Stable O/W Nanoemulsions for Skin and Other Topics: Literature Findings

By: Charles Fox, Independent Consultant

Posted: February 26, 2010, from the March 2010 issue of Cosmetics & Toiletries.

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Porous polyamide odor absorption: Henkel AG & Co. has disclosed porous polyamide particle-containing deodorants and/or antiperspirants with improved fragrance effects and odor absorption.¹⁰ The compositions contain at least one deodorant/antiperspirant active, 0.0001–5.0% w/w fragrance, and 0.1–10% w/w porous polyamide beads in a carrier. The beads were characterized by: a medium particle diameter of 1-30 mum; a specific surface according to BET of 5 m2/g or larger; oil absorption capacity (boiled linseed oil) of 200 mL/100 g or larger; crystallinity of 40% or larger; and a 1.0-1.5 ratio of volume medium particle diameter to average medium particle diameter. An example of a w/o sprayable emulsion is shown in Formula 7.

Sunscreens

Radiation-photostabilizing formulations: L’Oréal has also disclosed cosmetic compositions containing a combination of at least one dibenzoylmethane derivative and at least one neutral N-acylamino acid ester derivative, as well as a process for radiation-photostabilizing the dibenzoylmethane derivative with an effective amount of the neutral N-acylamino acid ester derivative.¹¹ The radiation-photostabilizing process is designed to improve the efficacy of the composition with respect to UVA rays. An example is shown in Formula 8.

Interesting Compositions and Raw Materials

Popping foam in aerosols: Daizo Co., Ltd. has disclosed an aerosol composition in which the forming foam generates a long-lasting popping sound and imparts a cooling effect to skin.¹² The composition comprises a liquid and a liquefied gas. The liquid contains 3.0–30.0% oily base materials, water-soluble polymers and surfactants. The liquefied gas, at a weight ratio 50:50–10:90, comprised an inorganic-organic balance of materials of 0.2–0.5. An aerosol container was packed with a liquid composition comprising: hydroxyethylcellulose, PEG-20 sorbitan cocoateb, cyclomethicone, methylpentanediol dineopentanoatec, talc, ethyl alcohol, methylparaben, disodium EDTA and water; and a 40:60 isobutane-butane liquefied petroleum gas mixture. Foams sprayed from the container generated a large popping sound when rubbed on a palm.

Phosphoric acid ester formulation: Clariant International Ltd. has disclosed cosmetic, pharmaceutical or dermatological compositions containing phosphoric acid esters and hydrophobically modified, cross-linked anionic polymers.¹³ Specifically, the invention relates to compositions comprising: one or more anionic, cross-linked and/or hydrophobically modified polymers, where the hydrophic modification is carried out by a hydrocarbon group with 6–50 carbon atoms; and one or more phosphoric acid esters. A phosphoric acid ester was prepared from 12.7 g phosphoric acid and 701.3 g ceteareth-50. The phosphoric acid ester product was formulated into a vitamin C gel at 1.0% w/w with additional 1.5% w/w ceteareth-25^d; 3.0% w/w ascorbic acid; 1.2% w/w ammonium acryloyldimethyltaurate/beheneth-25 methacrylate crosspolymer^e, and a water balance to 100% w/w.

Enhancing actives solubility: Dow Global Technologies Inc. has disclosed a method to enhance the aqueous solubility of poorly soluble actives using methoxypolyethylene glycol.¹⁴ The method combined an active compound of aqueous solubility ≤ 10 mg/mL with enough methoxypolyethylene glycol to increase the aqueous solubility of the active compound. Enhancement of aqueous solubility for this combination may be significantly greater than that of an active compound in combination with an equivalent amount of polyethylene glycol. Enhanced solubility was shown where a small amount of water was also included. This invention may be used in a variety of industries including pharmaceutical, agricultural, antimicrobial and personal care.