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Biomedical subjects

A Zesch

Publications and source records attributed to A Zesch.

At least 19 recordsLinked to original sources
PubMed1999

[Cosmetics: definition and legal aspects of the term].

Classification of cosmetics, which are more and more similar to topical therapeutic agents, is getting increasingly difficult for dermatologists. Their definition within the EU and the respective European directives, replacing national laws step by step, will be briefly presented. The problems of distinguishing cosmetics from medicinal products will be discussed in detail by examples from clinical practice. Finally, we will review the various active substances which tend to be added to cosmetics following the global trend in the cosmetic industry towards developing "medicinally" active cosmetics, and in the pharmaceutical industry towards "cosmetically" oriented medicinal products as part of a current "life-style" ideology. In some clinical dermatological fields these active substances may allow the dermatologists to use cosmetics as topical therapeutic agents.

Cosmetics↗
PubMed1991

Penetration, distribution and kinetics of 2,3,7,8-tetrachlorodibenzo-p-dioxin in human skin in vitro.

The in vitro penetration of 3H-labeled 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) into human cadaver skin was studied at concentrations of 65 and 6.5 ng TCDD per cm2 of skin surface. Vehicles used were acetone to simulate exposure to TCDD as a dry material, and mineral oil to simulate exposure to TCDD in an oily medium. Penetration was performed for 30, 100, 300, and 1000 min in improved Franz cells. Skin was used either intact, or with stripped horny layer. Skin was sectioned along its natural layers and radioactivity determined in epidermis and dermis. TCDD did not readily penetrate into human skin in vitro. The vehicle of exposure to TCDD played an important role in dermal penetration. The rapidly evaporating acetone allowed TCDD to penetrate deeply into the loose surface lamellae of the horny layer, but then appeared to be poorly available for further penetration. Mineral oil as the vehicle, on the other hand, represented a lipophilic compartment which competed with lipophilic constituents of the stratum corneum for TCDD and hence slowed its penetration even more. The stratum corneum acted as a protective barrier, as its removal increased the amount of TCDD absorbed into layers of the skin. Hourly rates of absorption of TCDD per unit area of skin were calculated in two ways: a worst case scenario where TCDD absorbed into any layer of skin including the stratum corneum was used for regression analysis; and a physiological approach where only that amount of TCDD was considered absorbed which had penetrated beyond the epidermis into the region of dermal vascularization.(ABSTRACT TRUNCATED AT 250 WORDS)

Epidermis↗
PubMed1990

[Local treatment with corticosteroids--limits on the duration of administration].

In local therapy with corticosteroids, undesirable effects are closely related to the duration of the treatment. These interactions are even more evident if the tolerance of different corticosteroids varying in strength of action is examined and referred to the duration of application. For example, symptoms of epidermal atrophy may occur even after as little as 4 weeks' treatment with very potent antiproliferative corticosteroids, whereas with the only moderately active hydrocortisone, which has an exclusively anti-inflammatory effect, these symptoms are hardly observed even after 10 weeks of application. The question of the origin of these undesirable effects is considered in post-marketing studies, for example, and in particular the question of when they are attributable, solely to the vehicle and when to the corticoid itself, is discussed. In addition, an attempt is made to classify the corticosteroids into those for which the permissible duration of treatment must be specified in the package insert and those for which this does not seem necessary. In this connection, the treatment periods required with fixed combinations are discussed with reference to the basic skin disease. Finally, the duration of treatment when application is limited to certain cutaneous areas or to a certain size of skin area or when the treatment is self-prescribed is discussed.

Administration, Topical↗
PubMed1990

[Topical therapy in pregnancy].

Any instance of drug administration during pregnancy can pose problems and will always take place after careful consideration and specific benefit risk evaluation. Even in the case of local therapy, which is rightly considered particularly safe, several active substances are applied whose embryotoxic potential is either relevant when given systemically in animals or humans, or unknown. With this in mind, several active substances designed for topical application are discussed that should not be applied at all during pregnancy or only within defined periods, even under various conditions of local therapy. The borderlines are unclear, and are indicated with particular reference to areas for which no reliable data are available.

Abnormalities, Drug-Induced↗
PubMed1989

[Aspects of tolerance to transdermal systems from the dermatologic viewpoint].

If active drugs are required to penetrate the skin in order to reach the systemic circulation the integrity of the skin has to be impaired. The nature of the horny layer which, as the uppermost barrier takes over the main part of the protective function of the skin against all locally applied substances, is shortly outlined. It is demonstrated that inactive ingredients of transdermal therapeutic systems should induce only the minimum irritation of the horny layer which is absolutely necessary for the action of the system. A good tolerance seems to be granted only if an occlusion at all events is of a short duration, and the sebum deficiency and the vulnerability of the aging skin as well as the xerosia and residual syndets in the horny layer after frequent washing, baths or showers are taken into account. Furthermore, the potential risk for skin sensitization is discussed as each patch application can primarily induce a sensitizing potential for the applied active or inactive ingredient, which possibly may cause a contact eczema on repeated therapy. However, only a wide application and unfortunately not the clinical trial will supply detailed information on this aspect of risk.

Administration, Cutaneous↗
PubMed1988

[Active ingredients, pharmaceutic aids and efficacy of topical drugs].

In local therapy, in contrast to all other forms of therapy, the galenic vehicle or various so-called inactive ingredients can influence the efficacy of the preparations to a great extent. This means that when such drugs are licensed, i.e. when their efficacy and safety are investigated, the therapeutic effects of the total compound under clinical conditions should form the basis for judgement, and not the pharmacological profile of the active substance alone. Taking these point into consideration, the value of application in phases, vehicle tolerance and the therapeutic properties of inactive ingredients, as compared with active ingredients, are assessed in relation to the range of indications of drugs. In this connection, the efficacy of generic products and the declaration of so-called inactive ingredients are discussed.

Dermatologic Agents↗
PubMed1986

[Topical therapy--risks and unwanted effects].

The kinetics of substances topically applied are different from those parenterally or orally applied. Chronic damage difficult to be recognized may be caused by long-term therapy, the high "reservoir effect" of an intact horny layer or the lack of barrier in a damaged horny layer, low substance concentration peaks, or lang diffusion periods in the circulation with very low plasma concentrations. Acute systemic damage is rare with percutaneously applied substances such as salicylic acid; it usually occurs under special conditions. Chronic damage to the skin is more often observed and usually judged by a dermatologist. These changes may not only be caused by active substances but also by excipients including apparently inert supplementary therapies such as the use of surfactants. Because of percutaneous absorption, the changes are either of systemic nature with no relationship to the skin or primarily affecting the skin.

Administration, Topical↗
PubMed1986

[Local and transcutaneous pharmacotherapy. Pharmacokinetic principles and clinical evaluation].

The pharmacological and pharmacokinetic postulates and preconditions for the various kinds of pharmaco-therapy (topical, systemic and transcutaneous) are presented. Taking into consideration mathematical and physical principles as well as anatomical and physiological factors, the possibilities for influencing the flow of drugs into and through the skin are described (choice of vehicle and concentrations, permeation enhancers). In the clinical part of the study, it is shown that following these guidelines can lead to new forms of therapy and to safer application of drugs and cosmetics.

Administration, Topical↗
PubMed1985

[Quantitative aspects of the percutaneous uptake of wool wax alcohols (cetyl alcohol) and paraffins (octadecane) from different ointment bases].

Since topical vehicles are partly responsible for the effects of active agents--both the wanted and the unwanted effects--attempt was made to obtain quantitative data on the possible penetration of cetyl alcohol contained in an aqueous hydrophilie cream (DAB 8) and in a wool fat alcohol ointment (lanoline) (DAB 8). Also the behaviour of the long-chained hydrocarbon, paraffin (octadecan), in these vehicles and in petrolatum (DAB 8) was studied. We found that the emulsifying agent in a W/O emulsion was detectable in the epidermis in low concentrations after 100 min, but the same agent in O/W emulsions only after 1000 min. It is, therefore, unlikely that cetyl alcohol penetrates the intact skin in allergicologically relevant concentrations. However, with diseased skin, a marked percutaneous absorption of cetyl alcohol, but not with paraffin, must be expected.

Alkanes↗
PubMed1984

Quantitative distribution of locally applied lindane in human skin and subcutaneous fat in vitro. Dependence of penetration on the applied concentration, skin state, duration of action and nature and time of washing.

Commercial concentrations of radiolabelled lindane emulsion were applied to human skin specimens. Penetration of the substance into the different layers of the skin was examined quantitatively under the common conditions of therapy, but with variation of the period of action (3, 10 and 24 h), condition of skin specimens (intact, stripped), concentration of the emulsion applied (0.3 and 1%) and washing with water only or water and soap after different periods of action (3 and 10 h) and examination at different times after the washing procedure (7 and 14 h). The flux of lindane in the skin was found to be time-dependent. Generally, the concentration increased with the depth of the layer. An increased availability of lindane (in absence of the stratum corneum, and at long application period) resulted in a preferential accumulation in the epidermis and not in the subcutaneous fat. When the intact skin had been washed with soap and water 3 h after application, the concentration of lindane found in the layer below the stratum corneum 7 h later was higher than the one found when the skin had not been washed. When intact skin had been washed after a short penetration period (3 h), this resulted in an introduction of lindane by the washing process. This effect did not occur with stripped skin. Lindane could be more efficiently removed from the stratum corneum with soap and water than with water alone. A threefold increase of the lindane concentration applied resulted in a threefold increase of the concentration in all layers of intact skin specimens. In stripped skin specimens, an increase could be observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗
PubMed1984

[Behavior of external adjuvants in human skin. In vitro penetration of various polyethylene glycols].

Polyethylene glycols (PEG), which serve as vehicles or additives in salves, sometimes appear to cause contact allergies, depending on their molecular weight. Whether this can be determined quantitatively should be proven. To this end we investigated the penetrative behavior of various PEG (mol. wts. 400 to 4000) on intact and damaged (stripped) human skin in vitro. It is shown here that in the course of time liquid PEG (mol. wt. 400) makes the intact horny layer more permeable than solid PEG does. The concentrations found in the intact epidermal horny layer were clearly dependent on molecular weight, indicating that liquid PEG penetrates better than solid high-molecular PEG. If the horny layer is damaged - as is the case with most dermatitis patients - all PEGs penetrate the dermis and epidermis independent of molecular weight. The allergological consequences, in particular for epicutaneous testing, are discussed briefly.

Adipose Tissue↗
PubMed1983

Skin irritation by topical drugs.

In order to develop topical drugs aside from galenic problems, there should be considerations how the skin could be made permeable. For the purpose of receiving an topical basis which favours penetration, ingredients known as auxiliary agents are used, which themselves have an effect on the horny layer and therefore impair the barrier function. The horny layer is irritated to a varying extent due to the chemical and physical properties of such substances. While the concentration of the active ingredients in the epidermis is improved, the irritation of the horny layer must be accepted. When using corticoids this fact may be misconstrued for lacking efficacy. Although auxiliary agents like polyethylene glycol, propylene glycol, o/w emulsifiers, alcohols or acetone show various effects on the horny layer, they all cause dehydration. Experimental data show that for propylene glycol this is clearly concentration related. Other only rarely used solvents like DMSO or dimethyl acetamide have properties directly altering the structure of the horny layer. Even topically applied ingredients only partially show the desired direct or indirect irritative effect on the horny layer. This is true for substances reacting directly with keratin as well as for substances which exhibit cytostatic or cytotoxic effects on the epidermis and for substances that lead to skin irritation. A risk/benefit evaluation is under discussion.

Administration, Topical↗
PubMed1982

[Acute, toxic, reversible hair loss through drain and sanitary cleansing vapors containing sodiumhypochloride and sodiumhydroxide].

Exposition to drain and sanitary cleansing vapors containing sodiumhypochloride and sodiumhydroxide provoked acute, reversible toxic alopecia. Trichograms of this depilatory type of alopecia showed that signs of hair dystrophy and loss of the hair sheath. Histological examination of skin and hair showed changes in hair structures and discrete lymphocytic infiltration. The prerequisite for this effect was the improper use of cleansing agents and the relative conditions during use which led to the intense exposition of the scalp to sodiumhypochloride vapor. A possible chemical reaction between cleansing agent and dirt may have been responsible, just as the condition of the scalp and hair e.g. increased transpiration, hydration may have led the way to hair loss. Acute hair loss occurred in the scalp and beard region following the use of cleansing agents; additional genital hair loss arose after sodiumhydroxide use. This condition persisted for 4 weeks. Body and scalp hair was completely restored after 1 year.

Alopecia↗
PubMed1982

Demonstration of the percutaneous resorption of a lipophilic pesticide and its possible storage in the human body.

The kinetics of lindane concentration in the serum and the time-dependent urinary excretion of two groups, one with healthy subjects and one with scabies-infested subjects, were comparatively analyzed by gas chromatography. Both groups showed similar cumulative excretion curves at completely different lindane concentrations in the serum. Comparison of serum concentration in healthy females (high lindane concentration in serum) and healthy males (low serum concentration) to the urinary excretion showed similar results. There appears to be a serum 'threshold concentration', above which it is possible that lindane is no longer primarily excreted by the kidney. Based on these results recommendations are presented, for the practical use of such data in the treatment of scabies.

Female↗