Introduction

To extol the virtues of modified phenol chemical face peeling is an exercise in the obvious. The main purpose of this chapter is to describe the author’s method of phenol face peeling. This method, based on objective clinical and experimental data, is easily incorporated into your practice of facial enhancement. It will show a brief evolution of phenol used by the author, which formulae were used, which were discarded and why, and which formulae are currently used and the reasons why.

Modified phenol as described in this chapter can be used for a variety of skin conditions. Hyperpigmentation in Hispanics will improve dramatically with a 15-second application of the Stone Venner-Kellson (Stone VK) formula. The author has no personal experience with hyperpigmentation in African Americans or Mestisos (Mexican Americans). Others have reported improvement with hyperpigmentation in these conditions. Mild rhytids and hyperpigmentation with early actinic and seborrheic keratoses will benefit significantly from a 1-minute application of the Stone VK formula. Moderate and severe rhytids and keratoses will improve 80 to 100% with 1 minute of Stone VK followed by 4 minutes of Stone II formula. With the control offered by modified phenol there is virtually no reason to continue with the laser juggernaut. Indeed, when Coherent introduced the CO₂ laser, soon to be followed by Sharplan, the author pursued this alternative to chemical peels. Now, countless others and many iterations of technological wizardry later, the mortal among us are confused and financially unable to keep up. Modified phenol has been a better substitute for facial rejuvenation because of safety, efficiency, efficacy and, lastly, economics.

The formulae described in this chapter have been standardized and are readily available from Delasco Laboratories (Council Bluffs, Iowa) at no financial gain to the author. The author has been a student of phenol since 1971 – first with industrial phenol burns, next with Baker-Gordon formula (1975–1991), and currently with modified phenol (1991 to date). The author is convinced that virtually any type of resurfacing need can be met with chemicals.

The Baker-Gordon formula, published in its revised form in 1962 (3 mL phenol, 2 mL H₂O, 8 drops of septisol, and 3 drops of croton oil yield 48.5% phenol and 2.2% croton oil) was used for deep rhytids. Healing time was said to be long, redness prolonged, hypopigmentation common, and scars not unusual.

The reported unfavorable and variable results from phenol can be attributed to the belief that the formula itself was of paramount importance. Little or no effort was given to skin preparation since it was thought that the ‘formula’ was inherently deep and that no additional exfoliation or pigment control (not widely utilized before 1991) was necessary. Little attention was given to the application technique since it was commonly held that phenol was ‘all-or-none’ and that technique of application was inconsequential. The importance of application technique was described by Stone in 1998 and 2001.

The story of modified phenol was elegantly told by Marmelzat and Hetter. Hetter is to be congratulated on his award-winning papers where he called attention to the importance of croton oil. Although Hetter states that application techniques are important, it is this author’s opinion that he leads his students to the conclusion that croton oil is the agent most responsible for the changes in peel depth on the five described facial zones. In this author’s opinion this may be so, but only if application technique is concurrently modified. Hetter states that ‘the end point is a subjective one based on the degree of whitening, which is based on experience’. Hetter’s results are exceptionally good. His formulae dilutions, use of cotton pads dipped in solution and wrung out, folded over thumb and brushed over face and neck in multiple coats – more in some areas than others – represent a change in technique from the standard Q-tip (cotton bud) application. These techniques were difficult for this author to translate to his practice. Hetter’s Obagi technique of application of phenol raised some questions for this author such as:

It was the author’s goal to simplify the process and make learning easier by standardizing the peel formulae and quantifying the application technique, thereby facilitating the procedure for any interested physician.

The distribution of peel patients used for this chapter are seen in Table 8.1. Factors affecting phenol peel depth are shown in Box 8.1. One hundred and fifty-nine full face phenol peels and nine human biopsy studies were used in this study. Results of these efforts were published in Clinics in Plastic Surgery.

Table 8.1 Distribution of peel patients in this study

Based on these studies and two new experiments reported below, the author concluded that: (1) rubbing increased the depth of injury (agree with Hetter); (2) the thickness of papillary dermis injury, the degree of fibrosis, and the degree of inflammation were less with 5 rubs and more with 50 rubs (Fig. 8.1); (3) phenol is not all-or-none (agree with Hetter); (4) croton oil increased depth of injury (agree with Hetter); (5) there was little observable difference between 0.4% croton oil and 2.2% croton oil when application techniques were kept constant (disagree with Hetter), and (6) human experimental models have inherent variables.

Figure 8.1 Test peel patches on day 4, left cheek, in Fitzpatrick skin type I treated with four formulae: (1) 48% phenol, 0% croton oil; (2) 35% phenol, 0.4% croton oil; (3) 35% phenol, 2.2% croton oil, and (4) 35% phenol, 0% croton oil. Each formula was tested with 50, 20 or 5 rubs with small semi-dry Q-tips (cotton buds). Results showed: (1) phenol is not ‘all-or-none’; (2) croton oil increases depth of injury; (3) in this study there was little observable difference between 0.4% and 2.2% croton oil; (4) rubbing increases depth of injury, and (5) human experimental models have inherent variables

Based on quantifiably reproducible experimental test peel patch studies on the right cheek and, later, left cheek test peel patches (reported below), using 48% phenol with 0.0% croton oil, 35% phenol with 0.4% croton oil, 35% phenol with 2.2% croton oil, and 35% phenol with 0.0% croton oil (see Fig. 8.1), a lowering of the threshold affect to create injury (Fig. 8.2) to between 5 and 20 rubs can be seen when croton oil is added. This is down from the 20 to 50 rubs required when croton oil is excluded. The early appearance of coagulation is not a true indicator of depth of peel, nor is the immediate density of frost as evidenced by the reported superficial results from 88% USP Phenol which can produce an immediate, dense, white frost. The length of time a given formula is applied, the concentration of phenol and croton oil, the volume of acid, the vigor and abrasiveness of the application and predegreasing procedure, and the occlusive technique all play a vital role in the final result.

Figure 8.2 Threshold effect: the depth of peel, as measured by papillary thickness injury, degree of fibrosis, and degree of inflammation, is more readily reached with fewer applications when croton oil is added. The same degree of injury is seen between 5 and 20 rubs with croton oil and 20 to 50 rubs without croton oil. There is little difference between 2.2% croton oil and 0.4% croton oil

In order to further test the hypothesis that length of application or number of rubs plays a paramount role in peel result, an African-American male, age 37, with a truncal congenital nevus of Becker was tested with one formula: the Stone II (60% phenol, 0.2% croton oil) (Fig. 8.3A–E). Twelve test patches, six in each of two rows, were rubbed with 1, 5, 10, 20, 50, and 100 coats using twice-blotted, semi-dried Q-tips. The top row was covered with tape for 48 hours followed by thymol iodide powder (Delasco Laboratories, Council Bluffs, IA) for 7 days. The bottom row was covered with Aquaphor ointment until healed. A clear threshold between 10 and 20 rubs was seen by day 10 and persisted through to day 73, the last day of the study.

Figure 8.3 African-American with truncal congenital Becker nevus treated with one formula (Stone II: 60% phenol, 0.2% croton oil) over twelve test patches, six in each of two rows. (A) Immediately after peel applications (from left to right) of 1, 5, 10, 20, 50, and 100 rubs; (B) top row covered with waterproof tape, bottom row covered with Aquaphor ointment; (C) at 48 hours; tape removed, thymol iodide powder applied. Threshold effect between 10 and 20 rubs seen at 10 days (D) and 73 days (E) post peel

This patient, with melanin as a biological marker, clearly demonstrated that when all factors are kept constant and time/quantity of application is controlled, a threshold is reached where melanin is either preserved or reduced. The return of melanin is least with 100 rubs and normal with one to five rubs. This correlated well with changing depth of peel.

Translating number of rubs to a timed approach relied on the appearance of the skin during the procedure (like Hetter). It was clear that Obagi, using TCA (trichloroacetic acid) and Hetter, using the Heresy formulae, relied on the appearance of frost density to reach a given end point. The use of the Stone VK and Stone II formulae employ the same principles, but in addition add a time component to the application process, thus standardizing and controlling the procedure.

Based on this objective data, it is the author’s conclusion that both the Hetter and Stone techniques can produce excellent results with modified phenol. The student is left with a clear choice. Using the Hetter technique the student will employ several dilutions over multiple facial and neck zones with an ointment occlusion, or will choose one formula with a timed application and a waterproof tape/ powder occlusion. It is a bit like comparing proven facelift techniques. Not one method is good for all students or all patients. See Box 8.2 for key features.

Treatment Approach

• Definition of zones

It is a well known fact that a thorough phenol peel should take a minimum of 1 hour to avoid too rapid absorption of phenol. Therefore, the face is divided into zones for the purpose of ensuring that the procedure takes a minimum of 90 minutes to complete (Fig. 8.4).

Zone I – forehead and upper lids.

Zone II – right cheek and lower lid.

Zone III – left cheek and lower lid.

Zone IV – nose, lips, chin.

Zone V – neck.

Figure 8.4 Peeling zones

Each zone is peeled, wiped lightly with a gauze pad to remove any oil and occluded with waterproof tape (when indicated) before proceeding to the next zone. In this way the proper time will elapse between zones to preclude phenol toxicity.