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Introduction: Coenzyme Q10 (CoQ10) has been widely used in topical and cosmeceutical products due to its cutaneous antioxidant and energizer effects. CoQ10 is found in a higher concentration in the epidermis compared to dermis. The epidermal level of CoQ10 can be reduced due to several factors such as skin UV irradiation and photoaging. Various dermal nano-formulations have been investigated to overcome the skin barrier and enhance the poor penetration of CoQ10. The nanocarriers are designed to target and concentrate the CoQ10 in the viable epidermis. Most of these studies, however, failed to show the depth and extent of penetration of CoQ10 from the various carrier systems., Objective: The distribution of CoQ10 across the various skin layers has to be shown using skin slices representing the different skin layers., Methods: To realize this objective, a sensitive and selective HPLC method was developed and validated for the quantification of CoQ10 in the different skin slices. The method applicability to skin penetration (using excised human skin) as well as stability studies was investigated using CoQ10-loaded lecithin-based microemulsion (ME) and hydrophilic cream formulations., Results: It could be shown that the highest concentration of CoQ10 in the viable epidermis, the target skin layer for CoQ10, was observed after application of the CoQ10 in the hydrophilic cream. This cream contains 10% of 2-ethylhexyl laurate which works obviously as a penetration enhancer for CoQ10. In contrast, the penetration of CoQ10 was lower from the ME. Just in the deeper dermis, a certain amount of CoQ10 could be detected., Conclusions: The HPLC method quantified the trace quantities of the CoQ10 distributed across the various skin layers and, hence, can be used to investigate the skin penetration of CoQ10 from various dermal standard and nano-formulations., (© 2020 The Author(s) Published by S. Karger AG, Basel.)

Patients with self-inflicted skin disorders form a rather heterogeneous group. Our paper is intended to provide the practitioner with some orientation concerning interaction and therapeutic procedure in patients with artefactual skin diseases. Basically, these patients should be differentiated according to what extent they are aware of their manipulations. This degree of awareness should then be the guideline for a well-dosed and sensitive confrontation with their manipulative behavior. In any case, a positive result of the confrontation largely depends on the confidential relationship between physician and patient.

The pathomorphological and pathophysiological reactions of the first skincycle of the mutant (Ng) were histologically investigated. 1. During the hair growth disturbances as the result of imperfect keratinisation changes of the morphology and function of different skin areas could be observed. 2. The developments of abnormal thinner hair growth were correlated to hyperorthokeratotic, inter-respectively intrafollicular hyperplasia of the epidermis and to infraseboglandular hypoplasia of the follicles. 3. The hyper- and hypoplasia of the epidermis corresponded with a functional pseudohypo- and pseudohypertrophy of the cutis. 4. During the skincycle the perifollicular epithelium ranged from the inter- to intrafollicular skin areas. The inter- and intrafollicular epidermal sections varied simultaneously. 5. These results are important for the understanding of some pathomorphological and pathophysiological reactions of skin compartments of man.

In the "clean" rat skin purified from the panniculus carnosus the oxygen consumption of the spontaneous and artificially induced skincycle was measured at different times of day. The level of oxygen consumption correlated to diurnal and nocturnal periods. During the skincycle the oxygen consumption showed fluctuations. There were indications that the value of oxygen consumption of the early anagen is influenced by that phase of the cycle at which the new cycle is artificially induced. Furthermore, it was found that a certain decrease of oxygen consumption stimulates the quiescent hair follicles to spontaneous proliferation. During the katagen the peak value of the oxygen consumption seemed to be correlated with specially morphofunctional perifollicular changes. The application of these findings to the pathophysiology of human hair growth disturbances is discussed.