Effect on Skin

No naturally occurring bi and trithiophenes are currently used as drugs. However, plants containing such compounds have been used in traditional medicine. For example, the juice of Eclipta alba leaves has reportedly been used in India for the treatment of vitiligo, athlete s foot, ringworm and some chronic skin diseases 234 but whether any pharmacological activity must be attributed to a-terthienyl or congeners present in this plant has not been established with certainty. 

On two occasions, individuals working in the author s laboratory came in contact with accidentally spilled solutions containing either a dithiophene (6) or a trithiophene (T9). Shortly thereafter they went outdoors and their skin experienced immediate reaction matching the description of the effect reported for the exposure to a-terthienyl. The response due to 6 is documented on a photograph shown below (Fig. la). Dr. D. A. Perrine, S. J., demonstrated that skin response could be used as a novel and sensitive detector for poly thiophenes. Fractions from the final column chromatographic purification of synthetic 6 had been spotted in duplicate on his forearm. One row was covered with tape and 

In both these cases the skin returned to normal in less than 2 weeks rather than the ten months reported for Tl. It is quite remarkable that there have been no other published reports of adverse effects on the skin of the scientists involved, despite the large number of studies using bi-and trithiophenes (particularly Tl). 

The cutaneous phototoxicity of a-terthienyl was studied in guinea pig skin, both in vitro and in vivo 203). Effective penetration through the epidermis and superficial dermis produced cutaneous photosensitization comparable to that of intradermally administered a-terthienyl. Phototoxicity was accompanied by a corresponding inhibition of epidermal DNA synthesis in normal and hyperproliferative skin. The authors suggested that a-terthienyl might provide a selective and safer alternative to coal tar and furanocoumarin derivatives for the treatment of psoriasis and other cutaneous diseases by photosensitization. However, no clinical studies in this direction have yet been published. 

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Rate of action. Immediate effect on eyes, effects on skin delayed Vi to 1 hr (Ref 1)... 

Sulfamic acid (HOS02NH2). Clean at only 120 °F (49 °C) for cast iron and up to 140 °F for marstenitic SS (60 °C). It is not suitable for galvanizing or aluminum over 150 °F, but it is suitable for copper, brass, and SS. Sulfamic acid tends to be used only in small systems because of its relatively high cost. It is a ciystalline solid and so is easily transported. Additionally, in the diy form it is relatively safe and has a negligible effect on skin. Typically, it is used at 10% strength, and when 5% sodium chloride is added, it is reasonably successful at dissolving ferric oxide. 

Sulfuric acid. As a 10 to 20% v/v solution, sulfuric acid can be used to clean 300 series SS, as well as other steels and metals, but not galvanized steel or magnesium. The cleaned SS can then be passivated with nitric acid. In practice, sulfuric acid is seldom used, except by specialist cleaning companies, because of its high heat of dilution and terrible burning effect on skin and other tissues. Add acid to water. 

Lethal concentrations and doses are parameters of acute, systemic poisoning. There are also specific protocols to evaluate the irritant and corrosive effects on skin, eyes and mucous membranes. 

Immediate effect on eyes effects on skin are delayed 30 min to 1 h. 

Rat, mouse 10 mg/kg BW Dermal application daily for 10 days causes severe effect on skin and bile duct 3... 

The properties of a formulation and its composition affect skin permeability. For example, the pH of formulations was shown to have an effect on skin permeability. Using experimental data a predictive model could be established [86], A mechanistic understanding of this effect is still missing—as well as a purely computational model. Various substances are known to enhance... 

Effects on skin color Hypopigmentation Hyperpigmentation Striae... 

When investigating the effects of water on transdermal permeation, animal skin may yield results markedly different to human data. For example, hairless mouse skin is unsuitable for modeling human stratum corneum regarding hydration effects the murine skin, when hydrated for 24 h, became grossly more permeable than human skin membranes [8]. Thus water effects on skin permeability obtained using animal models need cautious assessment. 

FIGURE 16.4 Schematic presentation of ultrasound/SLS synergistic effect on skin permeability. (From Lavon, I., Grossman, N., and Kost, J., J. Control. Release, 107, 484, 2005. With permission.)... 

Sulfur mustard is a known human carcinogen, and some of its degradation products may also be carcinogenic (IOM, 1993). Sulfur mustard acts as a vesicant or blister agent and shows acute systemic toxicity in addition to its effects on skin, eyes, and the respiratory tract. 

Limited information is available regarding the health effects of barium following dermal exposure. Barium salts would be expected to have a local effect on skin surfaces and would not likely be absorbed systematically to any great extent. Available studies include a case report of an individual exposed dermally to molten barium chloride (Stewart and Hummel 1984), a skin irritation study evaluating barium carbonate in experimental animals (Tarasenko et al. 1977), and a skin-painting study in which mice were exposed dermally to a barium hydroxide extract of tobacco leaf (Van Duuren et al. 1968). No reliable information was available from any of these dermal studies to identify study NOAELs or LOAELs for barium. In the case report (Stewart and Hummel 1984), the dermal burns that developed in the individual exposed to molten barium chloride may potentially have contributed to some of the reported health effects, which are described briefly in Section 2.2.3.2 (Systemic Effects). 

The considerations mentioned earlier also bring up the subsequent questions that wait to be answered, for example, about the influence of moisturizers on pH-gradient inside the epidermis and the activity of enzymes, effect on skin barrier function and skin barrier recovery, or the difference in... 

Skin is also an important target organ for estrogens. The estrogenic effect on skin is well characterized, as well as the effect of estrogen withdrawal. A major effect of estrogen is the increased levels of HA deposition and the associated water of hydration. Topical estrogens are also able to enhance HA deposition in skin, as documented in the hairless mouse skin model.280... 

Lanolin and its numerous derivatives have been widely used in the pharmaceutical and cosmetic industries for many years as vehicles for active ingredients and for their beneficial effects on skin function.3 Although purified lanolin is used without incident by millions of people, confusion still exists concerning the possible allergenic potential of lanolin. The extremely low incidence of sensitization of healthy individuals to purified lanolin used in the cosmetic and pharmaceutical industries has been comprehensively reviewed.4-6... 

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