Acne is a disorder of the pilosebaceous follicles on the face, chest, and back. Follicular obstruction leads to comedones, and inflammation results in papules, pustules, and nodules. The four most important steps in acne pathogenesis are (1) sebum overproduction related to androgenic hormones and genetics, (2) abnormal desquamation of follicular epithelium (keratin plugging), (3) Propionibacterium acnes proliferation, and (4) follicular obstruction, which leads to inflammation and follicular disruption. These steps are stimulated by androgens, and strong genetic factors determine a person's likelihood of developing acne. Although common, acne can cause physical pain, psychosocial suffering, and scarring. Acne may be associated with fever, arthritis, and other systemic symptoms in acne fulminans (Fig. 33-13).
Topical treatments include retinoids, antibiotics, benzoyl peroxide (BP), azelaic acid, and alpha or beta hydroxyl acid products. Topical retinoids are comedolytic and antiinflammatory, normalize follicular hyperproliferation and hyper-keratinization, and reduce the numbers of microcomedones, comedones, and inflammatory lesions. The most frequently prescribed topical retinoids include tretinoin (Retin-A), adapalene (Differin), and tazarotene (Tazorac, Avage). Patients are frequently sensitive to topical retinoids and may have skin irritation, peeling, and redness. Mild cleansers and noncomedogenic moisturizers can reduce the inflammation, as does less frequent dosing of the retinoids. Glycolic acid (a-hydroxy acid) or salicylic acid (p-hydroxy acid) come in various products, are used in chemical peels, and are also effective for hyperkeratinization.
Topical antibiotics are effective against P. acnes and also act as anti-inflammatories. Erythromycin and clindamycin are frequently used once or twice daily. Topical dap-sone (Aczone) was approved in 2008 for acne treatment. Benzoyl peroxide is also effective against P. acnes and is available over the counter (OTC) in various preparations. Combination products with antibiotics and BP are a convenient method of delivering synergistic medications in one preparation.
Oral medications used in acne treatment include antibiotics, hormone therapies, and isotretinoin. Isotretinoin is a known teratogen and should not be used in women of childbearing age unless avoidance of pregnancy is ensured. Contraception counseling is mandatory, and two negative pregnancy test results are required before initiation of therapy. The baseline laboratory examination should also include determination of cholesterol, fasting triglycerides, transaminase levels, blood urea nitrogen (BUN)/creatinine, and complete blood count (CBC). Pregnancy tests and laboratory examinations should be repeated monthly during treatment.
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