Delivery with Chitosan-coated Liposomes and Other Topics: Literature Findings

By: Charles Fox, Independent Consultant

Posted: February 26, 2009, from the March 2009 issue of Cosmetics & Toiletries.

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Nails
Treating nails with chitosan: Polichem S.A. discloses the use of chitosan to increase nail growth rate and to treat nail disorders.⁸ The described invention uses chitosan, a chitosan derivative or a physiologically acceptable salt thereof. The invention is further indicated for use in accelerating nail growth during treatment of nail diseases, nail dystrophy or other nail conditions to considerably shorten the specific treatments of the nail inflictions. The composition shown in Formula 6 had a clear, homogeneous appearance even after prolonged storage. Moreover, when applied on the nails, the liquid formed a nonsticky, elastic film that could strongly adhere to the nail surface.

Nail lacquer additive: Evonik Degussa GmbH discloses a shiny and scratch-proof nail varnish obtained via the addition of silanes to nail lacquer.⁹ The additives contain at least one silane and one solvent; water; and a catalyst selected from: hydrochloric, nitric, phosphoric, sulfuric, formic, propionic, acetic or citric acid or their mixture. The additive is mixed with conventional or unconventional nail lacquers and prepared from: 10% w/w orthosilicate (and) tetraethoxysilane; 50% methyltriethoxysilane^b; 12 % nitric acid (1%); 12% propanol and 16% butyl acetate. The additive was mixed at 10% with 90% available nail lacquer.

Scratch-proof silane nail varnish: Evonik Degussa GmbH also discloses the formation of a shiny and scratch-proof nail varnish through addition of silanes to nail lacquer.¹⁰ The additives contain at least one silane and one solvent and are mixed with conventional or unconventional nail lacquers. Thus, an additive was composed from 30 g tetraethyl orthosilicate (and) tetraethoxysilane^b and 30 g butyl acetate in an impeller blade mixer. The additive was mixed at 5% with 95% available nail lacquer.

Sunscreens
Spectrophotometric SPF evaluation: Bleasel et al. have published on the in vitro evaluation of sun protection factors (SPFs) of sunscreen agents using a novel UV spectrophotometric technique.¹¹ The method described determines the low and high value SPF of sunscreens using artificial substrates and a novel pseudo-double-beam (PDB) mode of operation of a standard double beam UV spectrophotometer. This technique allows transmittance to be calculated from detector responses of reference and sample beams measured at different gain levels. The method facilitates the accurate quantification of low levels of electromagnetic radiation transmitted through highly absorbing samples.

The standard double beam UV spectrophotometer was modified to hold quartz diffusing plates onto which a substrate—Transpore adhesive tape or human SC obtained from a skin surface biopsy (SSB)—and the sunscreens to be tested were applied. The PDB mode of operation increased the effective linear range of the detector response of the spectrophotometer by approximately 20,000-fold, enabling the in vitro SPF determination technique to be applied to both high and low SPF value sunscreens. Eight commercial sunscreens with known SPF values of 4–77, previously determined by in vivo methods, were tested using both test substrates and correlations between the in vivo and in vitro values. The SPF values measured using the described in vitro method correlated well with the known in vivo results—Transpore tape, R2 = 0.611 : SSB, R2 = 0.7928). However, the in vitro SPF obtained for one of the tested products differed substantially from the cited in vivo SPF value. The independent in vitro and in vivo re-evaluation of the SPF of this product matched the value predicted by the present method much more closely than the originally cited in vivo value. All determined SPF values were ordered correctly in comparison with their in vivo ranking, and the technique appeared to correctly identify a sunscreen that had a labeled SPF value that was significantly higher than its true SPF.