The role of topical vitamin D modulators in psoriasis therapy.

Psoriasis affects more than 5 million adults in the United States (U.S.), causing significant impairments in quality of life and incurring substantial costs in treatment. The disease is characterized by hyperproliferation and abnormal differentiation of epidermal keratinocytes resulting from a disordered immune response. Topical therapies, such as corticosteroids, are the most common treatment for psoriasis. However, long-term use of more potent topical corticosteroids is associated with potential risk for side effects. Topical vitamin D agents have been developed as a newer therapeutic option for use in place of, or in addition to, topical corticosteroids. These agents act to inhibit keratinocyte proliferation, normalize differentiation and modulate the activity of immune cells with minimal effect on serum calcium hemostasis. Calcipotriene is the most widely used member of this class, and is one of the most frequently prescribed topical agents for psoriasis. Although evidence suggests that it is approximately as effective as low-to-medium potency corticosteroids, it is associated with cutaneous irritation, especially when used in sensitive areas. Calcitriol ointment is a new option for topical therapy and is the only vitamin D3 ointment available for use in the U.S. and contains the naturally occurring active form of vitamin D3 that is associated with a relatively low rate of side effects.