Use within 60 days prior to the baseline Visit of: 1) immunosuppressive drugs (e.g., tacrolimus, pimecrolimus), or 2) systemic antipsoriatic treatment (e.g., methotrexate, cyclosporine, hydroxyurea) Use within 30 days prior to the Baseline Visit of: 1) topical antipsoriatic drugs (salicylic acid, anthralin, coal tar, calcipotriene), 2) PUVA therapy, 3) systemic anti-inflammatory agents (e.g., mycophenolate mofetil, sulfasalazine, 6-thioguanine), or 4) UVB therapy.