Darker skin types

Published on 26/02/2015 by admin

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Last modified 26/02/2015

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21 Darker skin types

Pearl E. Grimes, Andrew F. Alexis

Summary and Key Features

• Botulinum toxin is a safe and effective procedure in darker skin types

• In general, efficacy and safety profiles are similar to lighter skin types

• With appropriate use, side effects are uncommon

• Injection techniques are similar to lighter skin types

• Commonly treated areas are glabellar and horizontal forehead lines

Introduction

Demographic trends coupled with the increased availability of minimally invasive treatment options have led to an increasingly diverse patient population in the aesthetic arena. According to the American Society for Aesthetic Plastic Surgery, 19% of the 10 million cosmetic procedures performed in the United States (US) in 2010, were performed on racial / ethnic minorities (8% Hispanic, 6% African-American, 4% Asian descent, 1% other non-Caucasian race / ethnicity). This proportion is expected to increase over the next decade as non-white racial and ethnic groups form a rapidly growing segment of the US population. Similar trends are likely to be seen globally. As such, understanding racial or ethnic variations in safety, efficacy, and approaches to treatment is of increasing importance to the aesthetic physician.

Racial / ethnic differences in photoaging

Facial rhytides are a common concern across the racial and ethnic spectrum. However, variations in severity, age of onset, and cultural impact can be seen in different populations. In general, as the studies by Hexsel & Brunetto and Rossi & Alexis reported, individuals with richly pigmented skin (i.e. Fitzpatrick skin types IV–VI) demonstrate signs of photoaging, including rhytides, at a later age than do individuals with fair skin (Fitzpatrick skin types I–III). This is largely due to the photoprotective effect of increased epidermal melanin, which has been demonstrated in several studies. Most notably, the mean protective factor from ultraviolet (UV) B in black skin was found to be 13.4 versus 3.4 for white skin in a cadaveric skin study by Kaidbey and colleagues. Furthermore, in a more recent study by Yamaguchi and co-workers, UV-induced apoptosis was found to be greater in the epidermis of black skin compared with white skin, suggesting that photodamaged cells may be removed more efficiently in darker phototypes.

In a comparative study by Nouveau-Richard et al of Chinese and French women, the onset of facial wrinkles was found to be approximately 10 years later in Chinese versus French women. Other studies in African-Americans have reported similar findings of later onset of facial rhytides or fine lines; Grimes found a much lower percentage of women of color perceived having wrinkles than did their Caucasian counterparts. In general, signs of facial aging in darker skin occur 10–20 years later than in Caucasians, and is more often evident in the deeper muscular layers in the face.

Loss of volume in the mid-face and prominent tear troughs have also been reported to be more striking features of aging in African-Americans. Perioral rhytides are uncommon in darker skin types and therefore the upper face is the primary site of facial rhytides in patients with skin of color. Photoaging differences in Hispanics / Latinos are less well characterized, but vary considerably, given the broad range of Fitzpatrick skin types (I–VI) found in this population.

Safety and efficacy of botulinum toxins in darker skin types

The safety and efficacy of botulinum neurotoxin type A in the treatment of glabellar lines has been well studied in numerous populations (Table 21.1). Published data pertaining to the safety and efficacy of botulinum toxin in non-white patient populations are reviewed herein.

Table 21.1 Published studies of botulinum toxin in darker skin types

A multicenter, double-blind, placebo controlled study of onabotulinumtoxinA (onabot-A) (Botox Cosmetic^®, Allergan, Inc., Irvine, CA) by Carruthers and colleagues in 2002 investigated safety and efficacy in the treatment of glabellar lines in 409 patients. No appreciable differences were observed between various skin phototypes.

African-Americans

Grimes & Shabazz conducted a Phase IV study of onabot-A in the treatment of glabellar lines in 31 African-American women with Fitzpatrick skin types V and VI. The authors assessed the safety and efficacy at doses of 20 and 30 units (U) of onabot-A. No statistically significant differences in efficacy or safety were observed between the two doses (Figs 21.1, 21.2). A maximal response was observed on day 30, with 92.4% and 100% response rates (i.e. a score of ‘none’ or ‘mild’ on the facial wrinkle scale) in the 20 U and 30 U groups respectively. Adverse events were mild and transient and did not differ between the dosing groups. They included mild tingling, slight headaches, and dullness of the forehead.

Figure 21.1 Glabellar rhytides at maximum frown in patient injected with 30 U botulinum toxin type A at: (A) baseline, (B) day 30, (C) day 60, (D) day 90, (E) day 120.

Reproduced with permission from Grimes PE, Shabazz D A four-month randomized, double-blind evaluation of the efficacy of botulinum toxin type A for the treatment of glabellar lines in women with skin types V and VI. Dermatol Surg. Mar 2009; 35(3):429–436.

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