Selection of topical therapy should be based on the severity and type of acne. Topical retinoids,benzoyl peroxide, and azelaic acid are effective treatments for mild acne. Topical antibiotics and medications with bacteriostatic and anti-inflammatory properties are effective for treating mild to moderate inflammator acne. Proper selection of topical formulations may decrease side effects and increase patient compliance. Fortunately, most acne medications are available in several forms. Creams and lotions typically are reserved for dry or sensitive skin, whereas gels are prescribed for oil-prone complexions. During treatment with prescribed medications, patients should use bland facial washes and moisturizers. Retinoids and Retinoid Analogs. Topical tretinoin is a comedolytic agent that normalizes desquamation of the epithelial lining, thereby preventing obstruction of the pilosebaceous outlet.8 This agent also appears to have direct anti-inflammatory effects. A derivative of vitamin A, tretinoin is available in cream, gel, and liquid forms. In tretinoin microsphere, tretinoin is encapsulated in a polymer that slowly releases
the active medication, resulting in less irritation than with other tretinoin preparations. With all retinoids, visible improvement occurs after eight to 12 weeks of treatment. Tretinoin is inactivated by ultraviolet (UV) light and oxidized by benzoyl peroxide. It therefore should be applied only at night and never with benzoyl peroxide. Tretinoin may decrease the amount of native UV protection by thinning the stratum corneum; thus, daily use of sunscreen is recommended. Because
the irritation caused by tretinoin is dosedependent, treatment should be initiated in a low dose. Patients only need a pea-sized amount of product per application. There is no strong evidence for the teratogenicity of tretinoin, which remains pregnancy category C. A study11 published in 1998 focused on the transdermal absorption of topical tretinoin and found the absorbed concentration to be below endogenous retinoid levels. However, no definitive consensus has been reached on the use of topical tretinoin in pregnancy. It may be wise to avoid use of topical retinoids or retinoid analogs in women who may become pregnant during treatment. Adapalene is a topical synthetic retinoid analog that normalizes differentiation of follicular epithelial cells and demonstrates direct anti-inflammatory properties.
double-blind studies have shown 0.1 percent adapalene gel to be as effective as 0.025 percent tretinoin gel. Adapalene is superior to 0.025 percent tretinoin gel in both tolerability and speed of efficacy,12 and is equivalent in efficacy to 0.1 percent tretinoin microsphere. Adapalene is a reasonable choice as a first-line topical retinoid; this agent may
be especially useful in patients who are unable to tolerate the irritation caused by tretinoin. Tazarotene (Tazorac) is available in 0.05 and 0.1 percent gel and cream formulations. It is a pregnancy category X agent. Tazarotene may be more irritating than other retinoids. Doserelated erythema and burning are the most common adverse effects. Studies have indicated that tazarotene gel is a more efficacious keratolytic than tretinoin 0.025 percent gel14 and tretinoin 0.1 percent microsphere gel.Because tazarotene may increase irritation, it usually is considered a second-line retinoid option in patients who have not responded to topical tretinoin or adapalene therapy.