A place for deep peels in acne scar treatment

Phenol-croton oil deep peels have been used for decades and the effects are longer lasting than many other resurfacing procedures, so the technique still has an important place among modern techniques.

Twenty years ago the Baker-Gordon phenol-croton oil peel (2.1% croton oil) was the gold standard for deep facial resurfacing, but it has largely been replaced by lower concentration peels, says Kachiu Lee, M.D., assistant professor of dermatology, Brown University, Providence, RI in a review in the Journal of the American Academy of Dermatology. 1

“The improved safety profile of deep peels has ushered in a new era in chemical peeling,” Dr. Lee says.

Croton oil is the active ingredient in phenol-croton peels. Its medicinal applications date back as far as the 1800s, and the first phenol and croton oil formula was patented in 1959.

Baker’s first published a formula containing 1.2% croton oil in 47.5% phenol in 1961, and a year later, he reduced the volume of the formula increasing the croton oil concentration to 2.1%, which was associated with increased risks of scarring and persistent hypopigmentation.

This “Baker-Gordon” formula was widely adopted with a standard emulsifying agent, Septisol, with 0.25% triclosan as the antibacterial agent, and sorbitol as the humectant.

Phenol was presumed to be the active agent until 1996, when it was shown that wounding depth was determined by the croton oil concentration, and Hetter’s formula (≤1.6% croton oil) then became the standard.

Deep phonol-croton peels produce mid-reticular dermal injury with marked collagen formation and organization of elastic fibers, and these changes persist for over a decade. They are usually used for the treatment of severe acne scars, severe rhytides, and moderate photodamage on the face and neck, but also sometimes for the treatment of xanthelasma, actinic keratosis, actinic cheilitis, and augmentation and eversion of the lips.

One randomized comparative trial showed classic Baker’s peel was superior to pulsed CO2 laser in the treatment of upper lip wrinkles.2

Unfortunately, most split-face studies fail to randomise properly, which is a problem as most drivers have more intense sun damage on one side. One study comparing Baker-Gordon’s formula against medium Hetter’s formula concluded outcomes were similar, but Baker-Gordon’s formula, was associated with greater adverse events, such as post-inflammatory hyperpigmentation (PIH).3 Another comparing unoccluded Baker-Gordon’s formula with passes of CO2 laser reported more hypopigmentation, but greater uniformity and effacement of wrinkles with the laser treatment.4

“Randomized comparative trials are needed to better define the clinical and the histologic outcomes of deep peels relative to other approaches to resurfacing currently in use, such as fractional ablative and non-ablative lasers, fractional ablative radiofrequency, and microneedling,” Dr. Lee says.

Patients offered deep peels must have realistic expectations, be fully aware that the healing period is long, and be willing to adhere to pre- and post-procedure regimens, she adds.

Before application of the peel, it is vital to wash the skin thoroughly with soap and water followed by acetone, because lipids, make-up, and other particles prevent penetration of the phenol-croton oil ingredients. Fibrotic, oily skin, such as phymatous rosacea skin, may retard the chemical action of the peel, and should be pretreated with topical retinoids and/or alpha-hydroxy acids for at least one month. Patients with thick, oily facial skin may benefit from a course of isotretinoin, which should be discontinued at least one month before the peel.

Patients with Fitzpatrick type IV-VI skin are rarely candidates for deep peels, and a history of malnutrition or poor facial wound healing are contraindications. It is recommended that smokers should quit at least a year before the procedure because smoking impairs healing.

The effect of the peel is increased with more strokes, volume, pressure, and concentration of croton oil. For severe scars and deep wrinkles or rhytides, the solution can be rubbed aggressively or etched into the area to increase penetration. A solid white frost is observed immediately after application, and then a fine gray cast over the skin after additional peel layers are applied. Mild purpura is observed where increased pressure has been used over scars.

The treated area must be protected by tape or ointment occlusion. Petrolatum jelly can be applied every two to six hours to protect against irritants, prevents fissures, and facilitates eating and mouth hygiene; or waterproof zinc oxide tape strips are applied, parallel to the anterior hairline, to the entire face except the eyes and mouth for 24 to 48 hours, followed by bismuth subgallate powder. Antiviral, antibacterial, and yeast prophylaxis, including against herpes should be given.

“Cardiac safety is a concern for procedures involving more than one cosmetic unit,” Dr. Lee adds. A cosmetic unit is equivalent to a palm without fingers or >0.5% of the body-surface area (BSA).

“Air circulation and safety pauses of 10 to15 minutes between each cosmetic unit of the face (forehead, perioral, periocular, nose, and each cheek) are recommended to allow phenol to be excreted regardless of the number of cosmetic units peeled,” she says.

A full-face peel takes at least 60-90 minutes with adequate pauses. IV hydration, continuous ECG monitoring, and ventilation/exhaustion of room air are recommended for peels exceeding 1% BSA, Dr. Lee says.

Around 7% of patients will experience transient cardiac arrhythmias, which usually resolved within 15 minutes of completion of the procedure. Patients taking medications known to prolong the transient rate-corrected QT interval (QTc), such as antihypertensives and antidepressants, are at particular risk.

Atrial extrasystolic beats and premature ventricular beats are an early warning sign, Lee says.

“If these occur, longer pauses are taken, treatment area is reduced before each pause, air circulation is rechecked, and intravenous fluid delivery is increased.”

Short acting beta-blockers, such as esmolol or propranolol, can be given prophylactically to reduce risk of arrhythmia in patients without contraindications, such as chronic obstructive pulmonary disease, asthma, severe bradycardia, and advanced atrioventricular blocks, she adds, and arrhythmic events may also be controlled with an intravenous bolus of up to 5mL of 2% lidocaine (1-1.5mg/kg).

Eye irritation is also possible, so the eyes should remain shut and the patient’s tears dried throughout the procedure.

Prolonged erythema is expected; it starts during the first post-operative week and peaks during the second week post-operatively.

“Erythema is a normal part of the healing process and is a surrogate sign of reticular dermal collagen formation,” Dr. Lee explains. “The depth of peel and long-term effectiveness are directly proportional to the degree and duration of the erythema.”