Several systemic drugs are available for the treatment of moderate-to-severe plaque psoriasis, including photochemotherapy, retinoids, cyclosporin, methotrexate, and fumarates. Although these options have been shown to maintain efficacy, frequently they produce significant subjective side effects. Recently, there has been a significant advance in developing newer medications that may be used for psoriasis. The progress in laboratory techniques has improved our understanding of the immuno-pathogenesis of psoriasis to a point where a number of key cytokines and immune cells - notably tumor necrosis factor-alpha (TNF-α) and T-cells respectively have been identified as critical factors contributing to the immuno-pathogenesis of the disease. Many of these medications are termed