Sunless tanning products containing dihydroxyacetone in combination with a perfluoropolyether phosphate.

It is well known that the shelf-life of products containing dihydroxyacetone (DHA) is quite unsatisfactory, and that in this area the adjustment to an acidic pH is the way usually recommended to improve DHA stability. The adoption of this rule, however, is a challenge for the cosmetic chemist not only because of the risks of skin irritation, but also because of the strong limitations in the choice of the acidic agent. It occurs that the use of either hydroxy-acids and phosphoric acid/phosphate buffers has the opposite effect on the one intended. Recently, a perfluoropolyether phosphate (PFPE phosphate) was introduced as a new acidic agent to lower the pH without increasing the skin irritation. Starting from a rationale based on this potential, we investigated sunless tanners containing PFPE phosphate and DHA. We monitored the ageing of sunless tanners with and without PFPE phosphate, by visual observation and instrumentation (pH measures and (1)H-NMR spectroscopy). Furthermore, to evaluate whether the substances produced from the DHA degradation are potential irritants, patch tests on volunteers were used to check the safety and indirectly the stability of the compositions. In conclusion, our investigations on the guidelines to formulate DHA-containing sunless tanners: confirmed that the pH is a key parameter in formulating these compositions; proved that PFPE phosphate is a safe and compatible ingredient to lower the pH; gave some evidence of the critical importance of thickeners; suggested a strategy based on multifunctional agents to minimize the ingredients.

Perfluoropolyether phosphate: skin exfoliation after a topical pre-treatment, TEWL and skin elasticity, by in-vivo non-invasive methods.

Glycolic acid (GA) and other alpha-hydroxyacids (AHAs) are common ingredients of products designed to accelerate exfoliation of the skin. It is known that acidic pHs are essential in order to increase the efficacy of AHA-based products. The formulator is, therefore, obliged to achieve a difficult balance between performance (skin exfoliation) and risks (skin irritation). In order to overcome this problem, many common organic acids, and combinations of them, have been proposed, with marginal improvements. The need for a new chemistry, in order to achieve better results, was evident, particularly from the point of view of safety. We decided, therefore, to investigate the efficacy of perfluoropolyether (PFPE) phosphate, a new acidic material, already proposed for lowering the pH without increasing skin irritation. Two gels containing PFPE phosphate at different pH values (3 and 7), an acidic gel containing GA at pH 3, and a neutral gel, without an active compound, were applied on 20 healthy volunteers and evaluated with regard to effects on the skin: *Exfoliation after a topical pre-treatment with these gels *Transepidermal water loss (TEWL) and elasticity The main conclusion of the investigation was that PFPE phosphate has effects, particularly skin exfoliation rate, quite independent of the pH, and comparable to the gel containing GA at pH 3, apparently without the typical drawbacks of AHAs.

Safety evaluation of perfluoropolyethers, liquid polymers used in barrier creams and other skin-care products.

Fomblin HC products are a 'family' of high-purity perfluoropolyethers manufactured for barrier cream and other personal care applications which involve direct application to the skin. To confirm the safety of such use, representative Fomblin HC products were tested in experimental animals for acute toxicity, primary and repeated insult irritancy, sensitization and photosensitization, subacute oral toxicity and comedogenicity; mutagenicity was examined in vitro, and irritancy or sensitization was also investigated on human skin (in patch tests with volunteers). A high molecular weight Fomblin HC only was tested in rats for subacute oral toxicity and in man for dermal effects. Single oral doses of 15 g/kg body weight were without evident toxicity to rats, as were single dermal applications or an ip injection at 5 g/kg. No primary irritant action was seen in rabbits or man, and similarly there was no evidence of skin sensitization or photosensitization in guinea pigs, or sensitization in man. No mutagenic action on Salmonella strains of tester bacteria was seen. In repeat dose irritancy or oral toxicity tests in rabbits or rats, no adverse effects of Fomblin HC products were noted; in particular, daily oral administration (1000 mg/kg/day) to rats over 28 days produced no significant reaction. No comedogenic action was found. From the known chemistry of the perfluoropolyethers, the test programme reported here and the limited published data, it is concluded that the intended use of Fomblin HC products in formulations applied to human skin has a high margin of safety.

Perfluoropolyethers in the prevention of irritant contact dermatitis.

BACKGROUND: Perfluoropolyethers (PFPEs) are non-reactive perfluorinated (no hydrogen atoms) liquid polymers that showed promise as ingredients of protective preparations in occupational dermatology. OBJECTIVE: The aim of this study was to investigate if oil-in-water (o/w) emulsions containing 0.5, 1.0, 2.0 and 4.0% PFPEs (molecular weight 6,250 D) prevent epidermal barrier disruption induced by a repetitive irritation test (RIT). METHODS: PFPE-containing o/w emulsions and the emulsion base alone were evaluated against a set of 4 irritants [10% sodium lauryl sulphate (SLS), 0.5% sodium hydroxide (NaOH), 15% lactic acid (LA), and undiluted toluene (TOL)] in the RIT. Ten subjects were tested on the paravertebral skin of the mid-back. Irritation was assessed by visual scoring, transepidermal water loss (TEWL) and colorimetry. RESULTS: Both the emulsion base and all PFPE-containing preparations significantly suppressed irritation by SLS and NaOH. Against LA and TOL, only the 4% PFPE-containing preparation was significant as assessed by TEWL. CONCLUSION: A 4% PFPE-containing o/w emulsion significantly inhibits irritation due to a wide spectrum of hydrophilic and lipophilic irritants. o/w emulsions with lower concentrations of PFPE are also effective against SLS and NaOH, but this is also true for the cream base alone. Therefore, further studies are necessary to evaluate if a minimum of 4% PFPE in the base provides additional benefit.

Preliminary Communication: Treatment of irritant contact dermatitis in workmen with perfluoropolymethylisopropyl ether (Fomblin HC).

Synopsis Non-allergic contact dermatitis is a major dermatological problem for the workmen of an important factory which manufactures industrial machines (SAIMP SpA) located at Padua. Such dermatitis is due to the presence in the environment of paints, solvents, surfactants, lubricants and metal powders (steel and cast-iron). As medical treatment, the factory doctor practises the use of common barrier creams which do not give completely satisfactory results. To cope with this problem, some workmen were treated with preparations containing Fomblin HC. The highly successful results of this new type of treatment are reported: among other findings this study shows, through experimental evidence, that Fomblin HC has a protective effect not only against water soluble substances but also against oil soluble substances (in fact, the latter are probably the main cause of contact dermatitis contracted by these workmen).