Clinical Pearls & Morning Reports
Acne is a primary inflammatory disorder involving the pilosebaceous unit. The pathogenesis is multifactorial, involving four key factors with interrelated mechanisms: increased sebum production, hyperkeratinization of the follicular infundibulum, inflammation, and Cutibacterium acnes (formerly Propionibacterium acnes). Read the latest NEJM Clinical Practice here.
Q: What is the role of retinoids in the treatment of acne?
A: A topical retinoid should be used as the foundation for most acne treatment regimens. Topical retinoids are comedolytic, normalize desquamation at the follicular infundibulum, and have antiinflammatory properties. In the United States, three topical retinoids are used in patients with acne: tretinoin, adapalene, and tazarotene. All the retinoids are mildly photosensitizing, but this situation can be managed easily with sunscreen use.
Q: What combinations of topical medications are typically used to treat acne?
A: In addition to topical retinoids, benzoyl peroxide is a key component of acne therapy. Benzoyl peroxide is highly effective at reducing C. acnes through the release of free oxygen radicals, without allowing microbial resistance. The combination of a topical retinoid and benzoyl peroxide has greater efficacy than either product alone. Topical antibiotics, primarily clindamycin and erythromycin, also reduce C. acnes. The combination of benzoyl peroxide with a topical antibiotic has been shown to decrease the concentration of antibiotic-resistant strains of C. acnes and has greater efficacy than either product alone. However, owing to the excellent bactericidal properties of benzoyl peroxide alone, the complementary comedolytic and antiinflammatory effects of topical retinoids, and efforts to reduce antibiotic use overall, the use of topical antibiotics in patients with acne is declining.
A: Oral antibiotics are widely used in patients with acne to gain control of the inflammation in moderate-to-severe acne. Given concerns regarding increasing antibiotic resistance, current acne treatment guidelines recommend limiting the use of oral antibiotics to 3 to 4 months whenever possible. Clinical improvement should be maintained with the continued use of a topical retinoid, with or without benzoyl peroxide, depending on lesion types. Typically, tetracyclines are prescribed for acne treatment because they decrease the concentration of C. acnes, but they also have anti-inflammatory effects. They decrease retinoic acid and enzyme degradation, are antiapoptotic and antioxidant, and regulate cell proliferation. In the United States, minocycline is the most commonly used antibiotic for acne, followed closely by doxycycline. Tetracycline is less often used, owing to inconsistent bioavailability and the need for it to be taken on an empty stomach.
A: Isotretinoin is a systemic retinoid that is highly effective for treating recalcitrant nodulocystic acne. It is also used in patients with moderate-to-severe acne who do not have a response to other therapy, including oral antibiotics. It is a potent teratogen, and various pregnancy-prevention programs are in place worldwide. Common cutaneous side effects of isotretinoin include dryness of skin and mucosa. Elevations in serum triglyceride, low-density lipoprotein cholesterol, and aminotransferase levels may occur, although they are usually mild. One serious concern is a possible link between isotretinoin use and depression and suicide. Although prospective studies have shown an overall improvement in depression scores (indicating lessening in depression) in patients with severe acne taking isotretinoin, these studies were not powered to detect an increase in the incidence of depression or suicidal ideation. Given that retinoids readily cross the blood–brain barrier and that depression is common in the adolescent population and in patients with severe acne, it is prudent to counsel and monitor patients taking isotretinoin for the risk of depression at each visit.