Читать книгу Cosmeceuticals - Группа авторов - Страница 54

Over the past few decades, an abundance of information regarding cosmeceuticals utilizing AHAs, BHAs, and PHAs has emerged. Many studies have determined the family of HAs to be efficacious in the treatment of a copious amount of skin ailments and issues, as well as being heralded as some of the most classic anti-aging ingredients [1]. HAs treat hyperkeratotic conditions by regulating the attachment of corneocytes to the stratum corneum. This produces a highly specific result of epidermal shedding compared to nonspecific results from other keratolytic products [11] like coal tar or tazarotene. In conjunction with the exfoliative properties that HAs possess, their anti-aging capabilities stem from the collagen stimulation that occurs when keratinocytes compensate for their own loss following exfoliation due to the acid’s effects, also known as dermal matrix remodeling [11]. This leads to the impressive effects on fine lines and wrinkles that HAs deliver, whether they are used topically in a cream, gel, serum, or in a peel. They have been found to act on hyperpigmentation through the promotion of desquamation that takes place when the HAs interact with the skin, as well as PHAs exhibiting antioxidant traits [11]. Gluconolactone, as previously stated, is one of the most well-known PHAs and has demonstrated free radical inhibition of a solar elastosis due to photoaging activity in a study that was conducted when compared to other antioxidants (i.e., vitamin C and vitamin E). The results of the study yielded revealing information about gluconolactone, summing up the concept that it is comparable to the more notable antioxidants, and that it should be regarded as one in its own right [11].

Combination peels have been around for years because their results are exceptional. The famous Jessner’s peel solution contains 14% resorcinol, 14% lactic acid, 14% salicylic acid, and they are all mixed into a base of ethyl alcohol [12]. Used chiefly for sun-exposed conditions like actinic keratosis, hyperpigmentation, rhytides, and solar lentigines, it can also treat acne. Jessner’s peels are our first-choice peel for the treatment of melasma in all skin types I–VI. Its depth is superficial, it is self-neutralizing, it is typically difficult to overpeel using Jessner’s, and any complications are rare [12]. The Jessner’s mechanism of action derives from the keratolytic property in the resorcinol and salicylic acid, as well as the epidermolytic property in the lactic acid. Corneocyte cohesion is broken in the stratum corneum due to the resorcinol and salicylic acid, thus causing edema in the epidermis at both the intercellular as well as the intracellular levels. Clinically, the end point hallmarks are erythema and frosting. Possible complications include activating a dormant Herpes outbreak, experiencing delayed healing or lengthened redness, scarring, PIH or post-hypopigmentation, and contact dermatitis [12]. Contraindications for Jessner’s include having an active HSV outbreak, having been on isotretinoin within the previous 6 months, and pregnancy [12].

TCA is a corrosive agent used frequently in the dermatological field, and typically stored in an opaque glass bottle so as to prevent photodamage to the solution. Utilizing higher concentration percentages of TCA and/or applying more coats will lead to a deeper depth of the peel’s penetration. TCA used alone reaches a medium depth of the dermis and TCA 30% is our choice peel for dermal melasma in patients who first tolerated the Jessner’s peel well and who are not prone to PIH. TCA is frequently used in combination with other solutions and/or acids. For example, combining TCA 35% with Jessner’s solution will produce the Monheit combination, which is a medium-depth peel. This amalgamation is very popular for actinic keratosis as well as other symptoms derived from photoaging [13]. It has been found to be as effective as 5-fluorouracil topical chemotherapy with fewer side effects [13]. This particular combination is extremely beneficial for the TCA’s penetration capability, because the foundation layer of the Jessner’s peel allows for keratolysis and epidermolysis. In turn, the TCA is more readily available to the stratum corneum [13].

Combining TCA 35% and glycolic acid 70% forms the Coleman combination, which allows for medium-depth penetration [13]. The peel is self-neutralizing and is commonly used for reversing actinic damage, reducing rhytides and pigmentation, and improving scarring [14]. When TCA 35% is combined with solid CO₂, the Brody combination is created [13]. According to Brody and Coleman, the medium depth peel occurs when TCA 35% is preceded by solid CO₂ to allow for further penetration of the TCA to a greater depth of penetration. This process takes place through the papillary dermis. Jessner’s plus unbuffered 70% glycolic acid can be used to do the same as solid CO₂ but with less depth histologically. Solid CO₂ is much warmer than liquid nitrogen and therefore is not capable of scarring the dermis by only freezing it under customary circumstances. Additionally, freezing with solid CO₂ can cause edema without collagen destruction. The ensuing edema will stretch the distance between cells, and will allow the active acids to penetrate to the papillary dermis. As a result, it will provide better clinical results, while avoiding the loss of pigmentation or scarring when performed with the proper technique and on the proper skin type [15].

In general, medium-depth peels with TCA provide better results than those from superficial peels alone. TCA has a lengthy shelf life and the desquamation from TCA peels does not cause systemic toxicity. These authors often follow the TCA peels with a sweep of liquid nitrogen (rolled cotton on a cotton swab dipped in LN₂ and swept over the frosted skin to cool the skin and remove some dead keratinocytes). The results of these peels are predictable and safe, and have been shown to reduce future occurrences of basal or squamous cell carcinomas [13].

One of the most common agents utilized for deep-level peels is phenol, which is a carbolic acid compound obtained from coal tar and is absorbed very quickly. Phenol is indicated for moderate to deep wrinkles, acne scars, actinic keratoses and cheilitis, verrucae, xanthelasma [16], and even nonsurgical closures of earlobe clefts [17]. When phenol is blended with croton oil to form the phenol-croton oil peel, it reaches deep-level penetration to the dermis and the need for covering pigment changes may last as long as 6 months post-procedure [18]. Phenol peels are completely contraindicated in people with cardiac disease as the toxicity from the peeling has been found in some cases to cause undesired cardiac side effects [18]. It is preferable that windows and exhaust fans are used throughout the procedure [18].