent le potentiel prometteur du sérum d'émulsion à base d'extrait d'Acmella oleracea développé comme un produit anti-rides naturel sûr, efficace et non invasif.

The Implications of Regulatory Framework for Topical Semisolid Drug Products: From Critical Quality and Performance Attributes towards Establishing Bioequivalence.

Due to complex interdependent relationships affecting their microstructure, topical semisolid drug formulations face unique obstacles to the development of generics compared to other drug products. Traditionally, establishing bioequivalence is based on comparative clinical trials, which are expensive and often associated with high degrees of variability and low sensitivity in detecting formulation differences. To address this issue, leading regulatory agencies have aimed to advance guidelines relevant to topical generics, ultimately accepting different non-clinical, in vitro/in vivo surrogate methods for topical bioequivalence assessment. Unfortunately, according to both industry and academia stakeholders, these efforts are far from flawless, and often upsurge the potential for result variability and a number of other failure modes. This paper offers a comprehensive review of the literature focused on amending regulatory positions concerning the demonstration of (i) extended pharmaceutical equivalence and (ii) equivalence with respect to the efficacy of topical semisolids. The proposed corrective measures are disclosed and critically discussed, as they span from mere demands to widen the acceptance range (e.g., from ±10% to ±20%/±25% for rheology and in vitro release parameters highly prone to batch-to-batch variability) or reassess the optimal number of samples required to reach the desired statistical power, but also rely on specific data modeling or novel statistical approaches.

Comparative efficacy evaluation of different penetration enhancement strategies for dermal delivery of poorly soluble drugs - A case with sertaconazole nitrate.

The aim of this study was to compare the efficacy of different approaches for enhancement of dermal availability of the highly lipophilic antifungal model drug - sertaconazole nitrate (SN). For this purpose, a physical penetration enhancer - dissolving microneedles (MNs) was fabricated by filling moulds with liquid formulation based on polyvinylpyrrolidone and loaded with SN. Dissolving MNs were characterised regarding their morphological and mechanical characteristics. A penetration enhancement efficacy of MNs was evaluated in vitro using porcine ear skin in parallel with the efficacy of formerly developed chemical penetration enhancer - biocompatible microemulsion (ME) formulation. Moreover, an ability of solid silicon MNs to significantly improve delivery of SN from ME into the skin has also been investigated. The obtained results showed that dissolving MNs had satisfying morphological properties and mechanical strength. This type of MNs provided comparable drug deposition in the skin as ME formulation, but also revealed an indication of percutaneous absorption of a portion of the administered drug dose. However, the penetration/permeation study results were largely influenced by experimental setup and dosing regimen. Although solid silicon MNs assisted SN dermal delivery led to increase of drug cutaneous retention (1.9-fold) under infinite dosing regimen, the synergistic action of solid MNs and ME applied under finite dosing was more pronounced in comparison with the application either of physical (dissolving MNs) or chemical enhancer (ME) alone. Namely, SN amount accumulated into the skin increased up to 4.67 and 4.37 folds in comparison with ME and dissolving MNs alone, respectively, while reaching a significant decrease in drug permeation through the skin compared to the use of dissolving MNs. Application of ME per se was the only approach that provided selective in vitro dermal drug delivery without SN permeation across the skin. However, despite both types of the used MNs lead to SN permeation in vitro, the ratio between the drug amount deposited in the skin and SN content permeated was significantly higher for the combined approach (12.05) than for dissolving MNs (2.10). Therefore, a combination of solid silicon MNs and biocompatible ME favoured more pronouncedly SN skin accumulation, which is preferable in the treatment of skin fungal infections.