Roflumilast is a phosphodiesterase-4 (PDE-4) inhibitor, which is approved in its oral form for chronic obstructive pulmonary disease, and in its topical form in the treatment of plaque psoriasis. Methotrexate is one of the conventional systemic treatments of psoriasis, so the aim of this study is to compare the efficacy and safety of roflumilast and methotrexate in the treatment of psoriasis

Phosphodiesterase (PDE-4) activity was found to be greater in psoriatic skin than in healthy skin. Inhibition of PDE-4 inhibits the hydrolysis of cyclic AMP in inflammatory cells, which increases intracellular cAMP and results in down-regulation of immune modulators, including tumor necrosis factor (TNF)- α, interferon-γ, interleukin (IL)-17, and IL-23. Roflumilast is a potent and selective inhibitor of PDE-4 which is already approved in its oral form for chronic obstructive pulmonary disease. Regarding Roflumilast's topical form, it is currently also approved in the treatment of psoriasis. Lebwohl et al., 2020 found that roflumilast cream was efficacious in reducing the severity of psoriasis in a 12-week, randomized, double-blind, placebo vehicle-controlled trial.

Inclusion Criteria:

1. Patients with psoriasis vulgaris
2. Psoriatic patients not receiving any relevant systemic treatment for at least 4 weeks before initiation of our study
3. Psoriatic patients not receiving any relevant topical treatment for at least 2 weeks before initiation of our study

Exclusion Criteria:

1. Erythrodermic or pustular psoriasis
2. Pregnant and lactating females
3. Patients with autoimmune diseases e.g. systemic lupus erythematosus
4. Patients with solid or hematological malignancies e.g., breast cancer, leukemia, etc.