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Print version ISSN 0365-0596On-line version ISSN 1806-4841
An. Bras. Dermatol. vol.79 no.1 Rio de Janeiro Jan./Feb. 2004
Facial skin rejuvenation by chemical peeling: focus on phenol peeling*
Maria Valéria Robles VelascoI; Fernanda Rumi OkuboII; Maria Elizette RibeiroIII; Denise SteinerIV; Valcenir BedinV
M.D. of "Faculdade de Ciências Farmacêuticas da Universidade de
IIAcademic of "Faculdade de Ciências Farmacêuticas e Bioquímica Oswaldo Cruz, São Paulo"
IIIProfessor, M.D. of "Faculdade de Ciências Farmacêuticas da Universidade de São Paulo" IVAdjunct Professor of "Faculdade de Medicina de Jundiaí; diretora da Clínica Stöckli, São Paulo"
VDirector of the "Sociedade Brasileira de Medicina Estética"; Director of the "Clínica Stöckli, São Paulo"
The natural aging of facial skin is a source of preoccupation for many, who seek out the aid of a specialized physician to minimize its signs. The skin's youthfulness can be obtained using chemical peeling made from various active substances such as glycolic, retinoic, and trichloroacetic acids and phenol. These substances proportion cutaneous exfoliation with subsequent cellular renovation. Depending on the formula concentration and pH value, peelings may be superficial, medium or deep. Phenol has been used in deep peeling. It is the main component of the Baker/Gordon formula, as well as other formula substances acting as penetration and permeation promoters. The use of these active substances results in an intensive process of cellular renovation. It decreases wrinkles, softens the presence of dark spots and gives the skin a youthful appearance. Due to its toxicity and side effects, phenol should be used carefully. Technical steps must be followed. The patient should be monitored in order to obtain maximum effectiveness from the peeling, thereby minimizing effects on the systemic functions.
Key words: chemexfoliation; skin aging; phenol
Rejuvenation techniques have been improved due not only to technological advances, but also to the population's preoccupations with health and physical appearance as well as longer life expectancy.
The process of aging results from either genetic reasons, hormonal changes in association with menopause (intrinsic aging), or environmental influences such as sunlight, wind, humidity, dermatological diseases, smoking, alcohol and eating habits.1
Changes occurring to skin through intrinsic aging lead to dryness, flaccidity, vascular alterations, wrinkles and a decrease in skin thickness.2
Cutaneous aging due to sun exposure is known as "photo-aging". It leads to the degeneration of elastic fibers and collagens, with pigmented spots appearing and pre-malignant or malignant lesions occurring. UV radiation promotes the formation of the free radicals produced, thereby increasing the number of non-localized oxidative lesions. The latter alter metabolism and are responsible for premature aging, which increases the risk of cutaneous cancer.2,3,4
Skin that has not been overly exposed to the sun is characterized by its spotless aspect, homogenous pigmentation and soft texture. As the years pass, the speed of cellular renovation slows. Peeling is a procedure that aims to accelerate the process of cutaneous exfoliation and promote cellular renovation by the use of chemical substances. This is a way in which the skin acquires a more youthful and renewed aspect.5
Chemical peeling is also called chemical resurfacing, chemoexfoliation or chemosurgery. It consists of applying one or more caustic agents to the skin so as to bring about the controlled destruction of the epidermis and its re-epithelialization. The popularity of the method is explained by the fact that it propitiates an improved appearance of facial skin, damaged by extrinsic and intrinsic factors, as well as of remaining scar tissue.6,7
Chemical peeling is classified into three types: superficial, medium and deep, as described forthwith.2,8
Superficial peeling acts on the epidermis. Alpha hydroxyacids (AHAs), beta hydroxyacids (salicylic acid), trichloroacetic acid (TCA), resorcinol, azelaic acid, Jessner's solution, solid carbon dioxide (CO2), and tretinoin are utilized as active substances. Superficial peeling is recommended for cases of acne, light photo-aging, hyperkeratotic eczema, actinic keratosis, fine winkles and melasma.2
Medium peeling acts at the level of the papillary dermis. It is used in combination with the following active substances: TCA with CO2, TCA with Jessner's solution, TCA with glycolic acid, or only TCA and resorcine. It is recommended for the same purposes as superficial peeling, in addition to being recommended for epidermal lesions.
Deep peeling acts on the reticular dermis. Active ingredients used are TCA at 50% and phenol (Baker/Gordon solution), among others. It is recommended for cases of epidermal lesions, blotches, scars, actinic dyschromias, moderate wrinkles, keratosis, melasmas and lentigos.
Superficial and medium peeling
Superficial peeling is usually epidermal and offers no risk of complications in patients. It can be used on all types of skin and in any area of the body. Jessner's solution is also used, as is a combination of resorcine, salicylic acid, lactic acid and ethanol. Solid CO2, or 'dry ice', is usually used for cases of acne. TCA, among numerous other active substances, may be employed in formulas (concentrations of 10 to 35 percent) to precipitate medium depth peelings.2
AHAs are part of a group of substances used in these peeling categories. They consist of milk derivatives (lactic acid), citrus (maleic and citric acid), grape (tartaric acid) and sugar cane (glycolic acid), but they may also be synthetic in origin. They differ according to molecular size, with glycolic acid being the smallest and yet the most powerful for penetrating the skin. AHAs are effective in treating wrinkles, dehydration, thickening and irregular pigmentation of the skin.2,9
Glycolic acid is used most in cosmetic formulas. Due especially to its small molecule size, it has a greater power of penetration in relation to other AHAs. In addition to the concentration used, it is important to consider the pH value of the preparation, which may vary from two to four. The lower (or more acidic) its value is, the higher the peeling's exfoliating action. Its irritant power on the skin (a pH value of 3.5) is ideal for good exfoliation. During the treatment it is important to use a sunscreen for better daytime skin protection.9
Medium peeling is used to remove actinic keratoses, wrinkles, pigmentary dyschromias, or to improve the appearance of scars. The classic chemical agent used for this type of peeling was TCA, in concentrations of 50 percent. But TCA has the inconvenience of causing skin problems, such as the appearance of scars and cutaneous hypopigmentation. Owing to this, TCA has been used in combination with other active substances, such as glycolic acid, CO2 or Jessner's solution (resorcinol, salicylic acid and lactic acid). TCA acts on the epidermis and dermis, while its active mechanism consists in exfoliation and the destruction of the corneal stratum, which occurs after cellular renewal.2,9
1. Phenol peeling
1.1. Characteristics of phenol
Phenol or carbolic acid (C6H5OH) is derived from coalter. With a molecular weight of 94.11g, it is characterized as needle-shaped crystals varying from colorless to pink, with a characteristic odor. It turns to liquid when heated, letting off an inflammable vapor in the process. Its color darkens when exposed to air and light. Its fusion point is approximately 39º C, with boiling point at 182º C. Phenol produces a coagulation of skin proteins. It is considered to be a chemical agent producing intense facial rejuvenation when used correctly.10,11,12
Clinically, phenol produces bacteriostatic effects in minimum concentrations of up to 1 percent. When above this concentration, it possesses bactericide action. In the nerve endings of the skin, phenol acts as a local anesthetic.12
As a chemical compound, phenol is soluble in oils and fats. In case of accidental contact, it is quickly removable from the skin with glycerin, vegetable oils or 5 percent ethyl alcohol.12
The best-known formula for phenol-based peeling is Baker-Gordon's (1962) in which phenol is diluted to a concentration varying from 45 to 55 percent.6,13,14
Croton oil is a fixed oil extracted from the seed of the Croton tiglium plant. In the formula, it is a component that raises the capacity of phenol to coagulate the skin's keratin, as it acts as a promoter of cutaneous penetration in elevating the site's vascularization. It is considered to be a resin, and its bioactivity is due to free hydroxyl groups. Highly toxic for the skin, croton oil causes edema and erythema. It is insoluble in water and highly soluble in alcohol and benzene (phenol is a mono-hydroxybenzene).10
Liquid soap, due to the presence of tensoactive detergents as a vehicle in the formula, reduces the superficial tension of fat present in the skin. It removes it in function of its emulsification, eases penetration of the phenol into the skin, and thereby promotes more homogenous peeling. In this way, it also acts as a penetration promotor.10,12
Baker-Gordon's Formula originally used Septisolâ (hexachlorophene in ethyl alcohol). McCollough and Langsdon believe that the aqueous solutions of hexachlorophene may deposit an oily residue on the skin which delays penetration of phenol and reduces the adherence of the tape mask subsequently placed over the peeling. However, the formula makes use of hexachlorophene in ethyl alcohol (Septisolâ) due to its probable keratolitic action and to facilitate phenol penetration.10,12
Water is the vehicle used to reach the desired concentration of phenol in the formula.15
Moy et al.16 mention that the intense and deep reaction of Baker's peeling occurs due to a combination of components in the formula causing increase of penetration and irritability of phenol. In the absence of these components in the formula, proportional reactions occurred with the concentration of phenol and less intense results on the skin with respect to the power of exfoliation in relation to Baker's peeling.16
Regarding pharmaceutical form, Baker's formula is a suspension - it is formed by fine particles of a solid component dispersed in a liquid medium. However, it has to be shaken prior to use in order to ensure homogeneity in the application and effectiveness in the treatment.17
Phenol in an 88 percent concentration penetrates the superior reticular dermis and is keratocoagulant, which prevents it from permeating to deeper layers. The phenol diluted in the formula acts as a keratolytic agent. It breaks keratin sulphur bridges and penetrates deeper, as it is 'biotransformed' by the liver and excreted by the kidneys. The higher the phenol concentration is in the formula, the greater the coagulation of keratin, the lower its penetration and the lower its toxicity.6,10
When applied to the skin, the phenol induces a chemical burn, which in time results in the rejuvenation of the skin. The application for a longer period of time occasions its penetration into the superior dermis, resulting in the formation of a new layer of stratified collagen. Epidermal regeneration is initiated 48 hours after application of the formula and is complete within an interval of seven to 10 days.18
Phenol peeling is recommended for the following cases:
• bleaching of skin
• hyperpigmentation or heterogeneous pigmentation
• treating acne
• actinic lentigos
• solar and seborrheic keratoses
1.3. Application procedures
a) Sedation: the phenol in Baker-Gordon's solution has an anesthetic effect, however its action on the intermediary reticular dermis is very painful for patients. Nonetheless, sedation may be used and, later, analgesics, while continually monitoring the patient.
b) Prior preparation of skin: ether can be used, but a less volatile solution may be opted for, such as ethyl alcohol, acetone alcohol mixture or other organic solvents. Removing any surface fat or oil is important for uniform penetration of the phenol. Facial hair must be removed to avoid discomfort for the patient.18
c) Preparation of phenol liquid suspension. According to what has been described in the course of the text.
d) Application of the phenol solution with cotton, gauze or cotton-tipped swab.
The face is subdivided into six areas. Peeling is first applied to the forehead region, followed by the right cheek, left cheek, perioral region, periorbital region and the nose or chin, depending on the physician's decision, though the application should always be initiated over the largest area.
The solution is allowed to rest for 10 to 15 minutes prior to continuing application on the next area. The phenol does not affect growth of hairs and may be applied in areas such as the beard, eyebrows and scalp.15,18
Vigorous friction must be avoided, but it may produce very rapid penetration of the phenol and, consequently, a greater risk of intoxication.19
e) Placement of the tape mask or Vaseline ointment, which will only be removed after 48 hours. Another option would be to leave the face at rest without the use of a mask. Occlusion with Vaseline ointment does not produce the same depth of penetration as with the use of adhesive tape mask. At some points, the adhesive block gives way almost spontaneously between 48 and 72 hours after peeling. There is no need for anesthetic, but only for an analgesic to remove the adhesives from the skin. Ice bags over the mask help to alleviate existing pain. The edema, exudation and crusts are intense, but the skin may be left without a curative. The use of Vaseline ointment is quite enough.12
The use of a waterproof tape mask with zinc oxide is the most occlusive system. It increases the penetration of phenol, but reduces water evaporation from the formula.18
After removing the mask from the patient, the skin is treated with thymol iodide (or another antiseptic) to help healing. For patients who feel pain after the peeling, analgesics may be recommended. Antibiotics may also be prescribed to avoid infections and cream or Vaseline ointment to hydrate the skin. The ideal is to apply a Vaseline ointment in association with an antibiotic, like the various specific options available on the market.12,15
According to each patient, after the second week of post-peeling, hypoallergenic make-up may be used and, by the end of the sixth week, a sunscreen.15 (Figures 1 to 6)
1.4. Toxicity and Precautions
Baker-Gordon's formula used in peeling may cause permanent cutaneous hypopigmentation in some individuals. It may also lead to phenol absorption, resulting in cardiac arrhythmia and kidney damage.7
Phenol is toxic for all cells. It penetrates and permeates the skin, is absorbed and is excreted in urine. Twenty to 25 percent of the absorbed quantity is transformed by the liver into glucuronic acid and sulfuric acid, and thereafter excreted. High concentrations in the blood may have a toxic effect for the myocardium, provoking tachycardia, premature ventricular contractions, atrial fibrillation, ventricular fibrillation and electromechanical dissociation. Seventy to 80 percent of the phenol absorbed is excreted in urine in 15 to 20 minute intervals after application. This is why when using phenol peeling, the face is divided into at least five regions. Thereafter, the product is applied to each region at 15-minute time intervals so that the concentration absorbed is eliminated in urine, without causing any cardiac problems.15,20
To increase phenol excretion and minimize systemic complications, patients are hydrated with endovenous fluids and followed up with cardiac monitoring.20
As precautions when using phenol peeling, patients who register the following ailments must be avoided: existence of heart, kidney and hepatic disease; appearance of herpes; continual exposure to UV rays; recent use of isotretinoin; psychological instability; predisposition towards keloids and skin types IV to VI, in accordance with Fitzpatrick or Glogau classification (including wrinkle types).2,13
The ideal patient for this type of peeling must have skin that is light in color, fine and dry, or in other words, individuals with Fitzpatrick skin types I and II with fine wrinkles. Men have thicker skin, which reduces the action of phenol and results in lower effectiveness of treatment when compared to women.13,18
a) Appearance of pigmentation alterations may occur as a result of the inflammatory process. Hypopigmentation may occur as a result of toxicity of phenol to melanocyte, but this is rare. The loss of pigmentation of the skin varies according to the patient and his/her skin type.12
b) Appearance of ectropia, with contraction of the lower eyelid possibly occurring.
c) Appearance of infection, mainly by microorganisms, such as Staphylococcus sp, Streptococcus sp and Pseudomonas aeruginosa.21
d) Appearance of prolonged erythema that may persist during a period varying from two to four months after the deep peeling. It may be treated with a 2.5 percent hydrocortisone-base cream.21
e) Appearance of deeper scars in post-peeling, possibly permanent ones. The most common regions affected are the lips, eyelids and mandible.21
f) Appearance of small white cysts or milias, due to the quick re-epithelialization of the skin.21
Phenol peeling results in intense facial rejuvenation, due to action of the drug employed in the formula that penetrates and permeates the skin deeply. It brings about deep-skin damage followed by a regeneration process with peculiar and long-term characteristics. The Baker-Gordon formula has components that intensify the phenol activity in the skin, performing like permeation promoters. For lack of these components, peeling diminishes its effectiveness to promote intense cellular regeneration.
In spite of the evident advantages of phenol peeling, the toxicity of the active component and the possible complications in post-peeling require the peeling procedure to be performed safely, according to instructions and with a medical follow up.
If used appropriately by the physician, the benefits of phenol peeling will be felt and appreciated by patients. It is an effective method to combat cutaneous ageing.
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Maria Valéria Robles Velasco de Paola
R. Estela, 287 apto 133 - Paraíso
São Paulo SP 04011-001
Tel/Fax: (11) 3091-3623 / 3815-4418
in September, 06th of 2001.
Approved by the Consultive Council and accepted for publication in January, 24th of 2003
* Work done at "Faculdade de Ciências Farmacêuticas, USP"