• Choosing a glycolic acid peel formulation

Glycolic acid in its raw form is a crystal which is then dissolved into a vehicle. The diluent’s vehicle can impact the peel’s efficacy and is an important part of the practical clinical consideration in peel selection. For example, glycolic acid peels that are formulated in a gel based vehicle may have a partition coefficient that slows the delivery of the active agent. The effect would be to make the active peel ingredient less bioavailable to the skin, thereby slowing the process and rendering it less attractive as an office-based procedure in which a quick response time is needed. However, AHA peels formulated in a gel base may be well received by patients with sensitive skin or rosacea who are desirous of the peel and are only interested in mild exfoliation and no irritation. On the other hand, aqueous based peel solutions containing glycolic acid allow ready passage through the stratum corneum and are generally favored in those wanting a quick response with a greater degree of desquamation post peel.

Glycolic acid peels are now available in a variety of delivery systems that are classified as follows:

A free glycolic acid solution refers to a non-neutralized solution of glycolic acid. The glycolic acid then exists in an acidic pH ranging from 0.6 (for a 70% glycolic acid solution) to 1.7 (for a 20% glycolic acid) or 7.0 to 20% glycolic acid in an aqueous vehicle. The free glycolic acid has greater bioavailability and reactivity when applied to the skin which is manifested by erythema. Epidermolysis can result if there is any disturbance in the skin barrier function prior to the peel application.

A partially neutralized glycolic acid peel formulation refers to the combination of the acid with a base; for example, with ammonium hydroxide to yield the salt ammonium glycolate. The pH of this solution is then increased (mean pH is 3.8).

A buffered glycolic acid peel formulation refers to a solution that resists pH changes on addition of acids or bases. When there are equal molar concentrations of glycolic acid and sodium glycolate, the glycolic acid peel solution is then stabilized against the addition of stronger acids in the pH range of 2.8 to 4.8. The role of buffered glycolic acid peels does not appear to offer any practical benefit in its sole use as a peeling agent in the office setting. Marketing tactics have blurred the science and have promoted the concept of buffered solutions to really denote partially neutralized solutions of glycolic acid.

Esterified glycolic acid peel solutions refer to a solution forming a glycol-citrate. This occurs when an ester bond forms between the carboxyl group of glycolic acid and the hydroxyl group of citric acid. The stability of the created dimer of glycolyl citrate or citryl glycolate is questioned. The marketing claims attributed to this admixture of AHAs are that there is less skin irritation; however, this needs further substantiation.

• Reviewing the history and examination

At the time of the prepeel consultation, the physician should obtain a detailed medical and skin history.

Any prior history of viral infections, such as chronic or recurrent herpes simplex, active dermatoses of the atopic, seborrheic or eczematous types, and medications such as topical or oral retinoids, must be reviewed. Those patients with a history of recurrent herpes infection should be treated prophylactically with oral antiviral agents, preferably Valtrex (valacyclovir), on the morning of the peel and continued for a routine course of therapy. If the patient presents on the morning of the peel with active herpetic infection in the areas to be treated, it is best to postpone the peel until complete resolution has occurred.

Oral and topical retinoids may cause disruption of the stratum corneum and thereby enhance the depth of penetration of the glycolic acid peel. Therefore, patients on oral isotretinoin or topicals, such as tretinoin, adapalene, or tazarotene, may experience increased reactivity to the glycolic acid peel. It is then recommended that the topical agents be stopped at least 7 days in advance of the peel. Because isotretinoin needs to be a continuous therapy and there are questions concerning delayed healing with this therapy, it is best left to the physician’s expertise when to undertake glycolic acid peels in this setting.

Other medications that may affect peel penetration are topical 5-fluorouracil, such as Efudex or Carac, or immiquimod, such as Aldara. The 5-fluorouracil agents and imiquimod will disrupt actinic keratoses and therefore glycolic acid peels may cause epidermolysis of these treated sites. This reaction is favored since effacement of the actinic lesions is integral in the destruction of these premalignant conditions. However, the patient must be prepared in advance that this reaction will occur and to expect a consequent increased recovery period marked by scabbing and desquamation. In addition, those patients on antiplatelet agents such as warfarin, heparin, aspirin, NSAIDs, and even vitamin E, may experience bleeding and eschar development in these combined treatment sites.

Patients using photosensitizing agents such as oral contraceptives and tetracyclines and their derivatives should be counseled to adhere to postpeel instructions regarding strict sunscreen use and photoprotection.

Patients with a history of atopy, eczema, dry and sensitive skin may favor the partially neutralized formulations or lower concentrations of the free glycolic acid peel, or may not be candidates for any peel at all, depending on the severity of their disorder. In order to determine their potential reactivity to the peel, it is recommended that these skin types in particular (and in my practice anyone undergoing a glycolic acid peel) first have a trial period at home using topical products containing glycolic acid for 2 weeks before the peel. I recommend that the patient be started on an 8 to 10% glycolic acid product initially. Any unusual sensitivity to glycolic acid can thereby be unveiled during this prepeel preparation and the peel then could be forfeited. It is best recommended that patients who have undergone dermabrasion, ablative laser resurfacing or other surgeries, or deeper chemical peeling agents wait at least 6 to 12 months for complete healing to take place before undertaking a glycolic acid peel.

• Exclusions to glycolic acid peels

Because of the potential for the herpes virus, or possibly papilloma and pox virus, to spread into sites of freshly desquamated skin, active herpes simplex infections, facial warts or molluscum contagiosum would exclude a patient from receiving a glycolic acid peel. It is best recommended that these conditions be treated first and resolved before the peel is undertaken.

Other cosmetic treatment programs, such as microdermabrasions, electrolysis, depilatories, hair removal lasers or waxing, bleaching agents, masks, scrub exfoliants, and loofahs, should be discontinued 1 week prior to the peel to minimize disrupting the epidermal barrier immediately before the peel. In some cases of acne scarring, etc., the combined used of microdermabrasion prior to the peel has been undertaken, but results may vary and the physician should consider this only if the effects of the peel have been established on the designated patient.

Patients who are not reliable in their photoprotective behavior should be excluded from the glycolic acid peels.

• Face peel procedure: supplies and technique

The equipment needed for a glycolic acid peel is in general readily available in a physician’s office, with perhaps a few exceptions. The required supplies include those listed in Box 4.3.

While the patient is recumbent on the table, the head should be slightly elevated and a drape sheet placed around the patient’s neck. The physician should first do an inspection of the skin to ensure that there is no existing abrasion, areas of irritation or inflammation. To a clean face, the peel cleansing solution (which is generally an alcohol based product) should be applied to remove any final debris. Petrolatum is then applied sparingly to the lateral and medial canthi, oral commissures, nasal alar grooves, and lips. This is used as a protectant against potential pooling sites of the acid after application. A fan should be directed at the patient’s face and turned on; a hand-held fan should be offered to the patient for further personal comfort.

Patients should be instructed to keep their eyes closed during the procedure. If the peel solution should enter the eye, immediately flush the eye with water. The sensation of the solution is akin to lemon juice in the eye. To date, this author has not seen any serious sequelae, even with 70% glycolic acid inadvertently entering the eye, if the eye is immediately flushed with water.

The peel procedure is begun by applying the solution to the face, beginning at the forehead and working it down over the cheeks, chin, nose, and upper cutaneous lip. A timer is activated, counting upwards at the start of the procedure to adequately record the time to erythema. If blanching or frosting indicating epidermolysis is encountered in any particular areas, then immediate neutralization should be performed at that site(s). Once the skin has achieved a uniform degree of erythema, the timer is then stopped and full face neutralization is administered with a bicarbonated solution. Neutralization is designated by a foaming reaction that is readily apparent. At the same time, cool water is sprayed onto the face for the patient’s comfort as it helps control the exothermic reaction achieved by the acid-base neutralization procedure. The patient should be apprised prior to the neutralization process that they may experience some initial stinging that may be more intense than the acid application itself but that this will swiftly subside.

Different manufacturers of the glycolic acid peel have varying techniques for applying the peel, ranging from the brush application to peel pads. The pads vary depending on whether they are individually wrapped or packed in jars of 30 to 60. The applicator may be chosen depending on the facility and competence of the operator performing the peel. The pads allow for easy application whereas more care may be needed for the brush technique to prevent drippage. Nonetheless, the brush technique may make application for the lower eyelids and upper cutaneous lip technically easier to perform. The overall results will be the same and really depends on operator’s preference.

This author recommends that the patient is first treated with low levels of free glycolic acid; that is, either 20 or 30%. This may be considered the introductory or baseline peel. By starting with low concentrations of the glycolic acid, the operator has an opportunity to determine the patient’s sensitivity to the peel. The glycolic acid should be left in contact with the skin until erythema erupts. The endpoint then of the peel is clinically evident and marked by an even erythema. This usually occurs after the acid has been left in contact with the skin for 2 to 5 minutes. If after a 5-minute contact time there is no visible erythema, it is still recommended that the reaction be stopped. If for any reason the patient is uncomfortable, the reaction can be neutralized before the endpoints of erythema or time are reached. The degree of discomfort may be assessed by asking the patient to rate it on a scale of 0 to 10 (with 10 noted as the greatest degree of discomfort). If the patient verbalizes a score of 8 to 10 at any time during the procedure then the reaction should be terminated. Furthermore, if at any time during the peel blanching (epidermolysis) is noted, the glycolic acid should be neutralized in that area(s) and rinsed with cool water. Some physicians then recommend a topical steroid to decrease irritation. A hydrocortisone cream 1% can be used here.

If the glycolic acid 20 or 30% peels solution is tolerated for 5 minutes, then subsequent glycolic acid peels should be performed at the next higher concentration. If the 5-minute time point has not been achieved, or if erythema occurs earlier than 5 minutes, then the peel should be neutralized. At the next visit, the next peel should resume at the previous concentration but maximized at the 5-minute time point.

The neutralization process, as mentioned above, is performed to stop the reaction of the acid on the skin. Neutralization is completed when there is no further foaming reaction on the skin. Before this process is initiated, the eyes can be protected by placing a damp 2″ × 2″ (5 cm²) gauze Versilon sponge on the patient’s closed eyelids. In addition, after the bicarbonated neutralizer and water spray, a postpeel moisturizer and a cold mask or frozen 4″ × 4″ (10 cm²) gauze sponges are applied for about 5 minutes. This is for furthering patient comfort after the peel.

• Body peel procedure

Any cosmetic unit can be treated with a glycolic acid peel. In general, chest, back, forearms, dorsal hands, and legs are easily treated with higher concentrations of glycolic acid without fear of overtreatment. However, necks are the more sensitive body area and conservative treatment with lower concentrations first is recommended.

• Epidermolysis

This can occur unexpectedly if a patient does not inform the physician that they have not discontinued their topical retinoids (Tazarotene, Adapalene, tretinoin), at least 1 week prior to the peel. This occurs because topical retinoids can enhance the penetration of the glycolic acid peel. Another risk of increasing peel penetration is prior treatment of the skin with aggressive scrubbing with loofahs or other exfoliating beads or puffs, or if microdermabrasion is employed immediately prior to the peel. Once epidermolysis does occur during the peel due to these situations, the patient may experience scabbing and should be informed that it may take up to a week for recovery to take place. Moisturization with glycolic-acid-free products is necessary and topical hydrocortisone may be employed, depending on the amount of irritation and edema. If severe edema occurs, a prednisone 6-day pack may be needed. Depending on the patient’s history, oral antiviral agents against herpes (Fig. 4.1), as well as oral antibiotics, should be considered. Topical antibiotic ointments such as Bactroban can be used on crusted areas to keep them moist.

Figure 4.1 Herpes simplex after a glycolic acid peel (GAP)

• Hyper- or hypopigmentation

The risk of hyper- or hypopigmentation is increased if deep penetration occurs on scrubbed or rubbed sites. A perioral acneiform dermatitis has been noted in a small number of patients, particularly on the chin (Figs 4.2 and 4.3). This phenomenon is unexplained. Nonetheless, it should be treated as a perioral dermatitis and further peels avoided on the chin. Other rare occurrences are urticaria development but this responds to topical hydrocortisone (Fig. 4.4).

Figure 4.2 Perioral dermatitis occurring a few days post GAP

Figure 4.3 Perioral dermatitis post GAP

Figure 4.4 Uritcaria post GAP

• Photoaging

The use of glycolic acid peels in photoaging is meant to help to improve fine lines but not coarse wrinkles. In order to treat coarse wrinkles there are many options, but it is possible to use combinations of 70% glycolic acid peels immediately prior to 20% tricholoracetic acid (TCA) peels to enhance the benefit of the TCA without increasing TCA concentrations (Fig. 4.5).

Figure 4.5 Combination peel of GAP 70% and TCA 20% showing: the baseline (A); immediately afterwards (B); peeling (C); after 12 days (D); after 1 month (E)

Glycolic acid peels should be considered when trying to improve the appearance of the skin by lightening lentigines, ephelides, and other dyschromias caused by sun damage. In addition, rough-textured skin can be softened and the overall tone and complexion of the skin improved. These peels are reserved for those patients seeking little recovery time and who are willing to return for a series of treatments to meet their goals. Many patients use the glycolic acid peel in conjunction with botox and fillers and other minimally invasive procedures.

Home-care products should be strongly encouraged in this population, as well as strict photoprotective measures.

• Acne

Since acne is a multifactorial condition it may be necessary to use combination therapies to achieve an improvement, especially in the case of comedonal, papular, and pustular subtypes. Glycolic acid peels have been proved to have an important role in the management of acne vulgaris. While it is by no means a solitary therapy nor an alternative to oral or other topical therapies, it is best recommended as a complementary treatment. The mechanism of action of glycolic acid peels in acne may be the promotion of exfoliation of the skin, thereby inducing a slough of the keratotic plug and reduction of microcomedone formation. Shallow acne scarring can also be improved, as well as postinflammatory hyperpigmentation, if these peels are performed on a consistent and serial basis (Figs 4.6–4.10).

Figure 4.6 Acne. Baseline (A); 1 day post-GAP 70% treatment (B)

Figure 4.7 Acne. Baseline (A); 2 weeks post-GAP 70% treatment (B)

Figure 4.8 Acne. Baseline (A); immediately post-GAP 70% treatment (B); 5 months after baseline (C)

Figure 4.9 Acne. Baseline (A); after treatment with a series of GAPs (B)

Figure 4.10 Acne. Baseline (A); after treatment with 1 × 20% and 2 × 35% GAPs (B)

• Seborrheic keratoses

Seborrheic keratoses can be treated with a variety of means, such as cryosurgery, electrodessications and curettage, lasers, intense pulse light, and other peeling agents. Glycolic acid peels can be used on these lesions if patients prefer another alternative.

These lesions can be treated singly with a 70% glycolic acid peel solution until epidermolysis occurs. The areas treated will then scab and peel within 7 days and heal easily. Topical antibiotic ointments or Vaseline or petrolatum jelly should be used in an effort to keep the skin moist.

• Melasma

Melasma is a particularly difficult dyschromia to treat with any of the current treatment options available today. Nonetheless, glycolic acid peels have proven to improve melasma if done over a series of treatments performed at least on a monthly basis. Higher concentrations, such as 70% peel solutions, have been shown to be the most effective of this peel type. Home-care products including bleaching agents, as well as topical retinoids and glycolic acids, are also recommended.

• Keratosis pilaris

Keratosis pilaris is amenable to treatment with glycolic acid peels of the face, upper arms, and thighs. The peels, especially in higher concentrations, can lead to desquamation and sloughing of the perifollicular keratotic lesions, thus yielding softer skin (Fig. 4.11). However, it is important to mention that the erythema generally associated with keratosis pilaris is not treatable with the glycolic acid peels. In addition, the condition will naturally recur as this is not a permanent treatment. It is best recommended that higher concentrations of glycolic acid lotions (12–20%) be used as maintenance therapy.

Figure 4.11 Keratosis pilaris rubra faceii (KPRF). Baseline (A); post-GAP 70% treatment (B)

• Warts

Recalcitrant warts have posed a treatment challenge. Glycolic acid peel solution can be applied to a small cotton pledget to a wart after being taped onto the affected extremity site. The pledget is removed after 1 hour exposure, earlier if the patient experiences any stinging or irritation. It is best to apply Vaseline around the site to prevent leakage onto normal skin (Figs 4.12 and 4.13). The success of this treatment is really dependent on the compliance of the patient. Patients should expect peeling and possible blistering after this treatment and the aftercare is similar to that post liquid nitrogen.

Figure 4.12 Wart showing epidermolysis 1 day post-GAP 70% treatment

Figure 4.13 Central clearing of warts on one foot

• Actinic keratoses and actinic cheilitis

There are many treatment options for actinic keratoses, as listed in Table 4.1. Nevertheless, glycolic acid peels can be added to that list. The use of glycolic acid peels in combination with 5-fluorouracil is recommended to ensure treatment of the actinic keratoses. It is felt that alpha-hydroxy acids increase skin permeability and thereby may enhance penetration and increase the efficacy of 5-fluorouracil in the treatment of actinic keratoses (Figs 4.14 and 4.15). In addition, since AHAs increase desquamation, there may be reduced 5-fluorouracil-associated inflammatory reactions. I recommend that patients be pretreated with 5-fluorouracil 5% cream for 1 week prior to a 70% glycolic acid peel that is usually applied to the point of epidermolysis, which usually occurs within 2 minutes of treatment (Fig. 4.16). It is believed that the actinic keratoses treatment is initiated with the 5-fluorouracil 5% cream which then allows for selective treatment of actinically damaged skin by the glycolic acid peel. In a 1998 actinic keratoses study evaluating 18 subjects in a half-face, randomized, comparison it was reported that the combination of 5-fluorouracil cream with 70% glycolic acid peel provided a 92% therapeutical effect of treating actinic keratoses, compared to a 20% clearance with glycolic acid peels alone. 5-Fluorouracil cream alone eliminated about 75% of the actinic keratoses. Therefore, there is an increase in efficacy with a shortening of 5-fluorouracil cream exposure time, which appeals to many patients with photodamaged skin.

Table 4.1 Some treatment options for actinic keratoses

Figure 4.14 Actinic keratosis. Baseline post-5-fluorouracil (A); 2 weeks post-GAP 70% treatment (B)

Figure 4.15 Actinic keratosis. Baseline post-5-fluorouracil (A); 2 weeks post-GAP 70% treatment (B)

Figure 4.16 Actinic cheilitis. Baseline (A); pretreated with 5-fluorouracil (B); 3 days after GAP 70% (C); clearing 1 week after GAP 70% (D)