Used primarily in the treatment of psoriatic arthritis and moderate to severe plaque psoriasis, (R)-Apremilast is a selective phosphodiesterase 4 (PDE4) inhibitor that works by modulating inflammatory pathways. It helps reduce swelling, joint pain, and skin lesions by inhibiting PDE4, which downregulates inflammatory cytokine production. It is also prescribed for oral ulcers associated with Behçet’s disease. The agent is valued for its oral bioavailability and targeted mechanism, offering an alternative to biologic therapies in chronic inflammatory conditions.