Ivana Pantelic

Moisturizing emulsion systems based on the novel long-chain alkyl polyglucoside emulsifier

Mesomorphic behavior of the novel long-chain alkyl polyglucoside emulsifier comprising arachidyl alcohol (C20), behenyl alcohol (C22), and arachidyl glucoside was investigated in order to determine the prevalent stabilization mechanism and moisturizing capacity of emulsion systems based on it. For this to be accomplished thermoanalytical methods (differential scanning calorimetry and thermogravimetric analysis) coupled with microscopy, rheological, X-ray diffraction methods and a short-term in vivo study of skin hydration level were performed. Obtained results have proved that C20/C22 alkyl polyglucoside mixed emulsifier is able to provide the synergism between the two main types of lamellar phases, the liquid-crystalline (Lα), and the gel crystalline (Lβ) one, building the emulsion systems of different stability and performance. Formation of lamellar structures influenced for more than one half of water within the system to be entrapped. Conducted investigation of hydration potential in real-time conditions provided valuable information on the investigated emulsion vehicles’ moisturizing potential as well as their contribution to the skin barrier improvement. Therefore, it could be expected that emulsions based on this alkyl polyglucoside emulsifier could influence the delivery of active ingredients of both the lipophilic and hydrophilic type. The employment of thermoanalytical methods in our work suggests the possibility for thermal methods to be used more frequently in the characterization of both the novel raw materials and the belonging emulsion systems.

An Overview of Novel Surfactants for Formulation of Cosmetics with Certain Emphasis on Acidic Active Substances

Abstract Novel surfactants which are nowadays available for incorporation into various formulations of personal care and cosmetic products are numerous, implying a permanent need for their classification. This overview provides essential information relating to synthesis, basic physicochemical characteristics, application and other relevant data on surfactants currently used in cosmetic products. In the second part of the paper an outline of acidic active substances with significant application in cosmetic products is given, as well as the problems that arise during preparation/manufacture of the containing formulations, accompanied with the review of scientific publications and other available reliable data dealing with the incorporation of these actives in the cosmetic formulations stabilized with novel (mainly natural) surfactants.

Usnea barbata CO2-supercritical extract in alkyl polyglucoside-based emulsion system: contribution of Confocal Raman imaging to the formulation development of a natural product

Abstract Topical treatment of skin infections is often limited by drawbacks related to both antimicrobial agents and their vehicles. In addition, considering the growing promotion of natural therapeutic products, our objective was to develop and evaluate naturally-based emulsion system, as prospective topical formulation for skin infections-treatment. Therefore, alkyl polyglucoside surfactants were used for stabilization of a vehicle serving as potential carrier for supercritical CO2-extract of Usnea barbata, lichen with well-documented antimicrobial activity, incorporated using two protocols and three concentrations. Comprehensive physicochemical characterization suggested possible involvement of extract’s particles in stabilization of the investigated system. Raman spectral imaging served as the key method in disclosing extract’s particles potential to participate in the microstructure of the tested emulsion system via three mechanisms: (1) particle–particle aggregation, (2) adsorption at the oil–water interface and (3) hydrophobic particle–surfactant interactions. Stated extract–vehicle interaction proved to be correlated to the preparation procedure and extract concentration on one hand and to affect the physicochemical and biopharmaceutical features of investigated system, on the other hand. Thereafter, formulation with the best preliminary stability and liberation profile was selected for further efficiency and in vivo skin irritation potential evaluation, implying pertinent in vitro antimicrobial activity against G+ bacteria and overall satisfying preliminary safety profile.

Effect of small changes in natural origin-based emulsion systems on hydrocortisone skin absorption and performance: a comparison of two in vivo methods

Abstract Context: Alkyl polyglucoside surfactants (APG) remain prominent natural origin stabilizers offering a prospect of combining satisfactory stability with mild dermatological properties and complete biodegradability. Objective: With the purpose of adjusting the dose to a patient’s needs, dilution of commercial corticosteroid formulations is a practice which may modify efficacy uncontrolledly. The rational of the study was to investigate whether a simple change in ready-to-use bases (co-solvent addition) could address these needs in a more predictive manner. Methods: Hydrocortisone (HC) delivery from such emulsion systems was comparatively assessed employing two in vivo methods: the established human skin blanching assay versus skin stripping technique. Results: HC permeation data obtained after three dose durations showed better overall performance of the APG-stabilized bases relative to reference ones. Although the solubility study showed that all the assessed active samples retained equal thermodynamic activity, diverse HC permeation/penetration implies the importance of the applied base’s colloidal structure and/or changes endured. Isopropyl alcohol (IPA) addition offered faster drug penetration enhancement, while glycerol as a moisturizing agent influenced HC penetration through the increase in skin hydration. Conclusion: Although the performed in vivo methods cannot be considered alternative, skin stripping technique proved to be a cost-efficient mode of percutaneous penetration assessment, providing additional information on vehicle–skin interactions.

Development of a prospective isopropyl alcohol-loaded pharmaceutical base using simultaneous in vitro/in vivo characterization methods of skin performance.

Abstract Context: Approaching of pharmaceutical and cosmetic industries in some aspects inevitably influence formulation of topical pharmaceuticals, urging researchers to introduce novel excipients with proven benefits over traditional ones. In that context, alkyl polyglucosides (APG) emerge as prominent natural-origin emulsifiers with numerous favorable features (biodegradability, dermatological acceptability, desirable sensory properties). Objective: To evaluate APG-stabilized bases (alone and upon addition of isopropyl alcohol) and their impact on skin performance. A simultaneous in vitro/in vivo skin absorption study was conducted to evaluate whether the tape stripping technique could be recommended as an in vivo tool for skin penetration assessment during formulation optimization process. Materials and methods: After a comprehensive physicochemical characterization, biopharmaceutical properties of APG-bases versus reference ones were assessed through a combined in vitro (release/permeation) and in vivo approach. Results and discussion: Physicochemical characterization revealed substantial difference in structural ordering due to the formation of various mesomorphic phases. The enhancer-loaded APG base resulted in significantly higher drug levels at all depths into the stratum corneum, indicating that the selected enhancer along with specific colloidal structure has increased the extent of drug delivery. Conclusion: Results recommend the investigated emulsifier for stabilization of topical drug delivery systems, not only for their ability to sustain the addition of isopropyl alcohol which proved to be a valuable enhancer, but also satisfactory skin absorption and tolerability when compared to samples stabilized by conventional emulsifier. Tape stripping proved to be a useful and yet inexpensive tool for in vivo trials, able to discriminate subtle differences in dermal availability.

Alkyl Polyglucosides: An emerging class of sugar surfactants

Abstract: Natural origin, dermal tolerability and biodegradability are the fundamental criteria for novel surfactants. Sugar-based surfactants represent a growing market. Among these, Alkyl Polyglucosides (APGs), produced from vegetable oils and starch, are in demand. They are claimed to possess advantages over other classes of surfactants in terms of dermatological and ocular safety, biodegradability, wettability, foam production, and cleaning ability. Studies show that there is no environmental risk even where APGs are used in large quantities. Some APGs have been granted the status of pharmaceutical excipients. Nevertheless, it remains a challenge to persuade some formulators to replace low-cost conventional surfactants with these alternatives. This volume aims to provide a concise compendium of current knowledge on APGs.

Feasibility of a Natural Surfactant as a Stabilizer for Cosmetics with Liposome-Encapsulated Plant Stem Cells: Pre-Formulation and Formulation Through Stability Studies

Abstract During the formulation of liposome-containing products different problems can occur and the selection of a suitable carrier remains the greatest challenge. To estimate feasibility of a novel alkyl polyglucoside surfactant (hydroxystearyl alcohol and hydroxystearyl glucoside) as an emulsifier for cosmetics with liposome-encapsulated plant stem cells, we performed a two-phase study. In the first, the pre-formulation phase, the emulsifiers critical micelle concentration (CMC) and liposome-encapsulated active-emulsifier interactions were determined. The second phase was carried out to develop and characterize a cosmetic emulsion suitable to serve as a carrier for liposomes. The investigated emulsifier, with the obtained CMC value of 0.0085 wt.%, could be classified as liposome-friendly and can be used to develop stable and aesthetically acceptable cosmetics or even prospective pharmaceutical liposome-containing emulsions.

Behind the Alkyl Polyglucoside-based structures: Lamellar liquid crystalline and lamellar gel phases in different emulsion systems

Abstract: Surfactants play an important role in the development of colloidal delivery systems for cosmetics and pharmaceutical ingredients. Alkyl Polyglucosides (APGs) show peculiar physicochemical behaviour, which affects their interfacial properties. For example, the phase behaviour of APG/water systems is only slightly influenced by temperature. Hence, no temperature-dependent phase inversion occurs in APG-containing emulsions. They may form thermotropic liquid crystalline phases on heating, and lyotropic liquid crystalline phases on addition of a solvent. In lyotropic liquid crystals, increasing alkyl chain length leads to destabilization of the hexagonal phase in favour of the lamellar one, which is interesting for pharmaceutical systems. The addition of fatty alcohol to APG/water mixtures leads to the appearance of different lamellar phases. Characteristics of APG-mediated systems will be discussed in this chapter.

Natural Emulsifiers of the Alkyl Polyglucoside Type and Their Influence on the Permeation of Drugs

Due to the unceasing progress in design of novel emulsifiers, powerful influence of the ongoing ‘green’ trends in cosmetic industry, but also global environmental concerns, there is an increasing demand in development and application of natural-origin, biodegradable and skin-friendly emulsifiers. The present work aims to provide a deeper insight into the group of alkyl polyglucoside emulsifiers and their prospective impact on drug percutaneous permeation. Complexity of the observed lamellar liquid crystal and lamellar gel phases, which represent the basic mechanism of physical stabilisation by the alkyl polyglucosides, entails a comprehensive physicochemical evaluation of any alkyl polyglucoside-based prospective vehicle, prior to assessing its impact on skin absorption. Research conducted so far has suggested several possible mechanisms of alkyl polyglucoside-mediated percutaneous penetration enhancement, which are carefully elaborated throughout the chapter: (1) the observed similarity between the aforementioned complex structures which dominate alkyl polyglucoside-stabilised systems and the inherent stratum corneum lipid ordering could enhance penetration due to the optimal balance between their order and fluidity, (2) the observed complex colloidal structure may lead to diverse modes of water distribution within these systems, providing sustained skin hydration and hence improved skin permeability, and/or (3) the impact on a drug’s thermodynamic activity, easily tailored by the addition of various co-solvents/potential penetration enhancers.

Alkyl Polyglucoside-based delivery systems: In vitro/in vivo skin absorption assessment

Abstract: Skin permeation and penetration assessment is important not only for determining efficacy of a topical product, but also when comparing different formulations during development. This chapter reviews methods for dermal availability assessment of delivery systems, with their advantages and shortcomings, and examples of their practical application with Alkyl Polyglucoside-based preparations. Alkyl Polyglucosides are used in many different delivery systems with various model actives. Systems stabilized with Alkyl Polyglucoside surfactants provide highly satisfactory cutaneous delivery compared with reference samples. This is mainly attributed to the characteristic APG-based colloidal structure and its ability to provide a combined enhancing effect with co-solvents. Microemulsions for dermal/transdermal delivery are also becoming popular due to their high solubilization potential. Alkyl Polyglucoside surfactants are also being considered for development of nanosystems.