The integral role of topical and oral retinoids in the early treatment of acne.
This article will review the rationale for early use of topical retinoids alone or in combination with topical antimicrobials in light of the pathogenesis of microcomedones and later lesions. Knowledge of the pathogenic processes in acne vulgaris has risen dramatically over the last three decades. It is now widely accepted that acne is the result of four distinct processes: increased proliferation, cornification, and shedding of follicular epithelium; increased sebum production; colonization of the follicle with Propionibacterium acnes; and induction of inflammatory responses by bacterial antigens and cell signals. Clinical focus of disease management has shifted toward earlier treatment targeting these fundamental processes. Elimination of microcomedones, the precursor to all subsequent lesions, would optimize acne therapy by preventing the later inflammatory stages of disease. With the exception of oral isotretinoin, no single first-line agent addresses all pathogenic mechanisms. Topical retinoids have comedolytic and in some cases anti-inflammatory effects, but have no direct impact on P. acnes. Thus treatment with a combination of topical retinoid and topical antimicrobial is warranted. The former can also enhance penetration of the latter by increasing microcomedonal extrusion. In selecting a combination, one must consider efficacy, cost, and likelihood of compliance. Once thought to be effective primarily for treating comedones, topical retinoids have also been demonstrated to be effective in reducing inflammatory lesions. The activity of a topical retinoid combined with an antimicrobial agent has been shown to clear more lesions and to clear them more rapidly than antimicrobial therapy alone. Topical retinoids are also used effectively to maintain remissions.