Fig. 15.1
(a) Before 70 % glycolic acid peels (b) after 4 biweekly sessions of 70 % glycolic acid peels
Mild desquamation.
Uneven penetration into the skin.
Neutralization with sodium bicarbonate solution is needed.
Adverse events are slight discomfort, burning, erythema, and pigmentary changes.
Glycolic acid, a derivative of sugar cane, is the most widely used alpha hydroxy acid. It has the smallest molecular weight of the AHAs and thus is able to penetrate the skin easily. Often used in concentrations of 20–70 %, its absorption into the skin is dependent on its pH, concentration, and length of application time on the skin. It should be used in lower concentrations initially, gradually increasing the concentration in subsequent sessions with an interval of 2 weeks between treatments. Peel neutralization is particularly important and should immediately follow the timed application of the peel. The longer the duration on the skin, the deeper the depth of the peel. Application of the GAP is associated with a mild stinging and/or a burning sensation. To counter this discomfort, the author prefers to use an ice cube wiped over the face followed by a peel neutralizer significantly alleviating any distress that the patient might be experiencing. Advising the patient in advance of the discomfort will also help them mentally prepare for this.
The usefulness of GAP for the treatment of melasma has been widely documented. In a study by Erbil et al., 28 women with melasma underwent serial glycolic acid peels (35–50 %, and 70 % every second peel) alone and in combination with topical azelaic acid 20 % cream and adapalene 0.1 % gel over a 20 week period [2]. There was significant decrease in the Melasma Area Severity Index (MASI) scores (p = 0.048) in the group receiving the chemical peels plus topical treatment but only with GAP of 50 % and higher. However, three patients in the glycolic acid peel group developed a mild degree of PIH with total clearance at the end of the treatment period.
Lim, et al. demonstrated in ten Asian women the efficacy of GAP done every 3 weeks (20–70 %) alone or in combination with 2 % hydroquinone and 10 % glycolic acid cream. After eight peels, the subjects on GAP with combination cream trended towards significant improvement (p < 0.06) in their melasma with lightening of the condition [3].
Sarkar, et al. found a significant decrease in the MASI scores (p < 0.001) of 20 Indian patients receiving six serial GAP (30–40 %) combined with a topical modified Kligman’s formula (2 % hydroquinone, 0.025 % tretinoin, and 1 % mometasone) as compared to the 20 patients who received the cream alone. The only adverse events observe with GAP were mild burning, erythema, desquamation, and transient hyperpigmentation [4]. A similar result was shown by Chaudhary and Dayal on 20 Indian patients who underwent serial GAP with a topical regimen (2 % hydroquinone, 1 % hydrocortisone, and 0.05 % tretinoin) versus cream alone. After 24 weeks, there was an overall decrease in MASI from baseline in both the groups (p value <0.05). The group receiving the glycolic acid peel with topical regimen showed early and greater improvement than the group which was receiving topical regimen only [5].
15.2.1.2 Lactic Acid Peel (LAP)
Fast Facts
Sour milk derivative.
Serial peels done every 2–3 weeks.
Peel neutralization is needed.
Adverse effects are uncommon: mild erythema, flaking, and burning sensation rare.
This is often called a “starter peel” because the lactic acid peel is the most gentle of all the chemical peels and usually results in few side effects. The following support its use as an option in brown skin. Lactic acid peels were found to be an effective and safe peeling agent in a study involving 20 Fitzpatrick skin type IV patients with melasma. Lactic acid peels (92 %, pH 3.5) were applied on the face once every 3 weeks. A maximum of six sessions resulted in marked improvement as seen in the MASI scores (56 % decrease) [6].
Sharquie compared the use of LAP (92 %, pH 3.5) on the left side of the face and Jessner’s solution on the right side of the face on 30 Fitzpatrick skin type IV patients with melasma. Peeling was done once every 3 weeks for 2–5 sessions. There was significant improvement in MASI scores from baseline in both groups without any side effects noted. LAPs were shown to be as effective as Jessner’s solution [7].
Further, Magalhães also reported the successful use of serial sessions of 85 % LAP on 33 melasma patients, predominantly of phototype IV. There was a significant reduction in both MASI (average decrease of 7 points) and melasma quality of life scales. This peel was also found to be safe, with an almost total absence of adverse events. The only events verified were light and transient erythema and edema immediately after the procedure [8]. Singh used LAP 82 % applied every 2 weeks for 12 weeks on 20 patients Fitzpatrick skin type IV–V with melasma. The decrease in MASI score was statistically significant (p < 0.05) at 12 weeks and all follow-ups. There was 35.7 % of total improvement at final visit (24 weeks) with a burning sensation noted as the only side effect of treatment [9].
15.2.2 Beta Hydroxy Acids (BHA)
15.2.2.1 Salicylic Acid Peels (SAP)
Fast Facts
Beta hydroxy acid from willow bark.
Anti-inflammatory and antimicrobial effects.
Lipophilic nature with a comedolytic effect.
White precipitate represents crystallization of the acid (pseudofrost).
Adverse events are a stinging sensation on application, erythema, dryness, excessive crusting and desquamation, and salicylism.
Salicylic acid is beta hydroxy acid which can be used in low concentrations of 1–2 % in over the counter acne products or in higher concentration of 20–30 % to produce a superficial chemical peel.
Its efficacy as a peeling agent has been demonstrated in darker skin patients treated with a series of 20–30 % SAP for acne vulgaris, post-inflammatory hyperpigmentation, and melasma [10]. Bari likewise documented its use in Fitzpatrick skin type IV and V patients, treated with a series of eight weekly sessions of 30 % SAP. There was a 35–63 % improvement (p < 0.05) in all facial dermatoses treated such as melasma, acne vulgaris, and post-inflammatory hyperpigmentations without significant side effects [11]. In a comparison of 30 % SAP and Jessner’s solution for epidermal melasma, it was shown that both were equally effective peeling agents with only mild adverse effects in sixty Asian patients predominantly skin type V with melasma [12]. Sarkar has documented the use of three consecutive 20 % and 30 % salicylic acid peels done weekly followed by the 2 % hydroquinone/0.025 % tretinoin cream in between peels in 20 Indian patients. This led to a significant decrease in MASI scores (p < 0.05) [13].
In the treatment of melasma, the author recommends a series of SAP done once every 2 weeks using a 20–30 % concentration (Fig. 15.2). As a precautionary measure, start with a 20 % SAP, left on the skin for 3 min to test the patient’s reaction to the solution. Frequently a stinging or burning sensation is experienced during the peel, followed by skin dryness lasting for a few days. The discomfort lasts only for 1–2 min and can be eased with the use of a handheld fan and application of ice post peel. There is also more visible peeling as compared to a GAP.
Fig. 15.2
(a) Before salicylic acid 20 % peels (b) after 4 biweekly sessions of salicylic acid 20 % peels
15.2.3 Trichloroacetic Acid Peels (TCA)
Fast Facts
Colorless crystalline solid.
Formulated using weight-in-volume method (TCA 10 % solution is 10 g TCA + water to make a 100 ml solution).
Uniform application.
Endpoint is frosting which indicates protein denaturation (Fig. 15.3a).
Fig. 15.3
(a) Immediately after a TCA 30 % peel with frosting and erythema (b) post-peel cracking
No need to neutralize.
Adverse events are a moderate to severe burning sensation, erythema, post-peel cracking (Fig. 15.3b), PIH, scarring.
Considered the gold standard of chemical peels, TCA is well researched, stable, and easy to prepare and has no systemic toxicity. It is considered the most versatile of the peeling agents and can be used alone or in combination with glycolic acid or Jessner’s solution to produce a medium-depth peel. TCA is a coat-dependent peel, and the operator has to carefully observe the skin for the frost which may be seen as only a wisp in brown skin patients. At times, erythema is seen, but frosting is not observed. Thus relying on the number of coats is more important than waiting for the frost. It is best to wait for a coat to sufficiently dry and observe for the color changes on the skin before applying another coat. The more coats, the deeper the peel; consequently, multiple coats of a 15 % TCA can mimic the results of one to two coats of 35 % TCA [14, 15]. Thus, it is prudent to use only TCA 10–30 % in the management of melasma in brown-skinned patients and start off with 1–3 coats. Using a lower concentration of TCA will likewise decrease the likelihood that the peel will cause uneven penetration into skin, so-called hot spots. A major complaint by most patients is the initial experience of heat that develops into a moderate to severe burning sensation, lasting for a couple of minutes. The use of a handheld battery-operated fan and the application of cold wet compresses alleviate the discomfort. Soliman, et al. reported that 20 % TCA plus 5 % ascorbic acid cream was superior to TCA alone in 30 women with Fitzpatrick skin type III-IV. There was a significant decrease in MASI score for this group (p < 0.001) as compared to TCA alone [16]. Some studies have compared the efficacy of TCA to GAP with insignificant differences between the two agents.
Kumari compared the efficacy of 20–30 % GAP to 10–20 % TCA in 40 Indian women with melasma. Gradually increasing peel concentrations were applied once every 15 days for a total of six treatments for both groups. There was a significant reduction in MASI scores from baseline but no difference between the two groups. Moderate to severe burning and post-peel cracking was reported in the TCA group but not in the GAP group [17]. Similar findings were reported by Puri who compared a 15 % TCA peel versus a 35 % glycolic acid peel for the treatment of melasma in 30 Indian patients. After six sessions spaced 3 weeks apart, the decrease in MASI score from baseline in both the groups was found to be statistically significant (p = 0.269). However, there was no difference between the two regimens in terms of efficacy. The adverse effects of burning, erythema, and hyperpigmentation were more common in the TCA group rather than in the GAP group [18].
For the author, the burning discomfort and the downtime associated with the TCA peel are the major drawbacks to this modality. The deeper penetration and injury to the skin means that there is more visible peeling and a higher risk for PIH.
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