Imiquimod

Abstract

Imiquimod is the first of the immune response modifiers to stimulate a localized immune response to treat infectious skin conditions. The reported TLR-7 activation to provoke an immune response suggests that imiquimod might mimic a microbial antigen. The immune response initiated by induced production of IFN-alpha and TFN-alpha is specifically aimed at an infectious antigen and appears mediated (in part) by enhanced migration of Langerhans' cells to regional lymph nodes. The approved indication for imiquimod is for treatment of genital warts. The drug has demonstrated a 50% to 60% clearance rate and a 12% to 20% recurrence rate for this indication (Table 1). This recurrence rate is the lowest reported among the currently recommended treatment modalities. The self-applied treatment avoids costly and painful office-based procedures. Case reports and open-label studies have demonstrated the efficacy of imiquimod in treating some cases of common, plantar, and flat warts, as well as molluscum contagiosum and leishmaniasis. Common and plantar warts respond better to imiquimod in combination with cryosurgery, occlusion, and keratolytics. Reports of successful imiquimod treatment of granuloma annulare, alopecia areata, and vitiligo might suggest an infectious etiology to those conditions, although this hypothesis is highly speculative.