Beeinflussung der Hautfunktion durch Externa

Influencing Skin Function by External Preparations The function of skin as a boundary as well as protecting layer between the body and surroundings and the regulatory processes in the skin for the maintenance of uniform milieu in body are discussed in short. The discussion on the action of external preparations covers the action of water, aqueous solutions, surfactants, powders and ointments, which is supported by experimental evidence. The mutual linkage between these effects and their evaluation, either positive or negative depending on constitution of the skin, are shown.     

Vitamin E: Absicherung bei der Anwendung in Externa

Safety of Vitamin E Used in Externa Several natural source vitamin E derivatives (free alpha tocopherol) and their acetate as well as d-mixed tocopherols (with a high content of d-gamma tocopherol) were compared in tests on their skin compatibility and sensibilization with test animals and humans according to the standard methods of toxicology and dermatology. In 2–20% concentrations and even with long-term or repeated application, all natural source derivatives proved to be very well skin-compatible. They did not cause any skin irritations or allergic reactions under the test conditions chosen. On the basis of extensive experimental works on the safety of vitamin E, the following application concentrations for natural source vitamin E derivatives are recommended: 2–5% for skin care products, 5–8% for sun-protective agents and 10–20% for dermatological products. Clinical tests showed that even on the skin of sensitive test persons, these concentrations did not cause any skin irritations. As far as skin compatibility with topical application is concerned, the biologically active phenol form did not differ from the chemically stabilized acetate. Free tocopherols should be used in preparations, which are intended to have an immediate antioxidant effect (e. g. sun-protective agents), whereas the acetate should be used for preparations aiming at a long-term effect such as the inhibition of premature ageing.     

Systematik bei der Entwicklung von Katalysatoren für Oxidationsreaktionen

Systematic approach to development of catalysts for oxidation reactions . The systematic catalyst development presented here for the example of a typical oxidation reaction shows that a systematic procedure is of value for a purposeful approach, and that statistically based planning and evaluation of experimental results represents an efficient tool. Physicochemical methods of study can provide important support for an understanding of catalytic action, with reaction-engineering studies in various kinds of reactors necessarily playing a central role in catalyst development. Technical and economic assessment of a catalyst under development is already feasible in laboratory experiments and ultimately decides for or against its technical applicability. Understandably, the scale-up of a production procedure developed in the laboratory to industrial quantities may also be beset with other problems which cannot be considered here.     

Wirkstofffreigabe aus Externa

Drug Release from Topicals Release rates of two topical corticosteroids and an antimicrobial substance were measured in a diffusion cell where the formulations and acceptor phases were separated by a thin porous polycarbonate film which, however, did not influence the kinetics of drug transport. Aqueous phosphate buffer (pH 6), n-octanol and isopropyl palmitate were selected as acceptor phases to represent both the hydrophilic and lipophilic substances found in the skin. Supported by microbiological agar diffusion tests it could be shown how drug release was influenced by drug solubility, its activity in solution and by its interactions with other components by e. g. adsorption, solubilization or inclusion in surfactant micelles. It is therefore suggested to determine the release rate from topicals independent of absorption into skin.     

Über die Eignung der Fluvographie als Meßmethode für die Hornschichtfeuchtigkeit nach Anwendung von Externa

Fluvography as a Suitable Method for Measurement of Epidermal Moisture after Application of Ointments A hydration of the horny layer and perhaps of the deeper layers of the epidermis was produced in 16 male volunteers by an increase of the relative humidity of air from 20 to 90% and in 10 male volunteers by an occlusive tape. The results indicate that the hydration of the horny layer and perhaps the deeper layers of the epidermis runs parallel with an increase of the heat transport coefficient Λ_G of the skin devoid of blood circulation. The results obtained from the present study indicate that the increase in the heat transport coefficient Λ_G with semiocclusive topical ointments which we found earlier is probably due to an increase of the water content of the horny layer and perhaps of deeper layers of the epidermis. It is concluded that fluvography is a useful method for determining the occlusive hydration effect of water free ointments.     

Welche Akzeptorphase ist am ehesten repräsentativ für die Hornschicht bei in vitro-Messungen der Wirkstoffabgabe aus Externa?

Which Acceptor Phase is Best Suited tor the Horny Layer for Tests of in vitro Drug Release of Topical Agents Applied to the Skin? Investigations were carried out to determine which of the three acceptor phases according to H Asche (phosphate buffer solution pH 6; isopropylpalmitate; n-octanol saturated with phosphate buffer solution pH 6) is best suited for tests of in vitro drug release of topical agents applied to the skin. In vitro determinations of salicylic acid release from the vehicles white petrolatum, aqueous wool fat ointment (w/o emulsion), and aqueous hydrophilic ointment (o/w emulsion) were compared with in vivo measurements of the size decreasing effect of salicylic acid on finger tip papillae using the same vehicles. The results demonstrate that the in vivo effect on the horny layer is best correlated with the drug release to the acceptor phase isopropylpalmitate.     

Modifizierung der integralen form der Mayo-Lewis-Gleichung zur berechnung der copolymerzusammensetzung bei der semikontinuierlichen polymerisation

Equations for the mathematical simulation of the semicontinuous copolymerization are proposed. With these equations it is possible to calculate the composition course of the monomer phase and of the just formed polymer, as well as the integral composition of the polymer as a function of conversion. The proposed relations form a system of differential equations, which are calculated numerically by stepwise integration. This calculation process is demonstrated using semicontinuous emulsion polymerization of the styrene/acrylonitrile system. The calculated relations show, that after a quasi-stationary phase has been reached, the polymerization ratio must be higher than the ratio of the monomer dosage.     

Neues aus der Chemie der Iminiumsalze

Recent Developments in Iminium Salt Chemistry Iminium salts are of continuing interest as versatile building blocks in organic synthesis. This progress report from different laboratories highlights some current research activities in iminium salt chemistry. Several contributions focus on novel synthetic applications of isolable, functionalized iminium systems such as α,β-unsaturated iminium salts (e.g. vinamidinium, 3-trifloxy, 3-chloro-, 3-isocyanato- and 3-thiopropene iminium, as well as propyne iminium salts), furthermore on phosgene iminium chloride and trifluoromethyl-substituted iminium salts. Iminium intermediates occur in various synthetic transformations; for example, cyclopropane iminium ions are intermediates in nucleophilic substitution reactions at bicyclic aminocyclopropanes. Also reported is the synthesis of a variety of novel orthoamides and their use as synthetic building blocks. Research directed to the application of vinamidinium salts in materials science is also presented.