Viral and nonviral uses of imiquimod: A review

Background: Imiquimod is a topical immunomodulator that is indicated for the treatment of external genital and perianal warts. This drug has been recently approved for the treatment of actinic keratoses and superficial basal cell carcinoma. There is a growing body of evidence for its effectiveness in treating a variety of other skin conditions. Objective: This review examines the role of imiquimod 5% cream in the treatment of skin diseases such as actinic keratoses, basal cell carcinoma, Bowen's disease, lentigo maligna, and extramammary Paget's disease. Methods: Published literature containing the words "Imiquimod" or "Aldara" was reviewed and summarized. Results: This agent has demonstrated indirect antiviral and antitumor effects in animal models. Although the exact mechanism of action is unknown, imiquimod is an agonist for toll-like receptor (TLR) 7 and is thought to act by inducing cytokines, such as interferon alpha (IFN-alpha), interleukin-12 (IL-12), and tumor necrosis factor alpha (TNF-alpha). These cytokines trigger the immune system to recognize the presence of a viral infection or tumor and the associated lesion is ultimately eradicated. Side effects are generally well tolerated with local skin reactions reported most frequently. Conclusion: Imiquimod has been shown to be a safe and effective treatment for a variety of skin conditions.