Chemical Peels and Retinoids

ALPHA HYDROXY ACIDS

Alpha-Hydroxy Acids or AHA is a compound found naturally in many common fruits and other foods. The principal AHA is glycolic acid which is found in sugar cane and sugar beets. Other AHAs include lactic acid from dairy products and malic acid from fruit. Glycolic acid is the most skin-active AHA; and its primary action is to accelerate shedding of abnormal cells in the topmost layers of the skin by decreasing their cohesiveness. Continued use of glycolic-acid-based products may result in a normalized, more compact top layer of the epidermis. This makes the skin smoother. Additionally, it helps to remove comedones (blackheads); and, like retinol, it helps to restore the barrier function of the skin, thereby helping naturally to increase its own moisture content. It also leads to increased collagen production in the upper dermis, resulting in reduction of fine lines. Glycolic acid also has an anti-inflammatory effect and is able to enhance the effects of other topical agents, such as hydroquinone and salicylic acid. It is well-tolerated by many people, but it can cause irritation and stinging in some. It can make the skin more sensitive to the effects of the sun’s UV rays; therefore use of effective sunscreen is essential.

The main benefits of alpha hydroxy acids come from its ability to exfoliate skin. Removal of the outermost layer of the skin stimulates the cells in lower layers to grow and divide, causing the skin to thicken and thus diminishing visible signs of aging. The more you exfoliate, the more cell divisions you have occurring in the lower skin layers. There is one problem though. Normal human cells cannot divide indefinitely. Fibroblasts (a key type of cells in the skin) will divide about fifty times and then enter a so-called stage of senescence. This is a state in which cell division becomes sluggish, inefficient and unresponsive to various signals from the body and unable to divide. This is similar to how a plant will slow its leaf and bloom production at the end of its growth cycle. Skin with many senescent cells is usually fragile, blotchy and easily wrinkled. This limit of about fifty cell divisions is called the Hayflick limit (after its discoverer, Dr. Leonard Hayflick).

Exfoliation remains a valuable cosmetic tool but if you overuse it, your skin may "hit the Hayflick limit" earlier than it should. In recent years, researchers have discovered the molecular mechanism of the Hayflick limit. (It has to do with the areas at the tips of chromosomes called telomeres). Medical technologies to eliminate the Hayflick limit may appear at a point in the future, although these advances in technology are likely to work only for those cells whose Hayflick limit has not yet been reached.

The most important precaution to take when using alpha hydroxy acids is to know the percent and pH level of the product. The ideal pH is 3.0-3.5, any lower and the product may be too acidic; any higher and the product's exfoliating benefits may be nullified. Even at lower levels, though, some alpha hydroxy acids can be irritating, depending on how sensitive your skin is. Mandelic acid is the recommended AHA for those with sensitive skin since it is the most non-irritating. Also, darker skin types should avoid most alpha hydroxy acids due to the risk of hyperpigmentation. Hyperpigmentation will occur in darker skin if it becomes irritated or inflamed. Those with a skin type which tans easily or rarely burns through skin types which always tan or never burn, should be especially careful and avoid possibly irritating products. Because alpha hydroxy acids peel away the tough outer layers of the skin, the newer and younger skin is more susceptible to the suns UV rays.

CHEMICAL PEELS

Having acid applied to your face probably doesn’t sound like something you’d want done, but it is the foundation of a very popular cosmetic procedure known as the chemical peel. Chemical peels can give your skin a healthy, “just refreshed” look, or can be aggressive, taking years off of your appearance. Just like other cosmetic procedures, there is a wide range of varying chemicals used and techniques that can be overwhelming if you have to decide which is best for you. Fortunately, this is one area where the physician will often guide the patient to the chemical peel most appropriate for their condition as well as the patient’s skin type. Listed below are some of the realistic vs. unrealistic goals of chemical peels. This may be helpful if you are trying to decide if this procedure is right for you.

Realistic Goals of Chemical Peels:

  1. Chemical peels can correct (sun) damage.
  2. They can reduce mild scarring.
  3. You can experience a reduction or eradication of your wrinkles.
  4. Improvement of dark skin discoloration is possible.
  5. Chemical peels can remove excessive or stubborn blackheads.
  6. The peel may temporarily reduce excessive skin oils.

Unrealistic Goals of Chemical Peels:

  1. It cannot remove or reduce the appearance of blood vessels on the skin.
  2. It is impossible to truly change pore diameter. However, by removing blackheads, the pores may actually appear less pronounced after treatment.
  3. This is not a procedure to get rid of keloidal types of scars
  4. Chemical peels are not a facelift.
  5. This is typically not appropriate for improving dark skin discoloration in people of color (Asians, African Americans, Caucasians of Mediterranean extraction, Hispanics, etc.)

There are a variety of different chemicals used for the purpose of rejuvenating the skin in what are called “chemical peels”. If the skin condition is predominantly superficial, then a milder, less caustic ingredient is selected. If deeply placed conditions exist, then far stronger products with matching levels of potential complications may be necessary.

Chemical peeling agents that perform mild or moderate peels typically provide a safer peel that has less associated long-term side effects. These peels work on the epidermis and possibly the most superficial portion of the dermis (known as the papillary dermis).

Deeper peels go midway into the dermal layer (into the reticular dermis), almost invariably leaving a permanently lighter skin tone. Instead of being able to tan as in the past, this lighter skin often freckles instead. These deeper peels should not be undertaken lightly, and you need to make sure in advance that the peel technique will be feathered into the scalp line and performed down the neck, possibly even the décolletage, or you may find that you have a highly noticeable line marking the difference in your original skin tone and the new one that is on the face.

The glycolic acid peels (ranging from 70%-99% glycolic acid compound) and the beta-hydroxy acid (salicylic acid) peels (ranging from 20%-30% salicylic acid in a microsponge delivery system) are among the most effective chemical peels.

Glycolic acid peels work by diminishing the cohesion of the skin cells (corneocytes) at the innermost levels of the surface layer of the skin (stratum corneum), by stimulating this layer of skin in its renewal process, increasing skin thickness, and promoting the formation of new epidermis and new dermal collagen. This process will result in skin shrinkage, reduction of wrinkling and "crepe-paper-like" skin, softening of "crow’s feet," and often helping to lighten hyperpigmentation.

The salicylic acid peels or Beta-Lift peels are effective in lifting the topmost layer of skin by dissolving the "glue" (desmosomes) which binds it to the underlying epidermis, triggering a "burst" of cell division which accelerates skin cell production and shedding. Its developer, Douglas Kligman, M.D., Ph.D.(who is the son of Albert Kligman, M.D., Ph.D., the founder of Retin-A), developed it for the cosmetic treatment of sun-damaged skin, hyperpigmentation (including melasma, "liver" or "age" spots, and freckles), superficial lines, and "weathered" or rough skin. The salicylic acid peels are often more intense than the glycolic acid peels.

If you are currently taking or have taken Accutane within the past six months, you are not a candidate for chemical peels. Patients with healing wounds from recent surgery, patients with active herpes simplex (fever blisters or cold sores) on their face, patients who have had radiation therapy to their face (or to the area which they wish to have peeled), or patients who have had cryotherapy in the past month should not have a chemical peel. A tendency toward hypertrophic or keloidal scarring may also make you not a good candidate for a peel. It is essential that you use very effective photoprotection after a peel; thus, if you are unwilling or unable to do so, you should not consider having a chemical peel.

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