(From the National Institutes of Health)

Americans spend billions of dollars each year on skin care products that promise to erase wrinkles, lighten age spots, and eliminate itching, flaking, or redness. But the simplest and cheapest way to keep your skin healthy and young looking is to stay out of the sun.

Sunlight is a major cause of the skin changes we think of as aging — changes such as wrinkles, dryness, and age spots. Your skin does change with age. For example, you sweat less, leading to increased dryness. As your skin ages, it becomes thinner and loses fat, so it looks less plump and smooth. Underlying structures — veins and bones in particular — become more prominent. Your skin can take longer to heal when injured.

You can delay these changes by staying out of the sun. Although nothing can completely undo sun damage, the skin sometimes can repair itself. So, it’s never too late to protect yourself from the harmful effects of the sun.

Wrinkles

Over time, the sun’s ultraviolet (UV) light damages the fibers in the skin called elastin. The breakdown of these fibers causes the skin to lose its ability to snap back after stretching. As a result, wrinkles form. Gravity also is at work, pulling at the skin and causing it to sag, most noticeably on the face, neck, and upper arms.

Cigarette smoking also contributes to wrinkles. People who smoke tend to have more wrinkles than nonsmokers of the same age, complexion, and history of sun exposure. The reason for this difference is not clear. It may be because smoking also plays a role in damaging elastin. Facial wrinkling increases with the amount of cigarettes and number of years a person has smoked.

Many products currently on the market claim to “revitalize aging skin.” According to the American Academy of Dermatology, over-the-counter “wrinkle” creams and lotions may soothe dry skin, but they do little or nothing to reverse wrinkles. At this time, the only products that have been studied for safety and effectiveness and approved by the Food and Drug Administration (FDA) to treat signs of sun-damaged or aging skin are tretinoin cream and carbon dioxide (CO2) and erbium (Er:YAG) lasers.

The use of sunscreen preparations is recently growing and their efficacy and safety must be taken into account since they are applied on the skin frequently and for many hours. Exposition to sunlight, in fact, can cause sunscreen photodegradation and determine their decrease in UV protection often with the occurrence of allergic and/or toxic degradation products. A high photostability is hence very important for their effectiveness and safety. The aim of this work is to obtain new sunscreen formulations stabilized by intercalating PABA, within the lamellar structures of two kinds of hydrotalcite. PABA was chosen as model sunscreen because of its high photoinstability and photosensitizing properties that nowadays bar its utilization. Both intercalated products showed an increased protection range and, in one case, an improved sunscreen photostability. Sunscreen release from creams containing intercalated or free PABA was evaluated as well. The very low or negligible sunscreen release, obtained from the intercalated product loaded formulations, resulted in a lack of a close contact between skin and filter with the consequence that cutaneous reactions and allergy problems are eliminated. The use of these materials resulted in a good strategic technological approach in order to increase efficacy and safety of solar products.

Development of photostable sunscreens is extremely important to preserve the UV protective capacity and to prevent the reactive intermediates of photounstable filter substances behaving as photo-oxidants when coming into direct contact with the skin. Thus, the objective of this study was to evaluate the photostability of four different UV filter combinations in a sunscreen by using HPLC analysis and spectrophotometry. The formulations that were investigated included four different UV filter combinations often used in SPF 15 sunscreens. The UV filter combinations were: octyl methoxycinnamate (OMC), benzophenone-3 (BP-3) and octyl salicylate (OS) (formulation 1); OMC, avobenzone (AVB) and 4-methylbenzilidene camphor (MBC) (formulation 2); OMC, BP-3 and octocrylene (OC) (formulation 3); OMC, AVB and OC (formulation 4). In the photostability studies, 40 mg of each formulation were spread onto a glass plate and left to dry before exposure to different UVA/UVB irradiation. Exposed samples were then immersed in isopropanol and the dried film dissolved ultrasonically. The filter components in the resulting solution were quantified by HPLC analysis with detection at 325 nm and by spectrophotometry. In this study, the four UV filter combinations showed different photostability profiles and the best one was formulation 3 (OMC, BP-3 and OC), followed by formulations 4, 1 and 2. In addition, OC improved the photostability of OMC, AVB and BP-3.

Because of increases in the number of skin cancers diagnosed annually, adverse effects of ultraviolet (UV) rays are being recognized, and major public education programs have been undertaken concerning photoprotection, including the use of sunscreen. In daily life, UV exposure is unavoidable; therefore sunscreen should be used regularly. Development in sunscreen manufacturing has grown tremendously in the last decade. Sunscreen active ingredients now are incorporated into cosmetics products to minimize photoaging changes. With the advances in technologies, many new UV filters have been developed recently. These have improved efficacy and safety. This article reviews these new filters, along with regulatory issues in the United States.