Roflumilast selectively inhibits phosphodiesterase-4 (PDE4), leading to increased intracellular cyclic adenosine monophosphate (cAMP) in inflammatory cells. This elevation of cAMP suppresses the release of pro-inflammatory mediators such as cytokines and chemokines, resulting in reduced inflammation within the airways. The anti-inflammatory effect contributes to decreased frequency and severity of COPD exacerbations.