Advances in the topical treatment of acne and rosacea

Journal of Drugs in Dermatology, Sept-Oct, 2004 by Roger I. Ceilley

Abstract

Acne and rosacea are common skin diseases which may present similarly and both involve inflammation. Both can result in significant cosmetic impairment and lead to quality of life decrements if not optimally treated. The conventional approach for both diseases involves the use of topical therapy to treat inflammatory lesions in combination, when needed, with a systemic or topical antibiotic. An important issue in the management of both diseases at present is the need to reduce antibiotic usage due to the increasing problem of bacterial resistance. One of the emerging treatment paradigms that is becoming increasingly useful as an antibiotic-sparing strategy is the use of procedural therapies in combination with medical management. Such procedural modalities include lasers, intense pulsed light (IPL), and photodynamic therapies (PDT). Topical regimens are used pre-treatment and following physical modalities for maintenance of remission.

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Introduction

Acne vulgaris and rosacea are two common skin diseases that may be challenging to diagnose and treat. Both can be cosmetically disfiguring to those afflicted with them and both can result in significant psychosocial impairment. Acne and rosacea are frequently discussed together, because their clinical presentation has a certain degree of overlap. Both are at least partly inflammatory disorders and both present with papules and pustules. Rosacea was once considered a form of acne. However, increasing understanding of the pathogenesis of acne and the new classification of subtypes of rosacea have permitted clinicians to diagnose these two skin diseases with more precision and to target therapies to specific aspects of their underlying pathophysiology. This is especially true in the case of acne, whose pathogenesis is well delineated, versus rosacea where less of its etiology and pathogenesis are known. Advances in the understanding of these diseases have led to much more effective therapies. Accordingly, the psychosocial and quality of life decrements that patients with these two diseases suffered in the past have been greatly reduced. An important new paradigm in the management of acne and rosacea is the use of appropriate combinations of topical, systemic and light or laser-based therapies to optimize clinical, but also cosmetic, results.

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Recently, the Global Alliance to Improve Outcomes in Acne published a set of consensus guidelines. The guidelines were evidence-based where possible and included input from numerous countries around the world. Their goal was to provide a comprehensive overview of acne therapy to "form the basis for more uniform therapeutic strategies throughout the world, enhanced patient compliance and more effective use of healthcare resources (1)."

Perhaps one of the most important advances in the management of acne has been the discovery of the role of vitamin A derivatives and other molecules that can interact with retinoid receptors. There are presently three topical agents--tretinoin, adapalene and tazarotene--that are active at retinoid receptors and can combat acne at its most proximal stage--the formation of the microcomedo.

In February 2002, a committee within the National Rosacea Society established a standard classification system for rosacea (2). The Committee delineated primary and secondary features of rosacea as well as subtypes that comprise clusters of primary and secondary features that tend to manifest together. The new system is intended to facilitate the diagnosis and treatment of rosacea as well as communication among researchers, healthcare providers, insurers, patients and the general public (2).

This paper will review relevant findings in the pathophysiology and topical treatment of acne and rosacea in the context of both the consensus recommendations of the Global Alliance to Improve Outcomes in Acne and the New Standard Classification of Rosacea.

Introduction to Acne

Acne is the most common of skin disorders. It affects 35%-85% of adolescents (3). A community-based study showed that 12% of women older than 25 had clinical acne and that this rate of prevalence did not decrease until after 44 years of age (4). Despite its wide prevalence, acne is a cause of great distress among many of its sufferers.

Acne Pathophysiology

A consensus of the Global Alliance to Improve Outcomes in Acne was that the increasing understanding of acne pathophysiology should guide its treatment. According to the guidelines, the primary pathophysiologic features in acne are: 1) excessive sebum production under androgenic stimulation, 2) abnormal desquamation of the follicular epithelium leading to the formation of the microcomedo and the creation of an environment conducive to bacterial growth, 3) proliferation of Propionibacterium acnes (P. acnes) and, 4) inflammation leading to the formation of papules and pustules (Table 1). The treatment of acne should target as many of these factors as possible.

Excessive sebum production: At pubarche, increasing levels of androgens, the major sebotrophic hormones, begin to drive an increase in sebum production. However, while androgenic stimulation is important in the pathogenesis of acne, the typical acne patient does not have significant endocrine abnormalities. Hormonal therapy is not indicated in the initial management of mild to moderate acne, although females who require oral contraception may be candidates for anti-androgen therapy early in the course of treatment.