INTRODUCTION
Acne vulgaris affects people of all ethnicities and races
in the United States with little difference in pathophysiology.
1 One report in the United Kingdom showed that
acne vulgaris is the most common dermatologic diagnosis
among adult black patients.2 Another study from 1965 revealed
that nine percent of black patients had acne versus 18 percent
of white patients.3 Halder and his group reported that acne was
the most common diagnosis in both black and white patient
populations: 29.5 percent of white patients compared to 27.7
percent of black patients.4 The fact that patients with skin of color
may seek treatment at lower rates than white patients may
affect these results. Therefore, efforts to identify differences in
the frequency of acne in skin of color have failed to provide
conclusive evidence.5 While the pathophysiology of acne is invariable
across all skin types, there is some evidence to suggest
that black patients may have larger sebaceous glands6 and increased
sebum production compared to whites.5,7 Nonetheless,
the experience of acne among patients with darker skin (Fitzpatrick
skin types IV to VI) may differ because these individuals
are more susceptible to post-inflammatory hyperpigmentation
(PIH), a common and troubling antecedent of acne.1,5
Treatments for PIH are available, but their efficacy and suitability
are not optimal. For example, topical tretinoin, a first-line
treatment for mild-to-moderate acne has been shown to reduce
the appearance of post-inflammatory hyperpigmentation,
but it was also shown to lighten normal skin.8 Additionally,
topical retinoids are known to contribute to PIH by causing
irritation. Azelaic acid (AzA), a naturally occurring dicarboxylic
acid with anti-inflammatory, antimicrobial, antikeratinizing,
antioxidant and antityrosinase mechanisms of action9,10 may be
ideal for both the management of acne and treatment of PIH
associated with it. AzA's anti-inflammatory, antimicrobial and
antikeratinizing effects have been shown to be beneficial in the
topical treatment for acne.11 Thought to inhibit the synthesis
and release of melanin,10,12 AzA has direct anti-tyrosinase
activity that has demonstrated efficacy in the management
of PIH.13 An AzA cream 20% formulation has been approved
for acne vulgaris, while AzA gel 15% has been approved for
papulopustular rosacea. While AzA has been used clinically for
the management of acne and associated PIH, this study is the
first to assess the effects of AzA gel 15% on both acne and PIH
in patients with skin of color.
METHODS AND STUDY DESIGN
This single-center, open-label, IRB-approved pilot study was
conducted over 16 weeks. Adults (n=20) with mild-to-moderate
acne and moderate-to-severe PIH and Fitzpatrick skin type IV
