• Anna Solana, science journalist

    Liposomes: transport via the skin

    Liposomes are used in anti-ageing creams, sunscreens, anti-cellulite products, hair treatments and even perfumes.  They are an excellent vehicle for transporting active ingredients directly to the body and releasing them in the right place in the right amount. There is no better transport for drugs and nutritional supplements that benefit the health of our skin.

     

    Although liposomes were described for the first time in 1965 by British haematologist Alec Bangham, the first preparation that contained them did not appear until 1988. That was in Switzerland, when the company Janssen-Cilag developed an anti-mycosis gel (to treat skin fungi).  Liposomes are spherical vesicles whose membrane is composed of a particular type of lipids (fats), called phospholipids, arranged in bilayers.

    Described another way, liposomes are small macromolecular structures capable of crossing cell membranes. Those used are mainly of natural origin (from soybean lecithin, egg, pumpkin seed or krill), although there are also synthetic phospholipids (dipalmitoylphosphatidylcholine).

    Their outer fatty layer is easily absorbed by the skin, so substance release is very effective. The cosmetic industry has recently begun to take advantage of this property. Liposomes are classified in terms of size and bilayer structure, making them suitable for different applications (including industrial applications, such as wool dyeing) and requiring specific production methods.

    Cosmetics laboratories for major brands first became aware of the phospholipid-enhanced moisturizing and tissue regenerating actions of the liposomes. They then became aware of the huge potential of liposomes to deliver therapeutic agents to different parts of the body, given their capacity to encapsulate very different kinds of active ingredients, their biodegradability and their non-toxicity.

    In fact, this is the area where most research efforts are currently being invested, principally in anti-ageing, firming, antioxidant and topical and injectable anti-cellulite formulations. There is some controversy surrounding oral formulations as the changes in pH can affect intestinal absorption.

    However, in recent years, some companies have been working on liposomal formulations of what are called nutraceuticals, that is, foods that provide a health plus over and above their nutritional value. These nutritive liposomes, which are claimed to deliver to the skin the elements it needs for natural self-regeneration, may contain hydrolyzed wheat germ, collagen, hyaluronic acid, vitamins, honey and royal jelly.

    However, liposomes also have their limitations. Preparation is costly and the phospholipids are affected by oxidation and chemical instability. This has led the more innovative cosmetic companies to explore other possibilities, such as neuropeptides or tissue engineering.

    That said, although expensive, liposomes are very effective because they manage to do something that is very difficult: they transport cosmetic or pharmacological active ingredients across the near-impermeable skin barrier and cell membranes.

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