GD — Society for Dermopharmacy
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Issue 1 (2002) |
Dermopharmacy News
Workshop Conversation with Professor Dr. Rolf Daniels
Surfactant-free Emulsion Systems as Bases for innovative Dermatics and Cosmetics
New dermal preparations reaching dermatologists, pharmacists and consumers, have normally passed a long and cost-intensive development. DermoTopics retraced this way and discussed the subject with professor Dr. Rolf Daniels of the Institut für Pharmazeutische Technologie (Institute for Pharmaceutical Technology) of the Technical University Brunswick. Daniels heads here a scientific team that sets a focus on stability factors and specific properties of surfactant-free emulsion systems since the year 1995.
The examination of surfactant-free emulsion systems belongs to the research priorities of Professor Daniels in the field of Dermopharmacy. At the beginning predominantly polymer-stabilized emulsions were analyzed in his working group on which thorough knowledge is available in the meantime regarding their stability factors and specific properties. The findings gained from analyses allow basically a large degree of flexibility dealing with these systems. Daniels considers it useful to acquire comprehensive knowledge of a galenic system and to make extensive use of its possibilities and properties. That is why the Brunswick working group decided to focus their analyses in essential on a macromolecule.
Following the polymer-stabilized emulsions, an examination of solid-matter emulsions has been started about three years ago. These systems do not contain surfactants in a classical sense and are therefore interesting for example as bases for sun protection products. For a long time it has been known that by the interaction of UVA-rays and certain ingredients in cosmetics, mainly lipids and surfactants, the so-called Majorca-acne can be induced. When applying sun protection products, which do not contain such components and have at the same time a comparably high UVA protection, this typical skin reaction is not to be expected.
The micro pigments incorporated as solid matters in surfactant-free sun protection emulsions as well as possibly the UV filter besides their actual intended purpose contribute to the stabilization of the prescription. Micro pigments bind to the oil phase of the system and improve thus the spreadibility of the formulation on the skin at the same time. Due to the stabilizing effect of the micro pigments other inactive ingredients are in the majority of cases not required. This reduces in general the risk of skin incompatibilities.
Benefits of surfactant-free Formulations
According to Daniels, a general target, to be able to develop formulations with improved skin tolerability and at the same time more pleasant cosmetic properties is connected with the processing of surfactant-free formulations - this comprises both emulsion systems and colloidal nano-emulsions. By not making use of surfactants their interactions with skin do not take place. As relatively small boundary layer-active molecules, surfactants have a particular tendency towards interactions with intracellular lipids of the stratum corneum and are thus able to weaken the epidermal barrier function. Moreover, based on their penetration-enhancing properties they are able to intensively infiltrate prescription components with irritative or allergenic potential into skin. In contrast emulsifiers applied in surfactant-free systems do not have this property because they cannot penetrate skin due to their molecule size but they remain in form of a film on the skin surface.
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Professor Dr. Rolf Daniel (middle) takes the opinion that the end user as well should be informed about new dermopharmaceutic developments at an early stage. At a press conference in the framework of the 6th GD-Annual Meeting in Hamburg in March 2002 he presented the information brochure "Dry Skin" published by the GD to the public. |
An additional advantage of surfactant-free emulsion systems is that they are very well qualified as bases for spray products. Mainly sun protection and personal hygiene sprays are established in the market and are considered to be pleasant products due to their easy applicability. As surfactant-containing spray emulsions leave a sticky feel on skin, Daniels believes that for spray applications polymer-stabilized emulsions will prevail in future. A further attribution is made to these fine-structured systems that they can cause active substances to swifter penetrate than formulations with large oil drops.
Spray emulsions are not yet applied as dermatic bases on a large scale. According to Daniels, the main reason for this development is the demanding authorization procedure, which is to be adhered to for innovative medicinal agent forms, as well as increased standards concerning dosage accuracy. A major advantage of surfactant-free spray emulsions is that they can be autoclaved after production. This allows a sterile application on skin without the necessity of using a preservative.
No Research in the Ivory Tower
Research work of the Brunswick working group does not at all take place
in the ivory tower. Besides the knowledge transfer in science, increasingly
symposia and congresses are used as platforms for scientific exchange
and spreading of information. Daniels particularly esteems the interdisciplinary
cooperation in the Gesellschaft für Dermopharmazie. By his active
cooperation in the GD as head of the department Dermocosmetics and the
exchange with experts of other professions resulting from it he obtains
impulses for his own work on a permanent basis. Among the public relation
activities of his institute, there are also events for experts serving
the professional further education and a mutual exchange of ideas.
Daniels sees an important task of the universities in making science understandable
to laymen. He takes the opinion that it is important to keep the end consumer
informed about dermopharmaceutic developments. This is for instance very
successfully done by means of the public relations of the GD. Also by
publishing the information brochure "Dry Skin", the GD complies
with this task. The brochure gives tips to persons with dry skin concerning
skin cleansing and skin care in compliance with the scientific guidelines
of the GD.
Offers directed to the Industry
The Brunswick Institute considers itself as a kind of service enterprise for the cosmetic and pharmaceutic industry. By the application-oriented basic research of the institute, producers could design their product development in a target-oriented way on the basis of ensured galenic systems, Daniels explains. This is why the companies could save time-consuming and cost-intensive development processes to a large extent. In cooperation with the Arbeitsgemeinschaft für industrielle Forschungsförderung (AiF) (Working Pool for industrial Research Promotion), the Forschungsvereinigung der Arzneimittelhersteller (Research Association of Drug Producers) as well as the Forschungsverband der kosmetischen Industrie (Research Association of the Cosmetic Industry) the institute elaborates - state-sponsored - among other projects, methods and strategies for stability tests of dermal preparations.
The institute also offers support for specific formulations of questions in particular to small and middle-sized companies. Detailed experience is available for example concerning the stability assurance of prescriptions with vegetable extracts, which are in general difficult to process in a stable way. Moreover, penetration investigations of active substances on excised human skin belong to the spectrum offered by the Brunswick institute.