PDE4B and pulmonary fibrosis: Specifically, PDE4B inhibition with nerandomilast therapeutically reduced fibrosis in both bleomycin and silica models of pulmonary fibrosis in mice.98A phase II RCT of nerandomilast in IPF showed stabilization of FVC at 12 weeks either alone (−81.7 mL in the placebo group and +5.7 mL in the nerandomilast group) or in combination therapy with background anti-fibrotics (−59.2 mL in the placebo group and +2.7 mL in the nerandomilast group).113Diarrhea was the most common side effect.